African Journal of Traditional, Complementary and Alternative Medicines, 2011
The present study determined the anti-inflammatory activity of Wissadula amplissima var rostrata ... more The present study determined the anti-inflammatory activity of Wissadula amplissima var rostrata (Schum. & Thonn.), and calculated the total phenolic content and total antioxidant capacity of the plant in an attempt to justify the traditional uses of the plant in the Ashanti region of Ghana for the management of spider,wasps and bee stings. Powdered dried leaves of Wissadula amplissima were Soxhlet extracted with Petroleum Ether (PWA, yield: 1.46% w / w); Chloroform (CWA, yield: 1.18% w / w) and Methanol (MWA, yield: 3.39% w / w). These fractions were tested for anti-inflammatory activity using carrageenan-induced foot edema in 7 day old chicks. The effect before the induction of inflammation (pre-emptive protocol) paradigm was used for the assessment. Oral administration of PWA, CWA and MWA (30-300 mg/kg) dose dependently reduced edema with maximal effects of 68.25±2.03%, 77.83±0.81% and 62.21±2.61% respectively. Similarly the NSAID, Diclofenac (10-100 mg/Kg, i.p) and the steroidal anti-inflammatory drug dexamethasone (0.3-3 mg/Kg, i.p) used as positive controls, dose-dependently inhibited the edema with maximal effect of 87.96±1.11% and 67.47±3.51% respectively. The potencies exhibited by all three extracts were comparable to that shown by Diclofenac but higher than that of Dexamethasone. Phenols were detected in all three extracts with the highest concentration in the MWA. The extracts also scavenged DPPH with EC 50 values of 0.9784, 0.9096 and 0.2767 for PWA, CWA, MWA respectively. The results of this study give scientific credence to the local use of Wissadula amplissima to modulate inflammation induced by stings of animals.
Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stre... more Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stress environment were studied. Climate change and low precipitation represents the main constraints in sunflower production in Pakistan. In present investigation two sunflower genotypes, viz S.28111 and SF0049 were selected to study their photosynthetic performance through non-destructive technique in field. Three treatments were applied to impose drought in plants i.e. irrigation after 6 days (D1), irrigation after 8 days (D2) and irrigation after 16 days (D3) with control irrigation after 4 days. Results revealed that drought stresses altered the electron transport rate through PSII (Fm/Fo), photochemical quenching (qP), efficiency of photosystem II (ΦPSII), linear electron transport rate (rETR), non-photochemical quenching (NPQ), size and number of active reaction centre of photosynthetic apparatus (Fv/Fo), driving forces (DFABS and DFCS) and performance indexes (PIABS and PICS) parameters that depends on the efficiency and yield of energy transfer and primary photochemistry. However, S.28111 maintained substantial quantum yield and enhanced photosynthetic performance under drought stress environment compared to SF0049. It is suggested that the assessment of photochemistry of PSII offers a practical and sensitive field screening regarding test for drought stress tolerance in sunflower. Results are discussed in relation to photosynthetic performance and florescence responses of sunflower genotypes in the drought stress environment.
A comparison to test the consistencies and discrepancies of two most commonly used screening tech... more A comparison to test the consistencies and discrepancies of two most commonly used screening techniques (soil and hydroponic) for salt tolerance in crop plants were examined. In this regard, physiological responses of four sunflower genotypes i.e. Hysun-33, Hysun-39 (known moderately salt tolerant) S.28111 and SF0049 (unreported genotypes) growing in soil filled pots and hydroponics were observed. This study was carried out under greenhouse condition in complete randomize design. plants were treated with 75, 125 and 175 mM NaCl concentrations. Stress was applied to the plants in aliquot levels 30 DAS and plants were harvested 44 DAS for further analysis. Some photosynthetic traits; chlorophyll fluorescence, chlorophyll contents, stomatal conductance and relative water content were analysed. Plants grown in a pot experiment had higher PIabs, stomatal conductance, photosynthetic pigments and hence higher plant fresh weight as compared to hydroponic plants. Despite differences in techn...
Abiotic stress like drought and salinity is the major environmental constraints that limit agricu... more Abiotic stress like drought and salinity is the major environmental constraints that limit agricultural production. Physiological mechanisms explaining plant tolerance offer valuable insights for the development of genetically modified crops. Plant water status and alteration in photosynthetic capacity are some common physiological depictions which are induced by abiotic stress like drought and salinity. Chiefly it is because both stresses caused cellular dehydration in the plants, predominantly, during the initial phase of stress imposition. In water stress CO2 availability is greatly reduced due to stomatal limitation; subsequently leaf temperature is elevated. So that studies on plant water status and stomatal regulation are important aspects in abiotic stress environment stabilizing the temperature inside plant/leaf. Therefore phenotyping using infrared thermography (heat sensitive sensor) could be a useful tool in the selection of tolerant genotypes. Generally infrared thermogr...
Comparative physiological assessment of some edible oilseed crops under drought stress environmen... more Comparative physiological assessment of some edible oilseed crops under drought stress environments were performed. In this regard, fluorescence and IR thermal imaging techniques were used. Seeds of each sunflower SF0049, SF0054 and soybean NARC-II, William-82 cultivars were germinated. Followed by uniform seedlings of each cultivar were transplanted in rectangular pots of an area 480cm. Three weeks old plants were subjected to drought stress for the next five days. Chlorophyll ‘a’ fluorescence, IR images, relative water content (RWC) and stomatal conductance (gs) were recorded. In drought stress, NARC II and William-82 showed 26-31% reduction in RWC as compared to 18-20% reduction in SF0049 and SF0054. Similarly, 6787% reduction in stomatal conductance was observed in soybean and 59-72% were recorded in sunflower cultivars. Further soybean cultivars displayed 44.4% to 85.7% decrease in performance index (PI) and darkadapted quantum yield (Fv/Fm) as compared to 40% to 87% in sunflow...
Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-... more Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-39, and SF0049, to salt, drought, and combined stresses were studied. The combined stress caused severe damage to photosynthetic apparatus as compared to single stress. The maximum quantum yield of PSII, phenomenological fluxes, plastoquinone pool size, performance indexes, and driving force of absorption were greatly affected by the combined stress. Among the cultivars, the combined stress produced synergistic effect (greater damage) in Hysun-33 and cross-tolerance (lesser damage) in S.28111. Similarly, concerning the ion imbalance, S.28111 and SF0049 showed lower Na + and Cl -concentrations with lesser electrolyte leakage as compared to Hysun-33 and Hysun-39 under salt and combined stress. Results revealed that the disturbance in photosynthetic performance could be easily determined using JIP test by measuring chlorophyll a fluorescence. This information can be useful for the screening of oil-seed crop plants having better photosynthetic performance under salinized and desertified conditions.
Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the... more Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the Capsicum annuum methionine sulfoxide reductase B2 (CaMsrB2) gene were selected for stress tolerance phenotyping under drought stress conditions. The two transgenic lines were selected on the basis of laboratory experiments and for performing well against drought. Field assessment of CaMsrB2 transgenic lines L-23 and L-8 in a drought stress environment was conducted. For the assessments, small plots were prepared at the Department of Botany of the University of Karachi to test the physiological response of transgenic lines. Relative water content, quantum yield (Fv/Fm ratio), photochemical quenching (qP) photosynthetic pigments, and performance index were high in transgenic lines compared to the wild type (WT). Antioxidant enzymes as represented by catalase and superoxide dismutase activities were increased while H 2 O 2 production was decreased in transgenic lines compared to the WT. The results are discussed with special reference to physiological response of the transgenic lines against drought in field conditions.
The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39) u... more The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39) under salt, drought stress separately and in combination was examined. Salt, drought and a combination of these stresses were applied to plants by gradual increments. The plants were exposed to stress for two weeks. Relative water content, osmotic potential, stomatal conductance, performance index, dark adapted quantum yield and chlorophyll contents were reduced upon salinity and drought stresses. However, when plants were subjected to a combination of these stresses, a greater reduction in all tested attributes was observed. Proline and carotenoid contents in drought stress were elevated compared to salt stress. Superoxide dismutase (SOD) and catalase (CAT) showed the highest activity in individual salt and drought stress with less accumulation of H2O2. Combined stress reduced the activity of antioxidant enzymes which ultimately decreased the physiological performance of sunflower plants...
Comparative physiological assessment of some edible oilseed crops under drought stress environmen... more Comparative physiological assessment of some edible oilseed crops under drought stress environments were performed. In this regard, fluorescence and IR thermal imaging techniques were used. Seeds of each sunflower SF0049, SF0054 and soybean NARC-II, William-82 cultivars were germinated. Followed by uniform seedlings of each cultivar were transplanted in rectangular pots of an area 480cm 2. Three weeks old plants were subjected to drought stress for the next five days. Chlorophyll 'a' fluorescence, IR images, relative water content (RWC) and stomatal conductance (gs) were recorded. In drought stress, NARC II and William-82 showed 26-31% reduction in RWC as compared to 18-20% reduction in SF0049 and SF0054. Similarly, 67-87% reduction in stomatal conductance was observed in soybean and 59-72% were recorded in sunflower cultivars. Further soybean cultivars displayed 44.4% to 85.7% decrease in performance index (PI) and dark-adapted quantum yield (Fv/Fm) as compared to 40% to 87% in sunflower cultivars. Maximum yield of photochemistry of PSII and chlorophyll content index were also reduced up to 28-68% in all tested cultivars under drought stress. Non-photochemical quenching, heat dissipation, and leaf temperature were increased over control under drought stress showing maximum in soybean as compared to sunflower. The importance of comparative physiological assessment using fluorescence and IR thermal imaging techniques are discussed.
Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stre... more Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stress environment were studied. Climate change and low precipitation represents the main constraints in sunflower production in Pakistan. In present investigation two sunflower genotypes, viz S.28111 and SF0049 were selected to study their photosynthetic performance through non-destructive technique in field. Three treatments were applied to impose drought in plants i.e. irrigation after 6 days (D1), irrigation after 8 days (D2) and irrigation after 16 days (D3) with control irrigation after 4 days. Results revealed that drought stresses altered the electron transport rate through PSII (Fm/Fo), photochemical quenching (qP), efficiency of photosystem II (ΦPSII), linear electron transport rate (rETR), non-photochemical quenching (NPQ), size and number of active reaction centre of photosynthetic apparatus (Fv/Fo), driving forces (DFABS and DFCS) and performance indexes (PIABS and PICS) parameters that depends on the efficiency and yield of energy transfer and primary photochemistry. However, S.28111 maintained substantial quantum yield and enhanced photosynthetic performance under drought stress environment compared to SF0049. It is suggested that the assessment of photochemistry of PSII offers a practical and sensitive field screening regarding test for drought stress tolerance in sunflower. Results are discussed in relation to photosynthetic performance and florescence responses of sunflower genotypes in the drought stress environment.
Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-... more Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-39, and SF0049, to salt, drought, and combined stresses were studied. The combined stress caused severe damage to photosynthetic apparatus as compared to single stress. The maximum quantum yield of PSII, phenomenological fluxes, plastoquinone pool size, performance indexes, and driving force of absorption were greatly affected by the combined stress. Among the cultivars, the combined stress produced synergistic effect (greater damage) in Hysun-33 and cross-tolerance (lesser damage) in S.28111. Similarly, concerning the ion imbalance, S.28111 and SF0049 showed lower Na + and Cl-concentrations with lesser electrolyte leakage as compared to Hysun-33 and Hysun-39 under salt and combined stress. Results revealed that the disturbance in photosynthetic performance could be easily determined using JIP test by measuring chlorophyll a fluorescence. This information can be useful for the screening of oilseed crop plants having better photosynthetic performance under salinized and desertified conditions. Additional key words: electron transport rate; malondialdehyde; nonphotochemical quenching; OJIP transient. Abbreviations: ABS/RC-apparent antenna size of active PSII RC; Area-area over the fluorescence curve between F0 and Fm; DFABS-driving force on absorption basis; DI0/RC-effective dissipation of energy in active RC; ET0/RC-electron transport per active reaction center; F0-minimum fluorescence; F0/Fv-efficiency of water-splitting complex; F0/Fm-quantum yield baseline; Fm-maximum fluorescence; Fm/F0-electron transport rate through PSII; Fv/F0-size and number of active reaction centers of photosynthetic apparatus; Fv/Fm-maximum quantum yield of PSII; J-linear electron transport rate; MDA-malondialdehyde; NPQ-nonphotochemical quenching; PIABS-performance index on absorption basis; PICS-performance index on cross-section basis; PItot-total performance index; qN-nonphotochemical quenching coefficient; qP-photochemical quenching; RC/ABS-density of reaction centers on chlorophyll basis; RC/CSm-amount of active reaction centers per excited cross section; TR0/DI0-ratio of trapping and dissipation fluxes; TR0/RC-maximal trapping rate of absorbed photons in RC; δR0 or RE0/ET0-probability that an electron is transported from reduced PQ to electron acceptor side of PSI; ΔVIP-amplitude of the relative variable fluorescence of the I-toP rise ; ΦPSII-efficiency of PSII or quantum yield of PSII; ϕR0-quantum yield for reduction of the end electron acceptors at the PSI acceptor side (RE); ψ0-yield of electron transport per trapped excitation or probability with which a PSII trapped electron is transferred from reduced QA to QB.
– The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39)... more – The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39) under salt, drought stress separately and in combination was examined. Salt, drought and a combination of these stresses were applied to plants by gradual increments. The plants were exposed to stress for two weeks. Relative water content, osmotic potential, stomatal conductance, performance index, dark adapted quantum yield and chlorophyll contents were reduced upon salinity and drought stresses. However, when plants were subjected to a combination of these stresses, a greater reduction in all tested attributes was observed. Proline and carotenoid contents in drought stress were elevated compared to salt stress. Superoxide dismutase (SOD) and catalase (CAT) showed the highest activity in individual salt and drought stress with less accumulation of H 2 O 2. Combined stress reduced the activity of antioxidant enzymes which ultimately decreased the physiological performance of sunflower plants. However, among the tested genotypes, S.28111 and SF0049 were found to be more tolerant to drought, salt and combined stress than both Hysun genotypes. The physiological performance of genotypes against salinity and drought individually and in combination is discussed in detail.
A comparison to test the consistencies and discrepancies of two most commonly used screening tech... more A comparison to test the consistencies and discrepancies of two most commonly used screening techniques (soil and hydroponic) for salt tolerance in crop plants were examined. In this regard, physiological responses of four sunflower genotypes i.e. Hysun-33, Hysun-39 (known moderately salt tolerant) S.28111 and SF0049 (unreported genotypes) growing in soil filled pots and hydroponics were observed. This study was carried out under greenhouse condition in complete randomize design. plants were treated with 75, 125 and 175 mM NaCl concentrations. Stress was applied to the plants in aliquot levels 30 DAS and plants were harvested 44 DAS for further analysis. Some photosynthetic traits; chlorophyll fluorescence, chlorophyll contents, stomatal conductance and relative water content were analysed. Plants grown in a pot experiment had higher PIabs, stomatal conductance, photosynthetic pigments and hence higher plant fresh weight as compared to hydroponic plants. Despite differences in techniques, results revealed that both systems have shown almost similar trends in physiological traits of tested genotypes under saline environment. A significant correlation in performance index (PIabs), RWC, stomatal conductance, proline contents and total carotenoids was found. Physiological assessment and their reliability of salt tolerance in crop plants using both experimental systems were discussed.
Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the... more Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the Capsicum annuum methionine sulfoxide reductase B2 (CaMsrB2) gene were selected for stress tolerance phenotyping under drought stress conditions. The two transgenic lines were selected on the basis of laboratory experiments and for performing well against drought. Field assessment of CaMsrB2 transgenic lines L-23 and L-8 in a drought stress environment was conducted. For the assessments, small plots were prepared at the Department of Botany of the University of Karachi to test the physiological response of transgenic lines. Relative water content, quantum yield (Fv/Fm ratio), photochemical quenching (qP) photosynthetic pigments, and performance index were high in transgenic lines compared to the wild type (WT). Antioxidant enzymes as represented by catalase and superoxide dismutase activities were increased while H2O2 production was decreased in transgenic lines compared to the WT. The results are discussed with special reference to physiological response of the transgenic lines against drought in field conditions.
Abiotic stress like drought and salinity is the major environmental constraints that limit agricu... more Abiotic stress like drought and salinity is the major environmental constraints that limit agricultural production. Physiological mechanisms explaining plant tolerance offer valuable insights for the development of genetically modified crops. Plant water status and alteration in photosynthetic capacity are some common physiological depictions which are induced by abiotic stress like drought and salinity. Chiefly it is because both stresses caused cellular dehydration in the plants, predominantly, during the initial phase of stress imposition. In water stress CO2 availability is greatly reduced due to stomatal limitation; subsequently leaf temperature is elevated. So that studies on plant water status and stomatal regulation are important aspects in abiotic stress environment stabilizing the temperature inside plant/leaf. Therefore phenotyping using infrared thermography (heat sensitive sensor) could be a useful tool in the selection of tolerant genotypes. Generally infrared thermography is sensitive, less time-consuming, and nondestructive methodology which detects heat produced or generated by leaf under the influence of external factors. In general, temperature display pattern on IR images is inversely proportional to leaf water status. It was observed that infrared images are significantly correlated with some of the physiological traits indicating tolerance grading among genotypes.
African Journal of Traditional, Complementary and Alternative Medicines, 2011
The present study determined the anti-inflammatory activity of Wissadula amplissima var rostrata ... more The present study determined the anti-inflammatory activity of Wissadula amplissima var rostrata (Schum. & Thonn.), and calculated the total phenolic content and total antioxidant capacity of the plant in an attempt to justify the traditional uses of the plant in the Ashanti region of Ghana for the management of spider,wasps and bee stings. Powdered dried leaves of Wissadula amplissima were Soxhlet extracted with Petroleum Ether (PWA, yield: 1.46% w / w); Chloroform (CWA, yield: 1.18% w / w) and Methanol (MWA, yield: 3.39% w / w). These fractions were tested for anti-inflammatory activity using carrageenan-induced foot edema in 7 day old chicks. The effect before the induction of inflammation (pre-emptive protocol) paradigm was used for the assessment. Oral administration of PWA, CWA and MWA (30-300 mg/kg) dose dependently reduced edema with maximal effects of 68.25±2.03%, 77.83±0.81% and 62.21±2.61% respectively. Similarly the NSAID, Diclofenac (10-100 mg/Kg, i.p) and the steroidal anti-inflammatory drug dexamethasone (0.3-3 mg/Kg, i.p) used as positive controls, dose-dependently inhibited the edema with maximal effect of 87.96±1.11% and 67.47±3.51% respectively. The potencies exhibited by all three extracts were comparable to that shown by Diclofenac but higher than that of Dexamethasone. Phenols were detected in all three extracts with the highest concentration in the MWA. The extracts also scavenged DPPH with EC 50 values of 0.9784, 0.9096 and 0.2767 for PWA, CWA, MWA respectively. The results of this study give scientific credence to the local use of Wissadula amplissima to modulate inflammation induced by stings of animals.
Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stre... more Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stress environment were studied. Climate change and low precipitation represents the main constraints in sunflower production in Pakistan. In present investigation two sunflower genotypes, viz S.28111 and SF0049 were selected to study their photosynthetic performance through non-destructive technique in field. Three treatments were applied to impose drought in plants i.e. irrigation after 6 days (D1), irrigation after 8 days (D2) and irrigation after 16 days (D3) with control irrigation after 4 days. Results revealed that drought stresses altered the electron transport rate through PSII (Fm/Fo), photochemical quenching (qP), efficiency of photosystem II (ΦPSII), linear electron transport rate (rETR), non-photochemical quenching (NPQ), size and number of active reaction centre of photosynthetic apparatus (Fv/Fo), driving forces (DFABS and DFCS) and performance indexes (PIABS and PICS) parameters that depends on the efficiency and yield of energy transfer and primary photochemistry. However, S.28111 maintained substantial quantum yield and enhanced photosynthetic performance under drought stress environment compared to SF0049. It is suggested that the assessment of photochemistry of PSII offers a practical and sensitive field screening regarding test for drought stress tolerance in sunflower. Results are discussed in relation to photosynthetic performance and florescence responses of sunflower genotypes in the drought stress environment.
A comparison to test the consistencies and discrepancies of two most commonly used screening tech... more A comparison to test the consistencies and discrepancies of two most commonly used screening techniques (soil and hydroponic) for salt tolerance in crop plants were examined. In this regard, physiological responses of four sunflower genotypes i.e. Hysun-33, Hysun-39 (known moderately salt tolerant) S.28111 and SF0049 (unreported genotypes) growing in soil filled pots and hydroponics were observed. This study was carried out under greenhouse condition in complete randomize design. plants were treated with 75, 125 and 175 mM NaCl concentrations. Stress was applied to the plants in aliquot levels 30 DAS and plants were harvested 44 DAS for further analysis. Some photosynthetic traits; chlorophyll fluorescence, chlorophyll contents, stomatal conductance and relative water content were analysed. Plants grown in a pot experiment had higher PIabs, stomatal conductance, photosynthetic pigments and hence higher plant fresh weight as compared to hydroponic plants. Despite differences in techn...
Abiotic stress like drought and salinity is the major environmental constraints that limit agricu... more Abiotic stress like drought and salinity is the major environmental constraints that limit agricultural production. Physiological mechanisms explaining plant tolerance offer valuable insights for the development of genetically modified crops. Plant water status and alteration in photosynthetic capacity are some common physiological depictions which are induced by abiotic stress like drought and salinity. Chiefly it is because both stresses caused cellular dehydration in the plants, predominantly, during the initial phase of stress imposition. In water stress CO2 availability is greatly reduced due to stomatal limitation; subsequently leaf temperature is elevated. So that studies on plant water status and stomatal regulation are important aspects in abiotic stress environment stabilizing the temperature inside plant/leaf. Therefore phenotyping using infrared thermography (heat sensitive sensor) could be a useful tool in the selection of tolerant genotypes. Generally infrared thermogr...
Comparative physiological assessment of some edible oilseed crops under drought stress environmen... more Comparative physiological assessment of some edible oilseed crops under drought stress environments were performed. In this regard, fluorescence and IR thermal imaging techniques were used. Seeds of each sunflower SF0049, SF0054 and soybean NARC-II, William-82 cultivars were germinated. Followed by uniform seedlings of each cultivar were transplanted in rectangular pots of an area 480cm. Three weeks old plants were subjected to drought stress for the next five days. Chlorophyll ‘a’ fluorescence, IR images, relative water content (RWC) and stomatal conductance (gs) were recorded. In drought stress, NARC II and William-82 showed 26-31% reduction in RWC as compared to 18-20% reduction in SF0049 and SF0054. Similarly, 6787% reduction in stomatal conductance was observed in soybean and 59-72% were recorded in sunflower cultivars. Further soybean cultivars displayed 44.4% to 85.7% decrease in performance index (PI) and darkadapted quantum yield (Fv/Fm) as compared to 40% to 87% in sunflow...
Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-... more Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-39, and SF0049, to salt, drought, and combined stresses were studied. The combined stress caused severe damage to photosynthetic apparatus as compared to single stress. The maximum quantum yield of PSII, phenomenological fluxes, plastoquinone pool size, performance indexes, and driving force of absorption were greatly affected by the combined stress. Among the cultivars, the combined stress produced synergistic effect (greater damage) in Hysun-33 and cross-tolerance (lesser damage) in S.28111. Similarly, concerning the ion imbalance, S.28111 and SF0049 showed lower Na + and Cl -concentrations with lesser electrolyte leakage as compared to Hysun-33 and Hysun-39 under salt and combined stress. Results revealed that the disturbance in photosynthetic performance could be easily determined using JIP test by measuring chlorophyll a fluorescence. This information can be useful for the screening of oil-seed crop plants having better photosynthetic performance under salinized and desertified conditions.
Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the... more Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the Capsicum annuum methionine sulfoxide reductase B2 (CaMsrB2) gene were selected for stress tolerance phenotyping under drought stress conditions. The two transgenic lines were selected on the basis of laboratory experiments and for performing well against drought. Field assessment of CaMsrB2 transgenic lines L-23 and L-8 in a drought stress environment was conducted. For the assessments, small plots were prepared at the Department of Botany of the University of Karachi to test the physiological response of transgenic lines. Relative water content, quantum yield (Fv/Fm ratio), photochemical quenching (qP) photosynthetic pigments, and performance index were high in transgenic lines compared to the wild type (WT). Antioxidant enzymes as represented by catalase and superoxide dismutase activities were increased while H 2 O 2 production was decreased in transgenic lines compared to the WT. The results are discussed with special reference to physiological response of the transgenic lines against drought in field conditions.
The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39) u... more The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39) under salt, drought stress separately and in combination was examined. Salt, drought and a combination of these stresses were applied to plants by gradual increments. The plants were exposed to stress for two weeks. Relative water content, osmotic potential, stomatal conductance, performance index, dark adapted quantum yield and chlorophyll contents were reduced upon salinity and drought stresses. However, when plants were subjected to a combination of these stresses, a greater reduction in all tested attributes was observed. Proline and carotenoid contents in drought stress were elevated compared to salt stress. Superoxide dismutase (SOD) and catalase (CAT) showed the highest activity in individual salt and drought stress with less accumulation of H2O2. Combined stress reduced the activity of antioxidant enzymes which ultimately decreased the physiological performance of sunflower plants...
Comparative physiological assessment of some edible oilseed crops under drought stress environmen... more Comparative physiological assessment of some edible oilseed crops under drought stress environments were performed. In this regard, fluorescence and IR thermal imaging techniques were used. Seeds of each sunflower SF0049, SF0054 and soybean NARC-II, William-82 cultivars were germinated. Followed by uniform seedlings of each cultivar were transplanted in rectangular pots of an area 480cm 2. Three weeks old plants were subjected to drought stress for the next five days. Chlorophyll 'a' fluorescence, IR images, relative water content (RWC) and stomatal conductance (gs) were recorded. In drought stress, NARC II and William-82 showed 26-31% reduction in RWC as compared to 18-20% reduction in SF0049 and SF0054. Similarly, 67-87% reduction in stomatal conductance was observed in soybean and 59-72% were recorded in sunflower cultivars. Further soybean cultivars displayed 44.4% to 85.7% decrease in performance index (PI) and dark-adapted quantum yield (Fv/Fm) as compared to 40% to 87% in sunflower cultivars. Maximum yield of photochemistry of PSII and chlorophyll content index were also reduced up to 28-68% in all tested cultivars under drought stress. Non-photochemical quenching, heat dissipation, and leaf temperature were increased over control under drought stress showing maximum in soybean as compared to sunflower. The importance of comparative physiological assessment using fluorescence and IR thermal imaging techniques are discussed.
Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stre... more Florescence assessments of Sunflower (Helianthus annuus L.) genotypes in field under drought stress environment were studied. Climate change and low precipitation represents the main constraints in sunflower production in Pakistan. In present investigation two sunflower genotypes, viz S.28111 and SF0049 were selected to study their photosynthetic performance through non-destructive technique in field. Three treatments were applied to impose drought in plants i.e. irrigation after 6 days (D1), irrigation after 8 days (D2) and irrigation after 16 days (D3) with control irrigation after 4 days. Results revealed that drought stresses altered the electron transport rate through PSII (Fm/Fo), photochemical quenching (qP), efficiency of photosystem II (ΦPSII), linear electron transport rate (rETR), non-photochemical quenching (NPQ), size and number of active reaction centre of photosynthetic apparatus (Fv/Fo), driving forces (DFABS and DFCS) and performance indexes (PIABS and PICS) parameters that depends on the efficiency and yield of energy transfer and primary photochemistry. However, S.28111 maintained substantial quantum yield and enhanced photosynthetic performance under drought stress environment compared to SF0049. It is suggested that the assessment of photochemistry of PSII offers a practical and sensitive field screening regarding test for drought stress tolerance in sunflower. Results are discussed in relation to photosynthetic performance and florescence responses of sunflower genotypes in the drought stress environment.
Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-... more Response of photosynthetic apparatus in some sunflower cultivars, i.e., S.28111, Hysun-33, Hysun-39, and SF0049, to salt, drought, and combined stresses were studied. The combined stress caused severe damage to photosynthetic apparatus as compared to single stress. The maximum quantum yield of PSII, phenomenological fluxes, plastoquinone pool size, performance indexes, and driving force of absorption were greatly affected by the combined stress. Among the cultivars, the combined stress produced synergistic effect (greater damage) in Hysun-33 and cross-tolerance (lesser damage) in S.28111. Similarly, concerning the ion imbalance, S.28111 and SF0049 showed lower Na + and Cl-concentrations with lesser electrolyte leakage as compared to Hysun-33 and Hysun-39 under salt and combined stress. Results revealed that the disturbance in photosynthetic performance could be easily determined using JIP test by measuring chlorophyll a fluorescence. This information can be useful for the screening of oilseed crop plants having better photosynthetic performance under salinized and desertified conditions. Additional key words: electron transport rate; malondialdehyde; nonphotochemical quenching; OJIP transient. Abbreviations: ABS/RC-apparent antenna size of active PSII RC; Area-area over the fluorescence curve between F0 and Fm; DFABS-driving force on absorption basis; DI0/RC-effective dissipation of energy in active RC; ET0/RC-electron transport per active reaction center; F0-minimum fluorescence; F0/Fv-efficiency of water-splitting complex; F0/Fm-quantum yield baseline; Fm-maximum fluorescence; Fm/F0-electron transport rate through PSII; Fv/F0-size and number of active reaction centers of photosynthetic apparatus; Fv/Fm-maximum quantum yield of PSII; J-linear electron transport rate; MDA-malondialdehyde; NPQ-nonphotochemical quenching; PIABS-performance index on absorption basis; PICS-performance index on cross-section basis; PItot-total performance index; qN-nonphotochemical quenching coefficient; qP-photochemical quenching; RC/ABS-density of reaction centers on chlorophyll basis; RC/CSm-amount of active reaction centers per excited cross section; TR0/DI0-ratio of trapping and dissipation fluxes; TR0/RC-maximal trapping rate of absorbed photons in RC; δR0 or RE0/ET0-probability that an electron is transported from reduced PQ to electron acceptor side of PSI; ΔVIP-amplitude of the relative variable fluorescence of the I-toP rise ; ΦPSII-efficiency of PSII or quantum yield of PSII; ϕR0-quantum yield for reduction of the end electron acceptors at the PSI acceptor side (RE); ψ0-yield of electron transport per trapped excitation or probability with which a PSII trapped electron is transferred from reduced QA to QB.
– The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39)... more – The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39) under salt, drought stress separately and in combination was examined. Salt, drought and a combination of these stresses were applied to plants by gradual increments. The plants were exposed to stress for two weeks. Relative water content, osmotic potential, stomatal conductance, performance index, dark adapted quantum yield and chlorophyll contents were reduced upon salinity and drought stresses. However, when plants were subjected to a combination of these stresses, a greater reduction in all tested attributes was observed. Proline and carotenoid contents in drought stress were elevated compared to salt stress. Superoxide dismutase (SOD) and catalase (CAT) showed the highest activity in individual salt and drought stress with less accumulation of H 2 O 2. Combined stress reduced the activity of antioxidant enzymes which ultimately decreased the physiological performance of sunflower plants. However, among the tested genotypes, S.28111 and SF0049 were found to be more tolerant to drought, salt and combined stress than both Hysun genotypes. The physiological performance of genotypes against salinity and drought individually and in combination is discussed in detail.
A comparison to test the consistencies and discrepancies of two most commonly used screening tech... more A comparison to test the consistencies and discrepancies of two most commonly used screening techniques (soil and hydroponic) for salt tolerance in crop plants were examined. In this regard, physiological responses of four sunflower genotypes i.e. Hysun-33, Hysun-39 (known moderately salt tolerant) S.28111 and SF0049 (unreported genotypes) growing in soil filled pots and hydroponics were observed. This study was carried out under greenhouse condition in complete randomize design. plants were treated with 75, 125 and 175 mM NaCl concentrations. Stress was applied to the plants in aliquot levels 30 DAS and plants were harvested 44 DAS for further analysis. Some photosynthetic traits; chlorophyll fluorescence, chlorophyll contents, stomatal conductance and relative water content were analysed. Plants grown in a pot experiment had higher PIabs, stomatal conductance, photosynthetic pigments and hence higher plant fresh weight as compared to hydroponic plants. Despite differences in techniques, results revealed that both systems have shown almost similar trends in physiological traits of tested genotypes under saline environment. A significant correlation in performance index (PIabs), RWC, stomatal conductance, proline contents and total carotenoids was found. Physiological assessment and their reliability of salt tolerance in crop plants using both experimental systems were discussed.
Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the... more Two drought-tolerant transgenic rice lines, L-8 (single copy) and L-23 (two copy), expressing the Capsicum annuum methionine sulfoxide reductase B2 (CaMsrB2) gene were selected for stress tolerance phenotyping under drought stress conditions. The two transgenic lines were selected on the basis of laboratory experiments and for performing well against drought. Field assessment of CaMsrB2 transgenic lines L-23 and L-8 in a drought stress environment was conducted. For the assessments, small plots were prepared at the Department of Botany of the University of Karachi to test the physiological response of transgenic lines. Relative water content, quantum yield (Fv/Fm ratio), photochemical quenching (qP) photosynthetic pigments, and performance index were high in transgenic lines compared to the wild type (WT). Antioxidant enzymes as represented by catalase and superoxide dismutase activities were increased while H2O2 production was decreased in transgenic lines compared to the WT. The results are discussed with special reference to physiological response of the transgenic lines against drought in field conditions.
Abiotic stress like drought and salinity is the major environmental constraints that limit agricu... more Abiotic stress like drought and salinity is the major environmental constraints that limit agricultural production. Physiological mechanisms explaining plant tolerance offer valuable insights for the development of genetically modified crops. Plant water status and alteration in photosynthetic capacity are some common physiological depictions which are induced by abiotic stress like drought and salinity. Chiefly it is because both stresses caused cellular dehydration in the plants, predominantly, during the initial phase of stress imposition. In water stress CO2 availability is greatly reduced due to stomatal limitation; subsequently leaf temperature is elevated. So that studies on plant water status and stomatal regulation are important aspects in abiotic stress environment stabilizing the temperature inside plant/leaf. Therefore phenotyping using infrared thermography (heat sensitive sensor) could be a useful tool in the selection of tolerant genotypes. Generally infrared thermography is sensitive, less time-consuming, and nondestructive methodology which detects heat produced or generated by leaf under the influence of external factors. In general, temperature display pattern on IR images is inversely proportional to leaf water status. It was observed that infrared images are significantly correlated with some of the physiological traits indicating tolerance grading among genotypes.
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