Papers by stefano gomarasca
Planta, 1997
Circumnutation is an oscillating movement of a growing plant organ that is believed to result fro... more Circumnutation is an oscillating movement of a growing plant organ that is believed to result from an endogenous rhythmic process intrinsic to growth. Circumnutating organs, as they extend, describe a helical trace. In Arabidopsis thaliana (L.) Heynh. circumnutation is particularly evident in primary roots and occurs, as in most plants, in a right-handed direction when viewed from above in the direction of the growing tips. We have discovered a pleiotropic mutant of Arabidopsis with left-handed root circumnutation. Major abnormalities of the mutant are: (i) a reduced size of all organs, mainly due to a defect in cell elongation or expansion; (ii) a zigzagging pattern of stem pith cells, reminiscent of the``erectoides'' phenotype of the lk mutant of Pisum; (iii) roots of the mutant are gravitropic but as they grow, they form tight, left-handed coils. Genetically, the mutant depends on the presence of two independent monogenic recessive factors acting additively. The mutant alleles of both factors alter the growth of the aerial organs in a similar manner but dier at the root level: one mainly produces non-circumnutating roots, the other changes the direction of circumnutation from right to left hand.
Plant Physiology, 1993
Because fusicoccin (FC) has the the capacity to promote solute uptake, a selective procedure for ... more Because fusicoccin (FC) has the the capacity to promote solute uptake, a selective procedure for isolating mutants of Arabidopsis fhaliana with a reduced response to the toxin has been developed. The procedure is based on the incubation of A. fhaliana seedlings in a solution containing the cation Paraquat (Pq) at a concentration that per se does not produce bleaching of the leaves upon illumination but does in the presence of FC because of the increased uptake of the toxic cation. Using this procedure, we identified, among the progenies of 2010 M1 ethyl methanesulfonate-mutagenized plants, two mutants that stay green after exposure to FC and Pq. Some properties and inheritance of one of the two mutants (5-2) are described. Morphology of mutant plants is almost indistinguishable from that of the wild type. However, 5-2 seeds germinate and produce viable seedlings in the presence of FC plus the aminoglycoside antibiotic hygromycin B: plants of the mutant do not wilt when exposed to FC and stomata do not open or open only partially. In the presence of FC, the mutant appears less responsive than the wild type as far as the increment in fresh weight, the enlargement of leaf disc area, or the stimulation of H+ extrusion is concerned. lnheritance of the trait is monogenic dominant or semidominant, depending on the test used.
South African Journal of Botany, 2014
Tropical and subtropical rangeland systems provide core ecosystem services for the welfare of hum... more Tropical and subtropical rangeland systems provide core ecosystem services for the welfare of human populations that rely on readiness and quality of forage resources. However, forage species are still widely overlooked by molecular biology studies. In the present study, we employ 366 AFLP markers to provide the first description of the genetic landscape of three Kenyan populations of Themeda triandra Forssk., a key wild grass forage species. By including Australian T. triandra accessions and other closely related species in a molecular phylogeny, we provide a first evaluation of the relationships existing between African and Australian germplasm. Genetic diversity, population genetic structure and recombination rates in Kenyan T. triandra populations were investigated in detail. GPS coordinates of each sampled population were used to retrieve meteorological data at specific locations, and environmental factors likely contributing to T. triandra genetic differentiation were taken into consideration using a correlative approach based on outlier loci distribution. The use of molecular markers unveiled some previously unknown aspects about the biology of T. triandra, namely: i) African and Australian T. triandra genotypes analyzed in this study are genetically undistinguishable, ii) sexual recombination of Kenyan T. triandra is likely to play a major role in its reproduction, and iii) environmental characteristics of the collection sites are correlated with the allelic distribution of a limited set of loci under selection.
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Papers by stefano gomarasca