Stomatal morphology and physiology explain varied sensitivity to abscisic acid across vascular plant lineages.

Abscisic acid (ABA) can induce rapid stomatal closure in seed plants, but the action of this hormone on the stomata of fern and lycophyte species remains equivocal. Here, ABA-induced stomatal closure, signaling components, guard cell K+ and Ca2+ fluxes, vacuolar and actin cytoskeleton dynamics, and the permeability coefficient of guard cell protoplasts (Pf) were analyzed in species spanning the diversity of vascular land plants including 11 seed plants, 6 ferns, and 1 lycophyte. We found that all 11 seed plants exhibited ABA-induced stomatal closure, but the fern and lycophyte species did not. ABA-induced hydrogen peroxide elevation was observed in all species, but the signaling pathway downstream of nitric oxide production, including ion channel activation, was only observed in seed plants. In the angiosperm faba bean (Vicia faba), ABA application caused large vacuolar compartments to disaggregate, actin filaments to disintegrate into short fragments and Pf to increase. None of these changes was observed in the guard cells of the fern Matteuccia struthiopteris and lycophyte Selaginella moellendorffii treated with ABA, but a hypertonic osmotic solution did induce stomatal closure in fern and the lycophyte. Our results suggest that there is a major difference in the regulation of stomata between the fern and lycophyte plants and the seed plants. Importantly, these findings have uncovered the physiological and biophysical mechanisms that may have been responsible for the evolution of a stomatal response to ABA in the earliest seed plants.

[Polymorphic and linkage analysis of microsatellite BMS2508 and FecB gene in sheep].

Genetic polymorphisms of microsatellite locus BMS2508, which was closely linked to the ovine fecundity gene FecB, were detected in prolific (Small Tail Han sheep) and non-prolific breeds of sheep (Texel, Dorset and Chinese Merino). The linkage disequilibrium between microsatellite locus BMS2508 and FecB gene of Small Tail Han sheep was also analyzed. There was the same mutation (A746G) of BMPR-IB gene in Small Tail Han sheep as that of FecB in Booroola Merino ewes, but the FecB mutation was absent in Texel, Dorset and Chinese Merino sheep. The genotype frequencies of BB, B+ and ++ were 0.485, 0.398 and 0.117 in Small Tail Han sheep, respectively. There were eight alleles varied from 94 bp to 116 bp and 15 genotypes detected at BMS2508 locus in four sheep breeds totally 438 individual. The preponderant allele was 100 bp, 94 bp, 94 bp, 112 bp, 100 bp, 100 bp, 112 bp, and the frequency was 0.453, 0.544, 0.802, 0.475, 0.483, 0.439, 0.389 in Small Tail Han (n=307), Texel (n=45), Dorset (n=46), Chinese Merino (n=40), and BB group (n=149), B+ group (n=122), ++ group (n=36) from Small Tail Han, respectively. In Small Tail Han sheep, linkage analysis indicated that there was certain linkage disequilibrium between 100 bp allele of microsatellite BMS2508 and B allele of FecB gene (D' =0.408), and certain linkage disequilibrium between 110 bp and 114 bp alleles of microsatellite BMS2508 and + allele of FecB gene (D'=0.513).