Ten novel α-gliadin genes (Gli-ta, Gli-turg1, Gli-turg2, Gli-turg3, Gli-turg4, Gli-turg5, Gli-turg6, Gli-cs1, Gli-cs2, and Gli-cs3) with unique characteristics were isolated from wheat (Triticum aestivumL.), among which Gli-cs1, Gli-cs2, Gli-cs3, and Gli-turg6 were pseudogenes. Gli-cs3 and nine other sequences were much larger and smaller, respectively, than the typical α-gliadins. This variation was caused by insertion or deletion of the unique domain I and a polyglutamine region, possibly the result of illegitimate recombination. Consequently, Gli-cs3 contained 10 cysteine residues, whereas there were 2 cysteine residues only in the other nine sequences. Gli-ta/Gli-ta-like α-gliadin genes are normally expressed during the development of seeds. SDS-PAGE analysis showed that in-vitro-expressed Gli-ta could form intermolecular disulphide bonds and could be chain extenders. A protein band similar in size to Gli-ta has been observed in seed extracts, and mass spectrometry results confirm that the band contains small molecular mass α-gliadins, which is a characteristic of the novel α-gliadins. Mass spectrometry results also indicated that the two cysteine residues of Gli-ta/Gli-ta-like proteins participated in the formation of intermolecular disulphide bonds in vivo.

Both historical (e.g., glaciations) and spatial (geological features) factors are considered to have had significant influences on the distribution and genetic structure of many plants. To understand the effects of such factors on the current genetic and geographical distributions of plant species in the Nanling and central regions in China, we examined genetic variation and phylogeographical patterns of Sagittaria lichuanensis J.K. Chen (Alismataceae), an endangered and endemic species in China, using chloroplast DNA atpB-rbcL intergenic spacer sequence variation. In this study, a total of 9 haplotypes from 47 individuals in 6 populations of S. lichuanensis were detected. The NST (0.193) was significantly higher than GST (0.082) (P < 0.05), indicating a significant phylogeographical structure. In the minimum spanning network (MSN) of the haplotypes, the distribution of haplotypes showed an east-west split. The results of the Mantel test analysis showed that there was no correlation between the genetic distance and geographical distance (r = 0.539, P > 0.05). The formation of barriers to dispersal might have played an important role in shaping the population genetic structure of S. lichuanensis. Within each region (east and west regions), high levels of gene flow between populations and low levels of population differentiation were found. Several conditions, such as co-ancestry due to recent common ancestry or short period of isolation, might have occurred among the populations studied. In the MSN, all tip haplotypes except for two (A and G) occurred in two or more populations, and the haplotype D in the interior node was widespread. The haplotype D is likely to be an ancestral haplotype and represents the relic, widely distributed haplotype before the populations were fragmented and isolated by mountain uplift. Résumé :On considère que les facteurs historiques (ex. glaciations) et spatiaux (caractères géologiques) exercent des influences significatives sur la distribution ainsi que la structure génétique de nombreuses plantes. Afin de comprendre les effets de tels facteurs sur la génétique actuelle et les distributions géographiques d'espèces végétales de la région de Nanling et du centre de la Chine, les auteurs ont examiné la variation génétique et les patrons phylogéographiques du Sagittaria lichuanensis J.K. Chen (Alismataceae), une espèce endémique menacée de la Chine, en utilisant la variation des séquences de l'espaceur intergénique atpB-rbcL de l'ADN chloroplastique. Dans cette étude, ils ont détecté un total de 9 haplotypes provenant de 47 individus issus de 6 populations du S. lichuanensis. Le N ST (0,193) étant significativement plus grand que le G ST (0,082) (P < 0,05) indique une structure phylogéographique robuste. Dans le réseau d'étalement minimum (MSN) des haplotypes, la distribution des haplotypes montre une fracture est-ouest. Les résultats d'analyse du test de Mantel montrent l'absence de corrélation entre la distance génétique et la distance géographique (r = 0,539, P > 0,05). La formation d...