Novel LMW-GS (low molecular weight glutenin subunit), α- and γ-gliadin from Triticum macha accessions were characterized via genomic PCR, which can do favor to improve the wheat quality. The complete coding regions of two α-gliadin, two γ-gliadin and two LMW-GS gene sequences, which designed as Gli-Mal, Gli-Ma2, Gli-Mr1, Gli-Mr2, Glu-LM1 and Glu-LM2, encoded the mature proteins with 307, 241, 348, 302, 474 and 377 amino acid residues, respectively. Gli-Mal and Gli-Ma2 were recognized as pseudogenes due to the in-frame stop codons. The amino acid sequences deduced from these gene sequences were characterized with the typical structure of α- or γ-gliadin or LMW-m type proteins with the exception of Gli-Ma2. Phylogenetic analysis showed Gli-Mal was closely related to those from T. aestivum, whereas Gli-Ma2 seemed to be more homologous with the gene sequences from Dasypyrum breviaristatum. Gli-Mr1 was closely related to those from T. turgidum ssp. dicoccoides, while Gli-Mr2 was the nearest to those from T. aestivum. Glu-LM1 was closely related to those from Aegilops tauschii, whereas Glu-LM2 seemed to be more homologous with those from T. durum.
Aluminum (Al) toxicity often takes place in acidic soils with a pH of 5.5 or lower. Breeding and cultivation of Al tolerance wheat can partially protect wheat escaping from Al toxicity. The scarcity of the tolerant sources impedes the wheat breeding. In order to find new Al tolerance sources, we screened 173 bread wheat landraces from Tibet of China using hydroponic screening. It was indicated that: (1) There were diversities on the root regenerate length (RRL). The RRL of a large of landraces were longer than 7.00 cm in pH 7 (58.38%) and pH 4.5 (66.47%), but shorter than 5.00 cm in pH 4.5 + 50 μM Al3+ (80.93%). The low pH showed either promotion or restraining effects depend on landraces, but Al toxicity under low pH only showed restraining effects on the root elongation. (2) There were also diversities on root tolerance index of low pH (RTI1) or root aluminum tolerance index (RTI2) among cultivars. The RTI1 varied from a narrow range but with relatively high value (0.8722-1.2953) in comparison with that of RTI2 (0.3829-1.0058), and the RTI1 of approximately 60% landraces was higher than 1.0000, the RTI2 of only 19.07% landraces was higher than 0.7000, suggesting that Al toxicity acted as an important factor for the reduction of the root elongation under acidic soils. (3) The RTI1 of many wheats was higher than 1.0000, and As2256 and As2295 were the most tolerant for low pH, with RTI1 1.2953 and 1.2925, respectively. (4) Based on RTI2, seven wheats showed similar or higher tolerance to Al toxicity than Chinese Spring (CS), a known tolerance wheat. Much better tolerance existed in landraces of As1543 and As1242, which can be used as the new parents for Al tolerant breeding.
DAI Shou-fen YAN Ze-hong LIU Deng-cai ZHANG Lian-quan WEI Yu-ming ZHENG You-liang
It was helpful for the wheat improvement to evaluate the genetic resources of Triticum turgidum L. ssp. turgidum landraces. In this study,68 turgidum landraces accessions,belonging to four geographic populations in China,were investigated by using EST-SSR markers. A total of 63 alleles were detected on 22 EST-SSR loci,and the number of alleles on each locus ranged from 1 to 5,with an average of 2.9. The results of the analysis of molecular variance (AMOVA) indicated that 92.5% of the total variations was attributed to the genetic variations within population,whereas only 7.5% variations among populations. Although the four populations had similar genetic diversity parameters,Sichuan population was yet distinguished from other populations when comparing the population samples in pairs. Significant correlations were detected by the statistic analysis among six genetic diversity parameters among each other. The selection difference between heterozygosty and homozygosty was also observed among different EST-SSR locus. The genetic similarity (GS) ranged from 0.18 to 0.98,with the mean of 0.72,and all accessions could be clustered into 7 groups. The dendrogram suggested that the genetic relationships among turgidum accessions evaluated by EST-SSR markers were unrelated to their geographic distributions. These results implied that turgidum landraces from China had the unique characters of genetic diversity.
LI WeiDONG PanWEI Yu-mingCHENG Guo-yueZHENG You-liang
Grain texture in barley (Hordeum vulgare L.) is an important quality character.The single nucleotide polymorphisms (SNPs) in Hordoindoline a (hina) gene and its relationship with hardness index among North American barley cultivars were investigated.The hina genes in 36 cultivars were sequenced for the SNP analyses,and 17 sets of SNP primers were designed to detect the SNP variations of hina locus in 92 North American barley cultivars.SNP detection indicated that there were four haplotypes in the hina genes of 92 barley cultivars,and haplotype 01 and 02 were shared by 68 and 14 cultivars,respectively,suggesting that there was a very limited diversity in hina genes among North American barley cultivars.Despite the wide range in hardness exists in 92 barley cultivars,however,unlike wheat,where a clear relationship has been demonstrated between a number of SNPs in the wheat hardness genes and quality (soft or hard wheat),there was no such relationship for barley.The genotypes used in this study demonstrated that there was a low level of polymorphism in hina gene in North American barley cultivars and these polymorphisms had no impact on grain hardness.
