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
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.
Barley chymotrypsin inhibitor-2 (CI-2) was considered to be a promising candidate for enhancing the nutritional value of other cereals by increasing its concentration as it is rich in lysine than any other storage protein. Also, it was proposed that CI-2 might play an important role in the inhibition of proteolytic enzymes from pests or pathogens as CI-2 can strongly inhibit chymotrypsin and subtilisin. In this study, a total of 93 CI-2 gene sequences were isolated from wild and cultivated barley. 48 SNPs and 4 indels were detected across the entire sequences. The frequency of SNPs in the non-coding region (1 out of 9 bases) was slightly higher than that in the coding region (1 out of 10.7 bases). In all, 33.3% of the candidate cSNPs resulted in amino acid changes. As a total, the 24 cSNPs resulted in 15 amino acid changes. Ten distinguishable haplotypes were detected, among which 3 haplotypes were shared in the most barley accessions, whereas the rest of the haplotypes appeared at a lower frequency. In addition, three haplotypes (haplotype 4, 8, and 9) were unique for single accessions. These results suggested that low diversity at the CI-2 locus was detected among the cultivated and wild barley.
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
The hina gene encodes a HINA protein in seeds of barley (Hordeum vulgare), which was known to affect the grainhardness. 171 hina gene sequences from Tibetan wild barley accessions and worldwide were characterized. Across 1 452nucleotides of 171 hina genes, 152 SNPs were detected, giving an average frequency of one SNP per 9.5 bases. There were93 singleton variable sites (the nucleotide polymorphism only observed in a single accession), 59 polymorphic sites (thepolymorphisms found in two or more accessions) and 8 indels. A total of 18 haplotypes were defined, and most of thebarley accessions shared one gene haplotype. H. spontaneum had a wider haplotype distribution. Through the analysisof median-joining network of the 18 haplotypes, 4 haplotype groups were found, which were testified by neighbor-joiningtree based on the complete sequence alignment. Extremely low level of hina gene diversity was observed in Tibetan wildbarley accessions, indicating that Tibet is unlikely a center of origin for cultivated barley.
YANG Shi-dongWEI Yu-mingQI Peng-feiZHENG You-liang
