Abstract
Tibetan wild barley (Hordeum vulgare L. ssp. spontaneum), originated and grown in harsh enviroment in Tibet, is well-known for its rich germpalsm with high tolerance to abiotic stresses. However, the genetic variation and genes involved in Al tolerance are not totally known for the wild barley. In this study, a genome-wide association analysis (GWAS) was performed by using four root parameters related with Al tolerance and 469 DArT markers on 7 chromosomes within or across 110 Tibetan wild accessions and 56 cultivated cultivars. Population structure and cluster analysis revealed that a wide genetic diversity was present in Tibetan wild barley. Linkage disequilibrium (LD) decayed more rapidly in Tibetan wild barley (9.30 cM) than cultivated barley (11.52 cM), indicating that GWAS may provide higher resolution in the Tibetan group. Two novel Tibetan group-specific loci, bpb-9458 and bpb-8524 were identified, which were associated with relative longest root growth (RLRG), located at 2H and 7H on barely genome, and could explain 12.9% and 9.7% of the phenotypic variation, respectively. Moreover, a common locus bpb-6949, localized 0.8 cM away from a candidate gene HvMATE, was detected in both wild and cultivated barleys, and showed significant association with total root growth (TRG). The present study highlights that Tibetan wild barley could provide elite germplasm novel genes for barley Al-tolerant improvement.
Highlights
Aluminium (Al3+) toxicity is considered as a major factor limiting crop production on acid soils [1,2]
relative longest root growth (RLRG) and Relative total root growth (RTRG) were present with a mean of 0.37360.094 and 0.39760.107, ranging from 0.183–0.767 and 0.116–0.696, respectively
It was reported that the application of different phenotypic indexes directly impacted the significance of QTLs detected in rice Al tolerance [13], which was confirmed in the current study, that different loci were detected as associated with Al tolerance by using different root parameters in genome-wide association analysis (GWAS)
Summary
Aluminium (Al3+) toxicity is considered as a major factor limiting crop production on acid soils [1,2]. The initial and visual symptom of Al toxicity is the inhibition of root elongation and development of lateral roots. An absolute root elongation was used for Al tolerance evaluation in short-term Al stress experiments [9,10,11,12]. Famoso et al [8] developed a novel and high-throughput Al tolerance phenotyping platform, which consists of a root imaging system and root computer program. This technology has been successfully applied in many research projects [14,15]
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