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Most arable lands in the world are quite low in available phosphorus (P), becoming an important factor restricting crop yield. However, the genotypic difference of low-P tolerance in barley is rarely understood at molecular level. In this study, low-P responses of three barley genotypes were explored by physiological, transcriptomic and metabolomic analysis. The results showed that low-P-tolerant genotypes Zaoaibai (cultivar) and X130 (Tibetan wild accession) showed less growth inhibition compared to low-P-sensitive Salooni2 under low-P stress. Omics analysis showed that many genes involved in Pi acquisition and transport were more upregulated in Zaoaibai, which had relatively higher concentrations of shoot P and glucose-6-phosphate, indicating that enhancement of P acquisition, P translocation and P availability contributed to low-P tolerance in Zaoaibai. On the other hand, the genes and metabolites involved in biosynthesis of Pi-free lipids were highly expressed and more abundant in X130, suggesting that remodeling of membrane lipids by replacing phospholipids with Pi-free lipids is an important strategy for X130 in its adaptation to low-P stress. The divergent evolution of low-P tolerance in Zaoaibai and X130 could be driven by diverse ecological factors in Eastern China (low soil P) and Tibet Plateau (high soil P and low temperature), respectively. • Zaoaibai and X130 showed less growth inhibition compared to Salooni2 under low-P stress. • Enhancement of P acquisition, P translocation and P availability contributed to low-P tolerance in a cultivated genotype Zaoaibai. • Remodeling of membrane lipids by replacing phospholipids with Pi-free lipids is an important strategy for a Tibetan wild accession X130 in adaptation to low-P stress. • Divergent evolution of low-P tolerance in Zaoaibai and X130 may be driven by ecological factors in Eastern China (low soil P) and Tibet Plateau (high soil P and low temperature), respectively. [ABSTRACT FROM AUTHOR]

Abstract Background The interest has been increasing on the phenolic compounds in plants because of their nutritive function as food and the roles regulating plant growth. However, their underlying genetic mechanism in barley is still not clear. Results A genome-wide association study (GWAS) was conducted for total phenolic content (TPC), total flavonoid content (FLC) and antioxidant activity (AOA) in 67 cultivated and 156 Tibetan wild barley genotypes. Most markers associated with phenolic content were different in cultivated and wild barleys. The markers bPb-0572 and bPb-4531 were identified as the major QTLs controlling phenolic compounds in Tibetan wild barley. Moreover, the marker bPb-4531 was co-located with the UDP- glycosyltransferase gene (HvUGT), which is a homolog to Arabidopsis UGTs and involved in biosynthesis of flavonoid glycosides . Conclusions GWAS is an efficient tool for exploring the genetic architecture of phenolic compounds in the cultivated and Tibetan wild barleys. The DArT markers applied in this study can be used in barley breeding for developing new barley cultivars with higher phenolics content. The candidate gene (HvUGT) provides a potential route for deep understanding of the molecular mechanism of flavonoid synthesis.

Background: The interest has been increasing on the phenolic compounds in plants because of their nutritive function as food and the roles regulating plant growth. However, their underlying genetic mechanism in barley is still not clear. Results: A genome-wide association study (GWAS) was conducted for total phenolic content (TPC), total flavonoid content (FLC) and antioxidant activity (AOA) in 67 cultivated and 156 Tibetan wild barley genotypes. Most markers associated with phenolic content were different in cultivated and wild barleys. The markers bPb-0572 and bPb-4531 were identified as the major QTLs controlling phenolic compounds in Tibetan wild barley. Moreover, the marker bPb-4531 was co-located with the UDP-glycosyltransferase gene (HvUGT), which is a homolog to Arabidopsis UGTs and involved in biosynthesis of flavonoid glycosides. Conclusions: GWAS is an efficient tool for exploring the genetic architecture of phenolic compounds in the cultivated and Tibetan wild barleys. The DArT markers applied in this study can be used in barley breeding for developing new barley cultivars with higher phenolics content. The candidate gene (HvUGT) provides a potential route for deep understanding of the molecular mechanism of flavonoid synthesis. [ABSTRACT FROM AUTHOR]