chinese

 

Abstract

Background

Acid soil is a serious limitation to crop production all over the world. Toxic aluminium (Al) cations in acid soil inhibit root growth and reduce yield. Although a gene tolerant to acid soil has been identified, it has not been widely used in malting barley breeding.

Results

A Brazilian malting barley variety Br2 was identified as tolerant to acid soil. A double haploid (DH) population was developed from a cross between Br2 and the Australian acid-sensitive cultivar Hamelin. The DH population was tested for acid soil tolerance in native acid soil and a hydroponic system with pH 4.2, pH 4.2+Al or pH 6.5, and genotyped using SSR, DArT and gene-specific markers. A single QTL was detected for all parameters related to acid soil tolerance. The QTL was mapped to the known HvMATE location on chromosome 4H. Sequence alignment of the HvMATE gene identified 13 INDELs and 87 SNPs, where one SNP resulted in amino acid change between the two varieties. A gene-specific marker was developed to detect the single nucleotide polymorphism between Hamelin and Br2. This marker co-segregated with aluminium tolerance and accounted for 79% of phenotypic variation for acid soil tolerance.

Conclusion

The present study identified a new source of acid soil/Al tolerance from a Brazilian cultivar Br2. This variety tolerated Al toxicity but was sensitive to low pH which is similar to most other Al-tolerant varieties. A new gene-specific marker Cit7 was developed based on the HvMATE gene sequence, which could predict phenotypic variation more precisely than other published markers. Cit7 will improve the efficiency of molecular-assisted selection of new barley varieties with tolerance to acid soil. Multiple alleles exist for the acid soil tolerance gene on chromosome 4H, so a malting barley variety that tolerates acid soil could be developed by selecting suitable tolerant alleles. Tolerance to low pH may play an important role for barley to adapt to acid soils.