A major QTL controlling the tolerance to manganese toxicity in barley (Hordeum vulgare L.)

Waterlogging stress disturbs plant metabolism through increased ion (manganese and iron) toxicity resulting from the changes in the soil redox potential under hypoxic conditions. Our previous study found a significant correlation between the tolerance to Mn²⁺ toxicity and waterlogging stress tolerance in barley, suggesting that waterlogging tolerance could be increased by improving the tolerance to Mn²⁺ toxicity. In this study, a doubled-haploid (DH) population from the cross between barley varieties Yerong and Franklin (waterlogging-tolerant and -sensitive, respectively) was used to identify QTL controlling tolerance to Mn²⁺ toxicity based on chlorophyll content and plant survival as selection criteria. Four significant QTL for plant survival under Mn²⁺ stress (QSur.yf.1H, QSur.yf.3H, QSur.yf.4H, and QSur.yf.6H) were identified in this population at the seedling stage. Two significant QTL (QLC.yf.3H and QLC.yf.6H) controlling leaf chlorosis under Mn²⁺ stress were identified on chromosomes 3H and 6H close to QSur.yf.3H and QSur.yf.6H. The major QTL QSur.yf.3H, located near the marker Bmag0013, explained 21% of the phenotypic variation. The major QTL for plant survival on 3H was validated in a different DH population (TX9425/Naso Nijo). This major QTL could potentially be used in breeding programmes to enhance tolerance to both manganese toxicity and waterlogging.