Abstract
Aluminium (Al) toxicity acts as a major delimiting factor in the productivity of many crops including lentil. To alleviate its effect, plants have evolved with Al exclusion and inclusion mechanisms. The former involves the exudation of organic acid to restrict the entry of Al3+ to the root cells while latter involves detoxification of entered Al3+ by organic acids. Al-induced secretion of organic acids from roots is a well-documented mechanism that chelates and neutralizes Al3+ toxicity. In this study, F6 recombinant inbred lines (RILs) derived from a cross between L-7903 (Al-resistant) and BM-4 (Al-sensitive) were phenotyped to assess variation in secretion levels of malate and was combined with genotypic data obtained from 10 Al-resistance linked simple sequence repeat (SSRs) markers. A major quantitative trait loci (QTL) was mapped for malate (qAlt_ma) secretion with a logarithm of odd (LOD) value of 7.7 and phenotypic variation of 60.2%.Validated SSRs associated with this major QTL will be useful in marker assisted selection programmes for improving Al resistance in lentil.
Highlights
Aluminium toxicity is amongst the crucial limiting factors which adversely affect growth and productivity
After 3 h exposure to Al stress, callose accumulation was higher in root tips and root cross-sections of Al-sensitive genotype (BM-4) as compared to Al-resistant one (L-7903)
To identify Al resistance quantitative trait loci (QTL) associated with organic acid secretion, a F2 mapping population derived from the cross between BARI Masur-4 (BM-4, Al-sensitive, high yielding variety form Bangladesh Agricultural Research Institute, Joydebpur, GazipurBangladesh) and L-7903 (Al-resistant, breeding line from Indian Agricultural Research Institute, New Delhi, India) [15,16] was advanced to F6 generation (n = 146) by single seed descent (SSD) method
Summary
Aluminium toxicity is amongst the crucial limiting factors which adversely affect growth and productivity. Transcriptional regulation of genes associated with these mechanisms has rendered Al resistance in many crops Genes such as Al-activated malate transporter (ALMT) and multi-drug and toxic compound extrusion (MATE) help in secretion of organic acids under Al stress in wheat [11] and barley [12]. MATE and aluminium-activated citrate transporter 1 (HvAACT1), which belongs to the MATE family, were found to be associated with Al-induced citrate secretion in sorghum and barley [13,14]. Higher expression of these genes under Al stress correlated Al3+-activated efflux of citrate with Al resistance in these species
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