Root-ABA1, a major constitutive QTL, affects maize root architecture and leaf ABA concentration at different water regimes

Abstract

Near-isogenic hybrids (NIHs), developed from crossing maize (Zea mays L.) backcross-derived lines (BDLs) differing for the parental alleles at a major QTL for leaf ABA concentration (L-ABA), were field-tested for 2 years under well-watered and water-stressed conditions. Differences among NIHs for L-ABA and other morpho-physiological traits were not affected by water regimes. On average, the QTL allele for high L-ABA markedly reduced stomatal conductance and root lodging. To elucidate the effects of the QTL on root architecture and L-ABA, root traits of two pairs of BDLs were measured in plants grown in soil columns at three water regimes. Differences among BDLs were not affected by water regimes. Across water regimes, the QTL confirmed its effect on L-ABA and showed a concurrent effect on root angle, branching, number, diameter, and dry weight. Based on these results, it is concluded that the QTL affects root lodging through a constitutive effect on root architecture. In addition, there is speculation that the QTL effects on root traits and L-ABA are probably due to pleiotropy rather than linkage and a model is proposed in which the QTL has a direct effect on root architecture, while indirectly affecting L-ABA.

Genome-wide analysis of yield in Europe: allelic effects as functions of drought and heat scenarios

“…6H). It was found to constitutively affect leaf ABA content (Giuliani et al, 2005), consistent with the fact that a gene coding for a zeaxanthin epoxidase involved in ABA biosynthesis was identified in the region of the QTL (Supplemental Table S7). This could explain the inversion of allelic effects of this QTL in WW and WD scenarios because high ABA can cause reduction in growth in WW while maintaining growth in WD Tardieu, 2012).…”

Quantitative Trait Loci and Crop Performance under Abiotic Stress: Where Do We Stand?: Table I.

“…In rice, following the identification of four major QTLs influencing root traits (Courtois et al, 2000), markerassisted backcrossing (MABC) was used to introgress the alleles for greater root length from Azucena into Kalinga III, an upland variety (Steele et al, 2006(Steele et al, , 2007. In maize, a major QTL originally reported for leaf ABA concentration (Tuberosa et al, 1998) was later shown to affect root size and architecture (Giuliani et al, 2005b) and grain yield (Landi et al, 2007). Following its isogenization (Landi et al, 2005), the positional cloning of this QTL is under way at present (S. Salvi, unpublished data).…”

Study of the Interactive Effects of Calcium and Abscisic Acid on Drought Stressed Triticum aestivum Seedlings

“…The increase in ABA level reprograms the expression patterns of many genes to regulate water relations through adjustment of cellular osmotic pressure. Furthermore, the increase in ABA level is a central player controlling downstream responses essential for adaptation to different stresses, especially drought (Davies et al, 2002 andGiuliani et al, 2005). These responses include changes in stomatal conductance (closure of stomata), osmolyte accumulation, gene expression, a reduced leaf canopy, deeper root growth and changes in root system architecture (Davies et al, 2002;Giuliani et al, 2005;Lee et al, 2013 andAn et al, 2016).…”