Developmental and quantitative trait loci analyses of root plasticity in response to soil moisture fluctuation in rice
2015
Suralta, R.R. | Lucob, N.B. | Perez, L.M. | Niones, J.M. | Nguyen, H.T.
Soil moisture fluctuation (SMF) stress, such as transient waterlogged-to-drought conditions and vice versa, negatively affect the productivity of rainfed lowland rice. This study was conducted to quantify root plastic developmental responses of doubled-haploid lines (DHLs) to soil moisture fluctuation stress and analyze the quantitative trait loci (QTL) associated with such plasticity. Ninety DHLs and their parents, CT9993 and IR62266, were grown under continuously waterlogged (CWL) and SMF conditions. Plasticity was calculated as the difference between the mean values of the trait between SMF and CWL grown plants for each DHL. Among component root traits, the number of L-type lateral roots (LR) had the greatest promotion under SMF, which greatly contributed to the plasticity of total LR length and hence total root length especially at deeper soil layer. Thirty QTLs for different root plasticity traits under SMF were detected at different soil depths, which explained about 8.3 to 20.9% of the total phenotypic variations. Three QTLs (qPLLR sub 20-3 and qPTLLR sub 20-7 at 10-20 cm soil depth, and qPLLR sub 30-2 at 20-30 cm soil depth) associated with the plasticity in the number of L-type LR were detected in chromosomes 3,7 and 2 respectively. The plasticity of correlated component-root traits, such as between the number of nodal roots and total nodal root length, and between total lateral root length and total root length at certain soil depth, have QTLs overlapping in the same regions, suggesting their possible similar genetic controls under SMF. The root plasticity QTLs for the number and length of L-type LR did not overlap in any of the chromosomal regions, indicating that the plasticity expressions of these two traits have different genetic controls under SMF.
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