engleski

Early detecting of drought stress in the maize IBM population – QTL analysis

The intermated B73 × Mo17 (IBM) recombinant inbred (RI) maize population is a valuable resource for the analysis of quantitative traits and is the maize breeders’ community standard for genetic mapping, as it has extensive recombination, and an extensive number of molecular genetic markers. Our previous study revealed that the IBM population is also recommendable for photosynthesis research. The status and functioning of the photosynthetic apparatus can be analyzed by measuring of the chlorophyll a fluorescence transient induced by pulse of saturating light (JIP-test). The JIP-test is particularly useful for probing the vitality of crop plants under water-limited conditions, thereby early detecting drought sress under field conditions. The aim of the present study was to conduct a quantitative trait loci (QTL) analysis for six JIP-test parameters (ABS/RC, TR0/RC, ET0/RC, DI0/RC, Fv/Fm and PI) in order to elucidate the genetic and physiological mechanism(s) in maize during flowering under water-limited and wellwatered field conditions. The IBM maize population of 206 recombinant inbred lines was mapped using set of 636 molecular markers across the whole maize genome. QTL analysis revealed 40 significant QTLs for six JIP-test parameters under water-limited conditions and 57 significant QTLs under well-watered conditions. None of these 97 QTLs were detected in both environments indicating significant locus by environment interactions for all six JIP-test parameters. Many of the detected QTLs are co-localized in each environment, particularly QTLs for ABS/RC, TR0/RC and DI0/RC. Weak correlations with other JIP-test parameters in both environments, as well as completely different set of detected QTLs compared to other parameters highlighted ET0/RC (electron transport per reaction center) as a genetically distinctive photosynthetic parameter. QTL analysis was capable to identify several candidate genes possibly associated with chlorophyll a fluorescence parameters. Our results suggest that the improvement of drought tolerance by marker-assisted selection for JIP-test parameters in maize is feasible.

JIP-test; maize; photosynthesis; QTL

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