Stomatal conductance responses to evaporative demand conferred by rice drought-yield quantitative trait locus qDTY12.1. uri icon

abstract

  • Rice quantitative trait locus (QTL) qDTY(12.1) is a major-effect drought yield QTL that was identified from a cross of Vandana (recipient parent) and Way Rarem (donor parent) through breeding efforts to improve rice yield under upland drought stress conditions. The two main physiological effects previously observed to be related to the presence of qDTY(12.1) were (i) increased lateral root growth, and (ii) increased transpiration efficiency. Since relatively more progress has thus far been made on characterising the lateral root growth response related to qDTY(12.1), the present study focussed on characterising how qDTY(12.1) confers higher transpiration efficiency under upland drought stress in the Vandana background. In a series of field experiments in which stomatal conductance was measured across different times of day in four qDTY(12.1) near isogenic lines (NILs), the NILs and Way Rarem showed consistently higher stomatal conductance than Vandana under conditions of low vapour pressure deficit (VPD) and low photosynthetically active radiation (PAR), and consistently lower stomatal conductance than Vandana under high VPD and high PAR. Leaf delta O-18 was higher in the qDTY(12.1) NIL than in Vandana, and although this trend was previously observed for leaf delta C-13 it appeared to be more consistent across measurement dates and treatments for leaf delta O-18. The qDTY(12.1) NILs and Way Rarem tended to show greater large vein to small vein interveinal distance and mesophyll area than Vandana, also consistent across treatments. In terms of aquaporin-related plant hydraulics, variation among NILs in terms of aquaporin inhibition of root hydraulic conductivity (Lpr) was observed, with the highest-yielding NIL showing a lack of Lpr inhibition similar to Way Rarem. The results reported here suggest that the effects of qDTY(12.1) are in response not only to soil moisture, but also to atmospheric conditions. An interaction among multiple mechanisms including leaf anatomy and aquaporin function appear to confer the transpiration efficiency effect of qDTY(12.1).

publication date

  • 2019
  • 2019