Heading date in rice is a typical quantitative trait controlled by multiple quantitative trait loci (QTLs). It is mainly regulated by environmental factors such as photoperiod and temperature (Izawa, 2007). Many QTLs for heading date have been identified using different mapping populations and methods (http:// www.gramene.org/qtl). Up to date, several major heading date QTLs have been cloned by map-based cloning strategy (Yano et al., 2000; Takahashi et al., 2001; Kojima et al., 2002; Doi et al., 2004; Xue et al., 2008; Wei et al., 2010; Yan et al.,
Following the idea of partial root-zone drying (PRD) in crop cultivation,the morphological and physiological responses to partial root osmotic stress (PROS) and whole root osmotic stress (WROS) were investigated in rice.WROS caused stress symptoms like leaf rolling and membrane leakage.PROS stimulated stress signals,but did not cause severe leaf damage.By proteomic analysis,a total of 58 proteins showed differential expression after one or both treatments,and functional classification of these proteins suggests that stress signals regulate photosynthesis,carbohydrate and energy metabolism.Two other proteins (anthranilate synthase and submergence-induced nickel-binding protein) were upregulated only in the PROS plants,indicating their important roles in stress resistance.Additionally,more enzymes were involved in stress defense,redox homeostasis,lignin and ethylene synthesis in WROS leaves,suggesting a more comprehensive regulatory mechanism induced by osmotic stress.This study provides new insights into the complex molecular networks within plant leaves involved in the adaptation to osmotic stress and stress signals.
Lie-Bo ShuWei DingJin-Hong WuFang-Jun FengLi-Jun LuoHan-Wei Mei