To clarify the complex regulatory relationship between changes in sugar content and leaf senescence during the grain-filling stage of rice, genotype-dependent differences in sugar content and the temporal transcriptional patterns of genes involved in sugar signaling pathways were determined in mutant rice exhibiting early leaf senescence and its wild type Zhefu 142. The effects of exogenous glucose or sucrose on the senescence of detached leaves under dark conditions were also investigated. Chlorophyll, soluble sugar, sucrose and fructose contents decreased, whereas electrolytic leakage and malondialdehyde levels increased in mutant leaves at the grain-filling stage. These results suggested that sugar starvation is positively correlated with the early leaf senescence of mutant plants. Detached leaf segments incubated in exogenous sugar solutions under dark conditions exhibited delayed senescence. The high expression of Hxk1 in leaves of mutant plants at the initial grain-filling stage suggested that Hxk1 is involved in the hexose-sensing process at the early stage of leaf senescence. The low expression levels of Hxk2 and Frk1 in the senescing leaves of mutant rice during the grain-filling stage are indicative of weakened hexose phosphorylation. In addition, the high expression levels of SuSy1, SuSy2 and SuSy4 in leaves of mutant plants at the initial grain-filling stage are accompanied by the high transcript levels of SUT1, which favor sucrose translocation and remobilization from the early senescing leaves of mutant rice. The relatively reduced transcript levels of chFBP, cyFBP, SPS1, SPS2 and SPS6 indicated that during the grain-filling stage, sucrose biosynthesis is weakened in the senescing leaves of mutant rice.

为了阐明水稻籽粒充实阶段糖含量变化与叶片衰老之间的复杂调控关系，确定了表现出早期叶片突变的水稻中糖含量的基因型依赖性差异和糖信号途径中相关基因的时间转录模式。 142.在黑暗条件下，还研究了外源葡萄糖或蔗糖对离体叶片衰老的影响。籽粒灌浆期叶片的叶绿素，可溶性糖，蔗糖和果糖含量降低，而电解渗漏和丙二醛水平升高。这些结果表明糖饥饿与突变植物的早期叶片衰老呈正相关。在黑暗条件下在外源糖溶液中孵育的分离的叶片段显示出延迟的衰老。高表达HXK1在初始灌浆期突变体植物的叶中提出，HXK1在叶子衰老的早期阶段中涉及的己糖的感测过程。Hxk2和Frk1在籽粒充实阶段的突变水稻的衰老叶片中的低表达水平表明己糖磷酸化减弱。此外，在灌浆初期，突变植物叶片中的SuSy1，SuSy2和SuSy4的高表达水平伴随着SUT1的高转录水平。，这有助于从突变水稻的早期衰老叶片中进行蔗糖的转运和迁移。chFBP，cyFBP，SPS1，SPS2和SPS6的转录水平相对降低，表明在灌浆期，突变稻的衰老叶片中蔗糖的生物合成被削弱。