Endogenous factors controlling monocarpic senescence in wheat plants

单果衰老是由开花和/或结果引起的，这表明果实在衰老中起着至关重要的作用。植物衰老的开始似乎是由抑制衰老的细胞分裂素水平和刺激衰老过程的化合物水平（如脱落酸（ABA）和茉莉酸（JA））之间的平衡控制的。衰老植株旗叶细胞分裂素水平高于抽穗前叶片，表明细胞分裂素缺乏与衰老无关。ABA、JA及其甲酯（JA- me）含量在穗发育的任何时期都很低，表明这些化合物与穗衰老无关。利用小麦初叶进行的叶绿素保持试验表明，从小麦穗部提取的己烷可溶性部分具有较强的促衰老活性。在乳熟后期的穗部活性最高，表明促衰老化合物是单果衰老的开始。活性化合物的色谱行为不同于ABA、JA和JA- me。这种化合物不吸收紫外线。该化合物的纯化和鉴定正在进行中。

Monocarpic senescence is known to be induced by flowering and/or fruiting, indicating that fruit plays an crucial role in the senescence. Commencement of the senescence of a plant seems to be controlled by a balance between the lovel of cytokinins that inhibit the senescence and the levels of compounds that stimulate the process, such as abscisic acid (ABA) and jasmonic acid (JA). The level of cytokinins in flag leaves in senescent plants was higher than those in plants before heading, indicating that deficiency of cytokinins is not involved in the senescence. The levels of ABA,JA and its methyl ester (JA-Me) in ears were very low at any time of the development of ears, suggesting that these compounds are not involved in the senescence.Chlorophyll retention test which was carried out by the first leaves of wheat showed the presence of strong senescence-promoting activity in the hexane-soluble fraction obtained from the ears. The maximum activity was found in the ears at late milk-ripe stage, suggesting that the senescence promoting compound is responsible for the commencement of the monocarpic senescence. Chromatographic behavior of the active compound was different from those of ABA,JA and JA-Me. The compound has no UV absorption. Purification and identification of the compound are now in progress.