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Analysis for the process of leaf senescence and the causes promoting its senescence in crop plants.

作物叶片衰老过程及促进其衰老的原因分析

基本信息

批准号：
02454039
负责人：
ISHIHARA Kuni
金额：
$ 4.8万
依托单位：
Tokyo University of Agric. & Tech.
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

项目摘要

It was reported that the yield in Akenohoshi (a high yielding rice cultivar) was about 1780 kg/ha higher than that in Nipponbare (a Japanese standard cultivar), and that Akenohoshi had a higher dry matter production capacity compared with Nipponbare. This was attributed to the maintenance of a higher net assimilation rate during the ripening period in the former. The higher net assimilation rate of Akenohoshi resulted from a slower leaf senescence than that of Nipponbare at the ripening stage. To clarify the cause of the slower senescence in Akenohoshi, changes in exudation rate and cytokinin activities in the exudates were measured in two varieties of rice. The exudation rates of Akenohoshi, the leaves of which remained green for a longer time, were higher than those of Nipponbare after the booting stage. Cytokinin activities in the exudates of Akenohoshi were higher than those of Nipponbare during the ripening period. Cytokinins in the exudates collected during the middle of the ripening stage were analyzed with mass spectrometry using deuterium-labeled standards. trans-Zeatin, trans-ribosylzeatin, and N^6-isopentenyladenosine were detected in the hydrolysates of highly polar fractions("conjugated zeatin") in the exudates of both cultivars. Therefore, we suggest that conjugated zeatin is an important form of cytokinin during the ripening stage. The level of each of the cytokinins in Akenohoshi was higher than that in Nipponbare.

据报道，高产水稻品种赤之星的产量比日本晴高1780 kg/hm 2，其干物质生产能力也比日本晴高。这是由于前者在成熟期维持了较高的净同化率。明之星的净同化率高于日本晴，这是由于成熟期叶片衰老慢于日本晴。为了阐明明之星衰老缓慢的原因，测定了两个水稻品种的分泌物速率和分泌物中细胞分裂素活性的变化。在孕穗期后，叶片保持绿色时间较长的明之星的分泌速率高于日本晴。在成熟期，赤之星的分泌物中细胞分裂素活性高于日本晴。在成熟阶段的中期收集的渗出液中的细胞分裂素进行了分析与质谱使用氘标记的标准。在两个品种的分泌物中的高极性组分（“结合玉米素”）的水解产物中检测到反式玉米素、反式玉米素核糖基和N^6-异戊烯基腺苷。因此，我们认为结合玉米素是成熟期细胞分裂素的一种重要形式。Akenohoshi中的每种细胞分裂素的水平均高于日本晴。