草莓果实发育过程中IAA及其代谢相关酶的变化特性

Changing characteristics of auxin and the relative enzymes during the process of strawberry fruit development

为了探索草莓果实中生长素的代谢变化及其发挥作用的机理,利用HPLC定量测定了草莓果实发育过程中瘦果和花托中的吲哚乙酸(IAA),结合生长素运输抑制剂NPA和TIBA处理考察了草莓果实中IAA含量以及不同存在状态的生长素氧化酶(IAO)和过氧化物酶(POD)活性变化,综合分析了草莓果实中IAA的变化特性、可能来源及其与生长素代谢相关酶的关系。结果表明:①盛花期的草莓瘦果(离生雌蕊)和花托中已存在一定水平的IAA,瘦果中的IAA含量远高于花托中的;授粉受精后IAA含量逐渐上升,花托和瘦果中分别在绿熟前期和白熟前期出现峰值,并在转色期出现小峰值。②瘦果和花托之间生长素的运转与生长素极性运输体系密切相关。果实发育前期,花托中IAA含量与细胞质可溶性IAO、以离子键结合的IAO的活性显著负相关;发育前期和后期IAA含量与POD活性显著正相关。表明草莓花托中对IAA的氧化分解起主要作用的可能是IAO,而POD除了参与IAA分解之外,可能还与维持生长素的动态平衡、协同促进果实的生长发育有关。

In order to explore the mechanisms of auxin action and metabolism,as well as the changing characteristics of its relative enzymes,IAA content in strawberry fruits with different treatments was determined by HPLC. Content of IAA and the activity of IAO and POD in fruits treated by NPA or TIBA,the inhibitor of auxin transport,were analyzed to investigate the changing characteristics and possible source of auxin,as well as the relation among IAA,POD and IAO. Results were showed as the followings：there had a certain count of IAA in receptacles and achenes,and IAA content in achenes was higher than that in receptacles. IAA increased quickly after fertilization. The IAA levels peaked in receptacles and achenes in the early green mature period and prior to the white mature period,respectively,and subsequently as the fruit matures,they both appeared a second peak in the color turning period. The movements of auxin between receptacles and achenes were correlated to the polar auxin transport. During the early stages of fruit development,content of IAA in receptacles was significantly negatively correlated with the activity of soluble IAO in cytoplasm and ionic bond IAO in cytoderm. While the content of IAA was significantly positively correlate with the activity of POD both during the early and later stage of strawberry fruit development,suggesting that IAO might play the crucial role in oxidized decomposition of IAA,yet POD might involve in the maintaining of dynamic balance of auxin and cooperat with it to promote the fruit development. These might put a substantive foundation to investigate the action mechanism of auxin in the development of strawberry fruits.