Variation of endobenous phytohormone in functional male and bisexual flowers of pomegranate (Punica granatum L.) during development

摘要

Pomegranate have two types of flowers: bisexual flower and functional male flower. Flower development is a complex process which is regulated by an intricate transcriptional regulatory network. To understand the molecular mechanisms of regulating flower development and female sterility in pomegranate, we performed a comprehensive analysis of endogenous phytohormone changes during flower differentiation. Plant hormones, such as indole-3-acetic acid (IAA), zeatin riboside (ZR), gibberellin (GA), jasmonic acid (JA), and abscisic acid (ABA) contents in the pomegranate flowers were measured to expound the relationship between floral differentiation and endogenous hormones by ELISA. The results showed that the high accumulations of ABA, GA, and high ratio of ABA/ZR in bisexual flower primordium might stimulate the sterility of ovary and promote the development of stamen organ, which led to functional male flower. Moreover, low levels of IAA in functional male flower from S6 to S8 might accelerate the development of stamen and the abortion of pistil, and low levels of the ABA/GA ratio at S3 and S6 might also promote the development of the male organ. Also, ZR and JA had a similar accumulation tendency, low levels of ZR and JA might contribute to the male organ development in the late period of bud development. ZR had significant positive correlation with JA (p0.05) in both bisexual and functional male flowers. With the above conclusions, ABA, GA and the ratio of ABA/ZR played determinant roles in the abortion of pistils of pomegranate. Under the premise of the bisexual stages which are identical in functional male flower and bisexual flower, specific hormones conditions are the key to the pomegranate flower sex determination.