Primary Studies On The Relationship Between Flower Bud Differentation-Bolting And Endogenous Hormones In Radish (Rapanus Sativus L.)

Flower bud differentation is the base of flowering and is the symbol of the transition from vegetative to reproductive development. Stem elongation begins in the midway going with flower bud differentiation and development and is closely relative to it. The involvement of plant endogenous hormones in the control of flowering has been studied on various plants.Recently, more and more investigations are focused on the mechanism of vernalization and flower bud differentiation and bolting.The method of ELISA was used to analyze the endogenous hormones including gibberellin(GA4), indole acetic acid(IAA), isopentenyl adenin(iPA) and abscisic acid (ABA) during the process of bolting in spring Tadish(Raphanus sativus L.). The results indicated that obvious peak value of GA₄ content occured at bud emergening point;The ABA and GA₄ had the similar changing trends; The IAA content of the leaves was relatively low; The content of iPA increased little by little at bud emergening period and had a peak value in the later bolting period. The conclusions also demonstrated that balanced endogenous hormones play a more important role than any single endogenous hormone in the bolting process. The high proportion of iPA/ABA and low proportion between GA₄/iPA,GA₄/IAA were beneficial to the flower bud differention.To obtain high-resolution MSAP pattern, the MSAP system was optimized with key factors and applied to access the DNA methylation patterns in the flower bud differentiation and bolting. The changes of genomic DNA methylation in the process of bolting were prelimimarily studied by 18 primer combinations in radish(NAULbsg-2003-6). The results indicated that DNA methylation level decreased in the early period, and increased gradually with stem elongation in the process of bolting. The full methylation of the internal cytosines was always higher than hemi-methylation of cytosine during each stage.The extent and pattern of cytosine methylation during flower bud differentiation was evaluated in 'Duanye NO. 13'. We found that the level of DNA methylation was higher in dry seeds (30.2%) than in leaves, and in the course of flower bud differentiation, the DNA methylation level of leaves had a trend of increase (14.7%<16.6%<16.9%<17.5%) by 18 primer combinations. Moreover, both new de novo methylation and de-methylation change...