The Preliminary Study On Anatomical Physiology And Molecular Basis Of Florescence Regulation On Kernel-Apricot

Kernel-apricot is an important economic forest tree species in the three north (for northwest China, north China, and northeast China) in China. It’s one of the six major nuts in the world, and also important woody oil species, Kernel-apricot including sweet kernel-apricot and bitter kernel-apricot, the planting area is more than 30millions mu, and to be the economic tree species which get impoverished mountainous area rich. But in the production due to the short period of dormancy, early flowering, flowers are vulnerable to late frost damage, often result in production cuts, even become the bottleneck of Kernel-apricot industry development. This paper carrying out a research which focus on kernel-apricot within the flower bud morphological differentiation and dormancy characteristic into the system, tries to reveal its flowering anatomical physiology and molecular basis, which can provide important theoretical basis for delaying flowering and avoiding the late spring chilling. The main results were as follows:1. Reveal the kernel-apricot named’Youyi’s relationship between the early blooming time and flower bud morphological differentiation starting time. Kernel-apricot’s main species’Youyi’flower bud differentiation’s characteristic is that in the middle of July start the flower bud differentiation, the fast differentiation from late July to mid-August, early September to female, stamen differentiation stage, then, the petals, calyx in the flower bud still growing, the female and stamen primordium further tissue differentiate. Kernel-apricot is earlier than ordinary peach on blossom time 15-30 days, flower bud differentiation of starting time is earlier than ordinary peach around 15 days, so the starting time of the flower bud morphological differentiation and the kernel-apricot flowering time have a close relationship.2. The time of kernel-apricot’s sex organs differentiation and sex cells development are impact on flowering time. Kernel-apricot’s sex organs differentiation starts before dormancy and completes after dormancy release.While the time on most of the flower bud differentiation of deciduous fruit trees was the summer, autumn of last year, completed the morphological differentiation before winter, and after dormancy release, sex organs starts differentiation then flowering in the second year. ’Youyi’ ovule formation is after the endodormancy breaking, but ’Longwangmao’ ovule forms before the endodormancy, and ’Youyi’ male gametophyte development is later than ’Longwangmao’ around 15 days, ’Youyi’ flowering time is later than ’Longwnagmao’ about 2-3 days, it’s cold resistance of flower is better than ’Longwangmao’. So the time of male and female gametophyte development may be closely related to flowering time and cold resistance. Compared to the result of Jiangfeixue’s research on the ornamental peach flower bud differentiation process is also found that the time of sex cells’ development take decisive role in the florescence.3. The relations between short endo-dormancy and early flowering for kernel-apricot. In Henan YuanYang, during 26 December 2014 to January 30, the most of ’Youyi’ buds growth stagnation, this period is confirmed to be in the endo-dormancy for kernel-apricot and the chilling requirement is about 720 h, which is much less than ordinary peach in the Yangtze river basin and north China plain. So the period of kernel-apricot endo-dormancy is shorter and flowering earlier in compared with ordinary peach. Compared kernel-apricot dormant bud in the change trend of endogenous hormones with ordinary peach and found that ’Youyi’ starts breaking endo-dormancy on February 5, while ordinary peach to begin endo-dormancy releasing after February 25. Obviously, peach endo-dormancy breaking time is later than kernel-apricot’s, which is fit to the result that kernel-apricot flowering time is earlier than ordinary peach around 15～30days, also explain the physiological characteristics of short endo-dormancy and early flowering.4. The relationship between differentially expressed genes about kernel-apricot dormant bud and early flowering. The research on the key gene expression patterns of some biological control approaches such as environment response, hormones response, moisture response, energy metabolism, cell development about the kernel-apricot dormant bud in different periods, and found that the moisture response related genes of kernel-apricot, such as TIP expression pattern is different from peach, the high expression is not in the time of endo-dormancy breaking, but raise expression in the early endo-dormancy stage. It may be a response to cold stress, and help to remove accumulation of H2O2, thus promoting the dormancy breaking. So TIP gene abundantly expressed in the early endo-dormancy stage may have certain relationship with kernel-apricot flowering time. PPA4 expression patterns is in agreement with the peach, but there are 5 PPA1 expression patterns which are different from peach, Kernel-apricot bloom earlier than ordinary peach, that may be the function of H+-ATPase whose expression was raised in dormant. It may prepare energy in advance for dormancy breaking which speeding up the dormancy breaking process and make the flower bud early flowering.Above all, kernel-apricot bloom early that is related to flower bud morphological differentiation starting time, the time of sex organs and sexual cells formation, and the short period of endo-dormancy. At the molecular level, some genes related to moisture response and energy metabolism are expression earlier in the process of dormancy, help to remove accumulation of H2O2 and prepare energy in advance for dormancy breaking which speeding up the dormancy breaking process, which can make flower buds blooming early. This sthudy result can lay the foundation for regulating flower bud differentiation and dormancy, and provide important theoretical basis for achieving delay flowering time of kernel-apricot.