Effects Of Drought Stress And Paclobutrazol Treatment Of Lemon Autumn Flower Bud Differentiation

Ruili City,Yunnan Province is an important lemon producing area,where the lemon trees may have three batches of concentrated flowers and fruits one year.The fruit riping in spring is very important.Spring is the fruit off-season and the fruit market has good prospects,and can make up for the domestic market in spring fruit vacancies.But this flower bud differentiates in summer,when it is always hot and rainy.As a result flower bud differentiation is very difficult,and the fruit yield is really low.The aim of this study was to explore the effects of moderating drought stress and paclobutrazol on the physiological,biochemical and related gene expression during the flower bud differentiation of lemon fruit in spring.This is in order to lay the foundation for the regulation and control of the fruit of lemons.The study can also lead the perennial plant flowering mechanism in depth.We can conclude as follow:1.Using the technology of paraffin section is intent to show the process of flower bud differentiation.Then comparing both of the treatment showed that drought stress has accelerated the differentiation process and increased the rate of bud differentiation in a certain extent.Similarly the PP333 treatment could promote the process of flower bud differentiation as well.2.ABA and IAA level which was drought for 15 d,30d and normal managed trees were determined by LC-MS/MS.As a result,15 d water control treatment increased the level of ABA significantly,while maintaining IAA at a low level and reaching a high value of ABA/IAA,which is conducive to flowering while 30 d water stress may lead to lemon plant hormone levels out of balance.3.By means of counting and analyzing the percentage of nutrient branch and flowering branch of control and treatment plants,we can consult that drought stress could significantly increase the proportion of flowering branches and reduce the percentage of nutrient branch.4.Through analyzing the expression profile of drought stress and recovery of water control treatment on lemon autumn flowers by the technology of Transcriptome Resequencing,comparing each of the two groups（Stage₁-vs-Stage₂ 、 Stage₁-vs-Stage₃ 、Stage₂-vs-Stage₃）indicate that the up-regulated genes respectively are 455,395 and 596.While down-regulated genes are 489,291 and 326,respectively.The GO function significant enrichment analysis and Pathway significance enrichment analysis showed that the different expressed genes were distributed throughout all the GO ontology.The largest group of biological processes is the cellular process,the metabolic process and the single-organism process.The largest cell population is the cell and the cell part.While the largest molecular function includes the catalytic activity and binding.Pathway enrichment analysis found thatsecondary metabolite biosynthesis,plant hormone signal transduction,starch and sucrose metabolism and other biological processes have undergone great changes.5.The expression of FT（FLOWERING LOCUS T）,TFL1（TERMINAL FLOWER 1）and BFT（BROTHER OF FT AND TFL1）was studied by real-time fluorescent PCR.The results showed that PP333 could induce FT（FLOWERING LOCUS T）,even when FT（FLOWERING LOCUS T）stop expressing within 1-2 weeks.At the same time this treatment can close the expression of TFL1（TERMINAL FLOWER 1）,BFT（BROTHER OF FT AND TFL1）to promote differentiation.