Effect And Regulation Mechanism Of Exogenous Hormones On Flowering And Fruiting In Common Buckwheat

Common Buckwheat has the effects of lowering cholesterol,blood sugar,blood lipids and other medicinal health benefits,possessing high development value and good market prospect.Due to the low yield and low economic benefit of common buckwheat,the rapid development of buckwheat industry is seriously limited.The most effective way to increase yield is improving the seed setting rate.In this study,exogenous hormones PP333 and 6-BA were used to treat at the stages of seedling,bud and full bloom.Screening out the optimal treatment period and concentration of exogenous hormones.First of all,the processes of flower bud differentiation and floret development were observed,the endogenous hormone content,photosynthetic parameters and dry matter content of different organs were determined.Secondly,RNA-seq technique was used to search for differential genes regulating flowering and fruiting of common buckwheat with exogenous hormones,and qRT-PCR was used to verify the differential gene expression of flowering and fruiting.The regulation mechanism of exogenous hormones PP333 and 6-BA on the flowering and fruiting of common buckwheat was revealed from the morphological,physiological and molecular levels.The main results are as follows:1.Both PP333 and 6-BA could increase the seed setting rate and yield,At the second true leaf stage,bud stage and full bloom stage,100mg·L-1 of PP333and 150mg·L-1 of 6-BA increasedthe yield by 31.8%and 16.5%,compared with the control,and the seed setting rate was increased by the percentage points were 5.4 and 3.1 compared with control,respectively.PP333 and 6-BA could increase the number of fruiting per plant,but PP333 reduced the number of flowers per plant,and 6-BA increased the number of flowers per plant.2.PP333 and 6-BA could accelerate the flower bud differentiation process,making the flowering time advance.Flower bud differentiation was divided into five stages,and it was found that there was a clear correspondence between the flower bud differentiation period and the true leaf emergence time,clearly proving that the second true leaf stage was the critical period that affected the number of flowering and flowering time of common buckwheat.3.Spraying PP333 and 6-BA can increase pollen fertility rate and stigma receptivity.Pollen fertility rate and stigma receptivity reached their highest at 10 a.m.when treated with PP333,and at 8 a.m.when treated with 6-BA.6-BA increased pollen fertility rate and stigma receptivity by 4.4%and 50%.PP333increasedpollen fertility rate and stigma receptivity by 5.0%and 36.9%.4.Transcriptome sequencing results:a total of 400,149 Unigenes were obtained,among which 26,877 Unigenes were annotated in the seven major databases,accounting for 6.71%of the total Unigenes.Twenty significantly differentially expressed genes related to the flowering of common buckwheat were screened,and 12 genes were involved in the photoperiod regulation pathway.Ten differentially expressed genes were randomly selected and verified by real-time PCR,proving that the RNA-seq sequencing results were reliable.Including FT/ELF3/PIF3FKF1/PHYA/PHYB/CHS/ARF/LHY/GIDI.5.The FT and ELF3 genes are related to the flowering time and flowering number of common buckwheat.Spraying PP333 and 6-BA increased the expression of FT and decreased the expression of ELF3 at the second true leaf stage and the bud stage,all ofwhich caused the flowering time to advance.However,PP333 decreased the expression of FT and increased the expression of ELF3 during the full flowering stage,the number of flowering per plant decreased;6-BA increased the expression of FT,decreased the expression of ELF3,and increased the number of flowering per plant.These results indicated that the FT and ELF3 genes regulate the flowering time of common buckwheat in the early stage of bud,and regulate the number of flowering in the flowering stage.6.Spraying PP333and6-BA regulated the flowering and fruiting process of common buckwheat by changing endogenous hormone content and phytochrome gene expression.It could regulate and accelerate flower bud differentiation,increase photosynthetic rate and dry matter of different organs of common buckwheat by PP333 increasing GA3 content,IAA content,and increasing PHYA and PIF3 expression levels or 6-BA increasing GA3 content,reducing ABA content,and increasing PHYA expression levels.