Physiological And Transcriptomics Studies Of Bougainvillea Flower Induced By Light And Water Control

Technical measures such as water control and light control are widely used in the regulation of flowering of bougainvillea.However,the flowering mechanism behind these technologies is still poorly understood,and the physiological changes and the expression of related genes in the process of flower bud formation are still unclear.In this paper,light control,water control and light + water control were used to induce flowering of potted bougainvillea,and their effects on flowering period and flowering quality were analyzed.The physiological changes during flower bud formation were analyzed.The differential expression profile of terminal bud transcriptome during flower induction was constructed by high-throughput sequencing,and the flowering related genes of bougainvillea were analyzed and mined.The main results are as follows:1.Light control,water control and light + water control treatments can effectively induce the rapid formation of flower buds and early flowering of bougainvillea.The flower bud formation time is 119,103 and 96 days earlier than that of the control group,respectively.And the flowering period is 11,9 and 6 days longer than that of the control group,respectively.Among them,light control treatment is easy to cause bracts to become smaller in size and lighter in color,but the number of flowers increases and the uniformity of flowers is higher;Water control treatment could make bracts larger,but the number of flowers decreased;Light control + water control treatment can effectively improve the problems of smaller bracts and lighter color in light control treatment and the reduction of flowering number in water control treatment.2.Gibberellin(GA),abscisic acid(ABA),auxin(IAA)and ethylene synthesis precursor ACC(1-Aminocyclopropyl-1-carboxylic acid)all accumulated rapidly during flowering induced by light control,water control and light + water control,and the increase of their content was positively correlated with the formation of flower buds.Light control,water control and light + water control treatments can induce the accumulation of soluble protein and promote flower bud formation while reducing the content of chlorophyll.Water control and light + water control treatments have a certain degree of damage to the plant as stress.3.Through high-throughput sequencing,the differential expression profiles of the transcriptome of shoot tip buds of bougainvillea during light control,water control and light + water control induced flowering were successfully constructed.Light control,water control and light + water control all caused a large number of genes to be differentially expressed compared with the control group during flower induction,among which light control for 15 days,water control for 3 days and 38 days were the most significant,with 2690,4180 and 5970 differential genes,respectively.These differential genes are mainly concentrated in the interaction between plants and pathogens,plant hormone signal transduction,phenylpropane synthesis,starch and glucose metabolism.4.Fifteen flowering related genes and 23 transcription factors were screened,including flowering related genes FT(FLOWERING LOCUS T)、FD(FLOWERING LOCUS D)、GI(GIGANTEA)、COL(CONSTANS-LIKE),and transcription factors NAC29、WRKY28、ERF5、ANT、PIF7、PIF7-like etc.that may be involved in the regulation of photoperiod-induced flower formation.