摘要
[目的]本研究旨在解析细胞分裂素受体基因SlHK4突变对番茄开花时间的影响,为揭示细胞分裂素途径调控植物开花的分子机制奠定基础。[方法]以细胞分裂素受体基因SlHK4的2个纯合突变株系slhk4-4和slhk4-5及野生型(WT)番茄为材料,统计各株系开花时间,并在发芽26 d后取植株茎尖进行石蜡切片显微观察、响应细胞分裂素的荧光信号检测以及转录组测序等分析。[结果]slhk4-4和slhk4-5突变体的始花节位与WT相同,但始花时间分别比WT晚6和4 d。与WT相比,slhk4-5茎尖花分生组织分化推迟,细胞显著减小,细胞数目略少;slhk4-4与细胞分裂素响应启动子TCSn驱动的绿色荧光蛋白基因GFP过表达株系的杂交F 1代茎尖中,响应细胞分裂素的GFP荧光信号显著减弱;slhk4-5茎尖中细胞周期正调控基因Cyclin-B1-2表达下调,开花正调控基因FUL2、SOC1表达上调,而花发育基因AGL12和AGL19表达下调,开花调控相关基因的表达变化趋势与slhk4-5开花推迟的性状变化不完全一致。差异表达基因(DEG)的功能分析显示,57.6%具有功能注释的DEG是富集于光合作用、呼吸作用、蛋白合成和代谢等相关通路中的结构基因,其中88.2%在slhk4-5茎尖中的表达下调,表明slhk4茎尖的细胞活性很可能弱于WT。[结论]细胞分裂素受体SlHK4的功能缺失导致slhk4茎尖细胞分裂素信号减弱,花分生组织细胞减小,活性降低,分化延后,进而导致slhk4开花推迟。SlHK4是番茄开花时间的正调控因子。
[Objectives]This study aimed to analyze the effects of mutation of cytokinin receptor gene SlHK4 on flowering time of tomato,and to lay a foundation for elucidating molecular mechanisms of the regulation of cytokinin pathways on plant flowering.[Methods]Two homozygous mutant lines slhk4-4 and slhk4-5 of cytokinin receptor gene SlHK4 and wild-type(WT)tomato plants were used as materials.The flowering time of each line was analyzed.The shoot apexes of plants at 26 days after germination were analyzed by microscopic observation of paraffin sections,detection of cytokinin-responsive fluorescence signals and transcriptome sequencing.[Results]slhk4-4 and slhk4-5 mutant plants had the same number of internodes as WT plants when the first flowers opened,but the time from germination to flowering for slhk4-4 and slhk4-5 was 6 and 4 days later than WT plants,respectively.Compared with WT plants,the differentiation of slhk4-5 floral meristem was delayed;the sizes of cells in the slhk4-5 floral meristems decreased significantly while the cell number was slightly smaller;and the cytokinin-responsive fluorescence signals were significantly reduced in the shoot apexes of the F 1 hybrids of slhk4-4 and the transgenic line with a GFP gene driven by the cytokinin-sensor promoter TCSn.In the slhk4-5 shoot apexes,expression of Cyclin-B1-2,a positive regulatory gene for cell cycle,was down-regulated;the expression of FUL2 and SOC1,positive regulatory genes for flowering,was up-regulated,while expression of floral homeotic genes AGL12 and AGL19 was down-regulated,in comparison to those in WT shoot apexes.The expression variation trends of the genes related to flowering regulation were not completely consistent with the trait change of slhk4-5 with delayed flowering time.The functional analyses of differentially expressed genes(DEG)showed that 57.6%of the DEG with functional annotation were structural genes enriched in the pathways related to photosynthesis,respiration,protein synthesis and metabolism,etc.Therein,88.2%of these DEG show
作者
刘艳洁
赵晓冰
王枫
丁静
LIU Yanjie;ZHAO Xiaobing;WANG Feng;DING Jing(State Key Laboratory of Crop Genetics&Germplasm Enhancement and Utilization/College of Horticulture,Nanjing Agricultural University,Nanjing 210095,China)
出处
《南京农业大学学报》
CAS
CSCD
北大核心
2024年第3期424-434,共11页
Journal of Nanjing Agricultural University
基金
国家自然科学基金项目(31972371)
江苏高校优势学科建设工程项目。
