果实维管束发育及其IAA调控‘库尔勒香梨’宿萼果与脱萼果形成的机制

‘Korla fragrant pear’ with or without calyx directly affect the high quality fruit rate and economic benefit. The development of vascular bundle and IAA are closely related to fruit calyx with or without calyx. but the mechanism has not been elucidated. This project is mainly that the formation of ‘Korla fragrant pear’ with or without calyx is regulated by development of vascular bundle of fruit and IAA. Development of vascular bundle of stalk, core line and sepals in ‘Korla fragrant pear’ with or without calyx were studied, to reveal the correlation of calyx and persistent and vascular bundle. Regularities of distribution and allocation, production site, and transport pathway of IAA of stalk, core line and sepals in ‘Korla fragrant pear’ with or without calyx were analyzed, to reveal the relationship between IAA and dropping calyx in the development of vascular bundle. On the basis of pear genomics, the PIN gene family of IAA transport of ‘Korla fragrant pear’ with or without calyx were screened and analyzed, and genetic transformation and traits of PIN gene in Arabidopsis thaliana were analyzed, to confirm the pear PIN gene involved in the transport of IAA. This project clarify mechanism which sepals of ‘Korla fragrant pear’ drop and persist, provide a theoretical basis for the research and technology for the development of dropping calyx pear.

果实萼片宿存与否决定‘库尔勒香梨’高档优质果率，直接影响经济效益。维管束发育和IAA与果实萼片宿存或脱落的关系密切，但其作用机制尚未明确。因而，本项目以梨果实维管束发育及其IAA的调控为切入点，研究‘库尔勒香梨’宿萼果和脱萼果形成的机制。通过研究‘库尔勒香梨’果柄、果心线和萼片的维管束发育状况，揭示萼片宿存与否和维管束的关系；研究IAA在‘库尔勒香梨’果柄、果心线和萼片维管束的分布和分配规律、产生位点、运输途径，揭示维管束发育过程中IAA与萼片宿存与否的关系；在梨基因组学基础上，进行‘库尔勒香梨’宿萼果与脱萼果IAA转运PIN基因家族筛选、表达分析，并进行拟南芥的遗传转化和性状分析，确定参与转运IAA的梨PIN基因，从而阐明‘库尔勒香梨’萼片的脱落与宿存的机理，为开展梨脱萼技术的研发提供理论依据。

香梨由于受到遗传特性的影响，花期萼片脱落形成脱萼果，萼片宿存则形成宿萼果。脱萼果果实品质显著优于宿萼果，且脱萼果售价高，受消费者欢迎。因此，研究萼片脱落/宿存的机制研究具有重要的意义。通过四年的研究，顺利完成了原计划内容。具体如下：1.萼片脱落与果柄维管束数目呈极显著负相关，与胴部维管束数目、萼筒维管束数目、胴部维管束面积和萼筒维管束面积呈显著负相关；萼筒出现离层脱落形成脱萼果。2. IAA在花期萼片脱落过程中起决定性作用。花后10天IAA含量越高，萼片脱落的难度越大。13C-IAA示踪处理后，第一序位和第四序位的花萼之间总有机碳含量差异不显著。采用免疫胶体金标记定位，第一序位花萼中免疫胶体金颗粒的密度显著高于第四序位的。证明了IAA含量的增加有利于宿萼果形成。3.采用生物信息学分析方法，从梨基因组数据库中筛选鉴定出梨15个PIN基因。采用qRT-PCR技术，鉴定出PbPIN02、PbPIN09和PbPIN11可能在‘香梨’萼筒脱落过程生长素的转运起着较大的作用。喷施IAA会抑制PbPIN基因的表达，喷施TIBA会促进脱萼果中PbPIN02、PbPIN09基因的表达。将PbPIN09基因转入拟南芥，有利于器官脱落。本项目结果研究表明，香梨萼片脱落脱落/宿存与维管束和IAA密切相关，相关研究成果为开展梨脱萼技术的研发提供理论依据。