TaER调控小麦蒸腾效率和抗旱耐热性的功能研究

Drought is one of the main limiting factors for wheat growth, development and yield. The increase of wheat production in the limited water condition is of great Increasing the transpiration efficiency and stress resistance of wheat is very important to the stability and improvement of wheat production. ER gene, regulating the formation and differentiation of plant organs, and play an important role on plant transpiration efficiency and stress resistance. So, we cloned the wheat ER gene, and found that TaER is also an key gene on transpiration efficiency in wheat by the expression and VIGS analysis. For further analysis of the function of TaER, the 8 transgenic overexpression lines will be used to understand the biological basis of TaER on wheat transpiration efficiency and its effects on drought or heat resistance. Additionally, the cultivar which have distinctive different TaER expression patterns was used to search the excellent alleles and develop specific markers for check these alleles. This study will promote the analysis of the regulatory mechanism on wheat transpiration efficiency and drought or heat resistance, and providing an effective tool for drought and heat resistance molecular design breeding of wheat.

干旱缺水严重制约着小麦生产的稳定和提高。提高小麦蒸腾效率及抗逆性是促进小麦生产可持续发展的关键。ER基因可调控植物器官的形成和分化，在调控蒸腾效率及抗逆防御反应中发挥着重要作用。因此，项目组克隆了小麦TaER基因，通过表达分析和VIGS分析，发现TaER基因也是调控小麦蒸腾效率的关键基因。为了进一步研究TaER基因的功能，项目组拟利用已获得的过表达TaER基因的12个小麦株系，进一步分析TaER调控小麦蒸腾效率的生物学基础及其调控抗旱耐热性的功能，明确其利用价值；进而通过TaER基因表达差异显著的小麦极端基因型材料，挖掘TaER基因的优异位点，建立鉴定TaER基因优异位点的技术。本研究将促进小麦蒸腾效率和抗旱耐热性的调控机制研究，为小麦抗旱、耐热分子设计育种提供有效工具。

通过对小麦TaER基因的过表达株系及其野生型在抗旱棚连续进行了3年的干旱与热胁迫处理，相关的生理及农艺性状的测定，及干旱和热胁迫后的转录组进行分析，初步解析了小麦TaER基因调控蒸腾效率和抗旱及耐热的功能，进而发掘了小麦TaER基因的3个关键拷贝的的优势位点。研究结果表明：（1）在正常灌水下，TaER过表达增加了小麦旗叶的长度和宽度，增大了旗叶面积，降低了气孔密度，同时提高了叶片的最大羧化速率（Vcmax）和最大电子传递速率（Jmax），进而提高了光合速率和气孔导度，降低了蒸腾速率。（2）在干旱胁迫下，TaER1_BS过表达也增加了小麦旗叶的气孔导度，提高了光合速率，降低了蒸腾速率；提高了过氧化物酶（CAT）和过氧化氢酶（POD）活性；进而提高了单株成穗数，单株生物量和单株产量，提高了小麦抗旱性。（3）在热胁迫下，TaER1_BS过表达提高了光合速率，蒸腾速率也显著增加，但对水分利用效率及农艺性状均有一定的不利效应，需要进一步深入分析。（4）对干旱和热胁迫下的转录组分析表明，在干旱胁迫下，响应热及非生物胁迫等相关途径的基因大量上调表达；在热胁迫下，大量与叶绿体及光合作用相关途径的基因上调表达，在干旱与热双胁迫下，很多与转录因子活性相关基因受到上调表达。这些结果表明，TaER的过表达可能是通过上调与光合作用、抗逆相关的转录因子的表达，进而调控小麦的抗旱性及耐热性。（5）依据对12个TaER表达和CID极端差异小麦的重测序分析检测到的TaER基因的SNP和Indel多态性位点，开发了分别检测TaER2_BL、TaER1_BS和TaER1_DS单倍型的3个CAPS标记，初步分析表明，可以用于TaER基因的优异单倍型的发掘和辅助育种。（6）对267个小麦品种组成的自然群体籽粒的CID值的GWAS分析，鉴定到了44个与CID显著相关的QTNs，发掘了新的调控小麦蒸腾效率的候选基因位点。这些研究结果为利用TaER基因改良小麦的蒸腾效率，及抗旱性和耐热性奠定了坚实基础。