Transcriptomic and metabolomic analysis of changes in grain weight potential induced by water stress in wheat

干旱胁迫促进小麦粒重潜力形成的转录和代谢分析

Yanmei Gao1, 3, Maoya Jing1, Meng Zhang1, Zhen Zhang2, Yuqing Liu2, Zhimin Wang2#, Yinghua Zhang2#

1 School of Life Science, Shanxi Normal University, Taiyuan 030031, China

2 College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China

3 Ministerial and Provincial Co-Innovation Centre for Endemic Crops Production with High-quality and Efficiency in Loess Plateau, Taigu 030801, China

摘要  

小麦子房发育的库强决定了粒重潜力。从孕穗到籽粒建成期是子房生长发育和潜在库强决定的关键时期。然而，水分胁迫下，小麦植株在这一时期如何平衡和协调小花数和子房/籽粒重的潜在调控机制尚不清楚。因此，我们设计了W0（生长季不灌溉）和W1（拔节期灌溉75 mm）两个灌溉处理，从表型、代谢和转录组水平分析了小麦子房/籽粒重对水分胁迫的响应。结果表明，W0处理降低了土壤含水量、株高和旗叶叶面积，从而减少了粒数，尤其是弱势粒的粒数，但是提高了强势粒和弱势粒的粒重以及成熟期籽粒的平均粒重，与此同时，花前3天到花后10天子房/籽粒的重量和体积也都增加了。转录组分析表明，W0处理显著促进了蔗糖代谢和植物激素信号转导相关基因的表达，并导致可溶性酸转化酶（SAI）和蔗糖合酶（Sus）活性以及脱落酸）（ABA）和吲哚-3-乙酸（IAA）水平升高，因此蔗糖含量降低，葡萄糖和果糖含量增加。此外，在W0处理下，花前几个TaTPP基因（尤其是TaTPP-6）下调，IAA生物合成基因TaTAR1和TaTAR2上调，这进一步提高了IAA水平。总的来说，水分胁迫减少了营养器官的生长，导致大部分弱势粒退化，但是提高了存活的子房/籽粒的ABA和IAA水平，提升了Sus酶的活性，将蔗糖降解为葡萄糖和果糖。由此可见，在水分胁迫下，较强的蔗糖利用能力，增强的SAI酶活性以及ABA和IAA介导的信号转导共同提高了小麦存活子房/籽粒的重量和体积，最终实现了子房/籽粒重和粒数之间的平衡。

Abstract  

The sink strength of developing ovaries in wheat determines the grain weight potential.  The period from booting to the grain setting stage is critical for ovary growth and development and potential sink capacity determination.  However, the underlying regulatory mechanism during this period by which the wheat plant balances and coordinates the floret number and ovary/grain weight under water stress has not been clarified.  Therefore, we designed two irrigation treatments of W0 (no seasonal irrigation) and W1 (additional 75 mm of irrigation at the jointing stage) and analyzed the responses of the ovary/grain weight to water stress at the phenotypic, metabolomic, and transcriptomic levels.  The results showed that the W0 irrigation treatment reduced the soil water content, plant height, and green area of the flag leaf, thus reducing grain number, especially for the inferior grains.  However, it improved the grain weight of the superior and inferior grains as well as average grain weight at maturity, while the average ovary/grain weight and volume during –3 to 10 days after anthesis (DAA) also increased.  Transcriptomic analysis indicated that the genes involved in both sucrose metabolism and phytohormone signal transduction were prominently accelerated by the W0 treatment, accompanied by greater enzymatic activities of soluble acid invertase (SAI) and sucrose synthase (Sus) and elevated abscisic acid (ABA) and indole-3-acetic acid (IAA) levels.  Thus, the sucrose content decreased, while the glucose and fructose contents increased.  In addition, several TaTPP genes (especially TaTPP-6) were down-regulated and the IAA biosynthesis genes TaTAR1 and TaTAR2 were up-regulated under the W0 treatment before anthesis, which further increased the IAA level.  Collectively, water stress reduced the growth of vegetative organs and eliminated most of the inferior grains, but increased the ABA and IAA levels of the surviving ovaries/grains, promoting the enzymatic activity of Sus and degrading sucrose into glucose and fructose.  As a result, the strong sucrose utilization ability, the enhanced enzymatic activity of SAI and the ABA- and IAA-mediated signaling jointly increased the weight and volume of the surviving ovaries/grains, and ultimately achieved the trade-off between ovary/grain weight and number in wheat under water stress.

全文链接：https://www.sciencedirect.com/science/article/pii/S2095311923004628

Journal of Integrative Agriculture (《农业科学学报》(英文), JIA) 由中华人民共和国农业农村部主管，中国农业科学院与中国农学会主办，中国农业科学院农业信息研究所承办。综合性英文学术期刊，月刊。创刊于2002年，现任主编为中国科学院院士陈化兰。JIA主要栏目有作物科学、园艺、植物保护、动物科学、动物医学、农业生态环境、食品科学、农业经济与管理等。刊稿类型有综述、研究论文、简报以及评述等。全部论文在Elsevier-ScienceDirect (SD) 平台OA出版。最新SCI影响因子4.6，位于SCI-JCR农业综合学科Q1区。中国科学院分区农林科学1区。2016年以来先后获得中国科协等部委 “提升计划”“登峰计划”“卓越计划”项目支持。