Savada Raghavendra P, Ozga Jocelyn A, Jayasinghege Charitha P A, Waduthanthri Kosala D, Reinecke Dennis M
Plant BioSystems Division, Department of Agricultural, Food and Nutritional Science, 4-10 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada.
Plant Mol Biol. 2017 Oct;95(3):313-331. doi: 10.1007/s11103-017-0653-1. Epub 2017 Aug 31.
Ethylene biosynthesis is regulated in reproductive tissues in response to heat stress in a manner to optimize resource allocation to pollinated fruits with developing seeds. High temperatures during reproductive development are particularly detrimental to crop fruit/seed production. Ethylene plays vital roles in plant development and abiotic stress responses; however, little is known about ethylene's role in reproductive tissues during development under heat stress. We assessed ethylene biosynthesis and signaling regulation within the reproductive and associated tissues of pea during the developmental phase that sets the stage for fruit-set and seed development under normal and heat-stress conditions. The transcript abundance profiles of PsACS [encode enzymes that convert S-adenosyl-L-methionine to 1-aminocyclopropane-1-carboxylic acid (ACC)] and PsACO (encode enzymes that convert ACC to ethylene), and ethylene evolution were developmentally, environmentally, and tissue-specifically regulated in the floral/fruit/pedicel tissues of pea. Higher transcript abundance of PsACS and PsACO in the ovaries, and PsACO in the pedicels was correlated with higher ethylene evolution and ovary senescence and pedicel abscission in fruits that were not pollinated under control temperature conditions. Under heat-stress conditions, up-regulation of ethylene biosynthesis gene expression in pre-pollinated ovaries was also associated with higher ethylene evolution and lower retention of these fruits. Following successful pollination and ovule fertilization, heat-stress modified PsACS and PsACO transcript profiles in a manner that suppressed ovary ethylene evolution. The normal ethylene burst in the stigma/style and petals following pollination was also suppressed by heat-stress. Transcript abundance profiles of ethylene receptor and signaling-related genes acted as qualitative markers of tissue ethylene signaling events. These data support the hypothesis that ethylene biosynthesis is regulated in reproductive tissues in response to heat stress to modulate resource allocation dynamics.
乙烯生物合成在生殖组织中受到热胁迫的调节，其方式是优化对有发育中种子的授粉果实的资源分配。生殖发育期间的高温对作物果实/种子生产特别有害。乙烯在植物发育和非生物胁迫反应中起着至关重要的作用；然而，关于乙烯在热胁迫下发育过程中在生殖组织中的作用却知之甚少。我们评估了在正常和热胁迫条件下，豌豆生殖及相关组织中乙烯生物合成和信号调节，该发育阶段为坐果和种子发育奠定了基础。豌豆花/果实/果柄组织中，PsACS（编码将S-腺苷-L-甲硫氨酸转化为1-氨基环丙烷-1-羧酸（ACC）的酶）和PsACO（编码将ACC转化为乙烯的酶）的转录本丰度谱以及乙烯释放量在发育、环境和组织特异性方面受到调节。在对照温度条件下未授粉的果实中，卵巢中PsACS和PsACO的转录本丰度较高，果柄中PsACO的转录本丰度较高，这与较高的乙烯释放量以及卵巢衰老和果柄脱落相关。在热胁迫条件下，授粉前卵巢中乙烯生物合成基因表达的上调也与较高的乙烯释放量和这些果实的较低保留率相关。成功授粉和胚珠受精后，热胁迫以抑制卵巢乙烯释放的方式改变了PsACS和PsACO的转录本谱。热胁迫也抑制了授粉后柱头/花柱和花瓣中正常的乙烯爆发。乙烯受体和信号相关基因的转录本丰度谱作为组织乙烯信号事件的定性标记。这些数据支持了以下假设：乙烯生物合成在生殖组织中受到热胁迫的调节，以调节资源分配动态。
