Department of Vegetable Research, Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, 50250, Bet Dagan, Israel.
The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
Plant Reprod. 2018 Dec;31(4):367-383. doi: 10.1007/s00497-018-0339-0. Epub 2018 Jun 9.
Tomato pollen grains have the capacity for ethylene production, possessing specific components of the ethylene-biosynthesis and -signaling pathways, being affected/responsive to high-temperature conditions. Exposure of plants to heat stress (HS) conditions reduces crop yield and quality, mainly due to sensitivity of pollen grains. Recently, it was demonstrated that ethylene, a gaseous plant hormone, plays a significant role in tomato pollen heat-tolerance. It is not clear, however, whether, or to what extent, pollen grains are dependent on the capacity of the surrounding anther tissues for ethylene synthesis and signaling, or can synthesize this hormone and possess an active signaling pathway. The aim of this work was (1) to investigate if isolated, maturing and mature, tomato pollen grains have the capacity for ethylene production, (2) to find out whether pollen grains possess an active ethylene-biosynthesis and -signaling pathway and characterize the respective tomato pollen components at the transcript level, (3) to look into the effect of short-term HS conditions. Results from accumulation studies showed that pollen, anthers, and flowers produced ethylene and HS affected differentially ethylene production by (rehydrated) mature pollen, compared to anthers and flowers, causing elevated ethylene levels. Furthermore, several ethylene synthesis genes were expressed, with SlACS3 and SlACS11 standing out as highly HS-induced genes of the pollen ethylene biosynthesis pathway. Specific components of the ethylene-signaling pathway as well as several ethylene-responsive factors were expressed in pollen, with SlETR3 (ethylene receptor; named also NR, for never ripe) and SlCTR2 (constitutive triple response2) being HS responsive. This work shows that tomato pollen grains have the capacity for ethylene production, possessing active ethylene-biosynthesis and -signaling pathways, highlighting specific pollen components that serve as a valuable resource for future research on the role of ethylene in pollen thermotolerance.
番茄花粉粒具有产生乙烯的能力，拥有乙烯生物合成和信号转导途径的特定组成部分，并对高温条件有响应。植物暴露于热胁迫（HS）条件下会降低作物产量和质量，主要是因为花粉粒对高温敏感。最近，有研究表明，乙烯作为一种气态植物激素，在番茄花粉耐热性中发挥着重要作用。然而，目前尚不清楚花粉粒是否依赖于周围花药组织合成和信号转导乙烯的能力，或者花粉粒本身是否能够合成这种激素并拥有活跃的信号转导途径。本研究的目的是：（1）研究分离的、成熟的和成熟的番茄花粉粒是否具有产生乙烯的能力；（2）探究花粉粒是否具有活跃的乙烯生物合成和信号转导途径，并在转录水平上鉴定相应的番茄花粉成分；（3）探讨短期 HS 条件的影响。积累研究的结果表明，花粉、花药和花朵都能产生乙烯，HS 对（复水的）成熟花粉的乙烯产生产生了不同的影响，与花药和花朵相比，成熟花粉的乙烯水平升高。此外，有几个乙烯合成基因表达，其中 SlACS3 和 SlACS11 是花粉乙烯生物合成途径中高度诱导的基因。乙烯信号转导途径的特定组成部分和几个乙烯响应因子在花粉中表达，其中 SlETR3（乙烯受体；也称为 NR，意为从不成熟）和 SlCTR2（组成型三重反应 2）对 HS 有响应。本研究表明，番茄花粉粒具有产生乙烯的能力，拥有活跃的乙烯生物合成和信号转导途径，突出了作为未来研究花粉耐热性中乙烯作用的有价值资源的特定花粉成分。
