Abstract Heat-induced leaf senescence may be regulated by nitrogen or nitrogen-enriched amino acids. The objectives of the current study were to examine whether exogenous application of у-aminobutyric acid (GABA), proline, and ammonium nitrate (N) could alleviate heat-induced leaf senescence in creeping bentgrass (Agrostis stolonifera L.) and to determine whether the effects of GABA, proline, and N on heat-induced leaf senescence were associated with the alteration of chlorophyll (Chl) metabolism. Plants were exposed to heat stress (35/30 °C, day/night) or non-stress (22/18 °C, day/night) temperature conditions for 35 d in controlled-environment growth chambers. Turf quality, Chl content, and photochemical efficiency declined whereas the activities of Chl-degrading enzymes (chlorophyllase and pheophytinase) increased in response to heat stress. Application of GABA, proline, or N significantly enhanced turf quality, Chl content, and photochemical efficiency, and suppressed Chl-degrading enzyme activities under heat stress. The activity of a Chl-synthesizing enzyme (porphobilinogen deaminase) was not affected by GABA, proline, or N application. These results indicate that heat-induced leaf senescence could be mainly due to heat-accelerated Chl degradation, and GABA, proline, or N could suppress Chl degradation, alleviating heat-induced leaf senescence in creeping bentgrass.

中文翻译：

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γ-氨基丁酸、脯氨酸和硝酸铵通过调节匍匐翦股颖叶绿素降解抑制热诱导的叶片衰老

摘要 热诱导的叶片衰老可能受氮或富氮氨基酸的调控。本研究的目的是检查外源施用 γ-氨基丁酸 (GABA)、脯氨酸和硝酸铵 (N) 是否可以减轻匍匐翦股颖 (Agrostis stolonifera L.) 热诱导的叶片衰老，并确定GABA、脯氨酸和 N 对热诱导的叶片衰老的影响与叶绿素 (Chl) 代谢的改变有关。植物在受控环境生长室中暴露于热应激（35/30°C，白天/黑夜）或非应激（22/18°C，白天/黑夜）温度条件下 35 天。草坪质量、叶绿素含量和光化学效率下降，而叶绿素降解酶（叶绿素酶和脱镁叶绿素酶）的活性随着热应激而增加。施用 GABA、脯氨酸或 N 可显着提高草坪质量、Chl 含量和光化学效率，并抑制热胁迫下 Chl 降解酶的活性。Chl 合成酶（胆色素原脱氨酶）的活性不受 GABA、脯氨酸或 N 应用的影响。这些结果表明，热诱导的叶片衰老可能主要是由于热加速了 Chl 的降解，而 GABA、脯氨酸或 N 可以抑制 Chl 的降解，缓解热诱导的匍匐翦股颖叶片衰老。