State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Daizong Street, Tai'an 271018, Shandong, PR China.
Experimental and Teaching Center, Shanxi Agricultural University, Jinzhong 030801, Shanxi, PR China.
Plant Physiol Biochem. 2020 Dec;157:316-327. doi: 10.1016/j.plaphy.2020.10.028. Epub 2020 Oct 29.
Chlorophyll (chl) degradation plays a vital role during green plant growth and development, including nutrient metabolism, fruit and seed maturation, and phototoxic detoxification. STAY-GREEN (SGR) is a plant-specific regulator involved in chl degradation. Previous studies showed that SlSGR1 functioned in chl degradation and lycopene accumulation during fruit ripening of tomato (Solanum lycopersicum). However, little is known about SlSGR-LIKE (SlSGRL) gene, which is a homolog of SlSGR1. We cloned the SlSGRL gene and created transgenic tomato plants overexpressing (OE) SlSGRL. Expression analysis showed that SlSGRL was up-regulated by abscisic acid (ABA). Our data showed that SlSGRL-OE lines exhibited earlier leaf yellowing than wild-type (WT) lines under ABA treatment. Yeast two-hybrid (Y2H) assay revealed that SlSGRL interacted with pheophytin pheophorbide hydrolase (SlPPH) and light-harvesting complex a2 (SlLHCa2) to promote the chl degradation. Further analysis demonstrated that ABA-INSENSITIVE5 (SlABI5) and SlABI5-LIKE regulated SlSGRL expression by directly binding to the sequence (-611 to -582) of the SlSGRL promoter that included an ABRE cis-element. We proposed that SlSGRL, which was regulated by SlABI5/SlABI5-LIKE, mainly acted in ABA-induced chl degradation via interacting with SlPPH and SlLHCa2.
叶绿素（chl）降解在绿色植物的生长和发育过程中起着至关重要的作用，包括营养代谢、果实和种子成熟以及光毒性解毒。STAY-GREEN（SGR）是一种参与chl 降解的植物特异性调节剂。先前的研究表明，SlSGR1 在番茄（Solanum lycopersicum）果实成熟过程中的chl 降解和番茄红素积累中起作用。然而，对于 SlSGR-LIKE（SlSGRL）基因，即 SlSGR1 的同源物，知之甚少。我们克隆了 SlSGRL 基因，并创建了过表达（OE）SlSGRL 的转基因番茄植株。表达分析表明，SlSGRL 受脱落酸（ABA）的上调。我们的数据表明，SlSGRL-OE 系在 ABA 处理下比野生型（WT）系更早出现叶片黄化。酵母双杂交（Y2H）分析表明，SlSGRL 与脱镁叶绿酸 pheophorbide 水解酶（SlPPH）和光捕获复合物 a2（SlLHCa2）相互作用，促进 chl 降解。进一步分析表明，ABA-INSENSITIVE5（SlABI5）和 SlABI5-LIKE 通过直接结合 SlSGRL 启动子序列（-611 至-582）来调节 SlSGRL 的表达，该序列包含一个 ABRE 顺式元件。我们提出，SlSGRL 受 SlABI5/SlABI5-LIKE 调控，主要通过与 SlPPH 和 SlLHCa2 相互作用，在 ABA 诱导的 chl 降解中起作用。
