Nakano Toshitsugu, Fujisawa Masaki, Shima Yoko, Ito Yasuhiro
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan
J Exp Bot. 2014 Jul;65(12):3111-9. doi: 10.1093/jxb/eru154. Epub 2014 Apr 17.
In plants, abscission removes senescent, injured, infected, or dispensable organs. Induced by auxin depletion and an ethylene burst, abscission requires pronounced changes in gene expression, including genes for cell separation enzymes and regulators of signal transduction and transcription. However, the understanding of the molecular basis of this regulation remains incomplete. To examine gene regulation in abscission, this study examined an ERF family transcription factor, tomato (Solanum lycopersicum) ETHYLENE-RESPONSIVE FACTOR 52 (SlERF52). SlERF52 is specifically expressed in pedicel abscission zones (AZs) and SlERF52 expression is suppressed in plants with impaired function of MACROCALYX and JOINTLESS, which regulate pedicel AZ development. RNA interference was used to knock down SlERF52 expression to show that SlERF52 functions in flower pedicel abscission. When treated with an abscission-inducing stimulus, the SlERF52-suppressed plants showed a significant delay in flower abscission compared with wild type. They also showed reduced upregulation of the genes for the abscission-associated enzymes cellulase and polygalacturonase. SlERF52 suppression also affected gene expression before the abscission stimulus, inhibiting the expression of pedicel AZ-specific transcription factor genes, such as the tomato WUSCHEL homologue, GOBLET, and Lateral suppressor, which may regulate meristematic activities in pedicel AZs. These results suggest that SlERF52 plays a pivotal role in transcriptional regulation in pedicel AZs at both pre-abscission and abscission stages.
在植物中，脱落作用会去除衰老、受损、受感染或多余的器官。脱落由生长素耗尽和乙烯爆发诱导，需要基因表达发生显著变化，包括细胞分离酶基因以及信号转导和转录调节因子基因。然而，对这种调节的分子基础的理解仍不完整。为了研究脱落过程中的基因调控，本研究检测了一个ERF家族转录因子，即番茄（Solanum lycopersicum）乙烯响应因子52（SlERF52）。SlERF52在花梗脱落区（AZs）特异性表达，并且在调节花梗AZ发育的MACROCALYX和JOINTLESS功能受损的植物中，SlERF52的表达受到抑制。采用RNA干扰技术敲低SlERF52的表达，以表明SlERF52在花柄脱落中发挥作用。用脱落诱导刺激处理时，与野生型相比，SlERF52抑制型植株的花脱落显著延迟。它们还表现出脱落相关酶纤维素酶和多聚半乳糖醛酸酶基因上调减少。SlERF52抑制还影响脱落刺激前的基因表达，抑制花梗AZ特异性转录因子基因的表达，如番茄WUSCHEL同源基因、GOBLET和侧抑制因子，这些基因可能调节花梗AZ中的分生组织活性。这些结果表明，SlERF52在花梗AZ脱落前和脱落阶段的转录调控中都起着关键作用。
