Tomato transcriptional repressor MYB70 directly regulates ethylene-dependent fruit ripening
Tomato transcriptional repressor MYB70 directly regulates ethylene-dependent fruit ripening
复制标题
番茄转录阻遏蛋白MYB70直接调节乙烯依赖性果实成熟
DOI：
10.1111/tpj.15021
复制
发表时间：
2020-11-18
期刊：
影响因子：
7.2
通讯作者：
Li, Zhengguo
中科院分区：
文献类型：
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作者：
Cao, Haohao;Chen, Jing;Li, Zhengguo
乙烯是控制跃变型果实成熟的关键激素，在番茄（Solanum lycopersicum）中发现了几种转录因子，它们是果实成熟的重要调控因子。这些转录因子中的绝大多数是转录激活因子，然而，大多数调节因子的相关转录调节机制尚不清楚。在这里，我们报告的番茄转录抑制因子（称为SLMYB 70），负调控果实成熟直接调节乙烯的生物合成。SlMYB 70是一个含有MYB转录因子编码区的基因，具有成熟相关的表达模式，对乙烯有反应。RNA干扰（RNAi）介导的抑制SlMYB 70促进果实成熟，但过表达SlMYB 70延迟果实成熟。与野生型番茄相比，SlMYB 70-RNAi和SlMYB 70过表达株系的乙烯产量分别显著增加和减少。SlMYB 70是一个转录抑制因子，依赖于转录抑制基序，抑制两个乙烯生物合成基因SlACS 2和SlACO 3的转录。SlACS 2和SlACO 3的启动子直接结合SlMYB 70，这是使用酵母单杂交染色质免疫沉淀定量聚合酶链反应和电泳迁移率变动测定的组合进行验证。这些结果表明，SlMYB 70负调控果实成熟通过直接转录抑制乙烯生物合成基因，这提供了深入了解乙烯介导的关键调控层次跃变型果实成熟，也突出了不同类型的转录调控果实成熟。
Ethylene is a key plant hormone controlling the ripening of climacteric fruits, and several transcription factors acting as important regulators of fruit ripening have been identified in tomato (Solanum lycopersicum), a model for climacteric fruits. The vast majority of these transcription factors are transcriptional activators, however, and the associated transcriptional regulatory mechanisms of most regulators are unclear. Here, we report on a tomato transcriptional repressor (termed SlMYB70) that negatively regulates fruit ripening by directly modulating ethylene biosynthesis. As an EAR motif-containing MYB transcription factor-encoding gene, SlMYB70 displayed a ripening-associated expression pattern and was responsive to ethylene. RNA interference (RNAi)-mediated repression of SlMYB70 accelerated fruit ripening, but overexpression of SlMYB70 delayed fruit ripening. Ethylene production was noticeably increased and decreased in SlMYB70-RNAi and SlMYB70-overexpressing lines, respectively, compared with wild-type tomatoes. SlMYB70 was proven to be a transcriptional repressor, dependent on the EAR repression motif, and to repress the transcription of two ethylene biosynthesis genes in fruit ripening, namely SlACS2 and SlACO3. The promoters of SlACS2 and SlACO3 are directly bound by SlMYB70, which was verified using a combination of yeast one-hybrid chromatin immunoprecipitation quantitative polymerase chain reaction and electrophoretic mobility shift assays. These results suggest that SlMYB70 negatively regulates fruit ripening via the direct transcriptional repression of ethylene biosynthesis genes, which provides insights into the ethylene-mediated key regulatory hierarchy in climacteric fruit ripening, and also highlights different types of transcriptional regulation of fruit ripening.