State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, China.
These authors contributed equally to this work.
Plant Cell Physiol. 2019 Jul 1;60(7):1619-1629. doi: 10.1093/pcp/pcz069.
Although exogenous applications of gibberellins (GAs) delay tomato ripening, the regulatory mechanisms of GAs in the process have never been well recognized. Here, we report that the concentration of endogenous GAs is declined before the increase of ethylene production in mature-green to breaker stage fruits. We further demonstrate that reductions in GA levels via overexpression of a GA catabolism gene SlGA2ox1 specifically in fruit tissues lead to early ripening. Consistently, we have also observed that application of a GA biosynthetic inhibitor, prohexadione-calcium, at the mature-green stage accelerates fruit ripening, while exogenous GA3 application delays the process. Furthermore, we demonstrate that ethylene biosynthetic gene expressions and ethylene production are activated prematurely in GA-deficient fruits but delayed/reduced in exogenous GA3-treated WT fruits. We also show that the GA deficiency-mediated activation of ethylene biosynthesis is due to the activation of the ripening regulator genes RIN, NOR and CNR. In conclusion, our results demonstrate that GAs play a negative role in tomato fruit ripening.
虽然外源施用赤霉素（GA）会延迟番茄成熟，但 GA 在该过程中的调控机制尚未得到充分认识。在这里，我们报告说，在成熟绿到破色阶段果实中乙烯产量增加之前，内源 GA 的浓度下降。我们进一步证明，通过在果实组织中特异性过表达 GA 分解代谢基因 SlGA2ox1 降低 GA 水平会导致果实提前成熟。一致地，我们还观察到在成熟绿期施用 GA 生物合成抑制剂 prohexadione-calcium 会加速果实成熟，而外源 GA3 处理则会延迟该过程。此外，我们证明在 GA 缺乏的果实中，乙烯生物合成基因的表达和乙烯的产生被过早激活，但在外源 GA3 处理的 WT 果实中则被延迟/减少。我们还表明，GA 缺乏介导的乙烯生物合成的激活是由于成熟调节剂基因 RIN、NOR 和 CNR 的激活。总之，我们的结果表明 GA 在番茄果实成熟过程中起负调控作用。
