Neris Daniel, Mattiello Lucia, Zuñiga Gustavo, Purgatto Eduardo, Menossi Marcelo
Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
Faculty of Chemistry and Biology, University of Santiago de Chile, Santiago, Chile.
Plant Cell Rep. 2022 Apr;41(4):979-993. doi: 10.1007/s00299-022-02832-7. Epub 2022 Feb 28.
Lower ethylene production in sugarcane results in plants with higher stature, expression of growth-promoting genes, higher photosynthetic rate, and increased antioxidant compounds. The hormone ethylene is involved in critical processes in sugarcane, such as the growth and accumulation of sucrose. The lack of mutants for ethylene biosynthesis or signaling genes makes it difficult to understand the role of this phytohormone throughout sugarcane development. This study aimed to evaluate the physiology and development of sugarcane plants with low ethylene production. To achieve this goal, we used RNA interference to silence three genes, ScACS1, ScACS2, and ScACS3, encoding 1-aminocyclopropane-1-carboxylic acid synthases (ACS), responsible for a limiting step of the ethylene biosynthesis pathway. Sugarcane plants with reduced ethylene levels presented increased growth, faster germination of lateral gems, and activation of non-enzymatic antioxidant mechanisms. We observed an augmentation in the expression of ScACO5, which encodes the final enzyme regulating ethylene biosynthesis, and ScERF1, encoding a transcription factor, linked to the ethylene response. The increase in plant height was correlated with higher expression of ScPIF3, ScPIF4, and ScPIF5, which encode for transcription factors related to growth induction. Interestingly, there was also an increase in the expression of the ScGAI gene, which encodes a DELLA protein, a growth repressor. The final content of sucrose in the stems was not affected by the low levels of ethylene, although the rate of CO assimilation was reduced. This study reports for the first time the impacts of low endogenous production of ethylene in sugarcane and provides helpful insights on the molecular mechanisms behind ethylene responses.
甘蔗中较低的乙烯产量会使植株更高大，促进生长的基因表达增加，光合速率提高，抗氧化化合物增多。激素乙烯参与甘蔗的关键过程，如蔗糖的生长和积累。缺乏乙烯生物合成或信号转导基因的突变体使得难以了解这种植物激素在甘蔗整个发育过程中的作用。本研究旨在评估乙烯产量低的甘蔗植株的生理和发育情况。为实现这一目标，我们利用RNA干扰使三个编码1-氨基环丙烷-1-羧酸合酶（ACS）的基因ScACS1、ScACS2和ScACS3沉默，ACS负责乙烯生物合成途径中的一个限速步骤。乙烯水平降低的甘蔗植株生长加快，侧芽萌发更快，非酶抗氧化机制被激活。我们观察到编码调节乙烯生物合成的最终酶的ScACO5和编码与乙烯反应相关的转录因子的ScERF1的表达增加。株高增加与编码与生长诱导相关转录因子的ScPIF3、ScPIF4和ScPIF5的较高表达相关。有趣的是，编码生长抑制因子DELLA蛋白的ScGAI基因的表达也增加了。尽管二氧化碳同化速率降低，但茎中蔗糖的最终含量不受低乙烯水平的影响。本研究首次报道了甘蔗中低内源性乙烯产生的影响，并为乙烯反应背后的分子机制提供了有益的见解。
