NAC transcription factors play an important role in ethylene biosynthesis, reception and signaling of tomato fruit ripening
NAC transcription factors play an important role in ethylene biosynthesis, reception and signaling of tomato fruit ripening
复制标题
NAC转录因子在番茄果实成熟的乙烯生物合成、接收和信号传导中发挥重要作用
DOI：
10.1007/s00438-016-1177-0
复制
发表时间：
2016-06-01
影响因子：
3.1
通讯作者：
Xue, Zhaohui
中科院分区：
文献类型：
--
作者：
Kou, Xiaohong;Liu, Chen;Xue, Zhaohui
NAC蛋白包括一个转录因子大家族，在发育过程中的各种生理过程中发挥重要作用。为了探讨NAC转录因子在果实成熟中的作用，我们预测了SNAC 4（SlNAC 48，Accession number：NM 001279348.2）和SNAC 9（SlNAC 19，Accession number：XM 004236996.2）转录因子的二级和三级结构及其调控功能。我们发现SNAC 9的三级结构与ATNAP相似，在果实衰老过程中起重要作用，是乙烯刺激所必需的。同样，生物功能预测结果表明SNAC 4和SNAC 9参与多种植物激素信号传导和衰老过程。通过应用VIGS（病毒诱导的基因沉默）获得了关于SNAC的更多信息。SNAC 4和SNAC 9的沉默显著抑制了LeACS2、LeACS4和LeACO1的表达，从而导致成熟过程的抑制。SNACs的沉默下调了乙烯感受基因的mRNA水平，同时抑制了除LeERF2外的乙烯信号相关基因的表达，但SNAC4的沉默诱导了LeERF2的表达。两种沉默果实中LeRIN的表达不同。此外，SNAC 4的沉默降低了其mRNA水平，而SNAC 9的沉默诱导了其表达。此外，LeACS4、LeACO1和LeERF2的沉默降低了SNAC4和SNAC9的表达，而NR的沉默则诱导了它们的表达。特别地，这些结果表明SNAC转录因子在体外结合到乙烯合成基因的启动子。这一实验证据表明，SNAC 4和SNAC 9可以通过乙烯合成基因上游的功能正向调节番茄果实的成熟过程。这些结果将有助于为进一步探讨番茄果实成熟衰老机制提供理论基础。
NAC proteins comprise a large family of transcription factors that play important roles in diverse physiological processes during development. To explore the role of NAC transcription factors in the ripening of fruits, we predicted the secondary and tertiary structure as well as regulative function of the SNAC4 (SlNAC48, Accession number: NM 001279348.2) and SNAC9 (SlNAC19, Accession number: XM 004236996.2) transcription factors in tomato. We found that the tertiary structure of SNAC9 was similar to that of ATNAP, which played an important role in the fruit senescence and was required for ethylene stimulation. Likewise, the bio-function prediction results indicated that SNAC4 and SNAC9 participated in various plant hormone signaling and senescence processes. More information about SNACs was obtained by the application of VIGS (virus-induced gene silencing). The silencing ofSNAC4andSNAC9dramatically repressed theLeACS2,LeACS4andLeACO1expression, which consequently led to the inhibition of the ripening process. The silencing of SNACs down-regulated the mRNA levels of the ethylene perception genes and, at the same time, suppressed the expression of ethylene signaling-related genes except forLeERF2which was induced by the silencing ofSNAC4. The expressions ofLeRINwere different in two silenced fruits. In addition, the silencing ofSNAC4reduced its mRNA level, while the silencing ofSNAC9induced its expression. Furthermore, the silencing ofLeACS4,LeACO1andLeERF2reduced the expression ofSNAC4andSNAC9, while the silencing ofNRinduced the expression of all of them. In particular, these results indicate that SNAC transcription factors bind to the promoter of the ethylene synthesis genes in vitro. This experimental evidence demonstrates that SNAC4 and SNAC9 could positively regulate the tomato fruit ripening process by functioning upstream of ethylene synthesis genes. These outcomes will be helpful to provide a theoretical foundation for further exploring the tomato fruit ripening and senescence mechanism.