Abstract：
Tomato fruit ripening is a unique process of nutritional and energy metabolism. Target of rapamycin (TOR), a conserved serine/threonine protein kinase in eukaryotes, controls cell growth and metabolism by integrating nutrient, energy, and hormone signals. However, it remains unclear whether TOR participates in the modulation of tomato fruit ripening. Here, we showed that the manipulation of SlTOR by chemical or genetic methods greatly alters the process of tomato fruit maturation. Expression pattern analysis revealed that the transcripts of SlTOR declined as fruit ripening progressed. Moreover, suppression of SlTOR by TOR inhibitor AZD8055 or knock down of its transcripts by inducible RNA interference, accelerated fruit ripening, and led to overall effects on fruit maturity, including changes in colour and metabolism, fruit softening, and expression of ripening-related genes. Genome-wide transcription analysis indicated that silencing SlTOR reprogrammed the transcript profile associated with ripening, including cell wall and phytohormone pathways, elevated the expression of ethylene biosynthetic genes, and further promoted ethylene production. In contrast, the ethylene action inhibitor 1-MCP efficiently blocked fruit maturation, even following SlTOR inhibition. These results suggest that accelerated fruit ripening caused by SlTOR inhibition depends on ethylene, and that SlTOR may function as a regulator in ethylene metabolism.
摘要：
番茄果实成熟是一个独特的营养和能量代谢过程。雷帕霉素靶蛋白(TOR),真核生物中保守的丝氨酸/苏氨酸蛋白激酶，通过整合营养来控制细胞生长和新陈代谢，能源,和激素信号。然而,目前尚不清楚TOR是否参与果实成熟的调节。这里,我们表明，通过化学或遗传方法对SlTOR的操纵极大地改变了番茄果实成熟的过程。表达模式分析显示，随着果实成熟，SlTOR的转录本下降。此外，通过TOR抑制剂AZD8055抑制SlTOR或通过诱导型RNA干扰抑制其转录物加速果实成熟并导致对果实成熟度的总体影响，包括颜色和新陈代谢的变化，水果软化，和成熟相关基因的表达。全基因组转录表明沉默SlTOR重编程与成熟相关的转录谱，如细胞壁和植物激素途径，特别是,提高了乙烯生物合成基因（SlACS2，SlACS4和SlACO1）的表达，并进一步促进了乙烯的生产。相比之下,乙烯作用抑制剂1-MCP即使在SlTOR抑制下也能有效阻断果实成熟。这些结果表明，由SlTOR抑制引起的加速果实成熟取决于乙烯，并且SlTOR可能在乙烯代谢中起调节剂的作用。
