Repository of Tomato Genomics Resources, Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
Plant Cell Environ. 2014 Jul;37(7):1688-702. doi: 10.1111/pce.12279. Epub 2014 Feb 19.
Tomato fruit ripening is a complex metabolic process regulated by a genetical hierarchy. A subset of this process is also modulated by light signalling, as mutants encoding negative regulators of phytochrome signal transduction show higher accumulation of carotenoids. In tomato, phytochromes are encoded by a multi-gene family, namely PHYA, PHYB1, PHYB2, PHYE and PHYF; however, their contribution to fruit development and ripening has not been examined. Using single phytochrome mutants phyA, phyB1 and phyB2 and multiple mutants phyAB1, phyB1B2 and phyAB1B2, we compared the on-vine transitory phases of ripening until fruit abscission. The phyAB1B2 mutant showed accelerated transitions during ripening, with shortest time to fruit abscission. Comparison of transition intervals in mutants indicated a phase-specific influence of different phytochrome species either singly or in combination on the ripening process. Examination of off-vine ripened fruits indicated that ripening-specific carotenoid accumulation was not obligatorily dependent upon light and even dark-incubated fruits accumulated carotenoids. The accumulation of transcripts and carotenoids in off-vine and on-vine ripened mutant fruits indicated a complex and shifting phase-dependent modulation by phytochromes. Our results indicate that, in addition to regulating carotenoid levels in tomato fruits, phytochromes also regulate the time required for phase transitions during ripening.
番茄果实成熟是一个受遗传等级调控的复杂代谢过程。该过程的一部分也受到光信号的调节，因为编码phytochrome 信号转导负调节剂的突变体显示出更高的类胡萝卜素积累。在番茄中，phytochrome 由一个多基因家族编码，即 PHYA、PHYB1、PHYB2、PHYE 和 PHYF；然而，它们对果实发育和成熟的贡献尚未被研究。使用单个 phytochrome 突变体 phyA、phyB1 和 phyB2 以及多个突变体 phyAB1、phyB1B2 和 phyAB1B2，我们比较了果实脱落前的葡萄藤上的成熟暂态阶段。phyAB1B2 突变体在成熟过程中表现出加速的转变，果实脱落的时间最短。在突变体中比较转变间隔表明，不同的 phytochrome 物种单独或组合对成熟过程具有特定阶段的影响。对离线成熟果实的检查表明，成熟特异性类胡萝卜素的积累不一定依赖于光，甚至黑暗孵育的果实也积累类胡萝卜素。离线和在线成熟突变体果实中的转录物和类胡萝卜素的积累表明，phytochrome 对成熟的复杂和不断变化的阶段依赖性调节。我们的结果表明，phytochrome 除了调节番茄果实中的类胡萝卜素水平外，还调节成熟过程中相变所需的时间。
