The James Hutton Institute, Invergowrie, Dundee, UK.
Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Pakistan.
J Exp Bot. 2019 Oct 24;70(20):5703-5714. doi: 10.1093/jxb/erz336.
For many potato cultivars, tuber yield is optimal at average daytime temperatures in the range 14-22 °C. Above this range, tuber yield is reduced for most cultivars. We previously reported that moderately elevated temperature increases steady-state expression of the core circadian clock gene TIMING OF CAB EXPRESSION 1 (StTOC1) in developing tubers, whereas expression of the StSP6A tuberization signal is reduced, along with tuber yield. In this study we provide evidence that StTOC1 links environmental signalling with potato tuberization by suppressing StSP6A autoactivation in the stolons. We show that transgenic lines silenced in StTOC1 expression exhibit enhanced StSP6A transcript levels and changes in gene expression in developing tubers that are indicative of an elevated sink strength. Nodal cuttings of StTOC1 antisense lines displayed increased tuber yields at moderately elevated temperatures, whereas tuber yield and StSP6A expression were reduced in StTOC1 overexpressor lines. Here we identify a number of StTOC1 binding partners and demonstrate that suppression of StSP6A expression is independent of StTOC1 complex formation with the potato homolog StPIF3. Down-regulation of StTOC1 thus provides a strategy to mitigate the effects of elevated temperature on tuber yield.
对于许多马铃薯品种而言，块茎产量在 14-22°C 的平均白天温度范围内达到最佳。在这个范围之上，大多数品种的块茎产量都会降低。我们之前曾报道过，适度升高的温度会增加发育中的块茎中核心生物钟基因 TIMING OF CAB EXPRESSION 1（StTOC1）的稳态表达，而 StSP6A 块茎形成信号的表达则会减少，从而降低块茎产量。在这项研究中，我们提供了证据表明，StTOC1 通过抑制匍匐茎中的 StSP6A 自动激活，将环境信号与马铃薯块茎形成联系起来。我们表明，沉默 StTOC1 表达的转基因系表现出增强的 StSP6A 转录本水平和发育中的块茎中基因表达的变化，表明存在较高的库强度。StTOC1 反义系的节间切段在适度升高的温度下显示出增加的块茎产量，而 StTOC1 过表达系的块茎产量和 StSP6A 表达则降低。在这里，我们鉴定了一些 StTOC1 结合伙伴，并证明 StSP6A 表达的抑制与 StTOC1 与马铃薯同源物 StPIF3 的复合物形成无关。因此，StTOC1 的下调提供了一种减轻高温对块茎产量影响的策略。
