Department of Horticulture, Clemson University, Clemson, SC 29634-0319, USA.
BMC Plant Biol. 2010 Feb 9;10:25. doi: 10.1186/1471-2229-10-25.
In many tree species the perception of short days (SD) can trigger growth cessation, dormancy entrance, and the establishment of a chilling requirement for bud break. The molecular mechanisms connecting photoperiod perception, growth cessation and dormancy entrance in perennials are not clearly understood. The peach [Prunus persica (L.) Batsch] evergrowing (evg) mutant fails to cease growth and therefore cannot enter dormancy under SD. We used the evg mutant to filter gene expression associated with growth cessation after exposure to SD. Wild-type and evg plants were grown under controlled conditions of long days (16 h/8 h) followed by transfer to SD (8 h/16 h) for eight weeks. Apical tissues were sampled at zero, one, two, four, and eight weeks of SD and suppression subtractive hybridization was performed between genotypes at the same time points.
We identified 23 up-regulated genes in the wild-type with respect to the mutant during SD exposure. We used quantitative real-time PCR to verify the expression of the differentially expressed genes in wild-type tissues following the transition to SD treatment. Three general expression patterns were evident: one group of genes decreased at the time of growth cessation (after 2 weeks in SD), another that increased immediately after the SD exposure and then remained steady, and another that increased throughout SD exposure.
The use of the dormancy-incapable mutant evg has allowed us to reduce the number of genes typically detected by differential display techniques for SD experiments. These genes are candidates for involvement in the signalling pathway leading from photoperiod perception to growth cessation and dormancy entrance and will be the target of future investigations.
在许多树种中，对短日照（SD）的感知可以触发生长停止、休眠进入和打破休眠的需冷要求。连接光周期感知、生长停止和休眠进入的多年生植物的分子机制尚不清楚。桃[Prunus persica (L.) Batsch]常绿（evg）突变体不能停止生长，因此不能在 SD 下进入休眠。我们使用 evg 突变体来筛选与 SD 暴露后生长停止相关的基因表达。野生型和 evg 植物在长日（16 h/8 h）的受控条件下生长，然后转移到 SD（8 h/16 h）8 周。在 SD 零、一、二、四和八周时，从顶端组织取样，并在相同的时间点在基因型之间进行抑制性消减杂交。
我们在 SD 暴露期间鉴定了 23 个在野生型中相对于突变体上调的基因。我们使用定量实时 PCR 验证了在 SD 处理后野生型组织中差异表达基因的表达。有三种明显的表达模式：一组基因在生长停止时减少（在 SD 2 周后），另一组基因在 SD 暴露后立即增加，然后保持稳定，另一组基因在整个 SD 暴露过程中增加。
使用休眠能力丧失的突变体 evg 使我们能够减少通常通过 SD 实验差异显示技术检测到的基因数量。这些基因是参与从光周期感知到生长停止和休眠进入的信号通路的候选基因，将成为未来研究的目标。
