National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
Plant Mol Biol. 2018 Sep;98(1-2):33-49. doi: 10.1007/s11103-018-0760-7. Epub 2018 Aug 25.
(1) We systematically analyze the promoter activities of AtCKLs in various tissues; (2) AtCKL2 and AtCKL7 were expressed in early developmental anthers under high temperature (HT) conditions; (3) AtMYB24 may function as a positive regulator of AtCKL2 and AtCKL7 expression under HT. High temperature (HT) can seriously impede plant growth and development, causing severe loss of crop production. In Arabidopsis, AtCKL genes show high similarity to GhCKI, a gene reported to disrupt tapetal programmed cell death in cotton. However, most of AtCKL genes are not well characterized. Here, we systematically analyzed the expression patterns of AtCKLs in various tissues. The expression of AtCKL2 and AtCKL7 was induced in early anther development under HT, which is similar to the case of GhCKI. In silico analysis of AtCKL2 and AtCKL7 promoters indicated that four types of transcription factors (TFs) (MADS, NAC, WRKY and R2R3-MYB) might bind to AtCKL2 and AtCKL7 promoters. Furthermore, three MADS, three NAC, one WRKY, and three R2R3-MYB TFs were up-regulated in stage 1-8 anthers and three R2R3-MYB TFs were up-regulated in stage 9-10 anthers under HT, implying the important roles of R2R3-MYB genes in the response of anthers to HT. Among the R2R3-MYB genes, AtMYB24 showed the similar expression as AtCKL2 and AtCKL7 in the anthers under HT. Additionally, yeast one-hybrid and dual-luciferase reporter system assays verified that AtMYB24 could bind to AtCKL2 and AtCKL7 promoters and activate the expression of these two genes. In brief, this study provides the overall expression profiles of AtCKLs, useful information for unraveling the molecular mechanism of AtCKL2 and AtCKL7 gene expression in early anther development under HT, and important clues for elucidating the mechanism of transcriptional regulation of CKI genes in plant anther under HT, which are critical to the reduction of crop yield loss resulting from HT.
（1）我们系统地分析了 AtCKLs 在各种组织中的启动子活性；（2）AtCKL2 和 AtCKL7 在高温（HT）条件下早期发育的花药中表达；（3）AtMYB24 可能在 HT 条件下作为 AtCKL2 和 AtCKL7 表达的正调节剂发挥作用。高温（HT）会严重阻碍植物的生长和发育，导致作物产量严重损失。在拟南芥中，AtCKL 基因与 GhCKI 高度相似，GhCKI 是一种被报道能破坏棉花绒毡层程序性细胞死亡的基因。然而，大多数 AtCKL 基因的特征尚未得到很好的描述。在这里，我们系统地分析了 AtCKLs 在各种组织中的表达模式。AtCKL2 和 AtCKL7 的表达在 HT 下早期花药发育过程中被诱导，这与 GhCKI 的情况类似。AtCKL2 和 AtCKL7 启动子的计算机分析表明，四种类型的转录因子（TFs）（MADS、NAC、WRKY 和 R2R3-MYB）可能与 AtCKL2 和 AtCKL7 启动子结合。此外，在 HT 下，MADS 有三个，NAC 有三个，WRKY 有一个，R2R3-MYB 有三个 TFs 在阶段 1-8 的花药中上调，R2R3-MYB 有三个 TFs 在阶段 9-10 的花药中上调，这表明 R2R3-MYB 基因在花药对 HT 的反应中起着重要作用。在 R2R3-MYB 基因中，AtMYB24 在 HT 下的花药中与 AtCKL2 和 AtCKL7 的表达相似。此外，酵母单杂交和双荧光素酶报告系统试验验证了 AtMYB24 可以与 AtCKL2 和 AtCKL7 启动子结合，并激活这两个基因的表达。总之，本研究提供了 AtCKLs 的整体表达谱，为揭示 AtCKL2 和 AtCKL7 基因在 HT 下早期花药发育过程中的表达分子机制提供了有用的信息，为阐明 HT 下植物花药中 CKI 基因转录调控的机制提供了重要线索，这对于减少 HT 导致的作物产量损失至关重要。
