Biology Department, Trent University, 1600 West Bank Drive, Peterborough, ON, K9L 0G2, Canada.
Dow Chemical Canada ULC, Suite 2400-215 2nd Street S.W., Calgary, AB, T2P 1M4, Canada.
Planta. 2020 Oct 8;252(5):76. doi: 10.1007/s00425-020-03483-2.
Early cytokinin activity and late abscisic acid dynamics during wheat kernel development correspond to cultivars with higher yield potential. Cytokinins represent prime targets for marker development for wheat breeding programs. Two major phytohormone groups, abscisic acid (ABA) and cytokinins (CKs), are of crucial importance for seed development. Wheat (Triticum aestivum L.) yield is, to a high degree, determined during the milk and dough stages of kernel development. Therefore, understanding the hormonal regulation of these early growth stages is fundamental for crop-improvement programs of this important cereal. Here, we profiled ABA and 25 CK metabolites (including active forms, precursors and inactive conjugates) during kernel development in five field-grown wheat cultivars. The levels of ABA and profiles of CK forms varied greatly among the tested cultivars and kernel stages suggesting that several types of CK metabolites are involved in spatiotemporal regulation of kernel development. The seed yield potential was associated with the elevated levels of active CK levels (tZ, cZ). Interestingly, the increased kernel cZ levels were followed by higher ABA production, suggesting there is an interaction between these two phytohormones. Furthermore, we analyzed the expression patterns of representatives of the four main CK metabolic gene families. The unique transcriptional patterns of the IPT (biosynthesis) and ZOG (reversible inactivation) gene family members (GFMs) in the high and low yield cultivars additionally indicate that there is a significant association between CK metabolism and yield potential in wheat. Based on these results, we suggest that both CK metabolites and their associated genes, can serve as important, early markers of yield performance in modern wheat breeding programs.
在小麦籽粒发育过程中，早期细胞分裂素活性和晚期脱落酸动态与具有更高产量潜力的品种相对应。细胞分裂素是小麦育种计划中标记开发的主要目标。两种主要的植物激素群体，脱落酸（ABA）和细胞分裂素（CKs），对种子发育至关重要。小麦（Triticum aestivum L.）的产量在很大程度上取决于籽粒发育的乳熟和面团阶段。因此，了解这些早期生长阶段的激素调控对于该重要谷物的作物改良计划至关重要。在这里，我们在五个田间生长的小麦品种中对 ABA 和 25 种 CK 代谢物（包括活性形式、前体和无活性缀合物）进行了籽粒发育过程中的分析。ABA 水平和 CK 形式的分布在测试品种和籽粒阶段之间差异很大，这表明几种类型的 CK 代谢物参与了籽粒发育的时空调节。种子产量潜力与活性 CK 水平（tZ、cZ）的升高有关。有趣的是，增加的核 cZ 水平伴随着较高的 ABA 产生，表明这两种植物激素之间存在相互作用。此外，我们分析了四个主要 CK 代谢基因家族的代表的表达模式。高、低产品种中 IPT（生物合成）和 ZOG（可逆失活）基因家族成员（GFMs）的独特转录模式进一步表明，CK 代谢与小麦产量潜力之间存在显著关联。基于这些结果，我们认为 CK 代谢物及其相关基因可以作为现代小麦育种计划中产量表现的重要早期标记。
