Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China.
National Nanfan Research Institute (Sanya), Chinese Academy of Agricultural Sciences, Sanya, China.
Plant Biotechnol J. 2022 Dec;20(12):2313-2331. doi: 10.1111/pbi.13909. Epub 2022 Sep 7.
Maize (Zea mays) is an important cereal crop with suitable stalk formation which is beneficial for acquiring an ideal agronomic trait to resist lodging and higher planting density. The elongation pattern of stalks arises from the variable growth of individual internodes driven by cell division and cell expansion comprising the maize stalk. However, the spatiotemporal dynamics and regulatory network of the maize stalk development and differentiation process remain unclear. Here, we report spatiotemporally resolved transcriptomes using all internodes of the whole stalks from developing maize at the elongation and maturation stages. We identified four distinct groups corresponding to four developmental zones and nine specific clusters with diverse spatiotemporal expression patterns among individual internodes of the stalk. Through weighted gene coexpression network analysis, we constructed transcriptional regulatory networks at a fine spatiotemporal resolution and uncovered key modules and candidate genes involved in internode maintenance, elongation, and division that determine stalk length and thickness in maize. Further CRISPR/Cas9-mediated knockout validated the function of a cytochrome P450 gene, ZmD1, in the regulation of stalk length and thickness as predicted by the WGCN. Collectively, these results provide insights into the high genetic complexity of stalk development and the potentially valuable resources with ideal stalk lengths and widths for genetic improvements in maize.
玉米（Zea mays）是一种重要的谷类作物，具有适宜的茎秆形成，有利于获得理想的农艺性状，以抵抗倒伏和提高种植密度。茎秆的伸长模式源于由细胞分裂和细胞扩展驱动的各个节间的可变生长，这些节间构成了玉米茎秆。然而，玉米茎秆发育和分化过程的时空动态和调控网络仍不清楚。在这里，我们使用伸长和成熟阶段整个茎秆的所有节间，报告了具有时间和空间分辨率的转录组。我们鉴定了四个不同的组，对应于四个发育区和九个具有不同时空表达模式的特定簇，这些模式存在于茎秆的各个节间之间。通过加权基因共表达网络分析，我们构建了在精细时空分辨率下的转录调控网络，并发现了关键模块和候选基因，这些基因参与节间的维持、伸长和分裂，从而决定了玉米茎秆的长度和厚度。进一步的 CRISPR/Cas9 介导的基因敲除实验验证了细胞色素 P450 基因 ZmD1 在调节茎秆长度和厚度方面的功能，这与 WGCN 的预测一致。总之，这些结果深入了解了茎秆发育的高度遗传复杂性，以及具有理想茎秆长度和宽度的潜在有价值资源，可用于玉米的遗传改良。
