In cultivated grasses, tillering, leaf, and inflorescence architecture, as well as abscission ability, are major agronomical traits. In barley (Hordeum vulgare), maize (Zea mays), rice (Oryza sativa), and brachypodium (Brachypodium distachyon), NOOT-BOP-COCH-LIKE (NBCL) genes are essential regulators of vegetative and reproductive development. Grass species usually possess 2–4 NBCL copies and until now a single study in O. sativa showed that the disruption of all NBCL genes strongly altered O. sativa leaf development. To improve our understanding of the role of NBCL genes in grasses, we extended the study of the two NBCL paralogs BdUNICULME4 (CUL4) and BdLAXATUM-A (LAXA) in the nondomesticated grass B. distachyon. For this, we applied reversed genetics and generated original B. distachyon single and double nbcl mutants by clustered regularly interspaced short palindromic repeats – CRISPR associated protein 9 (CRISPR-Cas9) approaches and genetic crossing between nbcl targeting induced local lesions in genomes (TILLING) mutants. Through the study of original single laxa CRISPR–Cas9 null alleles, we validated functions previously proposed for LAXA in tillering, leaf patterning, inflorescence, and flower development and also unveiled roles for these genes in seed yield. Furthermore, the characterization of cul4laxa double mutants revealed essential functions for nbcl genes in B. distachyon development, especially in the regulation of tillering, stem cell elongation and secondary cell wall composition as well as for the transition toward the reproductive phase. Our results also highlight recurrent antagonist interactions between NBCLs occurring in multiple aspects of B. distachyon development.

中文翻译：

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开发过程中，二穗短柄草 UNICULME4 和 LAXATUM-A 是多余的


在栽培禾本科植物中，分蘖、叶子和花序结构以及脱落能力是主要的农艺性状。在大麦 (Hordeum vulgare)、玉米 (Zea mays)、水稻 (Oryza sativa) 和短柄草 (Brachypodium distachyon) 中，NOOT-BOP-COCH-LIKE (NBCL) 基因是营养和生殖发育的重要调节因子。禾本科植物通常拥有 2-4 个 NBCL 拷贝，迄今为止，一项针对水稻的研究表明，所有 NBCL 基因的破坏都会强烈改变水稻叶片的发育。为了加深我们对 NBCL 基因在禾本科植物中作用的理解，我们扩展了对非驯化禾本科植物 B. distachyon 中两个 NBCL 旁系同源物 BdUNICULME4 (CUL4) 和 BdLAXATUM-A (LAXA) 的研究。为此，我们应用反向遗传学并通过成簇规则间隔的短回文重复序列生成原始 B. distachyon 单 nbcl 和双 nbcl 突变体 - CRISPR 相关蛋白 9 (CRISPR-Cas9) 方法和 nbcl 靶向诱导基因组局部损伤之间的遗传杂交 (TILLING)突变体。通过对原始单个 laxa CRISPR-Cas9 无效等位基因的研究，我们验证了之前提出的 LAXA 在分蘖、叶型、花序和花发育中的功能，并揭示了这些基因在种子产量中的作用。此外，cul4laxa 双突变体的表征揭示了 nbcl 基因在二穗芽孢杆菌发育中的重要功能，特别是在分蘖、干细胞伸长和次生细胞壁组成以及向生殖期过渡的调节中。我们的结果还强调了 NBCL 之间反复出现的拮抗剂相互作用，这些相互作用发生在 B. distachyon 发育的多个方面。