Chlorophyll is a tetrapyrrole metabolite essential for photosynthesis in plants. The first committed step of chlorophyll biosynthesis is catalyzed by a multimeric enzyme, magnesium chelatase, the subunit I of which is encoded by the oil yellow1 (oy1) gene in maize (Zea mays). A range of chlorophyll contents and net CO₂ assimilation rates can be achieved in maize by combining a semidominant mutant allele of oy1 (Oy1-N1989) and a cis-regulatory modifier named very oil yellow1 (vey1) that varies between different inbred lines. We previously demonstrated that these allelic interactions can delay reproductive maturity. In this study, we demonstrate that multiple gross morphological traits respond to a reduction in chlorophyll. We found that stalk width, number of lateral branches (tillers), and branching of the inflorescence decline with a decrease in chlorophyll level. Chlorophyll deficit suppressed tillering in multiple maize mutants, including teosinte branched1, Tillering1, and grassy tillers1. In contrast to these traits, plant height showed a nonlinear response to chlorophyll levels. Weak suppression of Oy1-N1989 by vey1^B73 resulted in a significant increase in mutant plant height. By contrast, enhancement of the severity of the Oy1-N1989 phenotype by the vey1^Mo17 allele resulted in reduced plant height. We demonstrate that the effects of reduced chlorophyll contents on plant growth and development are complex and depend on the trait being measured. We propose that the lack of chlorophyll exerts growth control via energy balance sensing, which is upstream of the known genetic networks for branching and architecture.

叶绿素是植物光合作用必需的四吡咯代谢物。叶绿素生物合成的第一个关键步骤是由多聚体酶镁螯合酶催化，其亚基 I 由玉米 ( Zea mays ) 中的油黄 1 ( oy1 ) 基因编码。通过结合oy1的半显性突变等位基因( Oy1-N1989 ) 和名为very oil Yellow1 ( vey1 )的顺式调节修饰剂（不同自交系之间存在差异），可以在玉米中实现一定范围的叶绿素含量和净 CO _{2同化率。}我们之前证明这些等位基因相互作用可以延迟生殖成熟。在这项研究中，我们证明了多种总体形态特征对叶绿素的减少有反应。我们发现茎宽度、侧枝（分蘖）数量和花序分枝随着叶绿素水平的降低而减少。叶绿素缺乏抑制了多种玉米突变体的分蘖，包括类蜀黍分蘖1、分蘖1和草分蘖1。与这些性状相反，植物高度对叶绿素水平表现出非线性响应。vey1 ^B73对Oy1-N1989的弱抑制导致突变体株高显着增加。相比之下， vey1 ^Mo17等位基因增强了Oy1-N1989表型的严重性，导致植物高度降低。我们证明，叶绿素含量降低对植物生长和发育的影响是复杂的，并且取决于所测量的性状。我们提出，叶绿素的缺乏通过能量平衡传感来施加生长控制，这是已知的分支和结构遗传网络的上游。