Maize is a major staple crop widely used for food, feedstocks and industrial products. Shade‐avoidance syndrome (SAS), which is triggered when plants sense competition of light from neighbouring vegetation, is detrimental for maize yield production under high‐density planting conditions. Previous studies have shown that the red and far‐red photoreceptor phytochromes are responsible for perceiving the shading signals and triggering SAS in Arabidopsis; however, their roles in maize are less clear. In this study, we examined the expression patterns of ZmPHYC1 and ZmPHYC2 and found that ZmPHYC1, but not ZmPHYC2, is highly expressed in leaves and is regulated by the circadian clock. Both ZmPHYC1 and ZmPHYC2 proteins are localized to both the nucleus and cytoplasm under light conditions and both of them can interact with themselves or with ZmPHYBs. Heterologous expression of ZmPHYCs can complement the Arabidopsis phyC‐2 mutant under constant red light conditions and confer an attenuated SAS in Arabidopsis in response to shading. Double knockout mutants of ZmPHYC1 and ZmPHYC2 created using the CRISPR/Cas9 technology display a moderate early‐flowering phenotype under long‐day conditions, whereas ZmPHYC2 overexpression plants exhibit a moderately reduced plant height and ear height. Together, these results provided new insight into the function of ZmPHYCs and guidance for breeding high‐density tolerant maize cultivars.

中文翻译：

---

CRISPR / Cas9介导的敲除和过表达研究揭示了玉米植物色素C在调节开花时间和植物高度中的作用。

玉米是主要的主食作物，广泛用于食品，原料和工业产品。当植物感觉到邻近植被的光竞争时会触发避荫综合症（SAS），这对高密度种植条件下的玉米单产不利。先前的研究表明，红色和远红外感光细胞色素负责感知拟南芥中的阴影信号并触发SAS。但是，它们在玉米中的作用尚不清楚。在这项研究中，我们检查了ZmPHYC1和ZmPHYC2的表达模式，发现ZmPHYC1而非ZmPHYC2，在叶子中高度表达，并受昼夜节律调节。ZmPHYC1和ZmPHYC2蛋白在光照条件下均位于细胞核和细胞质中，并且它们都可以与自身或与ZmPHYB相互作用。ZmPHYCs的异源表达可以在恒定的红光条件下补充拟南芥phyC-2突变体，并响应于阴影而使拟南芥中的SAS减弱。使用CRISPR / Cas9技术创建的ZmPHYC1和ZmPHYC2双敲除突变体在长期条件下显示出中等的早期开花表型，而ZmPHYC2过表达植物表现出适度降低的植物高度和穗高。这些结果共同为ZmPHYC的功能提供了新的见识，并为育种高密度耐性玉米品种提供了指导。