XiutingHua,HuihongShi,GuiZhuang,YuhongLan,ShaoliZhou,DongxuZhao,Ming-JuAmyLyu,SehrishAkbar,JiaLiu,YuanYuan,ZhenLi,QingJiang,KaixinHuang,YatingZhang,QingZhang,GangWang,YuWang,XiaominYu5,PinghuaLi6,XingtanZhang,JianpingWang7,ShenghuaXiao,WeiYao,RayMing,XinguangZhu,MuQingZhang,HaibaoTang,JisenZhang

Plant Physiol,2024 Sep 14:kiae455.Doi: 10.1093/plphys/kiae455.

Abstract

In agronomically important C4 grasses, efficient CO2 delivery to Rubisco is facilitated by NADP-malic enzyme (C4NADP-ME), which decarboxylates malate in bundle sheath cells. However, understanding the molecular regulation of the C4NADP-ME gene in sugarcane (Saccharum spp.) is hindered by its complex genetic background. Enzymatic activity assays demonstrated that decarboxylation in sugarcane Saccharum spontaneum predominantly relies on the NADP-ME pathway, similar to sorghum (Sorghum bicolor) and maize (Zea mays). Comparative genomics analysis revealed the recruitment of eight core C4 shuttle genes, including C4NADP-ME (SsC4NADP-ME2), in the C4 pathway of sugarcane. Contrasting to sorghum and maize, the expression of SsC4NADP-ME2 in sugarcane is regulated by different transcription factors (TFs). We propose a gene regulatory network for SsC4NADP-ME2, involving candidate TFs identified through gene co-expression analysis and yeast one-hybrid experiment. Among these, ABA INSENSITIVE5 (ABI5) was validated as the predominant regulator of SsC4NADP-ME2 expression, binding to a G-box within its promoter region. Interestingly, the core element ACGT within the regulatory G-box was conserved in sugarcane, sorghum, maize, and rice (Oryza sativa), suggesting an ancient regulatory code utilized in C4 photosynthesis. This study offers insights into SsC4NADP-ME2 regulation, crucial for optimizing sugarcane as a bioenergy crop.

论文链接：https://pubmed.ncbi.nlm.nih.gov/39276364/