AUTHOR=Li Caixia , Wang Juan , Lan Haiyan , Yu Qinghui 

TITLE=Enhanced drought tolerance and photosynthetic efficiency in Arabidopsis by overexpressing phosphoenolpyruvate carboxylase from a single-cell C4 halophyte Suaeda aralocaspica

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1443691

DOI=10.3389/fpls.2024.1443691

ISSN=1664-462X

ABSTRACT=<p>In crop genetic improvement, the introduction of C4 plants’ characteristics, known for high photosynthetic efficiency and water utilization, into C3 plants has been a significant challenge. This study investigates the effects of the desert halophyte <italic>Suaeda aralocaspica SaPEPC1</italic> gene from a single-cell C4 photosythetic pathway, on drought resistance and photosynthetic performance in <italic>Arabidopsis</italic>. We used transgenic <italic>Arabidopsis</italic> with <italic>Zea mays ZmPEPC1</italic> from C4 plant with classic Kranz anatomical structure and <italic>Arabidopsis AtPEPC1</italic> from C3 photosynthetic cycle plants as controls. The results demonstrated that C4 photosynthetic-type <italic>PEPCs</italic> could improve drought resistance in plants through stomatal closure, promoting antioxidant enzyme accumulation, and reducing reactive oxygen species (ROS) accumulation. Overexpression of <italic>SaPEPC1</italic> was significantly more effective than <italic>ZmPEPC1</italic> in enhancing drought tolerance. Notably, overexpressed <italic>SaPEPC1</italic> significantly improved light saturation intensity, electron transport rate (ETR), photosynthetic rate (Pn), and photoprotection ability under intense light. Furthermore, overexpression <italic>SaPEPC1</italic> or <italic>ZmPEPC1</italic> enhanced the activity of key C4 photosynthetic enzymes, including phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK) and NADP-malic enzyme (NADP-ME), and promoted photosynthetic product sugar accumulation. However, with <italic>AtPEPC1</italic> overexpression showing no obvious improvement effect on drought and photosynthetic performance. Therefore, these results indicated that introducing C4-type <italic>PEPC</italic> into C3 plants can significantly enhance drought resistance and photosynthetic performance. However, <italic>SaPEPC1</italic> from a single-cell C4 cycle plant exhibits more significant effect in ETR and PSII photosynthesis performance than <italic>ZmPEPC1</italic> from a classical C4 anatomical structure plant, although the underlying mechanism requires further exploration.</p>