AI Insight
Researchers studying rice discovered that a plasma membrane proton pump called OSA3 controls the elongation of bundle sheath cells through a process known as acid growth. When OSA3 was knocked out in C3 rice, bundle sheath cells became shorter but increased in number and chloroplast occupancy, closely mirroring the bundle sheath characteristics typically found in C4 plants. This finding reveals that the structural differences between C3 and C4 bundle sheaths are regulated by apoplastic acidification rather than exclusively by transcriptional developmental programs.
Why it matters
Engineering C4 photosynthetic traits into staple C3 crops like rice has long been a goal to increase agricultural yields by up to 50%, and OSA3 represents a potentially simpler genetic target than previously identified to help achieve this transformation. This discovery could accelerate efforts to develop higher-yielding, more resource-efficient crops in the context of growing global food security challenges.
⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
C4photosynthesis improves light, water and nitrogen-use efficiencies and can raise yieldby50% compared with the ancestral C3pathway.Engineering C4traits into C3crops could substantially boost food production but requires coordinated modifications to leaf anatomy and cell-specific photosynthetic function. For example, C4leaves contain morenumerous, shorter bundle sheath cells that are photosynthetically active. In searching for transcriptional regulators of bundle sheath development in C3 rice, we unexpectedly found OSA3, a plasma membrane H-ATPase that is expressed in bundle sheath cells as they elongate, and when knocked out reduces their length due to reduced apoplastic acidification. Bundle sheath cell number and chloroplast occupancy are increased. Thus, switching between C3 and C4 bundle sheath identity is controlled by acid growth, and OSA3 represents a simple tool for C4 engineering.