Recently, Researchers from Crop Photosynthesis Functional Genomics team of Biotechnology Research Institute, CAAS, have elucidated molecular mechanisms controlling minor vein development in rice, providing new gene resources and a theoretical basis for the effective assembly of C4 anatomy in C3 crops, such as rice. The results have been published in  The Plant Cell  . For details, please visit

https://doi.org/10.1093/plcell/koad125.

C4 crops, such as maize and sorghum, have special leaf anatomy called "Kranz structure" and C4 photosynthetic biochemical pathways. Their photosynthetic efficiency, biomass, grain yield, water and nitrogen use efficiency are significantly higher than those of C3 crops such as rice and wheat.

The minor vein is the organizing center for "Kranz structure". Minor vein densification and mesophyll cell/vascular bundle sheath cell patterning are the first key steps during C4 evolution from C3 plants. Scientists have been studying on the molecular mechanism of the C4 leaf anatomy formation for years, but little is known due to the complexity of the regulatory mechanisms.

Researchers found that the transcription factor OsSHR1/2 and OsIDD12/13 in rice formed a complex and bind to a specific motif located in the intron of  OsPIN5c , forming an SHR-IDD-PIN molecular module to regulate the  OsPIN5c  expression, affecting the distribution of auxin in leaf veins, thus control the density of minor veins and mesophyll cell/vascular bundle sheath cell patterning, formed a similar leaf anatomy of C4 plants. This study takes a crucial step toward to the C4 rice development.

This research was supported by National Key Research and Development Program and Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences.

By Zhang Zhiguo    (zhangzhiguo@caas.cn)