Chlorophyll retention caused by STAY-GREEN (SGR) gene mutation enhances photosynthetic efficiency and yield in soybean hybrid Z1

To study the effect of a stay-green mutation on photosynthetic efficiency in hybrid offspring of soybean (Glycine max [L.] Merr.), the parameters of photosynthesis and chlorophyll (Chl) fluorescence were compared between a new stay-green variety Jinda Zhilv No. 1 (Z1) and one of its parents Jinda No. 74 (JD74). During leaf natural senescence, the Chl degradation attenuated in Z1. The net photosynthetic rate, stomatal conductance, and transpiration rate were consistently higher in Z1 than that in JD74 after flowering. The decreases of maximum photochemical efficiency of PSII, actual photochemical efficiency of PSII, and photochemical quenching coefficient were greater in JD74 than in Z1. Transcriptional levels of most genes involved in photosystems were much higher in Z1. All these effectively contributed to maintained photosystem stability and enhanced photosynthetic efficiency and yield in Z1. We also revealed that the STAY-GREEN gene mutation was responsible for inhibiting Chl degradation in Z1.

Automated summary

The stay-green mutation in the soybean hybrid offspring led to slower chlorophyll degradation during leaf natural senescence in the new variety Z1 compared to its parent JD74. Z1 exhibited higher net photosynthetic rate, stomatal conductance, and transpiration rate, along with greater efficiency in maintaining photosystem stability and enhanced photosynthetic efficiency. This was attributed to the mutation in the STAY-GREEN gene, which inhibited chlorophyll degradation and resulted in improved overall photosynthetic performance.