Natural Variation of a PPR Coding Gene SST1 Confers Salt Tolerance During Soybean Domestication

Area of Science:

• Plant Biology
• Genetics
• Agronomy

Background:

• Soil salinity significantly hinders soybean seedling growth and yield.
• Identifying salt tolerance genes and their variants is key for genetic improvement of soybean cultivars.

Purpose of the Study:

• To identify genes conferring salt tolerance in soybean.
• To elucidate the mechanisms of salt tolerance and its role in soybean domestication.

Main Methods:

• Developed a salt-induced leaf senescence screening system.
• Utilized genome-wide association analysis to identify key genes.
• Investigated gene function through molecular and cellular analyses.

Main Results:

• Identified SST1, a pentatricopeptide repeat (PPR) gene, as crucial for salt tolerance.
• A truncated allele, SST1^HapT, confers increased salt tolerance, unlike the full-length allele SST1^HapC.
• SST1 regulates mitochondrial gene RNA editing, impacting cell morphology and H₂O₂ homeostasis.

Conclusions:

• SST1 is an adaptive domestication gene, with the beneficial truncated allele fixed in cultivated soybean.
• SST1 interacts synergistically with GmCHX1 to enhance salt tolerance.
• Findings provide targets for developing salt-tolerant soybean varieties and understanding crop domestication.