Early Leaf Senecence and Salt Stress Response Gene Found in Rice

Early leaf senescence can cause negative effects on rice yield and its regulation is relatively unknown. The team of Dong-Dong Zeng from Zhejiang University in China isolated and studied the bilateral blade senescence 1 (bbs1) rice (Oryza sativa), an early leaf senescence mutant with a premature senescence phenotype that occurs at the leaf margins, in hopes of understanding the mechanism of early leaf senescence.

The mutant showed premature leaf senescence beginning at the tillering stage and exhibited severe symptoms at the late grain-filling stage. The mutant also showed accelerated dark-induced leaf senescence. The OsBBS1 gene of the bbs1 mutant was analyzed and was found to have an insertion in its first exon. This gene encodes a receptor-like cytoplasmic kinase.

OsBBS1-knockout plants generated via CRISPR-Cas9 exhibited similar early leaf senescence phenotypes as did the bbs1 mutant. The OsBBS1 gene is expressed in all detected tissues and was predominantly expressed in the main vein region of mature leaves. The expression of OsBBS1 could be greatly induced by salt stress, and the bbs1 mutant exhibited hypersensitivity to salt stress.

This is the first identification of OsBBS1 being involved in leaf senescence and playing critical roles in the salt stress response in rice.

For more information, read the article in Plant Cell Reports.