Photosynthetic characteristics and genetic mapping of a new yellow leaf mutant in .

UNLABELLED

Chlorophyll is one of the key factors for photosynthesis and plays an important role in plant growth and development. We previously isolated an EMS mutagenized rapeseed (), which had yellow leaf, reduced chlorophyll content and fewer thylakoid stacks. Here, we found that showed attenuated utilization efficiency of both light energy and CO but enhanced heat dissipation efficiency and greater tolerance to high-light intensity. BSA-Seq analysis identified a single nucleotide change (C to T) and (G to A) in the third exon of the and , respectively. These two genes encode the magnesium chelatase subunit I 1 (CHLI1) that catalyzes the insertion of magnesium into protoporphyrin IX, a pivotal step in chlorophyll synthesis. The mutation sites resulted in an amino acid substitution P144S and G128E within the AAA+ domain of the CHLI1 protein. Two KASP markers were developed and co-segregated with the yellow leaf phenotype in segregating F population. Loss of and by CRISPR/Cas9 gene editing recapitulated the mutant phenotype. and were located in chloroplast and highly expressed in the leaves. Furthermore, RNA-seq analyses revealed the expression of chlorophyll synthesisrelated genes were upregulated in the mutant. These findings provide a new insight into the regulatory mechanism of chlorophyll synthesis in rapeseed and suggest a novel target for improving the photosynthetic efficiency and tolerance to high-light intensity in crops.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11032-023-01429-6.