A rice White-stripe leaf3 (wsl3) mutant lacking an HD domain-containing protein affects chlorophyll biosynthesis and chloroplast development

Abstract

Leaf-color mutants are ideal genetic materials for understanding the mechanism of chloroplast development and chlorophyll (Chl) biosynthesis. Here we isolated and identified a new leaf-color mutant of rice, named whitestripe leaf3 (wsl3), from a 60 Co-irradiated mutant pool. The wsl3 mutant displayed a visible white-stripe leaf in both young seedlings and flag leaves of mature plant. Chl content in homozygous wsl3 mutant was approximately 47% of that in the wild type. Besides, chloroplast development in the mutant was severely arrested. By a map-based cloning strategy, the wsl3 gene was finely confined to a 50.8 kb region on chromosome 1. Moreover, a 9-bp deletion was identified in the genomic region of LOC_Os01g01920, which encodes an HD (histidine and aspartic acid) domaincontaining protein. Genetic complementation confirmed that LOC_Os01g01920 could recover the lesion of wsl3 mutation. Real-time PCR analyses showed that the expression levels of WSL3 were the highest in young and flag leaves among various tissues, and most of the genes associated with Chl biosynthesis were significantly down-regulated in the wsl3 mutant. Meanwhile, in contrast to many nuclear geneencoded phage-type RNA polymerase(s) (NEP) transcribed genes were up-regulated, most of plastid-encoded bacterialtype RNA polymerase (PEP) transcribed genes were downregulated. These results demonstrated that the WSL3 gene, as an HD domain-containing protein, is involved in chl biosynthesis and chloroplast development in rice.

Candidate Genes for Yellow Leaf Color in Common Wheat (Triticum aestivum L.) and Major Related Metabolic Pathways according to Transcriptome Profiling

“…CHLH is crucial for the Mg-chelatase activity as a catalytic subunit [ 19 ]. It has been reported that mutation of the CHLH gene leads to defective Chl and the chlorina or yellow phenotype in rice [ 8 ] and Arabidopsis thaliana [ 20 ]. Our analysis of seven intermediate products involved in Chl biosynthesis showed that the level of the substrate for Mg-chelatase increased significantly in Y plants whereas the level of the product from Mg-chelatase decreased significantly ( Figure 11 ).…”

“…Mutations in any of these genes may lead to variations in the Chl contents [ 4 ], abnormal chloroplast development [ 5 ], and decreased photosynthetic efficiency [ 6 ], thereby yielding leaf color mutants. Mutants deficient in Chl biosynthesis have been identified in many higher plants, such as rice [ 7 , 8 ], Brassica napus [ 9 ], Arabidopsis thaliana [ 10 ], barley [ 11 ], and Camellia sinensis [ 12 ]. Many of the reported chlorotic mutants exhibit reduced Chl biosynthesis due to the lower activity of magnesium chelatase (Mg-chelatase) [ 11 , 13 , 14 , 15 ].…”

Genetic mapping and physiological analysis of chlorophyll-deficient mutant in Brassica napus L

“…Jung et al established T-DNA pools for rice mutants, and 189 lines showed a chlorophyll-deficient phenotype that segregated as a single recessive locus in the T 2 generation[ 7 ]. Zhao et al identified that HD domain-containing proteins affect chlorophyll biosynthesis and chloroplast development in the white stripe leaf3 mutant [ 8 ]. Zhang et al identified an incompletely dominant gene located on chromosome 2BS flanked by the simple sequence repeat marker Xwmc25 responsible for yellow leaf color [ 9 ].…”

The anatomical, physiological, and molecular analysis of a chlorophyll-deficient mutant in tree peony (Paeonia suffruticosa)

“…So far, a lot of work has been done on the mechanism of leaf color variation. It is generally believed that the block of chloroplast development and Chl synthesis or degradation pathways in plant leaves lead to changes in leaf color (Zhao et al 2016). It was reported that a rice (Oryza sativa) leaf color mutant (ygl1) exhibited a yellow-green leaf phenotype due to a decrease of Chl synthase (Wu et al 2007).…”