Characterization and transcriptomic analysis of a novel yellow-green leaf wucai (Brassica campestris L.) germplasm

Abstract

Background Leaf color mutants are the ideal materials to explore the pathways of chlorophyll (Chl) metabolism, chloroplast development, and photosynthesis system. In this study, a spontaneous yellow-green leaf wucai (Brassica campestris L.) mutant “WY16–13” was identified, which exhibited yellow-green leaf color during its entire growth period. However, current understanding of the molecular mechanism underlying Chl metabolism and chloroplast development of “WY16–13” is limited. Results Total Chl and carotenoid content in WY16–13 was reduced by 60.92 and 58.82%, respectively, as compared with its wild type parental line W16–13. Electron microscopic investigation revealed fewer chloroplasts per cell and looser stroma lamellae in WY16–13 than in W16–13. A comparative transcriptome profiling was performed using leaves from the yellow-green leaf type (WY16–13) and normal green-leaf type (W16–13). A total of 54.12 million (M) (WY16–13) and 56.17 M (W16–13) reads were generated. A total of 40,578 genes were identified from the mapped libraries. We identified 3882 differentially expressed genes (DEGs) in WY16–13 compared with W16–13 (i.e., 1603 upregulated genes and 2279 downregulated genes). According to the Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, these DEGs are involved in porphyrin and Chl metabolism [i.e., chlorophyllase (CLH), heme oxygenase (HO), chlorophyll (ide) b reductase (NYC), and protochlorophyllide oxidoreductase (POR) genes], carbohydrate metabolism, photosynthesis, and carbon fixation in photosynthetic organisms. Moreover, deficiency in Chl biosynthetic intermediates in WY16–13 revealed that the formation of the yellow-green phenotype was related to the disorder of heme metabolism. Conclusions Our results provide valuable insights into Chl deficiency in the yellow-green leaf mutant and a bioinformatics resource for further functional identification of key allelic genes responsible for differences in Chl content.

Identification and function analysis of yellow-leaf mutant (YX-yl) of broomcorn millet

“…The photosynthetic rate and chloroplast ultrastructure are directly affected by leaf color mutations [ 4 , 8 , 13 , 14 , 41 ]. In a leaf-color mutant of rice, the chloroplasts are degrade, the matrix is disordered, and the thylakoids almost completely disappear [ 4 ].…”

“…In a novel leaf-color mutant of foxtail millet, disorganized thylakoids and considerably fewer starch granules have been observed [ 8 ]. Moreover, a green-yellow leaf mutant of wucai exhibited fewer chloroplasts per cell and looser stromal lamellae [ 41 ]. Similar results were found in the present study: compared with that in the wild type (YX), chloroplast development was inhibited in the YX-yl mutant owing to degeneration of the chloroplast ultrastructure, with fewer grana thylakoids and almost no stroma thylakoids, which might result in poor chloroplast function and accelerated leaf yellowing.…”

Comparative physiology and transcriptome analysis reveals that chloroplast development influences silver-white leaf color formation in Hydrangea macrophylla var. maculata

“…These results revealed that the expression changes of genes involved in photosynthesis played an important role in the formation of the capacity of plant photosynthesis. Previous research reported that the expression change of genes related to photosynthesis in Brassica campestris mutants led to abnormal chloroplast development and reduced pigment content [ 30 ]. Therefore, the decreased capacity of photosynthesis in YB was likely due to the reduction of pigment contents and the low expression level of photosystem, chlorophyll a-b binding protein, ATP synthase and cytochrome genes.…”

Genome-wide analysis of the DREB family genes and functional identification of the involvement of BrDREB2B in abiotic stress in wucai (Brassica campestris L.)

“…chinensis var. rosularis ), a variant of non-heading Chinese cabbage, is a semi-hardy vegetable widely grown in the Yangtze-Huai River basin [ 23 , 24 ]. Recently, abiotic stresses such as high temperature, freezing, and drought have greatly affected the yield and quality of wucai.…”