Identification of BoFAR3a Reveals the Genetic Basis of a Glossy Green Trait in Broccoli

TL;DR

A broccoli mutant with a glossy green leaf was found to have a genetic mutation in the BoFAR3a gene, which affects wax production and could help breed better broccoli varieties.

Contribution

The study identifies BoFAR3a as the gene responsible for glossy green leaves in broccoli due to a start codon mutation.

Findings

The glossy green trait in broccoli mutant SY03 is controlled by a single recessive gene, BoFAR3a.

A point mutation in BoFAR3a replaces the start codon, reducing its expression and causing wax deficiency.

Restoring BoFAR3a in Arabidopsis thaliana reversed the glossy green phenotype, confirming its function.

Abstract

Mutants with a bright green appearance due to wax synthesis or deposition defects have been reported in various plants such as Arabidopsis thaliana, corn, and rice, but they are relatively rare in broccoli (a brassicaceae crop). Here, we describe SY03, a natural mutant of broccoli with a glossy green phenotype owing to epidermal wax deficiency. Genetic analysis indicated that the leaf luster trait of SY03 was controlled by a single recessive gene. By using the F2 generation and combining bulked segregant analysis and molecular marker techniques, the candidate gene BoFAR3a, homologous to the Arabidopsis FAR gene, was identified within a 96.678 kb interval of chromosome C01. The A→G point mutation in exon 1 of the BoFAR3a coding sequence substitutes the canonical ATG start codon with GTG, which is predicted to abrogate or severely reduce translation initiation. RT-qPCR indicated that the expression levels of BoFAR3a were significantly decreased in the leaves of the glossy green phenotype mutant. Heterologous expression of BoFAR3a in A. thaliana restored the phenotype of A. thaliana mutant FAR3. The discovery of BoFAR3a is of great significance for breeding lustrous and commercially appealing broccoli varieties. This study systematically analyzed the molecular basis of the lustrous green phenotype in broccoli, providing new insights into the epidermal waxy regulatory network of cruciferous crops. In the future, the wax synthesis pathway can be precisely improved through gene editing technology, achieving a coordinated enhancement of the appearance quality and stress resistance of broccoli.

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