The Lotus corniculatus MYB5 functions as a master regulator in proanthocyanidin biosynthesis and bioengineering

Area of Science:

• Plant Molecular Biology
• Agricultural Science
• Biotechnology

Background:

• Proanthocyanidins (PAs) are crucial quality traits in forage species, but their low accumulation in most forage crop leaves hinders research.
• Variability in PA content across different germplasm accessions of Lotus corniculatus presents an opportunity to identify key regulatory genes.

Purpose of the Study:

• To identify genes regulating proanthocyanidin (PA) biosynthesis in Lotus corniculatus leaves.
• To investigate the function of the LcMYB5 gene in PA accumulation.
• To explore the potential of bioengineering PA production in forage species.

Main Methods:

• Comparative analysis of PA content in Lotus corniculatus germplasm.
• Global transcriptional analysis, Gene Ontology (GO), KEGG pathway analysis, and phylogenetic analysis.
• Subcellular localization, transactivation assays, and gene overexpression in Lotus japonicus hairy roots.
• Quantitative real-time PCR (qRT-PCR) to assess gene expression.

Main Results:

• PA content significantly varied among Lotus corniculatus leaf germplasm accessions.
• LcMYB5 was identified as a key gene strongly correlated with leaf PA accumulation.
• Overexpression of LcMYB5 homologs (LcMYB5a and LcMYB5b) in Lotus japonicus hairy roots led to substantial increases in PA levels.
• LcMYB5 homologs were shown to up-regulate the expression of numerous structural and regulatory genes in the PA biosynthesis pathway.

Conclusions:

• LcMYB5 functions as a master transcriptional regulator of proanthocyanidin biosynthesis in Lotus leaves.
• The identified LcMYB5 gene can be utilized for bioengineering enhanced PA production in forage crops.
• This research provides a foundation for improving the nutritional quality of forage species through genetic manipulation.