MYB Transcription Factor OsC1 Involves the Regulation of Purple Leaf Sheath in Rice

Area of Science:

• Plant genetics
• Molecular biology
• Agricultural science

Background:

• The genetic control of purple traits in rice is not fully understood.
• The specific genetic basis for the purple sheath phenotype in rice remains elusive.

Purpose of the Study:

• To identify quantitative trait loci (QTL) associated with the purple sheath trait in rice.
• To elucidate the genetic mechanism underlying purple sheath coloration in rice.

Main Methods:

• Construction of F2 populations from crosses between purple and green sheath rice lines.
• Bulked Segregant Analysis (BSA) to identify QTLs.
• CRISPR/Cas9 gene editing to create homozygous mutants.
• RT-PCR to analyze gene expression patterns.
• Yeast reporter system to determine functional domains of candidate genes.

Main Results:

• A major QTL for purple sheath, qPLSr6, was mapped to chromosome 6.
• LOC_Os06g10350 (OsC1) was identified as a strong candidate gene.
• CRISPR/Cas9-induced mutants (KO-1, KO-2) exhibited loss of purple sheath.
• Expression of OsC1 and key anthocyanin biosynthesis genes (ANS, DFR, F3H, F3'H) was significantly downregulated in mutants.
• The C-terminal region of OsC1^PLSr was confirmed as a transcriptional activation domain.

Conclusions:

• OsC1 plays a crucial role in regulating anthocyanin biosynthesis, leading to the purple sheath phenotype in rice.
• OsC1 functions by controlling the expression of downstream genes involved in the anthocyanin pathway.
• This study enhances our understanding of the genetic architecture controlling plant pigmentation in rice.