Genes regulating gland development in the cotton plant

Area of Science:

• Plant Molecular Biology
• Agricultural Science
• Biochemistry

Background:

• Cotton (Gossypium hirsutum L.) possesses dark glands containing toxic terpenoids like gossypol, which serve as a natural defense mechanism against pests and pathogens.
• Gossypol in cottonseed presents challenges for its use as food or feed, particularly for monogastric animals.

Purpose of the Study:

• To identify and characterize genes responsible for the formation of gossypol-containing glands in cotton.
• To explore the potential of manipulating these genes for developing gossypol-free cottonseed.

Main Methods:

• RNA-sequencing (RNA-seq) analysis of embryos from glanded and glandless cotton near-isogenic lines.
• Virus-induced gene silencing (VIGS) to assess the function of candidate genes.
• Molecular analysis of gene sequences, including transposon insertion and promoter mutations.
• Gene overexpression and CRISPR/Cas9 gene editing to confirm gene function.

Main Results:

• Identified 33 candidate Cotton Gland Formation (CGF) genes involved in gland development and gossypol biosynthesis.
• Silencing of three CGF gene pairs significantly reduced gland number and gossypol levels.
• A transposon insertion in the GoPGF (CGF3) gene and promoter mutations in its homeolog were found in glandless cotton.
• Overexpression of GoPGF increased gossypol, while its knockout resulted in a glandless phenotype, confirming its critical role.

Conclusions:

• The GoPGF (CGF3) gene is essential for cotton gland formation and gossypol accumulation.
• Targeted silencing of CGF genes offers a promising strategy to eliminate gossypol from cottonseed, enhancing its safety for food and feed.