AUTHOR=Yan Minwen , Xi Hongyuan , Hu Shiyin , Song Jikun , Jia Bing , Feng Pan , Yang Liupeng , Ma Jianjiang , Wang Li , Pei Wenfeng , Zhang Bingbing , Yu Jiwen , Wu Man , Hu Shoulin 

TITLE=Genome-wide analysis of HACD family genes and functional characterization of GhHACD2 for very long chain fatty acids biosynthesis in Gossypium hirsutum

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=8

YEAR=2024

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2024.1413724

DOI=10.3389/fsufs.2024.1413724

ISSN=2571-581X

ABSTRACT=<p>Cotton (<italic>Gossypium</italic> spp.) not only serves as a primary textile fiber crop but also as a vital oilseed crop. It stands as the world’s fifth-largest oil crop and is rich in essential fatty acids. At present, the mechanisms underlying the biosynthesis of cottonseed oil have been extensively studied in cotton. <italic>3-Hydroxyacyl-CoA dehydratase</italic> (<italic>HACD</italic>) is the third rate-limiting enzyme in the elongase complex, which plays a critical role in the biosynthesis of Very Long Chain Fatty Acids (VLCFA). However, the members of the <italic>HACD</italic> family and their roles in cottonseed oil remain uncharacterized in cotton. This study identified that <italic>G. arboreum</italic> and <italic>G. raimondii</italic> have two <italic>HACD</italic> genes, while four <italic>HACD</italic> genes exists in <italic>G. hirsutum,</italic> and <italic>G. barbadense.</italic> The phylogenetic relationships of the 12 <italic>HACD</italic> genes from the four cotton species further divided them into two subfamilies. Gene structure and conserved motif analysis revealed that members of the <italic>HACD</italic> family were relatively conserved during the evolution of cotton, but members within the same subfamily exhibited more similar structures. Homology and collinearity analysis suggest whole-genome duplication/segmental duplication may be a key factor in the amplification of the cotton <italic>HACD</italic> gene family. The qRT-PCR analysis of high-oil and low-oil genotype found significant differences in the expression levels of <italic>GhHACD1-4,</italic> which indicates <italic>GhHACD1-4</italic> is expected to participate in the lipid oil biosynthesis process. Subcellular localization experiments confirmed the presence of the <italic>GhHACD2</italic> inendoplasmic reticulum. The KEGG pathway enrichment analysis of co-expressed genes of <italic>GhHACD1</italic> and <italic>GhHACD2</italic> genes were conducted to confirm their potential involvement in fatty acid elongation and oil biosynthesis. Furthermore, transgenic overexpression analysis of <italic>GhHACD2</italic> caused a 5.02% decrease in oil content compared with the control in yeast, while the levels of C28:0, C30:0, and VLCFAs were significantly improved. This study characterizes <italic>HACD</italic> gene family members in cotton and provides rich genetic resources for increasing cottonseed oil content and improving the nutritional value of cottonseed oil.</p>