A genome-wide analysis of the phospholipid: diacylglycerol acyltransferase gene family in Gossypium.

Background: Cotton (Gossypium spp.) is the most important natural fiber crop worldwide, and cottonseed oil is its most important byproduct. Phospholipid: diacylglycerol acyltransferase (PDAT) is important in TAG biosynthesis, as it catalyzes the transfer of a fatty acyl moiety from the sn-2 position of a phospholipid to the sn-3 position of sn-1, 2-diacylglyerol to form triacylglycerol (TAG) and a lysophospholipid. However, little is known about the genes encoding PDATs involved in cottonseed oil biosynthesis.

Results: A comprehensive genome-wide analysis of G. hirsutum, G. barbadense, G. arboreum, and G. raimondii herein identified 12, 11, 6 and 6 PDATs, respectively. These genes were divided into 3 subfamilies, and a PDAT-like subfamily was identified in comparison with dicotyledonous Arabidopsis. All GhPDATs contained one or two LCAT domains at the C-terminus, while most GhPDATs contained a preserved single transmembrane region at the N-terminus. A chromosomal distribution analysis showed that the 12 GhPDAT genes in G. hirsutum were distributed in 10 chromosomes. However, none of the GhPDATs was co-localized with quantitative trait loci (QTL) for cottonseed oil content, suggesting that their sequence variations are not genetically associated with the natural variation in cottonseed oil content. Most GhPDATs were expressed during the cottonseed oil accumulation stage. Ectopic expression of GhPDAT1d increased Arabidopsis seed oil content.

Conclusions: Our comprehensive genome-wide analysis of the cotton PDAT gene family provides a foundation for further studies into the use of PDAT genes to increase cottonseed oil content through biotechnology.