Fatty acids modulate the potential of somatic embryogenesis in cotton

Abstract

<p indent="0mm">Callus and embryogenic callus are the key stages of cell fate transformation during plant regeneration. The status of callus and embryogenic callus directly determines the ability of somatic embryogenesis of cotton. Callus cells and embryogenic callus cells (EC) of the highly differentiated material ZM24 and the difficult-to-differentiate material TM-1 were generated and selected for transcriptome and metabolome analysis. The fatty acid extension pathway genes <italic>KCS</italic> and <italic>KCR</italic> showed low expression levels in ZM24 and TM-1 callus and in TM-1 ECs, but showed high expression levels in ZM24 EC, suggesting that the expression levels of <italic>KCS</italic> and <italic>KCR</italic> modulate the potential of callus cells developing into ECs. When we measured the fatty acid content in the 20-day-old ZM24 and TM-1 callus cells, we found that the total fatty acid content and the content of individual fatty acid in TM-1 were significantly higher than those in ZM24, indicating that the differences in callus morphology, callus proliferation, and differentiation ability between TM-1 and ZM24 are correlated with changes in fatty acid content. Overexpression of the <italic>Gh_KCS13</italic> gene inhibits callus formation, confirming that KCS13 negatively regulates callus initiation and proliferation by increasing fatty acid content. Transcription factors related to somatic embryogenesis are predicted to regulate the expression of <italic>Gh_KCS13</italic>, providing potential insights into the regulation of cotton somatic embryogenesis. This study has clarified the function of fatty acids in cotton somatic embryogenesis, laying a foundation for optimizing this process through regulating levels of fatty acids.