Characterization of low temperature-induced plasma membrane lipidome remodeling combined with gene expression analysis reveals mechanisms that regulate membrane lipid desaturation in Carica papaya

Abstract

Carica papaya is a cold-sensitive horticultural crop, the mechanisms underlying its cold sensitivity remains unclear which limit its genetic improvements in cold tolerance. In this study, aqueous dextran-polyethylene glycol two-phase partition systems were applied to purify plasma membrane from papaya leaves grown under 28 °C and 10 °C, the plasma membrane total lipids were analyzed by lipidomic approach; meanwhile, the transcription levels of putative fatty acid desaturases were quantified by RT-qPCR. We found that cerebrosides are dominate plasma membrane lipid species, followed by phospholipids and free sterols. Cold treatment increased the mono-unsaturated and di-unsaturated phospholipids, and decreased di-saturated phospholipids, the proportion of total phospholipids was not affected. Cold stress enhanced the transcription of CpFAD4, CpFAD6 and CpFAB2−2. Pathway analysis suggested that the cold induction of CpFAB2−2 transcription and CpFAD2 enzyme activities play important roles for plasma membrane lipidome remodeling under cold stress. Our findings uncovered potential targets to improve papaya cold tolerance.