Cold affects the transcription of fatty acid desaturases and oil quality in the fruit of Olea europaea L. genotypes with different cold hardiness

Abstract

The olive tree lacks dormancy and is low temperature sensitive, with differences in cold tolerance and oil quality among genotypes. The oil is produced in the drupe, and the unsaturated fatty acids contribute to its quality. The aim of the present research was to investigate the relationship among development, cold response, expression of fatty acid desaturase (FAD) genes, and unsaturated fatty acid composition in drupes belonging to genotypes differing in leaf cold tolerance, but producing good oil (i.e. the non-hardy Moraiolo, the semi-hardy Frantoio, and the hardy Canino). In all genotypes, cold sensitivity, evaluated by cold-induced transient increases in cytosolic calcium, was high in the epi-mesocarp cells before oil body formation, and decreased during oil biogenesis. However, genotype-dependent differences in cold sensitivity appeared at the end of oil production. Genotype-dependent differences in FAD2.1, FAD2.2, FAD6, and FAD7 expression levels occurred in the epi-mesocarp cells during the oleogenic period. However, FAD2.1 and FAD7 were always the highest in the first part of this period. FAD2.2 and FAD7 increased after cold applications during oleogenesis, independently of the genotype. Unsaturated fatty acids increased in the drupes of the non-hardy genotype, but not in those of the hardy one, after cold exposure at the time of the highest FAD transcription. The results show a direct relationship between FAD expression and lipid desaturation in the drupes of the cold-sensitive genotype, and an inverse relationship in those of the cold-resistant genotype, suggesting that drupe cold acclimation requires a fine FAD post-transcriptional regulation. Hypotheses relating FAD desaturation to storage and membrane lipids, and genotype cold hardiness are discussed.

Opportunities and limitations related to the application of plant-derived lipid molecular proxies in soil science

“…Thus, a positive correlation of long-chain odd n-alkanes with temperature was observed (Maffei et al, 1993;Zhang et al, 2004). Also, the abundance of membrane fatty acids with 16 and 18 carbons can change as a result of temperature (Maffei et al, 1993;Williams et al, 1995;Matteucci et al, 2011). Under heat stress, the relative abundance of C 16:0 fatty acid was often found to increase, and the abundance of polyunsaturated C 18:3 fatty acid was found to decrease (Larkindale and Huang, 2004;Bakht et al, 2006).…”

Physiological and molecular changes in plants grown at low temperatures

“…Often, these adverse effects are accompanied by changes in cell membrane structure and lipid composition (Uemura and Steponkus 1999;Matteucci et al 2011), cellular leakage of electrolytes and amino acids, a diversion of electron flow to alternate pathways (Seo et al 2010), alterations in protoplasmic streaming and redistribution of intracellular calcium ions (Knight et al 1998) (Fig. 1).…”

“…However, the plant will exhibit necrosis or die if exposure is maintained (Lyons 1973;Raison and Lyons 1986) cold acclimation promotes the stabilization of membranes, which prevents damage leading to cell death. The acclimation process also activates mechanisms that protect membrane fluidity by ensuring the optimal activity of associated enzymes (Matteucci et al 2011). …”

Olive Tree Genomic

“…Only FAD 6 shows partial coverage, especially in the fruit assembly where only three matching singleton sequences were found (Figure 3). This is most probably due to the sharp decrease of FAD 6 transcript abundance in fruits sampled at late developing stages, from 15 to 20 weeks after flowering (Matteucci et al, 2011).…”