Cloning and expression of three fatty acid desaturase genes from cold-sensitive lima bean (Phaseolus lunatus L.)

Abstract

The critical chilling temperature of cold-sensitive lima bean (Phaseolus lunatus L.) seedlings was determined to be approx. 8°C. The full-length cDNAs of PlSAD, PlFAD2, and PlFAD3 encoding three fatty acid desaturases were isolated from lima bean leaves. The PlSAD open reading frame (ORF) had 1,317 bp and a single intron of 601 bp, encoding a polypeptide of 438 amino acids that showing 86% homology with the plastidial stearoyl-acyl carrier protein desaturase in soybean. The PlFAD2 ORF contained 1,059 bp and was uninterrupted, encoding a polypeptide of 352 amino acids having 85% identity with the microsomal omega-6 desaturase GmFAD2-3 in soybean. PlFAD3 ORF had 1,116 bp and seven introns, encoding a polypeptide of 371 amino acids showing 91% homology with the microsomal omega-3 desaturase FAD3 in cowpea. PlSAD and PlFAD2 were expressed highly in leaves but poorly in roots and stems, while PlFAD3 was expressed in three tissues. All three genes were significantly induced in leaves by drought. PlSAD and PlFAD3 in leaves were down-regulated by high temperature and salinity, whereas PlFAD2 was up-regulated by the two stresses. The expression patterns of the three genes in lima bean leaves under suboptimal temperature, 18°C, were different from those under 8°C. The down-regulation of PlSAD transcript at chilling temperature might be an important factor contributing to chilling susceptibility for lima bean plants.

Differences in cold tolerance and expression of two fatty acid desaturase genes in the leaves between fingered citron and its dwarf mutant

“…1). The genome region of CmsFAD2 was not interrupted by any intron, which was in line with other FAD2s reported in most plants (Zhang et al 2011).…”

“…Three replicates were averaged and the standard deviation is shown in cotton (Kargiotidou et al 2008), PoleFAD2 in purslane (Teixeira et al 2009) and PlFAD2 in Phaseolus lunatus (Zhang et al 2011) were induced by cold stress. FAD8 was also induced by low temperatures in A. thaliana (Gibson et al 1994), maize (Berberich et al 1998), rice (Wang et al 2006), Descurainia sophia (Tang et al 2007) and purslane (Teixeira et al 2010).…”

“…Total RNA was extracted with Trizol and genomic DNA was extracted by cetyltriethylammnonium bromide method (Zhang et al 2011). The quality and concentration of the extracted RNA were checked by agarose gel electrophoresis and measured by a NanoDrop 2000 Spectrophotometer (Thermo Scientific, San Jose, CA, USA).…”

“…The membrane-bound x-6 FADs (the microsomal FAD2 and the plastidial FAD6 genes) insert a double bond of monounsaturated oleic acid (18:1) to generate di-unsaturated linoleic acid (18:2). x-3 FADs (one microsomal FAD3 and two plastidial FAD7 and FAD8 genes) further catalyze the introduction of a third bond to form tri-unsaturated a-linolenic acid (18:3) (Teixeira et al 2009(Teixeira et al , 2010Zhang et al 2011). In some species, there is indeed a positive relationship between the composition of polyunsaturated fatty acids in chloroplast membranes and low-temperature tolerance (Upchurch 2008).…”

Landscape genetics, adaptive diversity and population structure in Phaseolus vulgaris

“…Nonetheless, some of the genes under selection are involved in responses to environmental stress (Kavar et al, 2008;Mao et al, 2010;Rapala-Kozik et al, 2012;Krause et al, 2013), as cold acclimation or chilling susceptibility (Liu et al, 2007;Alc azar et al, 2011;Zhang et al, 2011), adaptation to different conditions of light and temperature, and drought stress responses (Green et al, 1991;Bocobza et al, 2013). Four of these loci (Table S2) were also in common with those under selection during domestication (Schmutz et al, 2014).…”