Gene silencing of Sugar-dependent 1 (JcSDP1), encoding a patatin-domain triacylglycerol lipase, enhances seed oil accumulation in Jatropha curcas

Abstract

BackgroundTriacylglycerols (TAGs) are the most abundant form of storage oil in plants. They consist of three fatty acid chains (usually C16 or C18) covalently linked to glycerol. SDP1 is a specific lipase for the first step of TAG catabolism in Arabidopsis seeds. Arabidopsis mutants deficient in SDP1 accumulate high levels of oils, probably due to blockage in TAG degradation. We applied this knowledge from the model plant, Arabidopsis thaliana, to engineer increased seed oil content in the biodiesel plant Jatropha curcas using RNA interference (RNAi) technology.ResultsAs Jatropha is a biodiesel crop, any significant increase in its seed oil content would be an important agronomic trait. Using A. thaliana as a model plant, we found that a deficiency of SDP1 led to higher TAG accumulation and a larger number of oil bodies in seeds compared with wild type (Columbia-0; Col-0). We cloned Jatropha JcSDP1, and verified its function by complementation of the Arabidopsis sdp1-5 mutant. Taking advantage of the observation with Arabidopsis, we used RNAi technology to generate JcSDP1 deficiency in transgenic Jatropha. We found that Jatropha JcSDP1-RNAi plants accumulated 13 to 30% higher total seed storage lipid, along with a 7% compensatory decrease in protein content, compared with control (CK; 35S:GFP) plants. Free fatty acid (FFA) content in seeds was reduced from 27% in control plants to 8.5% in JcSDP1-RNAi plants.ConclusionHere, we showed that SDP1 deficiency enhances seed oil accumulation in Arabidopsis. Based on this result, we generated SDP1-deficient transgenic Jatropha plants using by RNAi technology with a native JcSDP1 promoter to silence endogenous JcSDP1 expression. Seeds of Jatropha JcSDP1-RNAi plants accumulated up to 30% higher total lipid and had reduced FFA content compared with control (CK; 35S:GFP) plants. Our strategy of improving an important agronomic trait of Jatropha can be extended to other oil crops to yield higher seed oil.

Multigene Engineering of Triacylglycerol Metabolism Boosts Seed Oil Content in Arabidopsis

“…The additive effect of overexpression of these two genes supports this conclusion. In addition to TAG biosynthetic capacity, TAG turnover can occur during late seed development and can reduce the final oil content of seeds (Kelly et al, 2013a;Kim et al, 2014). Therefore, it is consistent that combining WRI1 and DGAT1 overexpression with the suppression of SDP1 can result in a further increase in percentage seed oil content.…”

“…However, WRI1 and DGAT1 overexpression have been reported individually to boost seed oil content in maize (Zheng et al, 2008;Shen et al, 2010) and oilseed rape (Brassica napus; Weselake et al, 2008;Wu et al, 2014). Furthermore, suppression of SDP1 can also enhance seed oil content in oilseed rape (Kelly et al, 2013a) and Jatropha curcas (Kim et al, 2014). There is also potential for stacking additional genes to obtain a further increase in seed oil content.…”

“…To test whether combined expression of WRI1 and DGAT1 can have an additive effect on seed oil content, and also whether this might be further augmented by blocking TAG turnover by RNA interference (RNAi) suppression of the lipase SUGAR-DEPENDENT1 (SDP1; Kelly et al, 2013a;Kim et al, 2014), transfer DNA (T-DNA) constructs were designed for the manipulation of each gene under the control of a seed-specific promoter (Fig. 1B).…”

“…A number of studies have established that seed oil content can be increased by changing the expression levels of individual enzymes involved in oil metabolism (Roesler et al, 1997;Zou et al, 1997;Jako et al, 2001;Vigeolas et al, 2007;Kelly et al, 2013a;Kim et al, 2014). However, the impact of this approach is theoretically limited.…”

Contribution of Biotechnological Tools in the Enhancement of Secondary Metabolites in Selected Medicinal Climbers

“…miRNA or siRNA, are used for knocking down an enzymatic step in the biosynthetic pathways (Verpoorte and Memelink 2002 ). The genes responsible for the production of important metabolites will be overexpressed in the homologous or heterologous plant systems (Kim et al 2014 ). The most recent technique for the functional analysis of the gene is CRISPR Cas9, TALEN and ZFN system in which a gene can be knocked out (Gaj et al 2013 ;Shalem et al 2014 ) .…”