Evidence for Proteomic and Metabolic Adaptations Associated with Alterations of Seed Yield and Quality in Sulfur-limited Brassica napus L

Abstract

In Brassica napus, seed yield and quality are related to sulfate availability, but the seed metabolic changes in response to sulfate limitation remain largely unknown. To address this question, proteomics and biochemical studies were carried out on mature seeds obtained from plants grown under low sulfate applied at the bolting (LS32), early flowering (LS53), or start of pod filling (LS70) stage. The protein quality of all low-sulfate seeds was reduced and associated with a reduction of S-rich seed storage protein accumulation (as Cruciferin Cru4) and an increase of S-poor seed storage protein (as Cruciferin BnC1). This compensation allowed the protein content to be maintained in LS70 and LS53 seeds but was not sufficient to maintain the protein content in LS32 seeds. The lipid content and quality of LS53 and LS32 seeds were also affected, and these effects were primarily associated with a reduction of C18-derivative accumulation. Proteomics changes related to lipid storage, carbohydrate metabolism, and energy (reduction of caleosins, phosphoglycerate kinase, malate synthase, ATP-synthase ␤-subunit, and thiazole biosynthetic enzyme THI1 and accumulation of ␤-glucosidase and citrate synthase) provide insights into processes that may contribute to decreased oil content and altered lipid composition (in favor of long-chain fatty acids in LS53 and LS32 seeds). These data indicate that metabolic changes associated with S limitation responses affect seed storage protein composition and lipid quality. Proteins involved in plant stress response, such as dehydroascorbate reductase and Cu/Zn-superoxide dismutase, were also accumulated in LS53 and LS32 seeds, and this might be a consequence of reduced glutathione content under low S availability. LS32 treatment also resulted in (i) reduced germination vigor, as evidenced by lower germination indexes, (ii) reduced seed germination capacity, related to a lower seed viability, and (iii) a strong decrease of glyoxysomal malate synthase, which is essential for the use of fatty acids during seedling establishment. Molecular & Cellular Proteomics 13: 10.1074/mcp.M113.034215, 1165-1183, 2014.As the third main oil crop worldwide (58.5 Mt in 2011), oilseed rape represents a major renewable resource for food (oil, meal) and nonfood uses (green energy, green chemistry). Relative to other crops such as cereals, oilseed rape (Brassica napus L.) requires high amounts of sulfur (S) to sustain its growth and yield (1-3). The reduction of S atmospheric deposits observed over recent decades has forced farmers to add S fertilizer in order to maintain seed yield and quality. A previous study highlighted the necessity of satisfying plant S requirements until the start of pod filling to ensure yield as well as high lipid and protein contents (4). These observations emphasize the importance of a detailed understanding of the impact of S limitation on seed oil and protein quality and of the processes involved.During Brassica napus seed development, the carbon (C) provided by source organs as sucro...

Impact of sulfur applications on the agronomic performance of rapeseed–clover mixtures

“…Additionally, our study shows that cropping (monocrops or mixtures) or S application conditions had effect on either the seed quality components (protein, oil and glucosinolate concentrations, and oil composition) or on the ω‐6 : ω‐3 ratio (Tab. ) of rapeseed seeds, which remained close to 2, a value considered as good for rapeseed oil quality ( D'Hooghe et al, ).…”

“…In addition to these strong N requirements, winter oilseed rape also requires high inputs of sulfur (S) fertilizer (McGrath and Zhao, 1996;Scherer, 2001). Rapeseed is highly sensitive to S mineral limitation, which induces a reduction in yield and the quality of harvest products through modifications of lipids and protein composition of seeds (McGrath and Zhao, 1996;Malhi et al, 2007;Scherer, 2001;D'Hooghe et al, 2014). In addition, Dubousset et al (2010) have shown that decreased S availability reduces the N use efficiency of oilseed rape.…”

Non-Specific Root Transport of Nutrient Gives Access to an Early Nutritional Indicator: The Case of Sulfate and Molybdate

“…Considering the effects of S deficiency on the Mo accumulation previously described, it could be hypothesized that the leaf [Mo]:[S] ratio might serve as an indicator of S nutrition to predict S deficiency. For S-demanding crops such as oilseed rape, S deficiency provokes multiple plant physiological changes leading to losses in yield and seed quality through modified lipid and protein composition of seeds [30, 31, 32, 33, 34]. It has already been suggested that the analysis of plants rather than soil via total S, SO 4 2- or N:S, malate:sulfate or ([Cl - ]+[NO 3 - ]+[PO 4 3- ]):[SO 4 2- ] ratios could be used to detect plant S requirements (for review see [35, 36] but these parameters are affected by growth stage and growth rates or need laboratory analyses, making them unreliable as diagnostic indicators [35, 37].…”

The impact of sulfate restriction on seed yield and quality of winter oilseed rape depends on the ability to remobilize sulfate from vegetative tissues to reproductive organs

“…S deprivation in oilseed rape leads to reduced seed yields and oil quality (Janzen and Bettany, 1984 ; Scherer, 2001 ). Recent work based on proteomics approaches in mature seeds obtained from winter oilseed rape plants grown under low sulfate applied at the bolting, early flowering or start of pod filling stages (D'Hooghe et al, 2014 ) have revealed that the protein quality of seeds was reduced depending on the severity of S limitation and was associated with a reduction in S-rich seed storage protein accumulation (such as Cruciferin Cru4) which favored S-poor seed storage protein (such as Cruciferin BnC1). Nevertheless, our knowledge about the stages of development the more sensitive to S limitation or the physiological processes that are involved in S management by oilseed rape subjected to sulfate restriction remains largely unclear (Dubousset et al, 2010 ).…”