Selenomethionine and Total Methionine Ratio is Conserved in Seed Proteins of Selenium‐Treated and Nontreated Soybean, Flax, and Potato

Abstract

Crop biofortification with Se is widely accepted. However, little is known about the efficiency of selenomethionine (Se‐Met) incorporation into the seed and tuber protein fraction of crops. Here, we report on the efficiency of Se incorporation into the seed and tuber protein fraction of soybean, flax, and potato and the putative identity of some of the proteins that are likely targets for this random pretranslation modification. Soybean, flax, and potato plants received Se using different sodium selenate application methods and rates, and Se‐Met was determined in seed, tuber, and their protein fractions. Selenium content in seed and tuber tissues and in protein fractions was increased by 2 to 86 times. The methionine (Met) pool was increased, as was the proportion of Se‐Met in the Met pool, but the ratio of Se‐Met:total Met was well conserved (1:1) between the treated and nontreated plants. After two‐dimensional (2D) protein electrophoresis, five protein spots were identified as glycinin, trypsin inhibitor (soybean), patatin‐3‐Kuras‐1, patain‐B2, and phosphoenol carboxy kinase (potato), none of which showed S to Se substitution in their primary structure. Linking Se and three stress markers in fresh tuber extracts, glutathione (GSH) level, glutathione peroxidase (GPx), and glutathione reductase (GR) activities were increased by 20 to 35%. The data showed low protein modification in these non‐Se‐accumulator crops and indicated that rates of 5 to 10 g ha–1 Se, through foliar application, may ensure not only an adequate daily intake levels for humans but may also activate antioxidant enzyme systems within the tuber tissue.

Foliar selenium application reduces late blight severity and incidence in potato and acts as a pathogen growth inhibitor and elicitor of induced plant defence

“…Freshly growing cultures of these two fungal pathogens were removed from storage and maintained on agar medium prior to use. The identity of all pathogens included in this study was confirmed by morphological and molecular methods (Nelson et al 1983;Geiser et al 2004;De Boer et al 2012;Peters et al 2014).…”

“…The use of Se in crop biofortification for enhancing secondary metabolite production and improving Se content in crops for human consumption has been widely reported for several crops (Malagoli et al 2015), including Brassica and Allium species (Terry et al 2000), potato (Turakainen et al 2004a(Turakainen et al , 2004bFofana et al 2014;de Oliveira et al 2019), broccoli (Lyi et al 2005), lettuce (Ramos et al 2010), tomato (Brummell et al 2011), soybean and flax (Fofana et al 2014) and maize (Bocchini et al 2018). This study confirmed the above findings of increased Se uptake and production of health-promoting secondary metabolites.…”

“…The late blight strains used for foliar inoculation consisted of a local genotype of P. infestans (US 23; Peters et al 2014) obtained from our potato pathology laboratory collection (AAFC, Charlottetown, Canada) and stored on autoclaved rye kernels kept at 4°C. Before use in foliar inoculation, the pathogen was grown and sporulated on potato tuber slices with weekly transfer to maintain aggressiveness and on V8 medium (Jaime- Garcia et al 2000) to ensure cell viability.…”

“…Selenium extraction and quantification. Five hundred mg of powdered tuber or leaf tissue samples was transferred into a closed vessel microwave digestion system (MARS Xpress, CEM Corp., Matthews, NC), digested and the Se concentration was analyzed as described in Fofana et al (2014). The results were expressed as mg Se 100 g −1 dry weight (DW).…”

“…Se is nonessential to plants, but is an essential trace element in human and animal nutrition (Ellis and Salt 2003;Feng et al 2013). Since Atlantic Canadian soils are very deficient in Se (Gupta and Gupta 2000) and plants are the main source for dietary Se in the food chain (Rayman 2008), the use of Se for crop biofortification has been investigated in different crops in Atlantic Canada (Fofana et al 2014).…”