Comparative efficacy of selenate and selenium nanoparticles for improving growth, productivity, fruit quality, and postharvest longevity through modifying nutrition, metabolism, and gene expression in tomato; potential benefits and risk assessment.

This study attempted to address molecular, developmental, and physiological responses of tomato plants to foliar applications of selenium nanoparticles (nSe) at 0, 3, and 10 mgl-1 or corresponding doses of sodium selenate (BSe). The BSe/nSe treatment at 3 mgl-1 increased shoot and root biomass, while at 10 mgl-1 moderately reduced biomass accumulation. Foliar application of BSe/nSe, especially the latter, at the lower dose enhanced fruit production, and postharvest longevity, while at the higher dose induced moderate toxicity and restricted fruit production. In leaves, the BSe/nSe treatments transcriptionally upregulated miR172 (mean = 3.5-folds). The Se treatments stimulated the expression of the bZIP transcription factor (mean = 9.7-folds). Carotene isomerase (CRTISO) gene was transcriptionally induced in both leaves and fruits of the nSe-treated seedlings by an average of 5.5 folds. Both BSe or nSe at the higher concentration increased proline concentrations, H2O2 accumulation, and lipid peroxidation levels, suggesting oxidative stress and impaired membrane integrity. Both BSe or nSe treatments also led to the induction of enzymatic antioxidants (catalase and peroxidase), an increase in concentrations of ascorbate, non-protein thiols, and soluble phenols, as well as a rise in the activity of phenylalanine ammonia-lyase enzyme. Supplementation at 3 mgl-1 improved the concentration of mineral nutrients (Mg, Fe, and Zn) in fruits. The bioaccumulated Se contents in the nSe-treated plants were much higher than the corresponding concentration of selenate, implying a higher efficacy of the nanoform towards biofortification programs. Se at 10 mgl-1, especially in selenate form, reduced both size and density of pollen grains, indicating its potential toxicity at the higher doses. This study provides novel molecular and physiological insights into the nSe efficacy for improving plant productivity, fruit quality, and fruit post-harvest longevity.

Multiplying the efficiency and impact of biofortification through metabolic engineering.

Ending all forms of hunger by 2030, as set forward in the UN-Sustainable Development Goal 2 (UN-SDG2), is a daunting but essential task, given the limited timeline ahead and the negative global health and socio-economic impact of hunger. Malnutrition or hidden hunger due to micronutrient deficiencies affects about one third of the world population and severely jeopardizes economic development. Staple crop biofortification through gene stacking, using a rational combination of conventional breeding and metabolic engineering strategies, should enable a leap forward within the coming decade. A number of specific actions and policy interventions are proposed to reach this goal.

The social and economic impact of biofortification through genetic modification.

Genetic modification (GM) has been advocated as an alternative or complement to micronutrient interventions such as supplementation, fortification or dietary diversification. While proof-of-concept of various GM biofortified crops looks promising, the decision tree of policy makers is much more complex, and requires insight on their socio-economic impacts: Will it actually work? Is it financially sound? Will people accept it? Can it be implemented in a globalized world? This review shows that GM biofortification could effectively reduce the burden of micronutrient deficiencies, in an economically viable way, and is generally well received by target beneficiaries, despite some resistance and uncertainty. Practically, however, protectionist and/or unscientific regulations in some developed countries raise the (perceived) bar for implementation in target countries.

Compost biofortification with diazotrophic and P-solubilizing bacteria improves maturation process and P availability.

BACKGROUND: Phosphorus-containing fertilizers play an important role in tropical agriculture owing to the well documented shortage of plant-available P in soils. Traditional P fertilizer production is based on chemical processing of insoluble rock phosphate (RP), which includes an acid treatment at high temperature. Processing the RP increases fertilizer costs, making it unavailable for undercapitalized and typically family-based farmers. Biotechnological methods have been proposed as an alternative to increase phosphate availability in RP. In this study, Burkholderia silvatlantica and Herbaspirillum seropedicae were co-inoculated into an RP-enriched compost with the aim of determining the effects of this technology on the levels of phosphatase activities and release of plant-available P. RESULTS: Inoculation of both microorganisms resulted in higher organic matter decomposition and higher humic acid formation in composting. Herbaspirillum seropedicae was the most promising microorganism for the production of acid and alkaline phosphatase enzymes. Both microorganisms presented potential to increase the supply of P from poorly soluble sources owing to increased levels of water-soluble P and citric acid P. CONCLUSION: Burkholderia silvatlantica and H. seropedicae in RP-enriched compost may represent an important biotechnological tool to reduce the overall time required for composting and increase the supply of P from poorly soluble sources. © 2016 Society of Chemical Industry.