Abstract
Drought is a major abiotic stress that negatively impacts plant growth and crop production. Among various techniques used to alleviate drought stress in plants, nanoparticle application is considered to be effective and promising. In this study, the responses of plants treated with iron, copper, cobalt, and zinc oxide nanoparticles (NPs) were analyzed in soybean under drought-induced conditions. The obtained results indicated that these metal-based NPs supported the drought tolerance of NP-treated plants. The desired physiological traits, viz., relative water content, drought tolerance index, and biomass reduction rate, were significantly improved, especially in iron NP-treated plants. At the molecular level, quantitative PCR analysis of several drought-responsive genes revealed a gene-, tissue-, and NP-dependent upregulation of gene expression. Iron NP treatment promoted the expression of all tested genes in roots; additionally, the expression of three drought-responsive genes increased in leaves of all NP-treated plants, while the expression of GmERD1 (Early Responsive to Dehydration 1) was induced in both roots and shoots under the four NP treatments tested. Our findings suggest that NP application can improve drought tolerance of soybean plants by triggering drought-associated gene expression.
Highlights
Among the top 10 most widely grown crop species, soybean (Glycine max (L.) Merrill) is a globally important crop used for both food and animal feed [1]
The experiments were conducted under strictly monitored conditions to maintain soil moisture content (% Soil moisture content (SMC)) between 60 and 70% in the control treatment groups and to gradually reduce SMC to 30–40% by the last day of drought treatment
Plant height increased with NP treatment, shoot dry weight decreased from 1.2 g for controls to 0.9 g for Fe NP-treated plants under well-watered conditions, with the rest of NP treatments lying intermediate between these two extremes (Figure 1(d))
Summary
Among the top 10 most widely grown crop species, soybean (Glycine max (L.) Merrill) is a globally important crop used for both food and animal feed [1]. It is among the most drought-susceptible crop plants [2], with up to 40% of annual yield losses due to water shortage. The problem is even more serious in tropical countries, such as Vietnam, where the prevalence and duration of drought have increased over the years. The application of ZnO NPs increased soybean seed germination percentage under water stress [10]. The addition of ZnO NPs to the culture medium promoted somatic embryo formation and plant regeneration and increased
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