Incorporation of Selenium Derived from Nanoparticles into Plant Proteins in Vivo.

Diets comprising selenium-deficient crops have been linked to immune disorders and cardiomyopathy. Selenium nanoparticles (SeNPs) have emerged as a promising nanoplatform for selenium-biofortified agriculture. However, SeNPs fail to reach field-scale applications due to a poor understanding of the fundamental principles of its behavior. Here, we describe the transport, transformation, and bioavailability of SeNPs through a combination of in vivo and in vitro experiments. We show synthesized amorphous SeNPs, when sprayed onto the leaves of Arabidopsis thaliana, are rapidly biotransformed into selenium(IV), nonspecifically incorporated as selenomethionine (SeMet), and specifically incorporated into two selenium-binding proteins (SBPs). The SBPs identified were linked to stress and reactive oxygen species (mainly H2O2 and O2-) reduction, processes that enhance plant growth and primary root elongation. Selenium is transported both upwards and downwards in the plant when SeNPs are sprayed onto the leaves. With the application of Silwet L-77 (a common agrochemical surfactant), selenium distributed throughout the whole plant including the roots, where pristine SeNPs cannot reach. Our results demonstrate that foliar application of SeNPs promotes plant growth without causing nanomaterial accumulation, offering an efficient way to obtain selenium-fortified agriculture.

Expression analysis of five maize MAP kinase genes in response to various abiotic stresses and signal molecules.

Mitogen-activated protein kinase (MAPK) cascades are universal signal transduction modules in eukaryotes. Plant MAPK cascades are complicated networks and play vital roles in signal transduction induced by biotic and abiotic stresses. In this paper, expression patterns of MAPKs in maize roots treated with low-temperature, osmotic stresses, wounding, plant hormones and UV-C irradiation were investigated. Semi-quantitative RT-PCR reveals that the expression of MAPKs in maize roots which treated with low-temperature in light or in low light are inducible. The expression patterns of MAPKs in maize roots with treatments of CaCl2, SA, GA and wounding are approximately the same. A detailed time course experiment shows that the expression patterns of ZmSIMK are different with treatments of PEG and NaCl, respectively. These results suggest that the expression patterns of MAPKs are complicated and the signal pathways are interlaced into a network in maize roots.