Iono-metabolomic guided elucidation of arsenic induced physiological and metabolic dynamics in wheat genotypes.

Despite the growing concerns about arsenic (As) toxicity, information on wheat adaptability in such an aggravating environment is limited. Thus, the present investigation based on an iono-metabolomic approach is aimed to decipher the response of wheat genotypes towards As toxicity. Wheat genotypes procured from natural conditions were characterized as high As-contaminated (Shri ram-303 and HD-2967) and low As-contaminated (Malviya-234 and DBW-17) based on ICP-MS As accumulation analysis. Reduced chlorophyll fluorescence attributes, grain yield and quality traits, and low grain nutrient status were accompanied by remarkable grain As accumulation in high As-contaminated genotypes, thus imposing a higher potential cancer risk and hazard quotient. Contrarily, in low As-contaminated genotypes, the richness of Zn, N, Fe, Mn, Na, K, Mg, and Ca could probably have supported less grain As accumulation, imparting better agronomic and grain quality traits. Additionally, from metabolomic analysis (LC-MS/MS and UHPLC), abundances of alanine, aspartate, glutamate, quercetin, isoliquiritigenin, trans-ferrulic, cinnamic, caffeic, and syringic bestow Malviya-234 as the best edible wheat genotype. Further, the multivariate statistical analysis (HCA, PCA, and PLS-DA) revealed certain other key metabolites (rutin, nobletin, myricetin, catechin, and naringenin) based genotypic discrimination that imparts strength to genotypes for better adaptation in harsh conditions. Out of the 5 metabolic pathways ascertained through topological analysis, the two main pathways vital for plant's metabolic adjustments in an As-induced environment were: 1. The alanine, aspartate and glutamate metabolism pathway, and 2. The flavonoid biosynthesis pathway. This is also evident from network analysis, which stipulates amino acid metabolism as a prominent As regulatory factor closely associated with flavonoids and phenolics. Therefore, the present findings are useful for wheat breeding programs to develop As adaptive genotypes that are beneficial for crop improvement and human health.

Two homeologous MATE transporter genes, NtMATE21 and NtMATE22, are involved in the modulation of plant growth and flavonol transport in Nicotiana tabacum.

The multidrug and toxic compound extrusion (MATE) protein family has been implicated in the transport of a diverse range of molecules, including specialized metabolites. In tobacco (Nicotiana tabacum), only a limited number of MATE transporters have been functionally characterized, and no MATE transporter has been studied in the context of flavonoid transport in this plant species so far. In the present study, we characterize two homeologous tobacco MATE genes, NtMATE21 and NtMATE22, and demonstrate their role in flavonol transport and in plant growth and development. The expression of these two genes was reported to be up-regulated in trichomes as compared with the trichome-free leaf. The transcript levels of NtMATE21 and NtMATE22 were found to be higher in flavonol overproducing tobacco transgenic lines as compared with wild type tobacco. The two transporters were demonstrated to be localized to the plasma membrane. Genetic manipulation of NtMATE21 and NtMATE22 led to altered growth phenotypes and modulated flavonol contents in N. tabacum. The ß-glucuronidase and green fluorescent protein fusion transgenic lines of promoter regions suggested that NtMATE21 and NtMATE22 are exclusively expressed in the trichome heads in the leaf tissue and petals. Moreover, in a transient transactivation assay, NtMYB12, a flavonol-specific MYB transcription factor, was found to transactivate the expression of NtMATE21 and NtMATE22 genes. Together, our results strongly suggest the involvement of NtMATE21 and NtMATE22 in flavonol transport as well as in the regulation of plant growth and development.