Manganese (Mn) deficiency is a nutritional problem, causing significant reductions in crop yields and in severe cases resulting in complete loss of crops during winter time. Different plant species and genotypes within the same species vary in their tolerance with respect to growth in soils with low Mn availability, a phenomenon referred to as Mn efficiency. Iron-regulated transporter 1 (IRT1), known to be correlated with Mn uptake capacity and Mn efficiency in barley, was characterized using barley RNAi lines.

The obtained results showed that HvIRT1 was involved in uptake and root-to-shoot translocation of Mn in barley, and was crucial for ensuring sufficient shoot Mn levels. Furthermore, HvIRT1 also influenced Mn distribution in developing grains. Genomewide association study (GWAS) and next-generation sequencing were employed to examine the genetic architecture in relation to Mn efficiency and the interaction between latent Mn deficiency and light stress in maize plants. The obtained results showed that latent Mn deficiency decreased the utilization of photosynthetically active light, inhibited the ability to perform photosynthetic state transitions and the response of net photosynthetic CO2 assimilation to sub-saturating and saturating light.

The Mn deficiency was aggravated by high light intensities which intensified the loss of stability and functionality of photosynthetic apparatus. Latent Mn deficiency in combination with high light intensities caused up-regulation of the expression of a larger number of genes than did the two factors separately. Among the genes up-regulated by Mn deficiency were key genes related to Mnaffected physiological traits such as winter hardiness and disease resistance. GWAS based on chlorophyll a fluorescence measurements on the youngest fully developed leaves revealed a set of candidate genes related to Mn efficiency. The gene encoding PsbP domain-containing protein 7 was identified by both GWAS and transcriptome data, suggesting that it might be an important component contributing to Mn efficiency in maize.