Abstract:
Vigna radiata is the third important legume crop. It is a short duration crop with
low input requirements. Phosphorus plays an important role in developing the root
structures, enhancing the growth of legumes and elevating the nutrient uptake.
Phosphorus is an essential macronutrient after nitrogen and is usually present in
insufficient quantity in the soil. Fertilizers are applied to which cause many chemical
reactions to take place for the plants to absorb phosphate ions. Drought limits the
nutrient uptake of a plant, a definitive decline in phosphorus levels has been observed
under such conditions. Purple acid phosphatases (PAPs) are the proteins that are
having essential role in acclimating plants under phosphorus deficient conditions.
They liberate inorganic phosphorus from phosphomonoesters in soil and help in its
uptake by the plant. PAP gene family has been previously identified in many plants
but their identification in mung bean was not confirmed previously. In the current
study, VrPAP gene family was identified in the genome of Vigna radiata on the basis
of presence of metallophos superfamily domain and FN3 superfamily domain. The
conservation of five conserved motif blocks (DXG/ GDXXY/ GNH(D/E)/ VXXH/
GHXH) were also analysed. On the basis of the conservation pattern, this gene family
was divided into three main groups (1,2,3) during the phylogenetic analysis. This
categorization was further strengthened by the conserved motif analysis. The results
of gene structure were not that conserved throughout each group. Maximum exons
reported in a gene were 13 and minimum was 1. According to the gene ontology (GO)
annotations, maximum proteins were found to be involved in cellular metabolic
processes, dephosphorylation, hydrolase activity, catalase activity, metal ion binding
and phosphatase activity. They were located in cellular anatomical entity and in
membranes. Results of the expression profiling revealed that the expression of PAP
genes increased significantly under low phosphorus, drought and combined conditions
of low phosphorus and drought under early, flowering and rewatering stages in both
NCM-13 and MSPS-119. The maximum fold change was observed in MSPS-119
under flowering conditions. There was a slight decrease in the expression after
rewatering as compared to flowering stage.
