Purple acid phosphatases (PAPs) are members of the metallo-phosphoesterase family and have been known to play important roles in phosphorus (P) acquisition and recycling in plants. Low P availability is a major constraint to growth and production of soybean, Glycine max. Comparative studies on structure, transcription regulation and responses to phosphate (Pi) deprivation of the soybean PAP gene family should facilitate further insights into the potential physiological roles of GmPAPs. BLAST searches were performed to identify soybean PAP genes at the phytozome website. Bioinformatic analyses were carried out to investigate their gene structure, conserve motifs and phylogenetic relationships. Hydroponics and sand-culture experiments were carried out to obtain the plant materials. Quantitative real-time PCR was employed to analyse the expression patterns of PAP genes in response to P deficiency and symbiosis. In total, 35 PAP genes were identified from soybean genomes, which can be classified into three distinct groups including six subgroups in the phylogenetic tree. The expression pattern analysis showed flowers possessed the largest number of tissue-specific GmPAP genes under normal P conditions. The expression of 23 GmPAPs was induced or enhanced by Pi starvation in different tissues. Among them, nine GmPAP genes were highly expressed in the Pi-deprived nodules, whereas only two GmPAP genes showed significantly increased expression in the arbuscular mycorrhizal roots under low-P conditions. Most GmPAP genes are probably involved in P acquisition and recycling in plants. Also we provide the first evidence that some members of the GmPAP gene family are possibly involved in the response of plants to symbiosis with rhizobia or arbuscular mycorrhizal fungi under P-limited conditions.

Boron (B) is an indispensable micronutrient that ensures the optimal growth and productivity of the plant. However, excessive use of B fertilizers results in B toxicity which is relatively difficult to correct as compared to B deficiency. Moreover, underlying mechanisms of B toxicity induced changes in cell wall components and the association of B forms in the appearance of toxicity symptoms in rice seedlings are lacking. Therefore, the present investigation was carried out on rice seedlings by employing different concentrations of B (CK, B1; 100 µM, B2; 300 µM, and B3; 400 µM). The results showed that a high concentration of B caused inhibition of root and shoot growth with noticeable signs of stress on leaves in terms of chlorophyll contents. In addition, B toxicity caused oxidative stress and lipid oxidation of membranes. The higher concentrations of B were accumulated in the leaves than roots. In the roots and leaves, more than 80% B was adsorbed on the cell wall. In the treatment of B3, the free form of B was higher than the bound-B. Fourier Transform Infrared Spectrometer (FTIR) results showed that higher concentrations led to variation in functional groups of cell walls of leaves. The results of this investigation showed that B stress-induced inhibition of growth might be linked with higher B uptake in the upper parts, oxidative damages, and forms of B may play important role in the chlorosis. The findings of the study may help to understand the mechanisms of B stress-induced growth inhibition in rice seedlings.