Cloning and expression analysis of SgLPR1 in Stylosanthes guianensis

Plant growth and development are affected by phosphorus (P) availability in soils. Stylosanthes guianensis (stylo) is an important tropical forage plant that exhibits a high level of adaptability to low P stress. The multicopper oxidase encoded by the LPR (low phosphate root) gene has been demonstrated to be involved in regulating root growth and phosphate starvation responses. In this study, the effects of P deficiency on the growth of two stylo genotypes were investigated. The SgLPR1 gene was cloned, and its expression pattern was further examined. The results have shown that plant dry weight and P acquisition efficiency of the stylo genotype ‘TF0277’ were higher than those of ‘TF0285’. Root growth was enhanced in ‘TF0277’ by low P treatment but not in ‘TF0285’. The full length of the SgLPR1 gene was 1713 bp. The SgLPR1 protein included 570 amino acid residues with a predicted molecular weight of 64.1 kDa. The SgLPR1 protein belonged to the cupredoxin family and was predicted to be located in the endoplasmic reticulum. qRT-PCR analysis has shown that the expressions of SgLPR1 in stems were higher than those in other tissues. Furthermore, SgLPR1 had higher expression in root tips that were > 1 cm in length. The expressions of SgLPR1 in the leaves and roots were significantly increased by deficiencies in nitrogen (N), P and potassium (K), compared to their respective controls. Expression of SgLPR1 increased with low P treatment in ‘TF0277’ but not in ‘TF0285’. Therefore, these results suggest that SgLPR1 may play a key role in the response of root growth to low P stress in stylo.