Expression analysis of three phosphate transporter genes in the fast-growing mutants of Gracilariopsis lemaneiformis (Rhodophyta) under low phosphorus condition

Three phosphate transporter (PHT) genes of Gracilariopsis lemaneiformis were cloned, and the expression patterns under different phosphate concentrations were analyzed. The phylogenetic analysis indicated that the amino acid sequence of GlPHT2 shared high identity with high-affinity PHT in many species. Meanwhile, GlPHT1 and GlPHT3 showed significant similarity to the low-affinity PHT sequences of other species. The results of expression patterns analysis showed that glpht2 was significantly upregulated when glpht1 remained expression stable under low-phosphorus treatment. The expression of glpht3 is positively correlated with the concentration of environmental phosphorus. Therefore, these results provided important evidence of the mechanism of P-i uptake and use in G. lemaneiformis. In addition, the low-phosphorus fast-growing mutant WLP-22 showed traits superiority in both growth and photosynthetic activity.