Abstract
In previous report, we have shown the importance of proline accumulation in reproductive organs for heat-tolerance of cowpea and also reported that expression of proline transporter genes as well as P5CS and P5CR have correlation for the accumulation of proline in reproductive organs.
We have isolated the genes encoding a proline transporter, VuProT1 and VuProT2 from cowpea. In this study, we have undertaken functional analysis of two proline transporters. There is no reasonable start codon (ATG) could be found in VuProT1. Hence, we compared the nucleotide and amino acid sequence of VuProT1 to predicted ProT1 sequence of soybean and found VuProT1 has GTC (Val) instead of ATG (Met). VuProT1, nucleotide converted from GTC to ATG (VuProT1-long), non-converted VuProT1 (VuProT1-short), VuProT2 and Arabidopsis proline transporter AtProT1 have transformed into proline transporter deficient yeast strain 22574d. VuProT1-long, VuProT2 and AtProT1 could transport proline and 4-aminobutyrate (GABA) in low pH medium but VuProT1-short could not transport them. Only VuProT2 have grown on neutral pH medium.
