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As a typical compatible solute, proline is accumulated in plants under environmental stresses. Proline transporter(Pro T) plays an important role in proline distribution between plant organs. Using a candidate gene approach, we cloned a c DNA sequence for Pro T from common bean(Phaseolus vulgaris L.) and designated the gene Pv Pro T. The deduced amino acid sequence of Pv Pro T showed high similarity to Bet/Pro T proteins from other leguminous plants, and the highest similarity was observed with mothbean(Vigna aconitifolia L.) Vu Pro T.Relative quantification of the m RNA level of Pv Pro T using real-time PCR analysis showed that the Pv Pro T transcript level was higher in leaves than in stems and roots of common bean plants subjected to drought and salt stress. Under 20%(w/w) PEG-6000 treatment,drought-resistant plants expressed a higher level of Pv Pro T transcripts than droughtsensitive plants. Although heterologous expression of Pv Pro T in the Escherichia coli mutant mkh13 showed that Pv Pro T exhibited uptake activities for proline and betaine, no betaine content was detected in the common bean. These findings suggest that Pv Pro T plays an important role in the transportation of proline in common bean plants exposed to drought and salt stress.
As a typical compatible solute, proline is accumulated in plants under environmental stresses. Proline transporter (Pro T) plays an important role in proline distribution between plant organs. Using a candidate gene approach, we cloned ac DNA sequence for Pro T from common bean Phaseolus vulgaris L.) and designated the gene Pv Pro T. The deduced amino acid sequence of Pv Pro T showed high similarity to Bet / Pro T proteins from other leguminous plants, and the highest similarity was observed with mothbean (Vigna aconitifolia L.) Vu Pro T. Relative quantification of the m RNA level of Pv Pro T using real-time PCR analysis showed that the Pv Pro T transcript level was higher in leaves than in stems and roots of common bean plants subjected to drought and salt stress. Under 20% (w / w) PEG-6000 treatment, drought-resistant plants expressed a higher level of Pv Pro T transcripts than droughtsensitive plants. Although heterologous expression of Pv Pro T in the Escherichia coli mutant mkh13 showed t hat Pro Pro T up uptake activities for proline and betaine, no betaine content was detected in the common bean. These findings suggest that Pv Pro T plays an important role in the transportation of proline in common bean plants exposed to drought and salt stress.