Expression Analysis of Pathogenesis related Protein Gene under Heavy Metals in Bean

To probe the molecular mechanisms of plant resistance to heavy metals,a clone of PvSR4 was isolated from a mercuric chloride treated bean( Phaseolus vulgaris L.)cDNA library by differential screening.The sequences of the cDNA insert and protein homological analysis showed that PvSR4 encoded an intracellular pathogenesis related protein,and the purified protein showed ribonuclease activity.Northern blot analysis revealed that the PvSR4 transcripts were undetectable in unstressed bean leaves,but the gene expression was strongly induced by heavy metals and salicylic acid,wounding also stimulated the synthesis of PvSR4 mRNAs,whereas elevated temperature had almost no effect.These suggested that PvSR4 protein might play important roles in resistance to heavy metal stress.