Study of Powdery Mildew Resistance in seven Lines of Snow Pea, Pisumsativum

Snow pea is one of the important crops grown on highland of Thailand. However, it is very susceptible to powdery mildew. Thus, resistant cultivar increases the production of this crop at a reduced costs. Seven pea lines/cultivars, namely P117, P185, P309, No.3, No.4, No.5 and Fang No.7, were evaluated for phenotypic powdery mildew resistance at Pang Da Royal Agricultural Station, Samoeng district, Chiang Mai during the period of November, 2007 – March, 2008. They were divided into 3 groups: highly resistant group (R) i.e. P117, P185 and P309, moderately resistant group (M) i.e. No.3, No.4 and 5, and susceptible group (S) i.e. Fang No.7. In addition, DNA marker for powdery mildew resistance, er, was tested using PCR technique with 3 primers, ScOPD10, OPU17 and OPO02. It was found that only ScOPD10 could yield an 850-bp marker specific to resistant group. DNA sequencing of this 850 bp marker showed 618-624 bases. The sequence was compared with databases in NCBI GenBank. After BLAST searches, the 618-624 base sequences had 90-91% homology to the DNA sequence from clone JICPSV-598E15, complete sequence of P. sativum.