Construction of watermelon SSH cDNA libraries induced by Fusarium oxysporum and analysis of expressed sequence tags

Suppression subtractive hybridization (SSH) cDNA libraries were constructed with watermelon root induced by F. oxyporum race 1. The process of library construction was checked and analyzed; results showed that the technique was efficient in the subtractive hybridization. 562 ESTs with good quality were assembled to 550 contigs with DNAStar 5.0 software. After function annotation, the most prevalent category was disease and defense, which accounted for 33.5% of the ESTs; the second category was signal transduction which accounted for 13.1%. Systemic acquired resistance (SAR) was supposed to be the important element composing the resistance to F. oxysporum race 1 in PI 296341-FR after sequence analysis.