3.3 Evaluation of defence gene expression against M. incognita infection in tomato
Significant (P < 0.05 ) differences were observed in expression levels of the three defense related genes (PR1-1b, JERF3 & CAT) in rhizobacteria (B. subtilis ,B. pumilus. B. megaterium, and B. cereus ) treated tomato (cv Pusa Ruby) againstM. incognita infection at intervals of 0, 2, 4, 8 & 16 days after inoculation (DAI) when compared with untreated control (Fig 1) . The expression of PR1-1b, JERF3 and CAT genes increased gradually in rhizobacterial treated roots at 2, 4 & 8 DAI, while the Velum prime treated plants did not show any enhanced expression. On day 0, the expression of CAT gene was most enhanced; 1.0 to 1.94 folds enhanced expression, as compared to untreated control; the maximum was observed in B. subtilis treatment. On day 2, PR1-1b was most enhanced with 5.7 fold expression in B. subtilistreatment. The expression of JERF-3 enhanced in the range of 2.4 to 3 folds. The expression of CAT was also the maximum in B. subtilis(3.9 fold), and about 3.0 folds in other rhizobacterial treatments. On day 4, the enhancement for PR1-1b was 6.94 folds for B.subtilisand it was close to 5 folds in B cereus , B. megaterium andB. pumilus treatments in presence of the nematode. The JERF-3 expression was 5.9 folds in B. subtilis and about 5.0 folds in other rhizobacterial treatments. The CAT expression was in the range of 4.02 to 4.49 folds in all rhizobacteria. On day 8, the enhanced gene expression was the maximum in all rhizobacterial treatments, for PR1-1b, it was 7.94 fold in B.subtilis treatment and close to 7 folds in other rhizobacterial treatments, in presence of the nematode. The gene JERF-3 enhanced 6.94 fold in B.subtilis and close to 6.0 folds in the other 3 rhizobacterial treatments. The expression of CAT was close to 3.0 folds in all rhizobacterial applications. On day 16, the enhancement in CAT expression was the maximum 4.3 folds in B. subtilis and was at par with JERF3 in the other three rhizobacteria. The expression of PR1-1b and JERF-3 declined in the range of 3.0 to 4.0 fold, as compared to earlier days of observations. The gene expression in Velum Prime treatment was at par with control on all days of observation, indicating there was no induction of systemic resistance in the plants