Induced Systemic Resistance Against Erwinia Soft-Rot of Aloe-Vera

Fifteen Pathogenic isolates of Erwinia chrysanthemi the soft rot of Aloe vera were established from different areas of Tamil Nadu and their identity was confirmed by MTCC & GeneBank, Chandigarh.Among 30 leaf extracts,ten plant oils,51 Pseudomonas and ten Bacillus isolates tested in vitro, zimmu, Mahua oil,Pf 32,Pf45 and Bs5 was the most effective.All the 51 isolates expressed amplified size 560 bp and 546bp confirmed as P.fluorescens and Bacillus Sp.Nucleotide sequences of 16s-23s rDNA genes of Pf32,Pf45 and Pf25 were submitted to Genbank No.,GQ339107,GQ339109 and GQ 848367 respectively.In the pot experiment,pre inoculation spraying of Pf32+ Pf45+Bs5 talk based formulation (1g/l) was the most effective which also induced the defense related genes of PO, PPO, PAL, Phenol,1,3 glucanase, chitinase,SOD and catalase.In the field,spraying of Pf32+Pf45+Bs5 talk formulation @ 1 kg / ha was most effective in significantly reducing the disease incidence and significantly increasing the yield with a C:B ratio of 1:10.80 besides improving the plant growth parameters. The microtomy section of diseased Aloe vera leaf showed more bacterial invasion, whereas it was absent in the healthy plants.