Author(s)

Shahran Ahmed Nayem¹, M. Salahuddin M. Chowdhury¹, F. M. Aminuzzaman¹, Belal Hossain^1*, Sahadat Ali²

¹Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh.
²Department of Horticultural Science, Technical University of Munich, Freising, Germany.

Citrus canker is a perilous disease caused by Xanthomonas axonopodis pv. citri (Xac) which is hardly manageable. Till now, chemicals used against Xac either proved less effective against the disease or hazardous for environment. In this study, we investigated how phytohormones such as Salicylic acid (SA, 3 mM), Jasmonic acid (JA, 0.3 mM), 3-indolacetonitrile (IAN, 0.6 mM), Nicotinic acid (NA, 5 mM), Folic acid (FA, 0.5 mM) influenced canker disease. Disease severity and lesion diameter were significantly mitigated by exogenous application of these phytohormones compared with water (control) accompanied by the increase of latent period. However, these phytohormones did not show any in vitro antimicrobial properties against Xac. Concomitant with boosted resistance, phytohormones treated leaves showed the higher level of phenyl ammonia lyase (PAL) activity. Besides, total phenolic compounds (TPC) and potassium contents were also higher in phytohormone treated plants compared with control. Phytohormones showed the significant and better performance on disease mitigation than control among which, SA showed the highest performance while JA and INA showed the moderate performance. However, NA and FA showed the lowest performance. This result recommended that application of some phytohormones had elicited some biochemical and physiological events which induced the resistance against Xac.

Citrus Canker, Induce Resistance, Phenolic Compounds, Phytohormone

Nayem, S. , Chowdhury, M. , Aminuzzaman, F. , Hossain, B. and Ali, S. (2017) Phytohormone-Induced Resistance against Xanthomonas axonopodis PV. citri in Citrus aurantifolia. American Journal of Plant Sciences, 8, 1135-1147. doi: 10.4236/ajps.2017.85074.