INDUCTION OF SYSTEMIC RESISTANCE IN COTTON BY THE NEEM CAKE

AND PSEUDOMONAS AERUGINOSA UNDER SALINITY STRESS

AND MACROPHOMINA PHASEOLINA INFECTION

 

AFSHAN RAHMAN¹, VIQAR SULTANA^2, JEHAN ARA³ AND SYED EHTESHAMUL-HAQUE^1*

 

¹Agricultural Biotechnology & Phytopathology Laboratory, Department of Botany,

University of Karachi, Karachi 75270, Pakistan

²Biotechnology & Drug Development Laboratory, Department of Biochemistry,

University of Karachi, Karachi 75270, Pakistan

³Postharvest & Food Biochemistry Laboratory, Department of Food Science & Technology,

University of Karachi, Karachi 75270, Pakistan

^*Corresponding author’s email: ehtesham12@hotmail.com, sehaq@uok.edu.pk

 

Abstract

 

Induction of systemic resistance by neem cake (Azadirachta indica) and endophytic Pseudomonas aeruginosa, a plant growth promoting bacterium, was evaluated in cotton (Gossypium hirsutum L.) under salinity stress and fungal infection. The combination of biocontrol agent and organic matter induced tolerance against fungal infection (Macrophomina phaseolina) and salinity stress (EC= 17.3 dS, m^-1) by producing salicylic acid 6.9–8.6 mg/ mL as compared to 2.8–4.6 mg/mL in control plants in field experiment, while polyphenols was found 3.1–3.7 mg/mL in neem cake + bacteria treated plants as compared 2.7–2.9 mg/mL in control plants. Cotton plants inoculated with M. phaseolina  showed maximum infection in control plants (75%), while 37.5% plants were found infected in  neem cake + P.aeruginosa  treatment in field experiments. A significant (p<0.05) increase in shoot length was observed in combined treatment of neem cake + P.aeruginosa (30.5–31.7 cm) compared to control plants (25.7–26.7 cm) kept under biotic or salinity stresses. Similarly, free radical scavenging activity was found highest in plants received P.aeruginosa in neem cake amended soil in both DPPH (2, 2-diphenyl-2-picrylhydrazyl) and ABTS (2,2 –azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) methods. Similar results were also observed in screen house experiment. Application of endophytic P.aeruginosa in neem cake amended soil hold promise for the induction of systemic resistance in cotton.

 

Key words: Pseudomonas, Neem cake, Induced systemic resistance, Biotic stress, Abiotic stress.