Effect of elevated temperature and CO2 on quorum sensing mediated virulence in soft rot causing Pectobacterium carotovorum pv. carotovorum

Abstract

The global climate is changing and in the last one century 0.7°C has already risen and as well for CO2 also, the same scenario came out. In this climate change condition the pathogen may behave differently for signal molecule (Acyl homoserine lactone) mediated communication and it essential for a successful host invasion and survival of the pathogen in the nature. The present experiment was conducted under controlled environmental condition to establish the effect of elevated temperature and CO2 towards signal molecules mediated Disease Severity Index, virulence factor production with six different treatment combinations of temperature and CO2. Pectobacterium carotovorum pv. carotovorum, a soft rot causing plant pathogen produce high levels of extracellular enzymes (cellulase) only after sensing the quorum or minimal amount of cell density by Acyl homoserine lactone mediated cross communication. The result showed significant effect for all the treatment combination. In comparison between T2C1 (24°C + 380 ppm CO2) and T2C2 (26°C + 600 ppm CO2), the disease progress was more rapid (27.1 mm on 9th day) in case of elevated CO2 conditions. The highest disease severity index (73.18%) was found in T3C2 (28°C + 600 ppm CO2) in the phytotron, whereas, maximum disease severity index (78.92%) was found at 33°C in the laboratory and minimum (23.19%) was found at 37°C. The maximum cellulose (4 cm diameter holo zone) was noticed in T3C2 (28°C + 600 ppm CO2). Therefore, at elevated temperature in combination with elevated CO2 there was more disease severity in case of soft rot in tomato.