IMPACT OF ELEVATED CO2 AND TEMPERATURE ON EPIDEMIOLOGY PATHOGEN VARIABILITY AND DEVELOPMENT OF STERILITY MOSAIC DISEASE OF PIGEONPEA Cajanus cajan L Huth UNDER CHANGING CLIMATIC CONDITIONS

Abstract

newline Sterility mosaic disease (SMD) is the most devastating biotic risk for production of newlinepigeonpea in Indian sub-continent. In this investigation, we have determined the spatial newlinedistribution of SMD covering of major pigeonpea growing states of Southern India, viz., newlineAndhra Pradesh, Karnataka, Maharashtra, Tamil Nadu, and Telangana. Results indicated the newlinehuge variation in SMD incidence ranging from 0.40 to 82.64 per cent and 0.96 to 36.84 per newlinecent respectively in Kharif 2021-22 and 2022-23. Based on geospatial analysis, the potential newlineSMD hotspots were largely noticed in the Chittoor, Bidar, Latur, Krishnagiri, Medak and newlineRanga Reddy districts. RNA-3 partial nucleotide sequencing analysis among the 29 isolates newlineof PPSMV in Southern India indicated the presence of significant variability among all the newlineisolates. Out of 29 isolates, three isolates were tested with mixed infection of PPSMV-I and newlinePPSMV-II, while the PPSMV-II was identified as more virulent strain. Out of 54 host newlinespecies, Nicotiana benthamiana, few accessions of wild Cajanus spp., two crop species and newlineone weed host were found to be positive for one or both strains of PPSMVs. The sanger newlinesequencing analysis of the rDNA of 11 Aceria cajani isolates revealed that no variability newlineamong the collected isolates. Under elevated CO2 concentrations, the disease incidence (%), newlineA. cajani populations (no s), total flavonoid content (µg cm-2 newline) and plant height (cm) were newlineincreased at 700 ppm, whereas the total chlorophyll content (µg cm-2 newline), NBI ratio and PPSMV newlinereplication (ng) were initially increased, but later declined. Significant variations in newlineexpression different genes namely PAL, LOX, F3H, and CHS8 were also noticed. Under newlinedifferent temperature levels, the disease incidence (%), A. cajani populations (no s) and newlinePPSMV replication (ng) were high at 30 and#8451;, whereas the total chlorophyll content (µg cm-2 newline) newlineinitially increased, but later declined. Significant increase in plant height (cm) was also newlineobserved. Similarly, significant variations in expression of diffe