Virulence pattern of leaf and neck blast isolates (Pyricularia oryzae Cavara) from basmati rice and identification of resistance donors

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dc.contributor.advisorJain, Jyoti
dc.contributor.authorAnjali
dc.date.accessioned2024-01-08T09:21:36Z
dc.date.available2024-01-08T09:21:36Z
dc.date.issued2023
dc.description.abstractThe blast disease caused by Pyricularia oryzae was prevalent throughout the Punjab state with leaf blast incidence ranging from 9.47 to 54.26 percent and neck blast incidence ranging from 23.73 to 46.11 percent respectively. The highest disease incidence and disease severity were observed in the agro-ecological Zone-III comprising of Bathinda, Sangrur, Barnala and Muktsar districts on variety Pusa Basmati 1401 followed by Pusa Basmati 1509 and Pusa Basmati 1121. Leaf and neck blast isolates were found to be variable with respect to colony colour, elevation, margin, form, sectoring, zonation, mean radial growth (mm), spore size and extent of sporulation. Three leaf blast isolates (LB-3, LB-10 and LB-11) and five neck blast isolates (NB-51, NB-52, NB-65, NB-83 and NB-89) were categorizedas fast growers with Kr value of more than 8.1mm/24hr. All the tested isolates sporulated better on Oatmeal agar medium than on Paspalum grass medium. Genetic analysis of the leaf and neck blast isolates using SSR markers revealed high degree of polymorphism with PIC values ranging from 0.44 to 0.90 and 0.44 to 0.93 respectively discerning the isolates into two major clusters. Studies on virulence pattern and cross-infectivity exhibited substantial variability among leaf and neck blast isolates on a set of eight basmati varieties. Univariate and multivariate analysis of isolates originating from leaf or neck portions of basmati rice with respect to various components of aggressiveness viz., infection efficiency (IE), Incubation period (IP50), Latent period (LP), Lesion size (LS), Sporulation intensity (SI), Disease incidence (DI) and Disease severity (DS) demonstrated their cross-pathogenic behaviour. However, the neck blast isolates proved to be more aggressive on rice leaves than leaf blast isolates on rice necks. Among the different components of aggressiveness, IE, LS and SI were positively correlated with each other, whereas IP50 and LP50 showed a negative correlation with all the aggressiveness components. Out of 96 germplasm lines screened against leaf and neck blast phases separately under artificial inoculation conditions, none of the genotypes was found to be resistant to both phases. Only six genotypes namely, IR 67417-75-3-2-2-3, IR 72860-62-1-1-3, Acharamati, Basmati C122, Pusa Basmati 1637 and Tetep showed moderately resistant reaction to both leaf and neck blast phases with susceptibility index <3. Ten genotypes IR 67017-73-1-4, IR 67418-131-2-3-3-3, IR 68726-3-3-1-2, IR 68740-3-2, IR 70418-112-1-2, Basmati Surkh 161, JJ-92, Tulsi Phoola, UPR-3519-18-1-1 and IET 15392 exhibited moderately resistant reaction to leaf blast but were moderately susceptible to neck blast. Under natural epiphytotic conditions at hotspot location (RWRC Malan, H.P.), twelve genotypes namely IR 67017-73-1-4, IR 67417-75-3-2-2-3, IR 68726-3-3-1-2, IR 68740-3-2, IR 70418-112-1-2, IR 71740-7-3-1, Basmati C122, JJ-92, Tulsi Phoola, IET 15392, Pusa Basmati 1637 and Tetep showed resistant reaction to leaf blast and moderately resistant reaction to neck blast. The present study established that resistance to the leaf blast phase does not necessarily imply resistance to the neck blast, indicating a need to evaluate rice genotypes for both the leaf and neck blast phases in the ongoing blast breeding programs. Furthermore, the new insights gained into the biology of P. oryzae, its organ specificity, comparative aggressiveness, and the genetic sources of resistance will be useful in designing better management strategies.
dc.identifier.citationAnjali (2023). Virulence pattern of leaf and neck blast isolates (Pyricularia oryzae Cavara) from basmati rice and identification of resistance donors (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810205952
dc.keywordsBasmati rice
dc.keywordsPyricularia oryzae
dc.keywordsMagnaporthe oryzae
dc.keywordsLeaf blast
dc.keywordsNeck blast
dc.language.isoEnglish
dc.pages178
dc.publisherPunjab Agricultural University
dc.research.problemVirulence pattern of leaf and neck blast isolates (Pyricularia oryzae Cavara) from basmati rice and identification of resistance donors
dc.subPlant Pathology
dc.themeVirulence pattern of leaf and neck blast isolates (Pyricularia oryzae Cavara) from basmati rice and identification of resistance donors
dc.these.typePh.D
dc.titleVirulence pattern of leaf and neck blast isolates (Pyricularia oryzae Cavara) from basmati rice and identification of resistance donors
dc.typeThesis
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