Determination of Pathogenicity Relationships of Rice Yellow Mottle Virus (RYMV) Isolates on Near Isogenic Lines (NILs) and Some Released Oryza Species in Nigeria

摘要

The study was carried out to investigatepathotypes relationship of six Rice Yellow Mottle Virus(RYMV) isolates from North Central Zone of Nigeria in2016 using some released Oryza species and NearIsogenic Lines (NILs). The experiment was laid out in asplit-split plot design in the screen house at Badeggi,Niger State, Nigeria. Yield and agronomic data weresubjected to statistical analysis using CropStat Version7.2. The result showed a non-significant interaction effectof rice genotypes, disease isolates and inoculation regimeson spikelets sterility (%) and a highly significant effect(p = 0.01) on yield per plant (g) at harvest. The impact ofthe virus on the number of panicles per plant at maturitywas significantly higher on test plants inoculated at activetillering stages which consistently produced lower meanpanicle numbers across the levels of virus isolates. Theresult also showed that NIL 54 produced high resistanceto the virus which is not due to immunity as the leafextract from inoculated plant was infectious onsusceptible FKR 28 during back inoculation test. NIL 54did not also record significant reduction on the averageleaf length (cm) per plant at maturity with the virusisolates; neither did it express the characteristic symptomsof the virus with the six isolates. Obubu-Ofu and Makurdiisolates circumvented the resistance in Gigante andshowed obvious yellow mottle symptoms. The serologicalanalysis and RYMV isolates characterization indicatedthat the six virus isolates belonged to sero groups 1 and 2(S1 and S2). NIL 54 is recommended for furtherpathogenicity investigation with more isolates of RYMVin Nigeria or elsewhere, since, no obvious symptom of thevirus was observed on the plant when challenged with S2and S1 isolates in the present study.