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ARS Home » Southeast Area » Stuttgart, Arkansas » Dale Bumpers National Rice Research Center » Research » Publications at this Location » Publication #341532
Title: Evaluation of Rice Responses to Blast Fungus Magnaporthe oryzae at Different Growth Stages

Author
item CHEN, XINGLONG - China Agricultural University
item Jia, Yulin
item WU, BOMING - China Agricultural University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2018
Publication Date: 7/11/2018
Citation: Chen, X., Jia, Y., Wu, B. 2018. Evaluation of Rice Responses to Blast Fungus Magnaporthe oryzae at Different Growth Stages. Plant Disease. https://doi.org/10.1094/PDIS-12-17-1873-RE.
DOI: https://doi.org/10.1094/PDIS-12-17-1873-RE

Interpretive Summary: Blast disease of rice caused by the fungus Magnaporthe oryzae is one of the most serious threats to stable rice production in the USA and worldwide. In the present study, we evaluated responses of two japonica rice varieties, M -202 and Nipponbare, to one commonly found US race/isolate of M. oryzae at different growth stages, V1 to V10, under greenhouse conditions. Despite minor differences of the two rice varieties, both were susceptible from V1 to V4; susceptibility was reduced after V5 and was completely resistant at V10. Similar results were obtained with M-202 when plants were inoculated at each growth stage individually from V1 to R8. The only difference was that the plants were resistant at V9 instead of V10. Together, we suggest that rice plants have enhanced resistance throughout growth period. These findings are useful for identifying effective genes for managing rice blast disease in commercial rice production worldwide.

Technical Abstract: Rice blast disease caused by the fungus Magnaporthe oryzae is the most damaging disease of rice worldwide. However, the disease reactions to M. oryzae at different growth stages of rice are largely unknown. In the present study, two temperate japonica rice varieties, M-202 and Nipponbare, at different vegetative growth stages, V1 to V10, were inoculated synchronously; and V1 to R8 of M-202 were sprayed specifically with M. oryzae race/isolate IB-49 (ZN61) under greenhouse conditions. The inoculated plants were maintained in black plastic bags for 24 h before they were moved into a greenhouse at 24°C with 80% relative humidity at for 6 d. Disease reactions were collected 7 d post inoculation by measuring the percentage of the diseased area of all leaves, excluding the youngest leaf. The results showed that M-202 at the V1-V4 stages was susceptible with a disease incidence of 65.22 to 70.97%, severity of 20.47 to 31.95%, and index of 13.35 to 22.37, and disease incidence of 75.86 to 78.95%, severity of 6.18 to 30.55%, and index of 4.73 to 23.18 for Nipponbare. Similar results for M-202 were observed when individual plants were inoculated at each growth stage, with a disease incidence of 68.75 to 97.81%, severity of 21.93 to 59.25%, and index of 15.38 to 57.95. Disease susceptibility was noticeably reduced after the V5 stage and disappeared in the V9-V10 stages, or reproductive stages, suggesting that the plants have enhanced disease tolerance at later growth stages. These findings are useful for managing rice blast disease in commercial rice production worldwide.