Blast (Pyricularia oryzae Cavara) is one of the most serious diseases in all rice (Oryza sativa L.) cultivating areas from temperate to tropical countries. The damage was estimated to be equivalent to 2 billion US$ (1% of rice production) annually. JIRCAS has led “Rice Blast Research Network” for years and accumulated important knowledge to tackle with this complex issue to assure stable and environmentally-friendly rice production. Recent studies using molecular tools to study pathogenic mechanisms of rice blast have made some progress, but the technologies and study tools are not yet widely applicable to agricultural practices, and thus the rice blast disease are not yet sufficiently resolved. This workshop will discuss the up-to-date research and encourage the development of practical technology for preventing or control of rice blast diseases through discussions among scientists and practitioners.
The workshop planned to invite experts from the Asian and Pacific Region to share experiences and discuss 1) the recent advancement in the area of rice blast research; 2) the successful research achievements for understanding of variations of rice blast and resistance in rice cultivars; 3) new rice breeding materials; 4) integrated solutions towards the effective control of rice blast; and 5) future directions for the effective international collaboration.
The workshop aimed to share current knowledge and identify effective approaches and future direction in the control of rice blast in Asia. Originally, a two-day meeting at Tsukuba, Japan followed by a field trip in the next day to visit research facilities and fields relating to rice blast in Japan was proposed. Due to the COVID-19 pandemic and local/ international travel restrictions, the workshop format was changed to online event using Webex virtual meeting room.This workshop addressed the FFTC’s Strategic Action Plan, Theme 4: ‘Environmentally friendly technologies. The workshop also fits well the mandates of JIRCAS and FFTC in considering global and trans-boundary nature of rice blast disease controls.
The one-day online workshop consisted of an opening session, a keynote presentation, and three thematic sessions with 3-6 presentations followed by a panel discussion in each session. Online participants were groups into panel (microphone on) and attendee (microphone muted) in the virtual meeting room.
The keynote presentation highlighted the 15-years of collective effort and results of the research network from Bangladesh, Cambodia, China, Indonesia, Korea, Japan, Lao PDR, Philippines, Thailand, Vietnam, and international organizations working on rice, such as International Rice Research Institute (IRRI) and Africa Rice Center (AfricaRice). Under JIRCAS Blast Research Network, differential systems were developed and distributed. Knowledge on dominant blast races, genetic variations of resistance, and genotype(s) in rice cultivars were generated. The information and application of differential system led to further genetic improvements of the elite rice cultivars in the collaborative countries. It was believed that the future international trials are crucial for construction of durable protection systems combating blast diseases.
Session 1: “International differential variety and characterization of resistance genes” was addressed by researchers from JIRCAS, NARO and Aichi Research Institute, Japan. Topics on using LTH monogenic lines as methods for pathogenicity study for blast isolates and designation system of blast race, development of international differential varieties for race study, and the possibility of partial resistance genes in genetic improvement for panicle blast, were discussed.
Session 2: “Pathological and genetic studies for durable protection system” highlighted the current rice blast work at MARDI (Malaysia), RDA (Korea), KU (Thailand), TARI (Taiwan), and Yunnan Agricultural University (China). Four speakers reported on pathological and genetic diversity of blast isolates in their countries on the way to identify useful genes for rice varietal improvement against rice blast. The speaker from Yunnan did not attend the workshop.
Session 3: “Blast studies using differential system” included 6 country reports of the JIRCAS-Rice Blast Research Network. While the keynote presentation summarized the combined results of the pathogenicity of blast isolates and genetic variation of resistance of rice cultivars in all network countries, the session speakers shared the country-specific results of their study using similar study design and the differential system developed and distributed by the Project Network. Speakers concluded the effectiveness and significance of using the differential system in better understanding the pathogenicity of the blast isolates, diversity in resistance of rice cultivars, and co-differentiations between blast races and resistances in rice cultivars.
Major Findings and Recommendations
Recognize that the differential system is a fundamental and essential research tool used in rice blast pathological studies and breeding strategy development.
Construct durable protection system to blast disease using differential systems, international differential varieties, and breeding materials harboring partial resistance genes in collaboration with breeders, pathologists, agronomists among others for developing a stable rice production system.
Collaborate internationally, and share hybrid populations with collaborative institutes; activate germplasm exchange within the region as a shuttle breeding and consider genetic resource and credit sharing.
Focus on the following areas of work for future research and development of the durable protection system against blast disease: (1) non-dominant blast race, (2) low virulence, (3) diversity of resistance in rice, (4) symbiosis between rice and blast fungus, and (5) artificial control of blast populations.