A Toolbox for Managing Blast and Sheath Blight Diseases of Rice in the United States of America

Abstract

Rice blast disease caused by the fungus Magnaporthe oryzae and rice sheath blight disease caused by the fungus Rhizoctonia solani are two major hurdles for stable rice production worldwide. Presently, fungicides are still needed to manage these two devastating fungal pathogens. After two decades of research efforts, a toolbox has been assembled with the following components: (1) insight into pathogen genomic identity and pathogen avirulence (AV R ) genes that can be used to enhance plant breeding; (2) new mapping populations and germplasm and genetic stocks that can be used as starting materials to identify effective host resistance (R) genes; (3) user-friendly disease evaluation methods that can be used to accelerate the identification and utilization of R genes; (4) validated effective R genes that are readily available for improving genetic resistance; (5) host genetic markers that can be used to accelerate the development of new resistant germplasms/cultivars; and (6) an improved understanding of resistance mechanisms that can facilitate the engineering of resistance in commercial varieties. Appropriate employment of these tools in breeding and crop protection will reduce production costs and create an environmentally benign, sustainable rice production system.

Enhancing the searchability, breeding utility, and efficient management of germplasm accessions in the USDA−ARS rice collection

“…From this, ∼10% of the 2K panel had been phenotyped for reaction to these blast isolates. Accessions with race‐specific rice blast disease scores rated on a 0 to 8 scale (0 being resistant and 8 being extremely susceptible) were associated with the markers for major blast resistance genes Pi‐k , Pi‐ta , Pi‐z , and Pi‐b (Jia, Jia, Wang, & Zhao, 2019) (Figure 7; Supplemental Figure S2). The Pi‐ta and Pi‐b resistance alleles are known to be effective against blast race IB‐1, whereas Pi‐z is not (Figure 7a and 7b).…”

“…Data is shown for blast race (a) IB‐1 (198 accessions) along with the p ‐value of the t ‐test comparing resistant vs. susceptible allele groups. (b) Diagram (from Jia et al., 2019) of overlapping race specific resistances conferred by each resistance gene with IB‐1 (circled). (c) For blast race IB‐33 (192 accessions), none of the three genes confer resistance to this race…”

The Potential of Using Chitosan on Cereal Crops in the Face of Climate Change

“…Chitosan and its nanoparticles have proven to be effective against rice diseases such as blast and sheath blight. These diseases are the main factors preventing stable rice production in the world [157]. However, the researchers also emphasise that despite promising results in disease control, chitosan nanoparticles have not yet found widespread application in rice cultivation [130].…”

Host induced gene silencing of Magnaporthe oryzae by targeting pathogenicity and development genes to control rice blast disease

“…Over 100 major blast R genes have been identified and more than 30 of them have been cloned ( Wang et al, 2017 ). Major blast R genes such as Pita , Ptr, Pi-z , Pi-b and Pikh, Pikm, Piks have been deployed in US rice varieties since 1960 ( Jia et al, 2019 ). Although incorporation of R genes into rice has proved to be an effective and environmentally friendly strategy for blast resistance breeding ( Singh et al, 2012 ; Wang and Valent, 2017 ), many years are required to develop new cultivars.…”