Elucidation of genetic relatedness of Magnaporthe grisea, an incitent of pearl millet blast disease by molecular markers associated with virulence of host differential cultivars. (December 2020)

• Record Type: Journal Article
• Authors: Adhikari, Shivakantkumar; Joshi, Shreya M.; Athoni, Bandenamaj K.; Patil, Prakashgouda V.; Jogaiah, Sudisha
• Is Part Of: Microbial pathogenesis. Volume 149(2020)
• Publication Date: 2020-12
• Subjects: Pearl millet -- Blast populations -- Host differentials -- Disease severity -- Virulence -- Molecular markers; Pathogenic microorganisms -- Periodicals; Pathology, Molecular -- Periodicals; Communicable Diseases -- microbiology -- Periodicals; Communicable Diseases -- parasitology -- Periodicals; Micro-organismes pathogènes -- Périodiques; Pathologie moléculaire -- Périodiques; Electronic journals; 616.9041
• DOI: 10.1016/j.micpath.2020.104533
• Languages: English
• ISSNs: 0882-4010

Abstract

Abstract: In recent years, blast disease caused by Magnaporthe grisea, an ascomycete fungus is becoming a serious threat to pearl millet crop in India and worldwide. Due to the increase in virulent races of pathogen, blast disease management strategies seemed to be very limited. Hence, unraveling the occurrence of blast isolates across India and understanding their virulence and genetic relatedness using molecular markers are the key objectives of this study. From Farmer's field survey we have evidenced variability in blast pathogen across India by recording 10.6 to 7.9 disease severities. A fair to good variation in cultural and conidial characters were also noticed for 17 field isolates. The identity of 17 isolates was confirmed as Magnaporthe grisea by internal transcribed spacer (ITS) region. Based on 12 host differential virulence reactions, five isolates BgKMg1, BdmMg2, MtgMg11, JprMg16 and JmnMg17 recorded highly susceptible (>5 grade) to nine differentials used in the study. While, host differentials ICMB95444, ICMR06222, ICMR11003, IP21187 and ICMV155 found effective for screening virulence of blast disease. Furthermore, genetic relatedness assessed by ITS, inter simple sequence repeats (ISSR) and simple sequence repeats (SSR) markers produced high degree of polymorphism and was able to distinguish the virulence pattern of 17 isolates that correlated with phenotypic screening. Among markers, clustering of isolates within groups was significantly different with remarkable genetic similarity coefficient and bootstrap values. Overall, these results confirm a significant morphological and genetic variation among 17 isolates, thereby helping to elucidate the virulence of pearl millet blast populations in India that could avoid breakdown of resistance and assist breeding improved pearl millet cultivars. Highlights: Severity of pearl millet blast disease on commercial hybrids has increased worldwide. Farmer's field survey witness high degree of variability in blast pathogen across India. The pathogen virulence was demonstrated based on disease severity using host differentials. Genetic relatedness assessed by molecular markers produced high level of polymorphism. Elucidation of virulence among blast populations in India could avoid breakdown of resistance.