EPIDEMIOLOGY, VIRULENCE DIVERSITY AND HOST-PLANT RESISTANCE IN BLAST [Magnaporthe grisea (Hebert) Barr.] OF FINGER MILLET [Eleusine coracana (L.) Gaertn.]
KrishiKosh
View Archive InfoField | Value | |
Title |
EPIDEMIOLOGY, VIRULENCE DIVERSITY AND HOST-PLANT RESISTANCE IN BLAST [Magnaporthe grisea (Hebert) Barr.] OF FINGER MILLET [Eleusine coracana (L.) Gaertn.]
|
|
Creator |
KIRAN BABU, T
|
|
Contributor |
NARAYAN REDDY, P
|
|
Subject |
millets, diseases, biological phenomena, developmental stages, planting, fungi, pathogens, rice, land resources, application methods
|
|
Description |
Studies were conducted on blast disease of finger millet that included cultural, morphological, pathological and molecular diversity, epidemiology and identification of host- plant resistance at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India and field trials were conducted at ICRISAT; ARS, Vizianagaram; RARS, Nandyal; ZARS, Mandya and OFRS, Naganahalli. A total of 125 blast disease specimens from finger millet, 6 from foxtail millet, 3 from rice and 5 from pearl millet were collected from major crop growing areas of India during 2008-2010. From these samples, a total of 70 monoconidial isolates of Magnaporthe grisea, 56 from finger millet, 6 from foxtail millet, 3 from rice and 5 from pearl millet were obtained. Of the 70 isolates, 15 each were from Patancheru and Vizianagaram, 13 from Nandyal, 14 from Mandya, 8 from Naganahalli and one each from Dholi, Aurangabad, Hissar, Jaipur and Solan. In pathogenicity studies, considerable variation was found among the isolates from finger millet for leaf blast however, no significant differences were found among the isolates from foxtail millet and pearl millet. In cross-inoculation tests M. grisea isolates from finger millet failed to infect foxtail millet and pearl millet, and vice versa. Diversity in cultural characters, such as colony colour, texture and growth pattern were noticed among the isolates, but no clear-cut groupings were observed between isolates from different hosts. The isolates that were grayish-green and sector-forming produced more spores than those having cottony and submerged growth. Variations in morphological characters, such as colony growth, size of the conidia and sporulation were observed. Variations in sporulation capacity were noticed within and between the isolates from the same location. Sixteen finger millet mini-core accessions developed varying reaction types for leaf, neck and finger infection over 2 years of evaluation at five locations. Five selected representative isolates (one isolate/location) were evaluated for pathogenicity (leaf blast) on Finger Millet Blast Resistance Stability Nursery (FMBRSN) consisting of 28 accessions and were found highly variable for virulence, disease severity and disease reaction. Among five isolates, the isolate FMNg55 was found highly virulent and FMP1 the weakly virulent. A set of 10 putative host differentials were identified based on field evaluation of FMBRSN accessions over 2 years at five locations and greenhouse screening. Twenty isolates (4 isolates/location) evaluated for pathogenicity on 10 host differentials, and one resistant and one susceptible check were found highly variable for virulence, disease severity and disease reaction. Among these, the isolates FMP5, FMV23, FMNg54 and FMNg55 were found highly virulent and FMV14 the weakly virulent. Based on leaf blast severity, M. grisea isolates were classified into four pathotype groups. High degree of polymorphism was detected among the isolates from finger millet and foxtail millet using SSR analysis with 17 markers. The isolates were grouped on the basis of their host origins however, two isolates from finger millet and one from foxtail millet were grouped together indicating the occurrence of some genetic drift between the two populations. Based on similarity coefficient, the isolates from finger millet were classified into nine groups. The isolates from different plant parts (leaf and neck) were randomly distributed in the dendrogram. In contrast, the isolates from neck and finger samples from the same genotype/plant were clustered in one group at 90% similarity matrix. No correlation was observed between pathogenicity data and SSR data of 25 M. grisea isolates. Model-based population structure analysis revealed three distinct populations based on their host origin with varying levels of ancestral admixtures among the 65 isolates. Epidemiological studies showed maximum disease development after 48 h of leaf wetness with 1×105 and 1×106 conidia ml-1 inoculum concentration. Influence of temperature on sporulation showed that 27°C was optimum for sporulation of M. grisea lesions in finger millet. Maximum growth and sporulation of finger millet isolates occurred at 25°C and those of pearl millet at 30°C whereas, maximum growth of foxtail millet isolates occurred at 25°C and sporulation at 30°C. Effective greenhouse and field screening techniques, and rating scales for neck blast (1–5 scale) and finger blast severity (%) were developed. From the resistance evaluation of 622 finger millet core collection, 402 accessions were found resistant to neck blast, 436 resistant to finger blast and 372 had combined resistance to both neck and finger blast in field under artificial inoculation at ICRISAT during the rainy season (kharif) 2009. Of the mini- core, 68 had combined resistance to all the three phases of blast in field during 2009 and 2010 at ICRISAT. A significant weak to moderate correlations were found between leaf blast with neck blast and finger blast whereas, significant strong positive correlation was found between neck and finger blast ratings. Of the mini-core, 58 accessions were found resistant to leaf blast in greenhouse to Patancheru isolate. These represented five basic races of finger millet that originated from 13 countries and exhibited considerable diversity for agronomic traits. Of the mini-core, 68 accessions were resistant to both neck and finger blast at Patancheru, 57 at Vizianagaram, 56 at Naganahalli, 11 at Naganahalli and 10 at Mandya during 2009 field screening. Among the mini-core, 7 accessions were resistant to both neck and finger blast across the 5 locations during 2009. Differential reactions across the locations was evident in 60 accessions that were categorized into seven groups. The FMBRSN-2010 comprising of 28 accessions including resistant and susceptible checks was constituted and evaluated at five locations during the kharif 2010. Of these, 17 were resistant to all the three phases of blast at Patancheru; 11 at Naganahalli; 10 at Vizianagaram; 8 at Mandya and 7 at Nandyal. Of the 7 resistant accessions during 2009, two were found susceptible to neck and finger blast in 2010 screening. Analysis of weather data from five locations over two years and neck, and finger blast severity on three highly susceptible accessions did not show any significant association between blast severity and weather variables (temperature and relative humidity) however, positive association was observed with amount and frequency of rainfall. Analysis of resistance stability (2009 and 2010) using relative variation and GGE biplot technique showed that, five accessions (IE 2589, -2911, -4497, -6337 and -7018) were most resistant to all the three phases of blast across the five locations over two years. Of the five accessions, IE 2911 was found resistant to all three phases of blast against five isolates (one representative isolate/location) under greenhouse conditions and thus appears to be the best source of stable resistance. |
|
Date |
2016-06-08T10:05:08Z
2016-06-08T10:05:08Z 2011 |
|
Type |
Thesis
|
|
Identifier |
http://krishikosh.egranth.ac.in/handle/1/66990
|
|
Language |
en
|
|
Relation |
D9093;
|
|
Format |
application/pdf
|
|
Publisher |
ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
|
|