pathogenic variability
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Author(s):  
Jitendra Sharma ◽  
G.S. Rathore ◽  
S.L. Yadav ◽  
S.K. Goyal ◽  
Suresh Meena

Background: Alternaria cyamopsidis (Rang. and Rao) causes Alternaria blight of clusterbean and it is one of the significant disease of clusterbean. Studies were conducted to compare the Cultural, morphological and pathogenic variability among ten isolates of Alternaria cyamopsidis from clusterbean, in five districts of Rajasthan viz., Bikaner, Barmer, Churu, Hanumangarh and Jaipur. Methods: During 2016-17 exhaustive survey was conducted in clusterbean growing areas of Rajasthan and collected diseased samples of clusterbean caused by Alternaria. All the samples were processed for isolation, purification and their pathogenicity was proved in cagehouse and laboratory and standard methods were adopted for cultural and morphological variability study. Result: All the isolates showed variation in their morphological characters, i.e., colony color and shape; conidial number, size, width, length, shape and septation on PDA. Out of ten isolates two isolate, viz., AlcyJp1 and AlcyJp2 showed maximum colony diameter 89.50 and 86.30 mm, respectively. All the isolates varied in their spore length and width and virulent on the tested variety of clusterbean for virulence. AlcyJp1 was the most virulent and produced maximum (65.50%) disease intensity, followed by AlcyJp2 isolate (61.22%).


2021 ◽  
Vol 13 (4) ◽  
pp. 1305-1309
Author(s):  
Sanjeev Kumar ◽  
Shambhu Roy ◽  
J. P. Upadhyay

Wilt is the most serious disease causing irreversible losses and lethal damage to the crop in Bihar, Jharkhand, Orissa and the West Bengal states of Eastern India. Because of the existence of high pathogen variability, management of the disease using resistant cultivars will be a challenging task. For breeding resistant varieties, knowledge of pathogen variability in the particular crop area is essential.  In present study, fifteen isolates viz., Fu-9, Fu-10, Fu-27,Fu-32, Fu-42, Fu-49, Fu-63, Fu-72, Fu-73, Fu-74,Fu-75,Fu-84, Fu-86, Fu-87, Fu-97of Fusarium udum  obtained from wilt infected pigeonpea plants of Bihar, Jharkhand, Orissa and West Bengal of Eastern India were assessed for the phenotypic variation.  The isolates exhibited considerable variations in cultural and morphological characters viz., radial growth, mycelial color, sporulation, size and shape of macroconidia. Pathogenic variability on soil inoculated pot grown plants of pigeonpea resulted in 12.0 to 57.1 percent wilt incidence. The isolates also exhibited significant variations in symptoms like drooping of shoots, latent period, timing of fungal invasion, vascular clogging, drooping of shoots, and wilt establishment etc.  Based on the wilt incidence, the fifteen isolates were distinguished into pathogenic groups. Fu- 10, Fu-27, Fu-32 and Fu-49  were found highly pathogenic and predominantly causing the typical wilt symptoms of more than one 31% wilt incidence. The present study indicates the existence of variability among isolates of vascular wilt pathogen collected from Eastern region of India.  


2021 ◽  
Vol 7 (12) ◽  
pp. 1056
Author(s):  
Alexandri María Brizuela ◽  
Justyna Lalak-Kańczugowska ◽  
Grzegorz Koczyk ◽  
Łukasz Stępień ◽  
Michał Kawaliło ◽  
...  

Asparagus crop is distributed worldwide, covering very different climatic regions. Among the different diseases that affect asparagus, vascular Fusarium wilt, caused by Fusarium oxysporum f. sp. aparagi (Foa), stands out. It is not only the cause of large economic losses due to a decrease in yield and shortened longevity of the plantation, but also prevents replanting. This work aimed to determine if F. oxysporum isolates associated with vascular wilt on asparagus have adapted differentially to the different agro-environmental conditions. The potential correlation between origin and mycelial growth under different temperatures and humidity conditions was analysed for isolates from asparagus fields cultivated in northern and southern Europe. The genetic and pathogenic variability were also analysed. While a clear effect of water activity on mycelial growth was observed, all isolates responded in a similar way to changes in water activity in the medium, regardless of their geographical origin. The results revealed a low genetic variability of F. oxysporum isolates associated with vascular wilt on asparagus without signs of differentiation correlated to geographical origin. The southernmost isolates of the two cultivated varieties inoculated did not express more pathogenicity than those isolated from the colder region.


Author(s):  
Farahnaz Rasool ◽  
Mushtaq Ahmed ◽  
Seemi Lohani ◽  
Shubana Bhat ◽  
Sushil Kumar ◽  
...  

The pathogenic variability of the sixty isolates of M. oryzae was confirmed by testing them for virulence and cultivar reaction against International rice blast differentials (IBD) viz., Raminad Str. 3, Zenith, Usen, NP-125, Kanto-51, Dular, Tsia-tiao-sio and Caloro lodging Piz, Pia, Pii, Pia, Pika, Pi-k and Piks resistance genes for rice blasteither singly or in combination or with an unknown background. The pathotype analysis of the isolates, collected from four surveyed districts of Kashmir valley revealed the presence of four races viz., IC-17, IC-25, ID-1 and II-1 according to the race classification and nomenclature proposed by Ling and Ou (1969). Of the 60 isolates of M. oryzae, 25 isolates pertained to race IC-17, 16 and 14 other isolates pertained to race ID-1 and II-1, respectively, whereas four other isolates pertained to race IC-25. The   predominant pathotype  was IC-17 with a virulence frequency of  60 %, followed by II-1 (46.67%) in district Pulwama, ID-1 (40%) and IC-25 (13.33%) in district Bandipora, respectively. IC-17 was seen to be the predominant race in each location in every district. Race ID-1 has been observed to overcome the maximum number of genes viz., Pia, Pika+, Piks and  Pik. but none of the isolates was able to overcome Raminad Str 3 and Zenith.


2021 ◽  
Vol 10 (10) ◽  
pp. 1719-1722
Author(s):  
S Yogalakshmi ◽  
S Thiruvudainambi ◽  
K Kalpana ◽  
R Thamizh Vendan

Author(s):  
R.K. Fagodiya ◽  
Amit Trivedi ◽  
B.L. Fagodia ◽  
P.K. Meena ◽  
M.K. Kaushik ◽  
...  

Background: Alternaria leaf spot caused by Alternaria alternata is one of the most important and destructive disease of soybean causing severe yield loss in all soybean growing areas of southern and eastern part of Rajasthan. Successful management of Alternaria leaf spot is mainly dependent on accurate and efficient detection of pathogen, amount of genetic and pathogenic variability present in pathogen population. The main reason for frequent “breakdown” of effective resistance is the variability that exists in the pathogen population, which necessitates a continual replacement of cultivars due to disease susceptibility. Methods: The twelve fungal isolates randomly were collected from six districts of major soybean growing part of Rajasthan i.e., Udaipur, Chittorgarh, Pratapgarh, Kota, Baran and Jhalawar. The culture was purified single spore techniques. These were then further compared among each other for any variations in cultural characters, colour of colonies, Growth rate, conidial morphology and pathogenic variability. Result: Twelve different isolates of A. alternata were obtained in pure culture and characterized for cultural, morphological variation and aggressiveness of this fungus varied in their cultural characters, colour of colonies, growth rate of isolates, conidial morphology and isolates also exhibited variations in incubation period, latent period, number and size of lesions were produced.


Author(s):  
Niloofar Vaghefi ◽  
Dante Adorada ◽  
Lauren Huth ◽  
Lisa A Kelly ◽  
Barsha Poudel ◽  
...  

Despite the substantial economic impact of Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) on legume productions worldwide, the genetic basis of its pathogenicity and potential host association is poorly understood. The production of high-quality reference genome assemblies of Cff strains associated with different hosts sheds light on the genetic basis of its pathogenic variability and host association. Moreover, the study of recent outbreaks of bacterial wilt and microevolution of the pathogen in Australia requires access to high-quality, reference genomes that are sufficiently closely related to the population being studied within Australia. We provide the first genome assemblies of Cff strains associated with mungbean and soybean, which revealed high variability in their plasmid composition. The analysis of Cff genomes revealed an extensive suite of carbohydrate-active enzymes potentially associated with pathogenicity, including four carbohydrate esterases, 50 glycoside hydrolases, 23 glycosyl transferases, and a polysaccharide lyase. We also identified 11 serine peptidases, three of which were located within a linear plasmid, pCff119. These high-quality assemblies and annotations will provide a foundation for population genomics studies of Cff in Australia and for answering fundamental questions regarding pathogenicity factors and adaptation of Cff to various hosts worldwide, and, at a broader scale, contribute to unravelling genomic features of Gram-positive, xylem-inhabiting bacterial pathogens.


Author(s):  
Amit Chauhan ◽  
Lokesh K. Mishra ◽  
R. V. Singh ◽  
Ramji Singh

Present study was conducted to analyse the cultural and pathogenic diversity in different isolates of Bipolaris sorokiniana the causal organism of spot blotch in bread wheat. Six isolates of Biplorais sorokiniana (BS-F-5, BS-D-2, BS-K,4, BS-DWR-K-1, BS-V-6, and BS-P-3) were evaluated simultaneously for cultural and pathogenic variability on the basis of diverse characteristics against seven different genotypes of wheat grown in the region viz: BOW’S’, HS 375, HUW 234, PBW 343, PBW 443, K9107 and A9-30-1. The results indicated that isolates varied significantly among themselves for all the characters analysed. The isolate BS-F-5 exhibited the maximum colony diameter, maximum average dimension (length and width) of conidiophore, maximum number of septa in conidiophore and conidia. Variations were also observed in texture of the colony. Among the seven genotypes tested against six isolates, BOW’S’ showed resistance against three isolates (BS-D-2, BS-K,4, BS-DWR-K-1) and genotype A-9-30-1 showed high susceptibility against all isolates except BS-D-2. The isolates BS-F-5 and BS-P-3 exhibited maximum pathogenic virulence among the isolates analysed in the present investigation.


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