Molecular and Cultural Characterization of Alternaria brassicae Infecting Cauliflower in Uttar Pradesh, India

Abstract

The Alternaria blight or leaf blight (Alternaria brassicae) causes severe damage to cauliflower at curd formation and seed setting stage. Roving survey revealed that the disease incidence on cauliflower in different farmer's fields ranged from 10 to 40 % with an average incidence of 20 % in Uttar Pradesh. Twenty-three (23) isolates of A. brassicae were collected from different cultivars in Uttar Pradesh and characterized for cultural, morphological, pathogenic and molecular variations. Based on the pathogenicity, isolates of A. brassicae were rated as virulent or less virulent based on the percentage disease incidence on cv. Hajipur local. Most of the isolates showed smooth mycelial growth with circular, irregular margin and without concentric zonation. The colony colour is white, dark brown to light brown and pinkish in white. Significant morphological variations in conidial length, conidial width, and number of horizontal septa were observed in all the isolates. The maximum length of conidia ranged from 150 to 122 lm with 8 to 9 transverse and 2 vertical septation.Further the genetic diversity of isolates based on RAPD-PCR using sixteen random primers were produced on clarity, repeatability and the number of polymorphic bands in all the isolates. Cluster analysis of DNA fragments was performed using NTSYSpc V2.2 based on UPGMA method and Jacard coefficient. Based on the analysis the isolates represented four major groups with 75 % similarity.

Morphological and physiological variation among different isolates of Alternaria spp. from Rapeseed-Mustard

“…The horizontal septation of 5 different isolates of A.brassicae varied from 4-13 and vertical from 0-6 [33]. 23 isolates of A. brassicae were collected and found maximum length of conidia ranged from 150 -122 μm with 8 -9 transverse and 2 vertical septation [27] Eight isolates of A. solani were examined [25] and found average conidial size (L×B) was 42.18×15.18 µm and beck size was 13.10µm. In ten isolates of A. macrospora size of conidia ranged from 20.81-56.23 x 9.2-27.10 μm with 1 -6 transverse and 0 -4 longitudinal septa were found [14].…”

Variation in Alternaria brassicae Population Causing Alternaria Blight of Rapeseed and Mustard in Assam

“…in different regions of India as well as in the world have been reported by several authors (Meena et al, 1972;Gherbawy, 2005;Goyal et al, 2011;Kaur et al, 2015;Saha et al, 2016;Aeneja et.al., 2014;Bind et al, 2014 andSelvamani, 2014).The importance of pathological as well as genetic level study has been highlighted for efficient management of the disease by Milgroom andFry, 1997 andAgnihotri, 2013. In Assam, though large scale survey has not been carried out on the total loss caused by the Alternaria brassicae but reports from farmers' field about the disease is alarming requiring a full scale study to understand the variability of Alternaria brassicae to help develop management strategies.…”

“…Kaur et al, 2015 found the colonies brown, while and olevaceous green with smooth or wavy margins and thick velvety to sparse growth. Aneja et al, 2014 andSaha et al, 2016 also reported. …”

“…The present findings were also in accordance with the findings of Goyal et al, (2011), who reported morphometric variation of thirteen Alternaria brassicae isolates of rapeseed and mustard and found that average conidial length ranged from 31.2μm to 51.8μm, average conidial breadth ranged from 6.7μm to 9.6μm, average beak length ranged from 8.2μm to 19.2μm, transverse septa ranged between 4.8 to 7.2 numbers while longitudinal septa ranged from 0.0 to 0.4 numbers. A number of research workers (Saha et al, 2016;Kaur et al, 2015;Meena et al, 2010 andVerma andSaharan, 1994) recorded morphological variations in Alternaria spp.…”

Diversity in Alternaria brassicae (Berk.) Sacc. isolates and characterization of host response in different oilseed Brassica species

“…The prevalence of such morphological and cultural variations in A. brassicae, had also been indicated by (Kolte et al, 1991, Viswanath and Kolte, 1997, Awasthi and Kolte, 1989. Variability in the morphological and cultural characteristics in A. brassicae isolates of different regions of India have been reported (Meena et al, 2005, Kaur et al, 2007, Goyal et al, 2013, Saha et al, 2015. Recently Kumar and Singh (2018) reported the morphological variability in Aletrnaria brassicae isolates collected in Madhya Pradesh region.…”