Bilal A. Padder

Cultural, morphological, pathogenic and molecular characterization of Alternaria mali associated with Alternaria leaf blotch of apple

Alternaria blotch (Alternaria mali) causes severe foliar damage to apple trees in Kashmir. Twenty one (21) isolates of A. mali were collected from different locations and characterized for cultural, morphological, pathogenic and molecular variations. A. mali colonies varied in their cultural behaviour ranging from velvety to cottony, mostly appressed, with regular to irregular margins. Colour of colonies ranged between light to dark olivacious. Isolates impregnated media with colour ranging between grey to brown. Growth rate of isolates was between 5.86 to 8.21 mm/day with fast growth in isolate Am-13 and least in Am-5. Morphological variations in size, shape and septation of hyphae, conidiophore and conidia were observed in the isolates with significant variations in conidiophore and conidial septation. Average conidial size ranged from 21.36 to 31.74 x 8.34 to 14.48 µm. Isolates exhibited variations in incubation period, number and size of the lesions were produced. The dendrogram analysis, based on cultural, morphological and pathogenic studies, revealed variation within A. mali population. At 67% similarity matrix, all the isolates formed 2 clusters with 12 and nine isolates in cluster I and II, respectively. However, dendrogram on molecular (random amplification of polymorphic DNA, RAPD) basis revealed five clusters at 68% Dice similarity coefficient. There was no congruence between RAPD pattern and cultural, morphological and pathogenic characters. Isolates identical for one spectrum were often dissimilar for other spectrum. The results demonstrate existence of considerable variation in cultural, morphological, pathogenic and molecular characters of A. mali isolates prevalent in Kashmir valley.

Pathogenic and coat protein characterization confirming the occurrence of Bean common mosaic virus on common bean (Phaseolus vulgaris) in Kashmir, India

Bean common mosaic virus (BCMV), belonging to the family Potyviridae, is a serious pathogen of common bean (Phaseolus vulgaris L.) causing considerable economic losses owing to seed, sap and aphid transmissibility. The viral nature of the test isolates and identity of the virus as BCMV were confirmed by mechanical transmission and DAS-ELISA using BCMV antiserum. Pathogenic variability studies in BCMV infecting common bean (Phaseolus vulgaris L.) in Jammu and Kashmir (a northwestern Himalayan state of India), revealed the existence of three pathogroups – PG-I, PG-II and PG-VII, accommodating five strains (NL-1, NL-1n, NL-4, NL-7 and NL-7n). Comparative sequence analysis of coat protein gene revealed that the strains NL-1, NL-4 and NL-7 shared more than 90% amino acid sequence homology with other BCMV isolates from other countries. DAG motif as well as BCMV specific conserved motif MVWCIDN were present in all the three strains. Phylogenetic analysis of coat protein also clustered them in the BCMV group. This study confirmed the occurrence of BCMV and its strains on common bean in Kashmir.

Marker-assisted introgression of three dominant blast resistance genes into an aromatic rice cultivar Mushk Budji

Modern high yielding rice varieties have replaced most of the traditional cultivars in recent past. Mushk Budji, is one such short grained landrace known for its aroma and exquisite quality, however, is highly susceptible to blast disease that has led to considerable decline in its area. Mushk Budji was crossed to a triple-gene donor line, DHMAS 70Q 164-1b and followed through marker-assisted foreground and background selection in first and second backcross generations that helped to incorporate blast resistance genes Pi54, Pi1 and Pita. Marker-assisted background selection was carried out using 78 SSR and STS markers that helped to reduce linkage drag around the genes Pi54, Pi1 and Pita to 2.74, 4.60 and 2.03 Mb, respectively. The three-gene lines in BC2F2:3 were genotyped using 50 K SNP chip and revealed more than 92% genome similarity to the RP. 2-D gel assay detected differentially expressing 171 protein spots among a set of backcross derived lines, of which 38 spots showing match score of 4 helped us to calculate the proteome recovery. MALDI-TOF analysis helped to detect four significant proteins that were linked to quality and disease resistance. The improved lines expressed resistance to blast under artificial and natural field conditions.

Morpho-cultural, pathological and molecular variability in Thyrostroma carpophilum causing shot hole of stone fruits in India

Shot hole disease of stone fruits caused by Thyrostroma carpophilum has become a major threat to stone fruit industry of Jammu and Kashmir, India because of the failure in its management with fungicides. To understand the diversity in shot hole pathogen, a combination of conventional (morphological, cultural and pathological) and molecular (ISSR and ITS markers) approaches were employed to discern variability in 25 isolates of T. carpophilum isolated from peach, plum, apricot, almond and cherry leaves collected from Srinagar, Ganderbal, and Baramulla districts of Jammu and Kashmir, India. The studies revealed a high level of variability among the pathogen. Based on the morpho-cultural and pathological studies, the isolates were grouped into different categories based on colony growth, texture, margin and colour besides change in media colour, incubation period, leaf area infected, etc. Using ISSR markers, a high level of polymorphism in different isolates of T. carpophilum was observed which indicated that these markers are suitable for studying the genetic diversity in this pathogen. Based on dendrogram, the isolates were grouped irrespective of their geographical origin or host species. Phylogenetic analysis of the 25 sequences based on ITS region showed maximum similarity with T. carpophilum (Syn. Wilsonomyces carpophilus) sequences retrieved from NCBI and grouped them in a single clade which proved it as a powerful tool for authentic identification. The pathogen was highly variable based on morpho-cultural, pathological and molecular (ISSR) characterisation.

Average Daily Gain in Physico-Chemical Characteristics and Yield Efficiency of Some Apricot Cultivars Grown in Himalayan Temperate Region

Apricot (Prunus armeniaca L.) is an attractive, delicious and highly nutritious fruit being cultivated in temperate climates of all the continents of the world, Asia and Europe being the largest producers (Bhat et al., 2013). Distribution of cultivated apricot, its wild forms and allied species in temperate zone of Asia is confined between 33 o and 70 o east longitude and 53 o and 30 o north latitude (Kostina, 1936). In India, apricot is grown in Jammu and Kashmir, Himachal Pradesh, Uttar Pradesh and to a limited extent in North-eastern hills. Its cultivation has not been successful in south India (Hayes, 1957). In Jammu and Kashmir the total production in the year 2016 was 14142 MT from an area of International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 8 (2017) pp. 2915-2922 Journal homepage: http://www.ijcmas.com

Molecular marker-based validation of blast resistance gene Pi54 and identification of potential donors in temperate high altitude rice (Oryza sativa L.)

More than 100 genes have been reported to impart resistance against rice blast, however, not all are equally effective. Their effectiveness relies on factors such as the diversity in pathogen races prevailing in a certain area, rate of pathogen evolution, genetic background of a host and few others. Pi54 is a major gene showing resistance to Magnaporthe populations in North-west Himalayas. In search of novel temperate donors suitable to high altitudes, a set of germplasm was screened using gene based markers for Pi54. Eighty three exotic and indigenous germplasm lines were genotyped using gene based markers and also validated for disease reaction using Pi54 gene specific isolate namely, Mo-nwi-kash-32. Nine out of 83 germplasm lines amplified resistance specific alleles with both the markers Pi54 MAS and Pikh-STS. All these lines expressed resistance against the said diagnostic isolate, thereby validating the possible presence of gene in the lines. Further validation using more number of isolates and sequence analysis will help in mining useful alleles for this gene.