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STUDIES ON VARIABILITY IN Fusarium udum THE INCITANT OF WILT IN PIGEONPEA

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Title STUDIES ON VARIABILITY IN Fusarium udum THE INCITANT OF WILT IN PIGEONPEA
 
Creator RANGASWAMY, E
 
Contributor PUSHPAVATHI, B
 
Subject diseases, fungi, pigeonpeas, pathogens, biological development, planting, rapd, concentrates, developmental stages, dna
Fusarium udum
 
Description In the present study characterization of the Fusarium udum populations with reference
to cultural, morphological, biochemical and amplification pattern of genomic DNA has been
taken up to ascertain the pathogenic and genetic variability in Fusarium udum isolates. A
total of 26 isolates were collected from major pigeonpea growing areas of Andhra Pradesh
and used for further investigation.
The isolates varied significantly for cultural and morphological characters. Among the
isolates the size of micro- and macroconidia varied between 7.27×2.88μm (Fu 24) to
13.25×2.68 μm (Fu 10) and 23.37×3.17μm (Fu 18) to 40.05×4.71μm (Fu 8) respectively.
Chlamydospores were observed in all the isolates and their diameter measured between
9.47μm (Fu 19) to 15.57μm (Fu 1). Colony characters ranged from sparse to dense mycelial
growth. According to colony characters they were categorized into four groups viz., white
cottony and fluffy growth, white cottony dense growth with smooth margin, white sparse
growth in concentric rings and white sparse growth. Considerable variation was also
observed in substrate pigmentation for all the isolates on PDA medium. Majorly, the isolates
developed different colours viz., yellow, pale yellow, reddish yellow, brownish yellow, pink
and light pink. Variation in colony diameter varied from 55.00mm (Fu 22) to 89.33mm
(Fu 21). Among the isolates Fu 20 and Fu 22 showed scanty sporulation while abundant
sporulation was recorded in isolates Fu 4, Fu 7, Fu 9, Fu 12, Fu 13, Fu 19 and Fu 24. Based on morphological characters isolates were categorized into five groups and one
representative isolate from each group was selected for further investigation. Five isolates
were evaluated for pathogenic variability on a set of seven host differentials and three
locally growing cultivars. Isolates varied greatly for virulence, disease incidence, disease
reaction, latent period and virulence index. As all the five isolates induced symptoms on all
the host differentials, they were considered as virulent isolates. However, among the isolates
tested based on virulence index, the isolate Fu 15 was found highly virulent and the isolate
Fu 24 was weakly virulent.
Among the isolates tested significant variation was found in bio-chemical
composition. Total sugars were found to be highest (16.40mg) in isolate Fu 2 and lowest
(5.70mg) in isolate Fu 25. Similarly, total protein content of different isolates was ranged
between 8.00mg (Fu 5) to 15.40mg (Fu 21). Across the isolates, isolate Fu 8 (5.50mg)
showed minimum quantity of total free amino acids, while the maximum quantity of free
amino acids was found in Fu 15 (20.16mg) followed by Fu 7 (20.08mg). All the 26 isolates
produced Poly Methyl Galacturonase (PMG) and Poly Methyl Esterase (PME) enzymes and
varied significantly in production of these enzymes. PMG activity varied from 25.20 percent
(Fu 9) to 64.39 percent (Fu 5) while PME activity varied from 6.40 (Fu 3) to 29.00 (Fu 24)
across the isolates.
The effect of different concentrations of culture filtrates was tested against
germination, root length and wilting of pigeonpea seedlings and the results showed that
germination and root length were reduced and seedling wilt was increased as the
concentration of culture filtrates increased.
RAPD analysis of F.udum showed polymorphism among the 26 isolates. Data
obtained through RAPD studies differentiated the isolates into two major clusters A and B.
Co-efficient value of each isolate derived from RAPD study showed that, among the 26
isolates of test pathogen highest similarity coefficient of 0.90 was observed between the
isolate Fu 1 and Fu 2; and 0.84 was observed between isolates Fu 6 and Fu 7 and isolates Fu
25 and Fu 26 followed by 0.83 between isolates Fu 16 and Fu 17.
 
Date 2016-06-09T13:43:30Z
2016-06-09T13:43:30Z
2011
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67108
 
Language en
 
Relation D8874;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY