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The present study was undertaken to investigate the inheritance of resistance against two variants of Fusarium wilt (Variant 1 and Variant 2), using highly resistant (ICP8863) and susceptible (Type 7) pigeonpea genotypes. In order to develop F2 mapping population from the cross Type 7 x ICP8863, homogeneity and true hybridity testing was carried out using molecular markers (OPP-17, CCB-10, PPMC-1, PPMC-2, and PPMC-3). Phenotyping of mapping population was carried against two variants in the pots inoculated with 5% of inoculum (w/w) under green house conditions. Chi-square test based on phenotypic data revealed that the resistance was governed by a single recessive gene against variant 1 and two recessive genes against variant 2 in ICP8863. These results will be helpful in developing appropriate mapping and resistance breeding strategies against these two variants of Fusarium wilt in pigeonpea. [ABSTRACT FROM AUTHOR]

The variability in cultural characteristics and the virulence among three isolates of Fusarium oxysporum f. sp. ciceri causing vascular wilt in chickpea was studied under laboratory conditions. The three isolates (Foc-1, Foc-2 and Foc-3) did not show any significant difference in their mycelial dry weight production at any temperature regimes, pH level or the growth media tested. The radial growth on PDA also did not differ significantly in the three isolates. However, some quantitative differences were noted in colony characters and septations in macroconidia of these isolates. The isolate Foc-1 exhibited dull white, thin and flat hairy growth, spreading out like thread, Foc-2 showed a white fluffy colony with irregular aerial margin, while Foc-3 exhibited a pinkish white, slightly fluffy colony with regular margin. Conidia also differed with regard to septation. Three to six septa were present in Foc-2, while there were 2-3 in isolates Foc-1 and Foc-2. These isolates differed significantly with regard to their virulence on test varieties. Isolate Foc-1 was more virulent that Foc-2 or Foc-3 and produced abundant spores. [ABSTRACT FROM AUTHOR]

With the objective to study the geographical distribution pattern and pathotype classification, isolates from 12 major pigeonpea growing states of India were examined at morphological and molecular levels. Two DNA based internal transcribe spacer (ITS) region derived primers FDP 3 (ITS1/ITS2), FDP 25 (mRNA, LOC100383610) and two elongation factors FDP 4 (F98-BKR5) and FDP 29 (M9968PY) were employed to genetically differentiate the isolates. As a result, each marker system gave an average of 3 alleles/marker. The higher efficiency of ITS over EF-1α marker was revealed using detailed comparative analysis that included various parameters like gene diversity index, effective marker ratio, and marker index. Neighbour Joining tree analysis grouped the isolates into three major clusters and showed narrow existence of genetic divergence. Combination of genotyping data with pathological measurements indicates dominance of variant 1 in the Central zone, South zone and North East Plain Zone, while North East Plain Zone and North West Plain Zone were largely dominated by variants 2 and 1, with strong possibility of evolving other variants. The present study would help in identifying specific isolate and patterns of its distribution in various pigeonpea growing regions thereby enhancing the scope for precise resistance breeding for crop improvement.