Abstract
Rhizoctonia solani is considered as one of the most destructive soil-and-seed borne plant pathogens infecting various agricultural crops including chickpea. The 50 chickpea isolates of R. solani representing 10 different states of India were variable in hyphal anastomosis reactions and they were grouped into seven AGs as AG1, AG2-2, AG2-2LP, AG2-3, AG3, AG4 and AG5. Genetic diversity of the pathogen was determined by using molecular markers namely, simple sequence repeats (SSR) and rDNA internal transcribed spacer (ITS). A neighbor-joining tree constructed based on the profiles generated by SSR markers grouped the isolates into eight categories. This revealed 90% of genetic similarity among the isolates and partial correlation with reference to their geographical origin and AGs. The isolates were amplified with a set of primers ITS 1 and ITS 4 and they produced a specific band ≈650 bp. Low level of (7%) variability was observed in the nucleotide sequences of the ITS regions of these isolates. The phylogenic tree generated from bootstrap neighboring joint analysis grouped the Indian populations of R. solani into two categories. Key words: Chickpea, wet root rot, genetic diversity, simple sequence repeats (SSR), internal transcribed spacer (ITS).
Highlights
Chickpea (Cicer arietinum L.) is an important winter legume crop of India and cultivated on an area of 8.21 m ha with an average annual production of 7.48 m tones along with productivity of 911 kg ha-1 (Anonymous, 2011)
Fifty (50) chickpea isolates of R. solani collected from different states of India were characterized into seven anastomosis groups namely, AG1, AG2-2, AG2-2LP, AG2-3, AG3, AG4 and AG5 with the help of international testers (Table 1, Figure 1)
The 50 isolates of R. solani causing Wet root rot (WRR) in chickpea collected from 10 different states of India were characterized and grouped into 7 AGs namely, AG1, AG2-2, AG2-2LP, AG2-3, AG3, AG4 and AG5
Summary
Chickpea (Cicer arietinum L.) is an important winter legume crop of India and cultivated on an area of 8.21 m ha with an average annual production of 7.48 m tones along with productivity of 911 kg ha-1 (Anonymous, 2011). Its production and productivity is affected by numerous diseases. Wet root rot (WRR) caused by Rhizoctonia solani Kühn (Teleomorph: Thanatephorus cucumeris (Frank) Donk. Is the most destructive in nature (Dubey et al, 2012). The disease is most commonly observed at early in the season when the soil moisture content is often high. Characteristic symptoms include root rotting, often originating at the distal tip of the young root and gradual yellowing and wilting of foliage (Dubey and Dwivedi, 2000). R. solani affects wide range of food crops because of its polyphagous nature and high saprophytic ability (Nelson et al, 1996). The fungi have been identify and classified mainly on the basis of characteristics of their sexual and asexual methods of reproduction (Hibbett et al, 2007); but, identification, grouping and taxonomy of R. solani was always challenging because of heterogeneous group of filamentous fungi that share similarities
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