Morphological and Molecular Characterization of Sclerotium ROLFSII SACC. and Integrated Management of Foot Rot Disease of Betel Vine (PIPER BETLE L.)

Abstract

Betel vine (Piper betle L.) is an important cash crop of Bangladesh but this crop suffers from several diseases and among them foot rot disease is the most devastatic. In the present research betel vine plantations were surveyed in different locations of Northern Parts of Bangladesh during June 2011 to December 2013. The highest disease incidence was recorded at Mohonpur area in Rajshahi district during 2011-2012. On the other hand in 2012-13 cropping season, the highest disease incidence was recorded in Baghmara area. Total twenty two isolates of S. rolfsii were isolated from foot rot affected portion of the betel vine boroj of different areas of Northern Parts of Bangladesh. These isolates were considered for pathogenesity test and morphological and molecular characterizations. The most virulence isolate was Baghmara-1 showed 23.42% disease severity. On the basis of mycelial growth rate the isolates were grouped as the fast grower BA-1, PA-1 and CH-2; slow grower MA-2, MO-2, PO-1, PO-2, DU-1, PU-2, N-2 and medium grower CH-1, BA-2, BA-3, BA-4, MA-1, MO-1, DU-2, PU-1, NA-1, PU-2, PA-2. For somatic compatibility test, total 22 isolates were tested in 122 combinations and only thirty eight combinations showed somatic compatible reaction and others showed somatic incompatible reaction. Combined morphological data of twenty two characters were analyzed by MVSP and the results showed six groups at 62% similarity level as cluster-1 BA-1, N-2, MO-2, BA-4, MA-2, MO-1, BA-5, DU-2, PU-1, BA-6, PO-2, PA-2`; cluster-2 DU-1 cluster-3 BA-3, PA-1,N-1; cluster-4 BA-2, CH-1; cluster-5 MA-1, PU-2 and PO-1 and cluster-6 CH-2. RAPD PCR was conducted using RAPD-1, RAPD-2, and RAPD-3 and RAPD-4 primer. Dendogram was constructed using PAST software which separated the isolates into two groups and each groups further divided by different sub groups. Representative isolates of betel vine were identified as S. rolfsii (teleomorph: Athelia rolfsii) based on phylogenetic analysis using rDNA gene sequicing. Based on the phylogenetic relationship and sequence alignment showed that there is variation exists among the S. rolfsii isolates in Bangladesh. So, the microclimates of different regions may influence the pathogen morphology and genetic diversity. In in vitro condition eight chemical fungicides namely secure, thiovit, ridomil, rovral, antracle, dithan M-45, cupravit, bavistin were evaluated. Among them the most effective chemical fungicides were bavistin and dithan M-45 which showed 100% inhibition at the concentrations of 100, 200, 400 and 800 ppm while no inhibition was exhibited in control. Twelve medicinal plants were evaluated against S. rolfsii using three solvents i.e. water, ethanol and acetone. Radial mycelial length (mm) and percent inhibition radial growth (PIRG) were measured. Out of twelve plants maximum antifungal activity (100%) were exhibited in D. metel, and L. inermis at all used solvents and concentrations while no inhibition was exhibited in H. indicum. Among the six antagonists, the highest inhibition was recorded (66.10%) in T. harzianum after 7 days of incubation in dual culture terchnique. On the other hand in poison agar technique, the highest inhibition (66.88%) was recorded in T. harziunum. Out of eleven soil amendments neem leaf dust amended soil was the most effective because hundred percent reduction of sclerotia germination was observed in this amendment. For management of foot rot disease different fungicides, plant extracts, bio-control agent and soil amendments were tested in boroj condition during 2014-15 cropping season. Out of three fungicides bavistin showed better performance and among the plants extracts, A. indica L. was the most effective. Among the antagonists the lowest percent disease incidence and highest yield was observed in T. harzianum. On the other hand, neem leaf dust showed better performance for every yield contributing characters. In integrated disease management the highest yield and the lowest disease incidence was recorded in treatment T6 (bavistin + datura leaf extracts + T. harzianum + neem leaf dust). To study the biochemical changes within the treated betel vine leaves, HPLC analysis were conducted. The total number of phytocompounds were varied with the treatments and the maximum number (31) of compounds and the highest (35%) percentage area was detected in T6 (T1+T2+T3+T4) treatment. Biochemical analysis of betel vine leaf also indicate that the integrated treatment enriched the amount of phytoconstituents of the plants. From the results it may be concluded that the isolates of S. rolfsii were morphologically and molecularly varied within the locations and integrated management will be fruitful means to control of foot rot disease of betel vine. Thus the present results will provide a valuable information to the farmers of Bangladesh for management of foot rot disease of betel vine and has scope to extend more research in this content in future.