Detection of banana streak virus (BSV) Tamil Nadu isolate (India) and its serological relationship with other badna viruses

Banana streak virus (BSV) is of quarantine significance since Musa is a vegetatively propagated crop. Diagnosis by symptomatology is unreliable because the symptoms are variable or absent. Hence, reliable and sensitive diagnostic tests are of major significance. Such sensitive diagnostic tests are also required for virus indexing of germplasm collections. Hence, attempts were made for diagnosis of BSV and to study the serological relationship with other badna viruses. BSV particles were purified from BSV infected plants, collected from the locality of Tamil Nadu, India. Immunosorbent electron microscopy studies revealed bacilliform viral particles with a size of 120 x 30 nm. Polyclonal antiserum raised against BSV reacted with the rice tungro bacilliform virus and sugarcane bacilliform virus in TAS ELISA. In PCR assays, the primers designed to amplify DNA of BSV Onne isolate amplified DNA of BSV Tamil Nadu isolate producing amplicons of about 644 bp in size. The primers used in PCR to amplify the BSV did not amplify other badna viruses tested such as Rice tungro bacilliform virus and Sugarcane bacilliform virus. Our results suggest that the BSV isolate from Tamil Nadu is closely related to Nigerian BSV (Onne) isolate.Keywords: Triple Antibody sandwich Enzyme linked immunosorbent Assay (TAS ELISA), banana streak virus (BSV), polymerase chain reaction (PCR), polyclonal antiseru

Study on changes in ultrastructure of Banana cv. Grand Naine during ripening

The periodical changes occurred at tissue level in fruit pulp and peel of banana cv. Grand Naine belongs to AAA genome was studied during storage period. In banana, structural modification in cell walls became apparent at advanced stages of ripening and showed predominantly dissolution of the middle lamella and gradual degradation of starch granules during ripening in fruit pulp and peel. In this study, four physiological stages of ripening of banana fruit peel and pulp were examined periodically under scanning electron microscope, elucidated degradation of starch granules at the time of ripening

Induction of defense-related proteins by mixtures of plant growth promoting endophytic bacteria against Banana bunchy top virus

Rhizosphere and endophytic bacterial isolates from the roots and corms of banana were tested for their biocontrol efficiency against Banana bunchy top virus (BBTV). Molecular characterization using RAPD and microsatellite markers revealed genomic variability in the endophytic Pseudomonas and Bacillus isolates. Bio-formulations of mixtures of the rhizobacterial isolate Pseudomonas fluorescens (Pf1) and endophytic Bacillus spp. (EPB22) were effective in reducing the incidence of BBTV under green-house (80%) and field conditions (52%). Reduction in virus titer (0.64) was noticed in the plants treated with compatible mixtures of rhizobacterial and endophytic bacterial isolates as evidenced by ELISA, in comparison to control plants (1.69). In addition to disease control, a significant increase in the yield (53.33%) was noticed in the bacterized plants when compared to the control plants. Pathogenesis-related (PR) proteins, chitinase and beta-1,3-glucanase and defense-related proteins, peroxidase, polyphenol oxidase, phenylalanine ammonialyase and phenolic compounds were significantly activated in the bacterized plants, thus inducing resistance against bunchy top virus. Populations of endophytic bacteria also remained high and stable throughout the growing period. Thus, application of mixtures of rhizosphere and endophytic bacteria increases yield and has a potential role in inducing resistance against Banana bunchy top virus. (C) 2009 Elsevier Inc. All rights reserved

Biohardening with Plant Growth Promoting Rhizosphere and Endophytic bacteria induces systemic resistance against Banana bunchy top virus

Tissue culture banana has emerged as one of the leading global agro based industrial technologies. However, the banana plants are found to be more susceptible to pests and diseases due to their pliable nature and lack of withstanding in the natural environment. Banana bunchy top disease (BBTD) caused by Banana bunchy top virus (BBTV) is the most serious virus disease of banana and plantain world wide. Biopriming (or) biohardening refers to treatment of tissue culture banana plantlets with microbial inoculants to strengthen the plantlets against biotic and abiotic stresses. Forty plant growth promoting endophytic bacteria (PGPE) were isolated from the corm and roots of banana and tested for the ability to induce systemic resistance against BBTV. Phenotypic and molecular characterization of the endophytic bacteria revealed the presence of Pseudomonas and Bacillus species. Micropropagated banana plantlets were tested for the presence of BBTV by ELISA, DIBA and PCR and the uninfected plants were biohardened with two rhizobacterial (Pseudomonas fluorescens, Pf1, CHA0) and endophytic bacterial (EPB5, EPB22) strains. Plants treated with mixtures of rhizobacterial and endophytic bacterial formulations viz., EPB5 + EPB22 + Pf1 + CHAO was significantly effective in reducing BBTV under field conditions recording 33.33% infection with 60% reduction over control. The expression of defense-related enzymes and pathogenesis related proteins were more in the plants treated with rhizosphere and endophytic bacterial formulations than the control plants. The morphological and physiological characters were also well pronounced in the treated plants indicating its plant growth promoting nature. Thus, the present study clearly demonstrated that PGPR and PGPE mediated induction of systemic resistance in banana plants against BBTV have the potential role in the management of BBTD. (c) 2008 Elsevier B.V. All rights reserved

Potential implications of biopriming in banana (Musa spp) plantlets against banana bunchy top virus (BBTV)

Transplant media as a means for the introduction of biological agents is currently being investigated in a variety of crops. This study aimed to investigate the impact of microbial inoculation in micropropagated banana plantlets to enhance their resistance against Banana bunchy top virus (BBTV). Virus indexed micropropagated plantlets of banana were subjected to root colonization followed by foliar spraying with bacterial strains Pseudomonas fluorescens Pf1, CHA0 and Bacillus subtilis EPB22 during primary and secondary hardening stage in the nursery, at the time of repotting and 3 months after planting in the pot. Microbe inoculated plantlets showed enhanced PR proteins and defense enzymes besides reducing banana bunchy top disease incidence under glasshouse condition. The results indicated the effective use of beneficial microbes in reducing the disease incidence of BBTV in tissue culture banana plantlets. In addition, the molecular characterization of endophytes isolated from banana plantlets, using SDS-PAGE and RAPD-PCR revealed that endophytes were categorized into two distinct groups. These results emphasize the significance of microorganisms in protection of young plantlets from transplanting stresses in field. Further, the use of beneficial microorganisms instead of chemicals sustains an ecological niche in the agricultural ecosystem

Histopathological changes in banana roots caused by Pratylenchuscoffeae, Meloidogyneincognita and Radopholussimilis and identification of RAPD markers associated with P.coffeae resistance.

Worldwide, nematodes are amongst the most important pests of banana. By damaging the root system, nematodes adversely affect the uptake of water and nutrients, the basic needs for plant growth and fruit production. Although phenolics in banana roots are formed in response to infection by various pathogens including nematodes, information on the nature of such compounds and their potential role in defence is scarce. 59 banana genotypes (10 diploids and 49 triploids) were infected with the root-lesion nematode Pratylenchus coffeae, the root-knot nematode Meloidogyne incognita and the burrowing nematode Radopholus similis in glasshouse experiments. The production of phenolic compounds in healthy and nematode-infected banana roots was investigated histochemically, and RAPD markers associated with nematode resistance were identified. Root histological studies revealed higher numbers of cells with phenols and lignified cells in resistant accessions Karthobiumtham (ABB) and Bhimkol (BB) compared to susceptible accessions Therahaw-1164 (ABB) and Jahaji (AAA). RAPD analysis using arbitrary oligonucleotide primers differentiated resistant and susceptible banana genotypes. The marker bands found in the resistant accessions could be used to study the molecular basis for resistance to nematodes. Sequencing of these bands could help to establish the mechanism responsible for nematode resistance