Cloning and characterization of NBS-LRR resistance gene analogues of Musa spp. and their expression profiling studies against Pratylenchus coffeae

Resistance gene analogues (RGAs) were isolated from two banana cultivars viz., Karthobiumtham and Rose using degernate primers designed from the conserved motifs of different plant resistance genes. A total of 40 sequences were hit with various R genes, of which 20 sequences were having uninterrupted open reading frame (ORFs). Based on the conserved domains like P loop, internal kinase 2, kinase 3a and hydrophobic domain motifs of the deduced amino acid sequences were grouped as NBS-LRR class of resistant genes. The phylogentic analysis of RGAs showed that all the Musa RGAs are grouped under non-TIR branch and grouped into six distinct Musa RGA cluster. To investigate the expression profile of the RGAs, specific primers were designed for one representative RGA from each RGA cluster and it was found that C1 and C5 were induced upon root lesion nematode infection in the resistant (cv. Karthobiumtham) and not in susceptible (cv.Nendran) cultivar. C6 was expressed only in resistant cultivar not in susceptible one. But there was no change in the expression of C2 and C3 in both resistant and susceptible cultivars. These results indicate that in depth study on C1, and C5 RGAs will be helpful for further improvement of P. coffeae resistance in banana.Keywords: Banana, P. coffeae, resistance gene analogues, expression levelAfrican Journal of Biotechnology Vol. 12(27), pp. 4256-426

Fragment-oriented synthesis: β-elaboration of cyclic amine fragments using enecarbamates as platform intermediates

A strategy for the β-sp3 functionalisation of cyclic amines is described. Regioselective conversion of protected amines to enecarbamates is achieved through electrochemical oxidation; these intermediates can be derivatised by functionalised alkyl halides under photoredox catalysis. The potential of the methods is highlighted by direct growth of a DCP2B-binding fragment

Identification of nematode resistant gene sources against root-lesion nematode (Pratylenchuscoffeae) in banana.

The root-lesion nematode, Pratylenchus coffeae considered to be the economically important nematode pests of banana is widely distributed in South India (Sundararaju, 1996). Crop losses caused by nematodes to banana are very high, with an average annual yield losses estimated at about 20% worldwide (Sasser & Freckman, 1987). Crop losses caused due to P.coffeae in cv.Nendran was reported as 44.4% (Sundararaju & Cannayane, 2003). These nematodes can be controlled with the chemicals, but they may have adverse environmental effects and the use of nematicides is too expensive dangerous for subsistence farmers. Breeding for host plant resistance is a promising strategy for controlling nematodes (Speijer & De Waele, 1997). Since the root-lesion nematode has been well documented to cause considerable yield losses to banana, the present study was undertaken to evaluate 72 banana germplasms in pots under greenhouse conditions for locating the resistant/tolerant reaction to root-lesion nematode.An experiment was conducted in pots under green house condition during 2003-04 to evaluate for tolerance/resistance in banana varieties against root-lesion nematode. Among 72 Musa germplasms screened against root-lesion nematode, cvs. Singhlal, Sakkarachayna, Malai Kali, Manik Champa, Madavazhai, Kartobiumtham and Marabale were found resistant to Pratylenchus coffeae, whereas cvs. Chakia, ReDia, Ratisa local, Dudh Sagar, Rersian, Karibale, Kechulepa, Rajapuri India, Raidi Chinna, Wather, Chakkara Kannan, Yenagu Rontha, Kachkel, Soniyal and Ambeli were found moderately resistant to root-lesion nematode. It is interesting to note that the cultivars Kothia, Gragric Sarpara, Elavalai, Myndoli and Virupakshi though recorded high root-lesion indices and nematode populations, the reaction of plant growth parameters was minimal which proved that they posses a high degree of tolerance to P. coffeae. The remaining 43 varieties were found susceptible to P. coffeae, of which nine varieties were exhibited highly susceptible to P. coffeae

Community structure of plant parasitic nematodes in banana plantations of andhraPradesh, India.

Banana (Musa spp.) is one of the most important fruit crops widely grown in Indian sub-continent. Plant parasitic nematodes have been recognized as a major constraint in banana production and are responsible for serious yield losses. Though banana is the most important fruit crop grown in Andhra Pradesh, but detailed survey for nematodes has not been carried out except for some sporadic reports on the occurrence of nematodes in banana from Andhra Pradesh (Koshy et al., 1978 & Singh et al., 1979). Hence, an extensive survey was undertaken to know the plant parasitic nematode species associated with banana in Andhra Pradesh.A total of 42 soil and root samples collected from different cultivars of banana grown in West Godavari, East Godavari, Guntur and Nellore districts of Andhra Pradesh during July, 2005 covering various soil types viz., alluvial, sandy loam, clay and black soils were processed and nematode populations were assessed. Analysis of the soil samples revealed the presence of 13 genera of plant parasitic nematodes. Root-knot nematode (Meloidogyne incognita) was the most predominant species having the highest prominence value, followed by root-lesion nematode (Pratylenchus coffeae) and spiral nematode (Helicotylenchus multicinctus). M. incognita was also recorded as a predominant species from all the cultivars surveyed, whereas the burrowing nematode, Radopholus similis was recorded only from cv. Robusta (100%). Cent per cent occurrence of M. incognita was recorded from alluvial soil followed by sandy loam soil (80%). P. coffeae was also recorded maximum in alluvial soil (83.3%) followed by sandy loam (80%)

Vertical and horizontal distribution of plant parasitic nematodes associated with banana.

An experiment was conducted at farmer's field to determine the vertical and horizontal distribution of root-lesion nematode, Pratylenchus coffeae and other major nematodes on banana in cv. Nendran. Periodic sampling was done from banana garden once in a month from vegetative to harvesting stages by using a 2.5 cm diam. soil auger at a distance of 25, 50 and 75 cm away from the base of the corm at different depths. The results revealed that the maximum nematode population was recorded at flowering stage followed by harvesting stage at a distance of 25 cm and 50 cm from the base of the corm with a depth of 26–50 cm. Negligible or nil population was noticed at a distance of 75 cm from the base of the corm at a depth of 51–75 cm. This clearly showed that the population build-up of major banana nematodes like P. coffeae, M. incognita and H. multicinctus and other nematodes would greatly vary depending on the distance, depth and availability of susceptible roots in banana plants

Effect of marigold (Tagetuserecta) intercropped with banana cv. Nendran against root-lesion nematode, Pratylenchus coffeae.

Banana (Musa spp.), the most important fruit crop grown in India ranked second, next to mango, in area and production. Plant parasitic nematodes are widespread and are the most important pests of banana. Crop losses caused by nematodes in bananas are very high, with an average annual yield losses estimated at about 20 per cent world wide (Sasser & Freckman, 1987). The rootlesion nematode, Pratylenchus coffeae is one of the most important nematode pests of banana next only to the burrowing nematode, Radopholus similis. In India, losses caused due to root-lesion nematodes on banana cv. Nendran was estimated at about 44.4% (Sundararaju & Cannayane, 2003). In recent years due to prohibitive cost of pesticides and their toxicity to human beings and soil flora, considerable attention has been paid towards the control of nematode diseases by the use of botanicals. Intercropping of various nematicidal plants viz. sunhemp, sesamum, mustard, marigold etc. have been reported to be effective against nematodes infecting several crops (Boride et al. 1970). As there was no such report on control of root-lesion nematode infected banana plants, the present investigation was carried out to find out the appropriate combination of growing marigold as an intercrop in banana field and its effect on plant growth, yield and nematode populations.An experiment was conducted at farmer's field on banana cv. Nendran (AAB) infested with root-lesion nematode. Maximum reduction in root-lesion index and nematode population was noticed, where Tagetes erecta was grown as an intercrop and on par with chemical treatment, whereas, maximum population was recorded in untreated control plants. The yield of banana increased significantly to 12.5 and 12 kg/plant in plants treated with chemical pesticides and intercropped with Tagetes respectively compared to a minimum bunch weight of 7 kg per plant in untreated control plants. Though the plants treated with chemical pesticides were found to be on par with marigold grown as an intercrop, but the use of marigold as an intercrop in banana field warrants more economical and ecofreindly compared to chemical nematicides

Integrated pest management approaches to minimize incidence of cashew stem and root borers (Plocaederus spp.)

Cashew (Anacardium occidentale L.) trees infested by cashew stem and root borers (Plocaederus spp.) were treated with insecticides, entomopathogenic fungal spawn and neem oil after extraction of the pest stages in such trees, to prevent fresh infestation; referred to as ‘post extraction prophylaxis’ (PEP). Chlorpyriphos (0.2%) was identified as the most feasible PEP treatment in extensive field trials. Treatment with either neem oil (5 %) swabbing or application of Metarhizium anisopliae spawn (250 g/ tree) were proved to be ineffective in minimizing pest reinfestation, being on par with untreated control. Adoption of phytosanitation by removing the infested trees having more than 50 % bark circumference damage was proved to considerably reduce the number of trees having fresh pest incidence during the subsequent years. The pest population in a given location and also the pest load in infested cashew trees could be drastically reduced by adopting regular phytosanitation