Browsing by Author "Rajesh, M.K."
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Item 3rd International Symposium on Coconut Research and Development(2016) Chowdappa, P.; Muralidharan, K.; Samsudeen, K.; Rajesh, M.K.Item Item Amplification and sequencing of partial–length disease resistant gene homologues coding NBS LRR-type proteins in coconut(2012-11) Rachana, K.E.; Naganeeswaran, S.; Rajesh, M.K.Pseudomonas spp. and compared with other gene predicting tools. This tool can be used for the functional annotation of the microbial genome data providing insights into genome evolution and identifying different strains containing LTTR genes.Item Analysis of genetic diversity in coconut and its conservation in root (wilt) disease affected areas of Kerala: A community participatory approach(2013) Thomas, R.J.; Rajesh, M.K.; Kalavati, S.; Krishnakumar, V.; George, D.J.; Jose, M.; Nair, R.V.Root (wilt) disease is a major constraint to coconut production in Kerala State. Conserving ecotypes with resistance or tolerance to the disease on a community basis is essential to sustain coconut production in the root (wilt) disease prevalent areas. Three communities viz., Pathiyoor and Devikulangara (Alappuzha District) and Thodiyoor (Kollam District) were selected and a survey was conducted with the participation of stakeholders, to characterize the local coconut ecotypes. Six ecotypes comprising of four talls and two dwarfs were identified and morphological data revealed that the local Jappanan ecotype closely resembled Evoor Green Tall ecotype. Simple Sequence Repeat (SSR) analysis in 90 selected coconut palms representing the six ecotypes using 14 markers indicated that the observed heterozygosity was higher in tall ecotypes (0.179-0.365) compared to the dwarfs (0.03-0.07). Lower values for observed heterozygosity compared to the expected heterozygosity in tall ecotypes are indications of genetic basis for disease resistance observed in diseasefree mother palms. Molecular characterization helped in identifying diverse coconut ecotypes having application in production of vigorous hybrids. In the dendrogram constructed using nut character data, three of the tall ecotypes (Green Tall, Brown Tall and Brick Red Tall) clustered together whereas Jappanan clustered separately. Mantel s correlation test using the ZT software revealed significant correlation (0.96) between the SSR data and morphological data.Item Analysis of population structure and genetic relatedness among root (wilt) disease-resistant and susceptible west coast tall coconut palms (Cocos nucifera) using microsatellite markers(2011-06) Devakumar, K.; Thomas, R.J.; Nair, R.V.; Augustine Jerard, B.; Rajesh, M.K.; Jacob, P.M.; Jayadev, K.; Parthasarathy, V.A.The population structures among the root (wilt) disease-resistant and susceptible coconut palms from 12 locations in the three disease-endemic districts of southern Kerala, were analyzed using nine microsatellite markers. The pair-wise population differentiation estimate (Fs) between the resistant and susceptible populations was 0.021. Two major populations and a subpopulation cluster were identified among the resistant palms. The analysis of genetic relatedness between the resistant mother palms showed that most of the palms located in a single locality shared sib relationship among them. The existence of close genetic relationship among resistant palms from Chengannur, Thiruvalla, Kottayam and Pavukkara localities in Kerala were reported. The results are discussed in terms of breeding strategies for increasing heterozygosity and obtaining the maximum number of disease-resistant seedlings.Item Analysis of segregating populations of West Coast Tall variety of coconut using microsatellite markers(2006) Manimekalai, R.; Rubavathi, V.B.; Thomas Regi, J.; Nair, R.V.; Rajesh, M.K.In vitro antagonistic studies with native Trichoderma spp viz., T.viride, T.harzianum & T.hamatum and a bacterial strain of Pseudomonas fluorescens revealed that the mycelial growth of the coconut pathogens viz., Ganoderma applanatum and G.lucidum (basal stem rot pathogens) and Thielaviopsis paradoxa (stem bleeding pathogen) was highly inhibited by T.viride (more then 80%). Pseudomonas fluorescens completely inhibited the growth of both the species of Ganoderma, whereas only 33% inhibition was observed in the growth of T.paradoxa. All the three species ofTrichoderma were found to be very effective in producing specific volatile met.abolites against T.paradoxa. The volatile metabolites of P.fluorescens completely inhibited G.applanatum and Glucidum but non-volatile metabolites were not effective. Application of 50 g of talc formulation of Trichoderma viride or T.harzianum or T.hamatum with combination of5 kg neem cake/palm/year in basins around the palm was found to be effective in the management ofbasal stem rot disease and smearing oftalc powder paste ofTrichoderma viride or T.harzianum or T.hamatum reduced bleeding patches due to stem bleeding disease. Developed a common biointensive "10M package against basal stem rot and stem bleeding diseases.Item Application of RAPD markers in hybrid verification in coconut(2014) Rajesh, M.K.; Jerard, B.A.; Preethi, P.; Regi Jacob Thomas; Anitha KarunCoconut palms are classified into two major types, viz., ‘talls’ and ‘dwarfs’, which mainly differ in their pollination behavior of cross- and self-pollination, respectively. Due to this difference, getting true-to-type progenies of desirable tall and dwarf cultivars has always been a challenge. The conventional practice of selection of seedlings based solely on morphological traits often results in selection of out-crossed seedlings and undesirable off-types. In the present investigation, RAPD markers for the tall/dwarf trait were identified in coconut using a bulked DNA approach. Screening of tall and dwarf palm bulk DNA with 200 primers revealed a RAPD primer OPBA3 which was able to clearly differentiate both the tall and dwarf bulks. For validation, the primer was used to screen individual tall and dwarf coconut palms representing different geographic regions. The primer was also used to screen the parents and validate hybrids of Dwarf x Tall crosses.Item Arabidopsis non-host resistance PSS30 gene enhances broad-spectrum disease resistance in the soybean cultivar Williams 82(2021) Sekhar Kambakam; Micheline N. Ngaki; Binod B. Sahu; Devi R. Kandel; Prashant Singh; Rishi Sumit; Sivakumar Swaminathan; Rajesh, M.K.; Madan K. BhattacharyyaItem Assembly and Annotation of the Nuclear and Organellar Genomes of a Dwarf Coconut (Chowghat Green Dwarf) Possessing Enhanced Disease Resistance(2020) Rajesh, M.K.; Chowdappa, P.; Santosh Kumar Behera; Sandeep Kasaragod; Gangaraj, K.P.; Chinmaya Narayana KotimooleItem Assessment of cross-taxa utility of coconut microsatellite markers(2008-09) Anitha, N.; Lakshmi Jayaraj, K.; Arun Kumar, E.P.; Jiji George; Rajesh, M.K.Micro-satellite or simple sequence repeats (SSRs) are abundant across eukaryotic genomes and show high levels of polymorphism. Micro-satellite DNA often has flanking regions that are highly conserved in related species and this renders the primer pairs designed in one species useful for the amplification of the same DNA region in related genomes, minimizing laborious cloning and screening steps. The present investigation explored the transferability of coconut SSRs to other palms, viz., oil palm, arecanut, palmyrah and date palm. The annealing temperature of 86 coconut-specific SSR primers was standardized using gradient PCR. Of the 86 primers, 55 primers gave clear bands of expected size range (100 to 300 bp) and these were tested for their cross-taxa amplification. The percentage of cross-amplification of coconut SSR loci were 36.36% in oil palm, 29.09% in arecanut, 18.18% in palmyrah and 12.70% in date palm. The results suggest usefulness of coconut SSRs for phylogenetic and comparative genomic studies in other palms.Item Assessment of genetic fidelity of arecanut plantlets derived through direct somatic embryogenesis by RAPD markers(Indian Society for Plantation Crops, 2008) Anitha Karun; Radha, E.; Sangeetha Vijayan, P.; Jiji George; Rajesh, M.K.; Ananda, K.S.Item Assessment of morphological, physiological and molecular characteristics of cocoa accessions from Central and South America in relation to drought tolerance(2013-12) Elain Apshara, S.; Rajesh, M.K.; Balasimha, D.Eleven cocoa accessions, representing collections from five central and south American countries, were assessed for their morphological, molecular and physiological parameters. Growth characters were observed in three year old plants and initial pod yields were recorded. Photosynthesis, related parameters and chlorophyll indices, measured during two seasons, showed significant differences between non-stress and stress periods as well as among the genotypes. The transpirational water loss was reduced with increased stomatal closure, which is a favourable drought trait in crops. The results indicated that the genotypes showing higher water potential and Fv/Fm ratio can be considered as drought tolerant. The rank sums of these parameters showed that genotypes JA-1/19, POU-16/A and SC-4 were the most droughttolerant. Microsatellite markers were used to assess the extent of genetic diversity between clones. The amplification of DNA from the 11 accessions using the 15 microsatellite loci revealed a total of 80 consistent and scorable alleles with an average of 5.33 alleles per locus and all the loci were 100 per cent polymorphic, the most polymorphic locus being mTcCIR33 with 8 alleles. The observed heterozygosity ranged from 0.36 to 0.63 with an average of 0.52. The inbreeding co-efficient (f) ranged from -0.22 (mTcCIR8) to 0.58 (mTcCIR40) with an average of 0.32. The microsatellite marker analysis revealed that the genotypes possess a wide genetic diversity. The drought tolerant types identified in this study viz., JA-1/19, POU-16/A and SC-4 could be used for cultivation in areas with moisture deficient stress and in selective cocoa breeding programs for drought tolerance.Item Assessment of the genetic diversity of Indian coconut accessions and their relationship to other cultivars, using microsatellite markers(No. 145 Plant Genetic Resources Newsletter, 2006) Devakumar, K.; Jayadev, K.; Rajesh, M.K.; Chandrasekhar, A.; Manimekalai, R.; Kumaran, P.M.; Parthasarathy, V.A.Coconut cultivation in the Indian subcontinent over many centuries has given rise to diverse cultivar types, identi- fied based on discernible morphological traits, geographical locations and farmers’ choice. The Indian coconut germplasm base has also been enriched through introductions from other major coconut growing regions of the world. This study assessed the genetic diversity in a range of coconut accessions, and their relationship to other major coconut cultivars, using microsatellite markers. Microsatellite assay was used for 23 Indian accessions (15 Talls and 6 Dwarfs) and for 21 exotic accessions (18 Talls and 6 Dwarfs). A total of 48 alleles were detected in the Indian accessions by using 8 microsatellite primers (average 6 alleles per locus). More alleles were detected in the Indian accessions than in the exotics, indicating the presence of a wide allelic spectrum in the Indian accessions. Mean gene diversity ranged from 0.00 for ‘Chowghat Green Dwarf’ to 0.59 for ‘Lakshadweep Ordinary Tall’, with an overall mean of 0.32. The within-population variation was slightly higher (53%) than the betweenpopulation variation (47%), suggesting recent local adaptation and subsequent divergence among Indian cultivars. An UPGMA dendrogram separated the Indian accessions into two groups, one clustering with South-east Asian cultivars, which are introgressed types, and another clustering with African and Sri Lankan cultivars. The results are discussed in terms of diversity of Indian coconut accessions and relationships to other major coconut cultivars.Item Assignment of Function and Homology Modelling of Serk and Lec Proteins in Cocoa(2011) Nithya, S.; Rajesh, M.K.; George V. ThomasItem Authentication of coconut hybrids using RAPD analysis(2012-11) Rajesh, M.K.; Preethi, P.; Jerard, B.A.; Regi Jacob Thomas; Anitha KarunItem Biology and cultivation of arecanut(2018) Nagaraja, N.R.; Ananda, K.S.; Rajesh, M.K.Item Biology, damage potential and molecular identification of Conogethes punctiferalis Guenee in cocoa (Theobroma cacao Linn.)(2013-12) Alagar, M.; Rachana, K.E.; Keshava Bhat, S.; Shafeeq Rahman; Rajesh, M.K.Conogethes punctiferalis is an important polyphagous pest attacking many economically important crops. Recently, C. punctiferalis has been found to be an emerging pest in cocoa and was found to feed and bore into cocoa pods. The larvae feed on the rind of cocoa cherelles/pods, later bore into pods, feed the internal contents of the pods, the granular faecal pellets are seen outside the pods. When pods/cherelles touch each other, it is easy for the larvae to damage more than one pod/cherelle. Pods damaged by Conogethes are exposed to secondary infection by pathogens that lead to pod rot. The larvae sometimes feed on flower buds and flowers cushions. The damaged flower cushions may dry and shed prematurely. The damage of C. punctiferalis on cocoa is observed from December and peak incidence is noticed during March to May. On an average 2 per cent damage was recorded in the Central Plantation Crops Research Institute, Regional Station, Vittal. In order to develop a DNA-based molecular identification system for this species, primers were designed based on two nuclear genes viz., ribosomal protein S5 (RPS5) gene and carbamoyl phosphate synthetase/aspartate transcarbamylase/dihydroorotase (CAD). PCR-amenable DNA was isolated from C. puntiferalis larva. The designed primers amplified single bands of expected sizes using genomic DNA as template. The amplicons were purified, cloned and sequenced and sequence analysis revealed close homology to the gene of interest from related moths.Item Biotechnological Approaches(2017) Anitha Karun; Rajesh, M.K.; Muralikrishna, K.S.; Sajini, K.K.; Chowdappa, P.Item Biotechnological strategies for improvement of cocoa(2011) Elain Apshara, S.; Rajesh, M.K.Item Biotechnology and Genomics in Palms(2013) Manimekalai, R.; Rajesh, M.K.; Manju, K.P.