Browsing by Author "Jeeva, M L"

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    Characterization, host range and management of sweet potato feathery mottle virus
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2001) Jeeva, M L; Balakrishnan, S
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    Detection and characterization of macluravirus infecting greater yam (Dioscorea alata L)
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2014) Manasa, V G; Jeeva, M L
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    Differential response of resistant gene analogues (RGAs) against Phytophthora colocasiae causing leaf blight in taro (Colocasia esculenta)
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2019) Jyothi Lekshmi, O B; Jeeva, M L
    Taro (Colocasia esculenta (L.) Schott.), an important tropical tuber crop with high nutritive, and medicinal potential, is ranked fourteen among the most consumed vegetable worldwide. Leaf blight caused by Phytophthora colocasiae, is one of the most destructive diseases of taro leads to severe yield loss up to 30-50%. The main objective of this study was the gene expression profiling of resistant gene analogues (RGAs) in resistant and susceptible taro cultivars upon leaf blight infection. For isolating the taro RGAs, PCR-based strategy with degenerate primers was used, and the obtained sequences showed similarity with other RGA sequences in the NCBI database, which categorised them into the NBS-LRR class of gene family. The conserved domain search has proved the presence of Nucleotide Binding-ARC domain in all the sequences. A phylogenetic tree constructed with the obtained taro RGAs and RGAs of other plant species in the database grouped them into the non-toll interleukin receptor (non-TIR) subclass of NBS sequences. RGA specific primer was designed based on sequence information, which is the first report in taro. The expression profiles of RGAs in Muktakeshi (resistant) and Sree Kiran (susceptible) genotypes in response to leaf blight infection determined by the SYBR green PCR assay demonstrated that, taro RGAs were up-regulated during the course of infection in both the resistant and susceptible cultivars. The normalized gene expression had shown a noticeable hike in the sample collected after 24 h of pathogen inoculation in the resistant variety, whereas in the susceptible variety it was observed at 36 h. Although, RGAs were expressed in both resistant and susceptible control plants, increased fold change was observed in the test plants following pathogen inoculation. The relative gene expression level of resistant and susceptible varieties was studied by using 2-ΔΔCT method and actin was used as the reference gene. These RGAs could be used as a good start point for further studies such as candidate gene mapping for taro leaf blight.
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    Genetic diversity analysis of phytophthora colocasiae using SSR markers
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2017) Akshara George; Jeeva, M L
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    Identification and characterization of viruses infecting lesser yam (Dioscorea esculenta (Lour.) Burkill)
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2015) Sudheer, K S; Jeeva, M L
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    Mining of resistance genes associated with anthracnose infection in greater yam (Dioscorea alata Linn.)
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2016) Saranya, G; Jeeva, M L
    Anthracnose caused by Colletotrichum gloeosporioides is the major fungal disease of greater yam (Dioscorea alata), which is one of the important tropical tuber crops with high production and nutritive potential. For identifying the Resistance Gene Analogues (RGAs) in greater yam, degenerate primers based on the conserved motifs were used to isolate nucleotide-binding site (NBS) type sequences. Cloning and sequencing of identified NBS-type sequences called resistance gene analogues (RGAs) showed similarity to other cloned RGA sequences available in the database and the presence of conserved domains, viz. P-loop, RNBS-B, RNBS-C, Kinase-2 and GLPL, categorising them with the NBS–leucine-rich repeat class gene family. Amino acid sequence alignment of the Dioscorea RGAs with RGAs of other plant species grouped them with the non-Toll interleukin receptor (TIR) subclasses of the NBS sequences. The expression profiles of RGAs determined using semi quantitative Reverse Transcriptase polymerase chain-reaction in Sree Keerthi (tolerant) and Orissa Elite (susceptible) genotypes in response to anthracnose infection demonstrated that, Dioscorea alata RGAs were up-regulated three days after disease inoculation in the tolerant genotype, whereas in the susceptible genotype it was observed on the 5th day. In contrast, RGAs were found to be expressed in both tolerant and susceptible control plants, but the level was found to be increased in the test plants following pathogen inoculation. The reverse transcription PCR product was normalized and the efficiency was evaluated using Actin primers, which serves as reference gene. The result suggests a role of Resistance Genes Analogues in the early pathogen recognition of Sree Keerthi against C. gloeosporioides, which may be one of the reasons for its tolerance to anthracnose disease. These genes could be a good start point for further studies such as candidate gene mapping or understand the bases for resistance in greater yam. The isolation and expression analysis of D. alata RGAs have been reported for the first time in this study.