Please use this identifier to cite or link to this item: http://krishikosh.egranth.ac.in/handle/1/71046
Authors: KHAGENDRA MANI, M
Advisor: SIVARAMAKRISHNAN, S
Title: IDENTIFICATION OF MOLECULAR MARKERS FOR ROOT KNOT NEMATODE RESISTANCE IN CHILLIES
Publisher: ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
Language: en
Type: Thesis
Series/Report no.: D8293;
Agrotags: IDENTIFICATION, MOLECULAR, MARKERS, ROOT, KNOT, NEMATODE, RESISTANCE, CHILLIES
Abstract: A survey of chilli grown areas of Andhra pradesh was undertaken to identify the predominant nematode race. The soil samples were collected and processed for nematode isolation and identification. Seven of the samples showed nematode infection of roots which were multiplied on the susceptible tomato cultivar, Rutgers for further race identification using host differentials. Chilli (Capsicum annuum L.) production is seriously affected by root knot nematode disease to which no resistant source is available in the cultivated germplasm. Degenerate primers based on the conserved motifs of plant disease resistance (R) genes were used to isolate analogous sequences called resistance gene candidates (RGCs) from cultivated Capsicum species. The NBS, LRR and kinase domain are characteristic features of many plant resistance genes. The NBS domain has many conserved amino acid sequences among different R genes. NBS domain was analysed in the present study on chilli using degenerate primers designed to the conserved region after PCR amplification. The PCR amplified DNA fragments were cloned. Of the 27 clones obtained, 12 clones were sequenced and 9 of them showed significant sequence homology both at nucleotide and amino acid levels with the known R genes and resistance gene analogs isolated from other dicots and monocots on BLAST search. The RGCs isolated from chilli showed sequence similarity with the NBS region of other known R genes viz. RPM1,CaMi,RPS2, N ,L6,Lettuce R gene, and RPP5. Multiple alignment of isolated chilli RGCs using CLUSTALW grouped these into two classes. An amino acid signature in the conserved motifs comprising the NBS domain clearly distinguishes the two classes. All chilli RGCs belonged to the class of R gene with LZ (leucine zipper) domain in the NBS region and TIR domain and three RGCs (CaRGC4, CaRGC8, CaRGC10) of chilli showed separate grouping. To identify the resistant and susceptible germplasm of chilli, 60 RAPD markers were analyzed by bulk segregant analysis. Of the 60 RAPD markers analyzed, none gave any polymorphism between the bulks.
Issue Date: 2008
Appears in Collections:Theses

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