title: Analysis of SSH library of rice variety Aganni reveals candidate gall midge resistance genes.
abstract: The Asian rice gall midge, Orseolia oryzae, is a serious insect pest causing extensive yield loss. Interaction between the gall midge and rice genotypes is known to be on a gene-for-gene basis. Here, we report molecular basis of HR- (hypersensitive reaction-negative) type of resistance in Aganni (an indica rice variety possessing gall midge resistance gene Gm8) through the construction and analysis of a suppressive subtraction hybridization (SSH) cDNA library. In all, 2,800 positive clones were sequenced and analyzed. The high-quality ESTs were assembled into 448 non-redundant gene sequences. Homology search with the NCBI databases, using BlastX and BlastN, revealed that 73% of the clones showed homology to genes with known function and majority of ESTs belonged to the gene ontology category 'biological process'. Validation of 27 putative candidate gall midge resistance genes through real-time PCR, following gall midge infestation, in contrasting parents and their derived pre-NILs (near isogenic lines) revealed induction of specific genes related to defense and metabolism. Interestingly, four genes, belonging to families of leucine-rich repeat (LRR), heat shock protein (HSP), pathogenesis related protein (PR), and NAC domain-containing protein, implicated in conferring HR+ type of resistance, were found to be up-regulated in Aganni. Two of the reactive oxygen intermediates (ROI)-scavenging-enzyme-coding genes Cytosolic Ascorbate Peroxidase1, 2 (OsAPx1 and OsAPx2) were found up-regulated in Aganni in incompatible interaction possibly suppressing HR. We suggest that Aganni has a deviant form of inducible, salicylic acid (SA)-mediated resistance but without HR.
authors.affiliation: Indian Institute of Rice Research, Rajendranagar, Hyderabad, 500030, India.|Agri Biotech Foundation, Rajendranagar, Hyderabad, 500030, India.
authors.forename: Dhanasekar
authors.initials: D
authors.lastname: Divya
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.|Department of Botany, Mizoram University, Tanhril, Aizawl, Mizoram, 796004, India.
authors.forename: Y Tunginba
authors.initials: YT
authors.lastname: Singh
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India. suresh@icgeb.res.in.
authors.forename: Suresh
authors.initials: S
authors.lastname: Nair
authors.affiliation: Indian Institute of Rice Research, Rajendranagar, Hyderabad, 500030, India. jbentur@yahoo.com.|Agri Biotech Foundation, Rajendranagar, Hyderabad, 500030, India. jbentur@yahoo.com.
authors.forename: J S
authors.initials: JS
authors.lastname: Bentur
mesh_terms: D000818:Animals; D060387:Ascorbate Peroxidases / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D003001:Cloning, Molecular; D004175:Diptera / Q000254:growth & development / Q000472:pathogenicity; D060467:Disease Resistance / Q000235:genetics* / Q000276:immunology; D020224:Expressed Sequence Tags; D015723:Gene Library; D063990:Gene Ontology; D017343:Genes, Plant; D006360:Heat-Shock Proteins / Q000235:genetics / Q000276:immunology; D006790:Host-Parasite Interactions; D000090263:Leucine-Rich Repeat Proteins; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000276:immunology / Q000469:parasitology; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000469:parasitology; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology; D011506:Proteins / Q000235:genetics / Q000276:immunology; D020156:Salicylic Acid / Q000276:immunology / Q000378:metabolism; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D066251:Subtractive Hybridization Techniques
chemical_list: D006360:Heat-Shock Proteins; D000090263:Leucine-Rich Repeat Proteins; D010940:Plant Proteins; D011506:Proteins; D060387:Ascorbate Peroxidases; D020156:Salicylic Acid
keywords: Biotype; ESTs; HR− type of resistance; Induced resistance; RT-PCR