title: Quantitative trait loci identification, fine mapping and gene expression profiling for ovicidal response to whitebacked planthopper (Sogatella furcifera Horvath) in rice (Oryza sativa L.).
abstract: BACKGROUND
  The whitebacked planthopper (WBPH), Sogatella furcifera Horváth, is a serious rice pest in Asia. Ovicidal resistance is a natural rice defense mechanism against WBPH and is characterized by the formation of watery lesions (WLs) and increased egg mortality (EM) at the WBPH oviposition sites.
  
  
  RESULTS
  This study aimed to understand the genetic and molecular basis of rice ovicidal resistance to WBPH by combining genetic and genomic analyses. First, the ovicidal trait in doubled haploid rice lines derived from a WBPH-resistant cultivar (CJ06) and a WBPH-susceptible cultivar (TN1) were phenotyped based on the necrotic symptoms of the leaf sheaths and EM. Using a constructed molecular linkage map, 19 quantitative trait loci (QTLs) associated with WLs and EM were identified on eight chromosomes. Of them, qWL6 was determined to be a major QTL for WL. Based on chromosome segment substitution lines and a residual heterozygous population, a high-resolution linkage analysis further defined the qWL6 locus to a 122-kb region on chromosome 6, which was annotated to encode 20 candidate genes. We then conducted an Affymetrix microarray analysis to determine the transcript abundance in the CJ06 and TN1 plants. Upon WBPH infestation, 432 genes in CJ06 and 257 genes in TN1 were significantly up-regulated, while 802 genes in CJ06 and 398 genes in TN1 were significantly down-regulated. This suggests that remarkable global changes in gene expression contribute to the ovicidal resistance of rice. Notably, four genes in the 122-kb region of the qWL6 locus were differentially regulated between CJ06 and TN1 in response to the WBPH infestation, suggesting they may be candidate resistance genes.
  
  
  CONCLUSIONS
  The information obtained from the fine mapping of qWL6 and the microarray analyses will facilitate the isolation of this important resistance gene and its use in breeding WBPH-resistant rice.
authors.forename: Yaolong
authors.initials: Y
authors.lastname: Yang
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Yujia
authors.initials: Y
authors.lastname: Leng
authors.forename: Guosheng
authors.initials: G
authors.lastname: Xiong
authors.forename: Jiang
authors.initials: J
authors.lastname: Hu
authors.forename: Guangheng
authors.initials: G
authors.lastname: Zhang
authors.forename: Lichao
authors.initials: L
authors.lastname: Huang
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.forename: Longbiao
authors.initials: L
authors.lastname: Guo
authors.forename: Jiayang
authors.initials: J
authors.lastname: Li
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Qian
authors.initials: Q
authors.lastname: Qian
authors.affiliation: State Key Lab for Rice Biology, China National Rice Research Institute, Hangzhou 310006, P, R, China. dalizeng@126.com.
authors.forename: Dali
authors.initials: D
authors.lastname: Zeng
mesh_terms: D000818:Animals; D020029:Base Pairing; D032461:Chromosomes, Plant / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D056726:Genetic Association Studies; D056426:Genetic Loci; D006238:Haploidy; D006430:Hemiptera / Q000502:physiology*; D060434:Herbivory; D012275:Oryza / Q000235:genetics* / Q000469:parasitology*; D010058:Oviposition; D010063:Ovum / Q000502:physiology*; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000235:genetics / Q000469:parasitology; D040641:Quantitative Trait Loci / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction