Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


osu1321389470.pdf (5.07 MB)

ETD Abstract Container

Abstract Header

Identification and Dissection of Soybean QTL Conferring Resistance to Phytophthora sojae

Wang, Hehe
http://rave.ohiolink.edu/etdc/view?acc_num=osu1321389470

Abstract Details

2011, Doctor of Philosophy, Ohio State University, Plant Pathology.
Phytophthora root and stem rot is the second most serious soybean disease in the USA. Partial resistance in soybean confers a broad-spectrum resistance to Phytophthora sojae and is expressed as reduced infection efficiency, smaller root lesions and reduction in oospore production, and is conferred by quantitative trait loci (QTL). In several host-pathosystems, the detection of an individual QTL differed depending on the specific pathogen isolate or phenotypic assay that was used. In soybean-P. sojae interaction, few broad-spectrum QTL have been identified and very little is known about the molecular mechanisms that contribute to this trait. The hypotheses for this study were that: i) there were more QTL in soybean conferring resistance to P. sojae; ii) soybean QTL with minor effect would respond differentially to P. sojae isolates and phenotypic assays; iii) candidate genes underlying the QTL vary in sequence between the resistant and susceptible genotypes, as well as different expression response during P. sojae infection; and iv) a complex network of defense-pathways is underlying each soybean QTL conferring resistance to P. sojae. Thus the first objective of this study was to map soybean QTL conferring broad-spectrum resistance to P. sojae in the soybean cultivar ‘Conrad’. A F 4:6 population from a cross of Conrad and susceptible ‘Sloan’ was challenged with three P. sojae isolates using two different phenotypic assays. Ten QTL were identified on Chr. 8, 12, 13 (13-1, 13-2), 14, 17, 18 (18-1, 18-2), and 19 (19-1, 19-2). Of these, the QTL 18-2, 19-1, and 19-2 from Conrad, responded to multiple isolates as well as both phenotypic assays, and explained the largest percent of phenotypic variation. RILs with resistance alleles at these QTL had significantly higher yields than those with susceptible alleles in a P. sojae infested field. These QTL were further confirmed in the Conrad x Sloan F 6:8 population. These results indicate these three QTL as the best candidates for resistance breeding. The second objective of this study was to identify the candidate genes conferring partial resistance under these QTL. Microarray analysis identified genes with significantly different expression patterns between Conrad and Sloan, both constitutively and following inoculation. Of these genes, those co-localized with the QTL encoded proteins with unknown functions, or proteins related to defense or physiological traits. Seventeen genes were selected and their expression patterns were confirmed by qRT-PCR. The QTL 19-1 and 19-2 were further dissected by sequence and expression analysis of genes between the resistant and susceptible genotypes. A total of 1025 SNPs were identified between Conrad and Sloan through sequencing of 153 genes. A list of candidate genes with significantly different infection response between the resistant and susceptible lines were identified, including those involved in signal transduction, hormone-mediated pathways, plant cell structural modification, ubiquitination, and basal resistance. These findings suggest a complex defense network with multiple mechanisms underlying individual soybean QTL conferring resistance to P. sojae. Overall, this study will contribute to soybean resistance breeding by providing additional QTL, candidate genes and SNP markers for marker-assisted resistance breeding.
Anne Dorrance (Advisor)
Margaret Redinbaugh (Committee Member)
Christopher Taylor (Committee Member)
Terrence Graham (Committee Member)
Guo-liang Wang (Committee Member)
Plant Pathology

Recommended Citations

Citations

  • Wang, H. (2011). Identification and Dissection of Soybean QTL Conferring Resistance to Phytophthora sojae [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1321389470

    APA Style (7th edition)

  • Wang, Hehe. Identification and Dissection of Soybean QTL Conferring Resistance to Phytophthora sojae. 2011. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1321389470.

    MLA Style (8th edition)

  • Wang, Hehe. "Identification and Dissection of Soybean QTL Conferring Resistance to Phytophthora sojae." Doctoral dissertation, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1321389470

    Chicago Manual of Style (17th edition)

osu1321389470
1,300
© 2011, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.