Corn Soybean Belt Seed Breeders Conference Workshop 2020
Corn Soybean Belt Seed Breeder’s Conference Workshop 2020 Genetic Solution to Phytophthora Root and Stem Rot of Soybeans Jianxin Ma Department of Agronomy, Purdue University Indianapolis, February 5, 2020
Soybean rot and stem rot caused by Phytophthora sojae Phytophthora Root Rot (PRR) is one of the most destructive diseases responsible for soybean production loss • PRR is caused by a soil-borne oomycete pathogen, Phytophthora sojae • Annual yield loss: 250 million dollars in US PRR at adult stage Development of PRR resistant soybean varieties with PRR at seedling stage Rps genes (resistance to P. sojae) is the most practical and economical solution for management of PRR. Rps 1 -a, 1 -b, 1 -c, 1 -d, 1 -k, 2, 3 -a, 3 -b, 3 -c, 4, 5, 6, 7, 8)
Why to Identify Novel Rps Genes? The races of P. sojae vary rapidly in number and types, and most of the known Rps genes have become partially effective or completely ineffective P. sojae Races 1 3 4 5 7 8 10 13 17 24 25 28 ISA 19 A-1 ISA 19 B-2 ISA 71 D-1 ISA 33 O-8 Genes/Alleles Clustered 1 -a R S S S R R R S S S S 1 -b R R R S R S S S R S 1 -c R R S S R R R S S 1 -d R R S I I S I R R R I R S 1 -k R R R R R S S S R S Isolate able to defeat Rps 1 -k Isolate unable to defeat Rps 1 -k Teresa Hughes
New Source of Resistance from Landraces Blue: Resistant to Race 17 73 52 126 58 Red: Resistant to Race 25 131 24 Excellent resistance to multiple (>10) races tested
Resistance spectrum of 23 accessions Evaluation of Resistance of 23 Accessions Old races Ma. Lab code MG Origin USDA 185 V South Korea USDA 188 VII Jiangsu, CHN USDA 190 VIII Japan USDA 191 VI Japan USDA 193 VIII Japan USDA 194 VII Japan USDA 195 VI Japan USDA 196 VII Japan USDA 201 VI CHN USDA 202 V South Korea USDA 002 IV Anhui, CHN USDA 021 IV Anhui, CHN USDA 046 IX Fujian, CHN USDA 203 V South Korea USDA 062 VI Jiangxi, CHN USDA 183 VI CHN USDA 052 VII Jiangxi, CHN Ma. Lab MG Origin code USDA 112 IX Yunnan, CHN USDA 186 USDA 198 USDA 018 V V IV South Korea Taiwan Anhui, CHN USDA 061 V USDA 069 VII ISA ISA Race 19 A-1 71 D-1 33 O-8 10 Race 13 Race 28 Race 17 Race Race Race 25 1 2 3 4 5 6 7 8 9 R R R R R R R R R R R R R R R R R ISAR 33 O Race R ISA 19 A-1 71 D-1 -8 10 R R R R R R Race 13 R R R R Race 28 R R R R Race 17 R RU RU R RU RU R RU RU R RU N/A R RU RU R RU N/A Race 25 1 2 R RU N/A R RU RU RU RU RU RU RU RU RU RU RU RU RU RU N/A N/A HU RU N/A N/A N/A RU RU RU RU N/A Race HU Rac 3 4 5 6 e 7 RU N/A N/A RU RU RU RU N/A N/A RU N/A Race 8 N/A RU RU RU N/A N/A RU N/A Race 9 N/A RU R R R R RU RU RU N/A N/A Jiangxi, CHN R R R R RU N/A N/A RU N/A Hunan, CHN R R R R RU N/A N/A RU N/A CONFIDENTIAL
PI 567139 B Contains Two Rps Genes Rps. UN 1 – chromosome 3, Rps. UN 2 – chromosome 16 PI 567139 B Introduced from Indonesia
Spectrum of Resistance Conferred by Rps. UN 1 and Rps. UN 2
PI 594527 is Highly Diverged from Known Rps Gene Donors PI 594527 introduced from Fujian Province, China Late maturity green seeds Low yield Rps 11 PI 594527
PI 594527 Carries a Novel Rps Gene, Designated as Rps 11: is responsible for the resistance to all 16 isolates (New data from USDA-ARS: >400 isolates) PI 594527 does not carry any of the known Rps genes
Molecular Mapping and Cloning of Rps 11 Ø Rps 11 gene fine mapped to 70 kb segment Ø >50 recombinants were found based on the boundary markers and can further narrow the gene to smaller region Ø Rps 11 has been now cloned and is in the process of functional validation through genetic transformation Ø Rps 11 is structurally very different from Rps 1 -k Ø Rps 11 gene initially mapped to 226 kb segment on chromosome 7
Yield Drag? -- may not be a concern! Profiling of possible yield regions Rps 1 -k Rps 11 From Nathan Honcock, Soy 2014
Proposed Timeline for implementation of Rps 11 markers 99. 99% accuracy of marker-assisted selection
Marker assisted selection for Rps 11 in breeding program Rps 11 seed comparison: -green seed is the donor - Yellow is the selected pop Courtesy by Evelyn Ortiz-Perez
Marker assisted selection for Rps 11 in breeding program BC 1 in summer 2016 BC 2, BC 3 in summer 2017
Additional new Rps genes showing excellent resistance • Rps. UN 1, Rps. UN 2, Rps 11 • Rps 2 -cas – to request for an official gene name: Rps 12 • Rps 1 -cas • Rps-1 f Now we have a set of excellent Rps genes for the next few decades !
Acknowledgements Purdue Weidong Wang Liyang Chen Josh Fitzgerald Jieqing Ping Austin Johnson Jianxin Ma Steve Scofield (USDA-ARS) Guohong Cai (USDA-ARS) Teresa Hughes (USDA-ARS) Corteva Agriscience Oswald Crasta Rajat Aggarwal Hunt Wiley Evelyn Ortiz-Perez Donna Hendersonnd More …
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