2018_TWC40_JinJing.pdf Characterizing the Adaptation of Phytophthora nicotianae to Partial Resistance in Tobacco Jing Jin and David Shew Department of Entomology and Plant Pathology North Carolina State University TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf Black Shank of Tobacco Disease: Black Shank of Tobacco Pathogen: Phytophthora nicotianae Hosts: Nicotiana tabacum and N. rustica TWC2018(48) - Document not peer-reviewed Phytophthora nicotianae 2018_TWC40_JinJing.pdf • Oomycete • Heterothallic • Produces both asexual and sexual spores • Variability through asexual cycle, potentially through sexual cycle The life cycle of Phytophthora nicotianae Meng et al. 2014 TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf Resistance Sources in Tobacco against P. nicotianae • Complete resistance - Confers resistance to race 0 -Phpgene from Nicotiana plumbaginifolia -Phlgene from N. longiflora • Partial resistance - Confers resistance to all races - Florida 301 (FL 301) - Beinhart 1000 (BH 1000) • A new source of black shank resistance: WZ region from N. rustica - Confers a high level of resistance to all races - Highly expressed in the roots TWC2018(48) - Document not peer-reviewed Types of P. nicotianae Adaptation to Resistance in Tobacco 2018_TWC40_JinJing.pdf A A. Adaptation to complete resistance - race shift in P. nicotianae B. Adaptation to partial resistance - increased aggressiveness in P. nicotianae TWC2018(48) - Document not peer-reviewed Schematic Representation of Greenhouse Adaptation Work 2018_TWC40_JinJing.pdf G1 G2 G3 G4 G5 G6 Aggressiveness evaluation TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf Adapted P. nicotianae Isolates Showing Increased Aggressiveness Above ground symptoms of tobacco variety DH06B 162-19, with major effect quantitative trait loci Phn 7.1 and Phn 15.1 from parent Beinhart 1000, after inoculation with a race 0 isolate of P. nicotianae. McCorkle, PhD thesis, 2016 TWC2018(48) - Document not peer-reviewed Components of Aggressiveness 2018_TWC40_JinJing.pdf Higher encyst and germination rate? Longer motile period? - More infection - More infection More sporangium and zoospore production ? - More secondary infection - Shorter generation time Faster hyphal growth? - Increased lesion size The life cycle of Phytophthora nicotianae Meng et al. 2014 TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf P. nicotianae Race 0 Isolates Selected for Adaptation Characterization G1 G2 G3 G4 G5 G6 FL301 R0-G2-3 R0-G6-3 P. nicotianae Race 0 K326WZ R0-G2-6 R0-G5-6 TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf P. nicotianae Race 1 Isolates Selected for Adaptation Characterization G1 G2 G3 G4 G5 G6 FL301 R1-G1-3 R1-G6-3 P. nicotianae Race 1 K326WZ R1-G2-6 R1-G6-6 TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf P. nicotianae Isolates Selected for Adaptation Characterization TWC2018(48) - Document not peer-reviewed In vivo Sporangium Production 2018_TWC40_JinJing.pdf • Two-week-old FL301 and K326WZ seedlings were transferred to calcined clay and grown for two weeks. • Seedlings were removed, washed and incubated for 2.5 h in 10 ml of a zoospore suspension at either 103 or 104 zoospores/ml and then moved to 10 cm deep Petri dishes containing 30 ml of a 5% sterile soil extract. • After 29 hours in the soil extract, the number of root tips with sporangia and d. the number of sporangia present around each root tip was counte TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf In vivo Sporangium Production TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf In vivo Sporangium Production TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf In vivo Sporangium Production TWC2018(48) - Document not peer-reviewed Proportion of Root Tips with Sporangia Tipswith Sporangia of Root Proportion TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf 2018_TWC40_JinJing.pdf What does adaptation mean in P. nicotianae? TWC2018(48) - Document not peer-reviewed 2018_TWC40_JinJing.pdf Is adaptation of P. nicotianae to partial resistance in tobacco specific? TWC2018(48) - Document not peer-reviewed Aggressiveness in Single-zoospore Progeny from 2018_TWC40_JinJing.pdf Adapted and Non-adapted Isolates • Oat grain inoculum was prepared with each isolate • 6-7 week old plants were inoculated with oat grain inoculum • Plants were observed for the development of above ground symptoms for 28 days • Disease severity values ranged from 0-10 and were based on time required for above ground symptom development TWC2018(48) - Document not peer-reviewed Aggressiveness in Single-zoospore Progeny from 2018_TWC40_JinJing.pdf Adapted and Non-adapted Isolates Single-zoospore progeny from non-adapted parent Single-zoospore progeny from non-adapted parent Single-zoospore progeny from adapted parent Single-zoospore progeny from adapted parent Single-zoospore progeny from non-adapted parent Single-zoospore progeny from non-adapted parent Single-zoospore progeny from adapted parent Single-zoospore progeny from adapted parent TWC2018(48) - Document not peer-reviewed Aggressiveness in Single-zoospore Progeny from Adapted and Non-adapted Isolates 2018_TWC40_JinJing.pdf Single zoospore progeny from non-adapted parent Single zoospore progeny from adapted parent TWC2018(48) - Document not peer-reviewed Aggressiveness in Single-zoospore Progeny from 2018_TWC40_JinJing.pdf Adapted and Non-adapted Isolates Single-zoospore progeny from non-adapted parent Single-zoospore progeny from non-adapted parent Single-zoospore progeny from adapted parent Single-zoospore progeny from adapted parent Single-zoospore progeny from non-adapted parent Single-zoospore progeny from non-adapted parent Single-zoospore progeny from adapted parent Single-zoospore progeny from adapted parent TWC2018(48) - Document not peer-reviewed Average Aggressiveness in Single-zoospore Progeny from 2018_TWC40_JinJing.pdf Adapted and Non-adapted Isolates Average aggressiveness in single zoospore progeny Average aggressiveness in single zoospore progeny from adapted and non-adapted Race 0 FL301 isolates from adapted and non-adapted Race 0 K326WZ isolates 10 10 9 9 8 8 B 7 7 index index 6 6 A B 5 5 severity severity 4 A 4 3 3 Disease Diswase 2 2 1 1 0 0 R0-G2-3 Progeny R0-G6-3 Progeny R0-G2-6 Progeny R0-G5-6 Progeny Average aggressiveness in single zoospore progeny Average aggressiveness in single zoospore progeny from adapted and non-adapted Race 1 FL301 isolates from adapted and non-adapted Race 1 K326WZ isolates 10 10 B 9 9 A 8 A 8 7 7 index index 6 6 A 5 5 severity severity 4 4 3 3 Diswase Diswase 2 2 1 1 0 0 Progeny R1-G6-3 Progeny R1-G2-6 Progeny R1-G6-6 Progeny R1-G1-3 TWC2018(48) - Document not peer-reviewed Summary 2018_TWC40_JinJing.pdf • Adapted isolates produced more sporangia per root tip and had a higher proportion of root tips sporulating than non-adapted isolates. • Race 0 isolates produced more sporangia and had a higher proportion of root tips sporulating than race 1 isolates. • A high zoospore concentration partially overcame the effects of adaptation, indicating that partial resistance can be overcome by high inoculum concentrations. • Adaptation of P. nicotianae to partial resistance in FL301 or K326WZ was not specific. • Single zoospore progeny from adapted parent had higher average nt. aggressiveness level than single zoospore progeny from non-adapted pare TWC2018(48) - Document not peer-reviewed.