Novel Sources of Wheat Head Blast Resistance in Modern Breeding Lines and Wheat Wild Relatives

Wheat head blast (WHB), caused by the fungus Magnaporthe oryzae pathotype triticum, is a devastating disease affecting South America and South Asia. Despite 30 years of intensive effort, the 2NVS translocation from Aegilops ventricosa contains the only useful source of resistance to WHB effective against M. oryzae triticum isolates. The objective of this study was to identify non-2NVS sources of resistance to WHB among elite cultivars, breeding lines, landraces, and wild-relative accessions. Over 780 accessions were evaluated under field and greenhouse conditions in Bolivia, greenhouse conditions in Brazil, and at two biosafety level-3 laboratories in the United States. The M. oryzae triticum isolates B-71 (2012), 008 (2015), and 16MoT001 (2016) were used for controlled experiments, while isolate 008 was used for field experiments. Resistant and susceptible checks were included in all experiments. Under field conditions, susceptible spreaders were inoculated at the tillering stage to guarantee sufficient inoculum. Disease incidence and severity were evaluated as the average rating for each 1-m-row plot. Under controlled conditions, heads were inoculated after full emergence and individually rated for percentage of diseased spikelets. The diagnostic marker Ventriup-LN2 was used to test for the presence of the 2NVS translocation. Four non-2NVS spring wheat International Maize and Wheat Improvement Center breeding lines (CM22, CM49, CM52, and CM61) and four wheat wild-relatives (A. tauschii TA10142, TA1624, TA1667, and TA10140) were identified as resistant (<5% of severity) or moderately resistant (5 to <25% severity) to WHB. Experiments conducted at the seedling stage showed little correlation with disease severity at the head stage. M. oryzae triticum isolate 16MoT001 was significantly more aggressive against 2NVS-based varieties. The low frequency of WHB resistance and the increase in aggressiveness of newer M. oryzae triticum isolates highlight the threat that the disease poses to wheat production worldwide and the urgent need to identify and characterize new resistance genes that can be used in breeding for durably resistant varieties.

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Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽

10.1094/pdis-06-10-0454 ◽

2011 ◽

Vol 95 (3) ◽

pp. 263-268 ◽

Cited By ~ 4

Author(s):

S. K. Gremillion ◽

A. K. Culbreath ◽

D. W. Gorbet ◽

B. G. Mullinix ◽

R. N. Pittman ◽

...

Keyword(s):

United States ◽

Disease Resistance ◽

Leaf Spot ◽

Field Experiments ◽

Disease Incidence ◽

The United States ◽

Yield Potential ◽

Cercospora Arachidicola ◽

Breeding Lines ◽

Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

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Evaluation of Host Resistance to Botrytis Bunch Rot in Vitis spp. and Its Correlation with Botrytis Leaf Spot

HortScience ◽

10.21273/hortsci12655-17 ◽

2018 ◽

Vol 53 (2) ◽

pp. 204-207 ◽

Cited By ~ 3

Author(s):

Rachel P. Naegele

Keyword(s):

Fruit Quality ◽

Host Resistance ◽

Leaf Spot ◽

Disease Incidence ◽

The United States ◽

Soluble Solids ◽

Postharvest Disease ◽

Breeding Lines ◽

Bunch Rot ◽

Moderate Resistance

Botrytis cinerea, the causal agent of Botrytis bunch rot and gray mold, is the number one postharvest disease of fresh grapes in the United States. Fungicide applications are used to manage the disease, but fungicide-resistant isolates are common and postharvest losses occur annually. Host resistance is needed for long-term management of the disease. Sources of resistance in grape have been identified, but often have poor fruit quality. In this study, 27 grape lines (cultigens and species), including high fruit–quality Vitis vinifera, were evaluated for fruit and leaf susceptibility to two isolates of B. cinerea. No significant differences in virulence or pathogenicity were detected between the two isolates, but differences in disease incidence were evident among lines in leaves and berries. Most V. vinifera cultivars evaluated had high disease incidence in berries, whereas complex hybrids, Vitis aestivalus and Vitis arizonica, had low- to moderate disease incidence. Two V. vinifera breeding lines had moderate susceptibility (<50% disease) to Botrytis bunch rot when inoculated with either isolate. Only one V. vinifera line had little (<5%) to no berry or leaf disease when inoculated with either isolate. Moderate resistance (10% to 25%) was detected in Vitis spp., and a single V. vinifera line. Correlations were examined among soluble solids, leaf susceptibility, and fruit susceptibility. No correlations between soluble solids and disease susceptibility (leaves or berries) were identified, but moderate correlations between leaf and berry susceptibility were observed. Moderate resistance to Botrytis bunch rot and leaf spot were detected in Vitis breeding lines, suggesting these may be useful for developing grape cultivars with high fruit quality and resistance to B. cinerea.

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Impact of Sclerotinia Stem Rot on Yield of Canola

Plant Disease ◽

10.1094/pdis-91-2-0191 ◽

2007 ◽

Vol 91 (2) ◽

pp. 191-194 ◽

Cited By ~ 45

Author(s):

L. E. del Río ◽

C. A. Bradley ◽

R. A. Henson ◽

G. J. Endres ◽

B. K. Hanson ◽

...

Keyword(s):

North Dakota ◽

Field Experiments ◽

Disease Incidence ◽

The United States ◽

Stem Rot ◽

Sclerotinia Stem Rot ◽

Potential Yield ◽

Naturally Occurring ◽

The Cost ◽

The Impact

Sclerotinia sclerotiorum is the causal agent of Sclerotinia stem rot (SSR) of canola (Brassica napus). In North Dakota, the leading canola producer in the United States, SSR is an endemic disease. In order to estimate the impact of this disease on canola yield, field experiments were conducted from 2000 to 2004 at several locations in North Dakota and Minnesota. Experimental plots were either inoculated with laboratory-produced ascospores or infected by naturally occurring inoculum in commercial fields. Applying fungicides at different concentrations and timings during the flowering period created epiphytotics of diverse intensities. Disease incidence was measured once prior to harvesting the crop on 50 to 100 plants per plot. Results of the study indicated that 0.5% of the potential yield (equivalent to 12.75 kg/ha) was lost for every unit percentage of SSR incidence (range of 0.18 to 0.96%). Considering the current cost of fungicide applications and the market value of this commodity, a 17% SSR incidence could cause losses similar to the cost of a fungicide application. Additional efforts are required to improve current levels of tolerance of canola plants to this pathogen.

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Transgressive Segregation and Long-Term Consistency for High TSWV Field Resistance in the ‘Georgia-06G’ Peanut Cultivar

Plant Health Progress ◽

10.1094/php-04-18-0018-rs ◽

2018 ◽

Vol 19 (3) ◽

pp. 201-206 ◽

Cited By ~ 1

Author(s):

W. D. Branch ◽

A. K. Culbreath

Keyword(s):

Disease Incidence ◽

The United States ◽

Transgressive Segregation ◽

Field Resistance ◽

Breeding Lines ◽

Tomato Spotted Wilt ◽

Arachis Hypogaea L ◽

Production Area ◽

Wilt Virus

Tomato spotted wilt disease caused by tomato spotted wilt virus (TSWV) is a major peanut (Arachis hypogaea L.) production problem in the United States. TSWV has become endemic since the mid-1980s in the southeastern U.S. peanut production area. ‘Georgia-06G’ is a large-seeded, TSWV-resistant, runner-type peanut cultivar, whereas ‘Georgia Greener’ is a sister line with a smaller seed size than Georgia-06G. Both Georgia-06G and Georgia Greener have greater TSWV general field resistance with higher yields, total sound mature kernels grade, and dollar values than the parents (‘Georgia Green’ and ‘C-99R’), which shows transgressive segregation for these desirable quantitative traits. Therefore, the objective of this 12-year study was to evaluate the higher TSWV host-plant resistance found in the Georgia-06G over time compared with many other runner- and virginia-type peanut cultivars and advanced breeding lines. Despite yearly variability in TSWV and total disease incidence, the data indicate that Georgia-06G exhibited long-term high TSWV and total disease field resistance at midseason and late season, respectively. Georgia-06G was also found to have among the highest pod yield and dollar value every year. The higher general TSWV field resistance of Georgia-06G appears to be consistent across many years and locations, similar to the moderate TSWV resistance in Georgia Green.

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Biplot evaluation of test environments and identification of lentil genotypes with durable resistance to fusarium wilt in India

Crop and Pasture Science ◽

10.1071/cp17258 ◽

2017 ◽

Vol 68 (11) ◽

pp. 1024 ◽

Cited By ~ 7

Author(s):

A. K. Parihar ◽

Ashwani K. Basandrai ◽

D. R. Saxena ◽

K. P. S. Kushwaha ◽

S. Chandra ◽

...

Keyword(s):

Fusarium Wilt ◽

Disease Incidence ◽

Durable Resistance ◽

Sources Of Resistance ◽

Breeding Programs ◽

Breeding Lines ◽

Disease Occurrence ◽

Sources Of Variation ◽

Testing Site ◽

Natural Incidence

Fusarium wilt (caused by Fusarium oxysporum f. sp. lentis) is the most crucial limiting variable for decreasing yield levels of lentils (Lens culinaris Medik.) around the world. A set of 20 diverse lentil genotypes comprising breeding lines and released varieties was evaluated, along with susceptible controls, for resistance to fusarium wilt through natural incidence for two continuous years (2010–11 and 2011–12) in six diverse lentil-growing environments in India. Analysis of variance showed that the effect of genotype (G) and environment (E) for disease incidence was highly significant. Among the three sources of variation, the biggest contribution in disease occurrence was accounted for by environment (54.68%), followed by G × E interaction (17.32%). The high G × E variation necessitated assessment of the genotypes at different locations (environments). GGE biplot analysis of the studied genotypes revealed that genotype PL 101 and released cultivar L 4076 had low levels of disease incidence. The sources of resistance to fusarium wilt have great potential for use in lentil-breeding programs. Another biplot of relationships among environments demonstrated that, among the test locations, Sehore and Faizabad, were the most effective for differentiation of genotypes. On the basis of discriminating ability and representativeness, the Sehore location appeared an ideal testing site for natural incidence of F. oxysporum f. sp. lentis.

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Testing of Inoculation Methods and Susceptibility Testing of Perspective Cabbage Breeding Lines (Brassica Oleracea convar. Capitata) to the Black Rot Disease Caused by Xanthomonas Campestris pv. Campestris

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis ◽

10.11118/actaun201866010139 ◽

2018 ◽

Vol 66 (1) ◽

pp. 139-148 ◽

Cited By ~ 1

Author(s):

Eliška Peňázová ◽

Tomáš Kopta ◽

Miloš Jurica ◽

Jakub Pečenka ◽

Aleš Eichmeier ◽

...

Keyword(s):

Xanthomonas Campestris ◽

Disease Incidence ◽

Resistance Testing ◽

Mature Stage ◽

Sources Of Resistance ◽

Breeding Lines ◽

Inoculation Methods ◽

Rot Disease ◽

Xanthomonas Campestris Pv Campestris ◽

Selection Of

The susceptibility of twenty‑four cabbage breeding lines to Xanthomonas campestris pv. campestris was evaluated. The selection of appropriate inoculation method was done on 4 cabbage cultivars (‘Cerox’, ‘Sintex’, ‘Sonja’ and ‘Avak’). One month old plants were infected by 5 inoculation methods (spraying, injection by syringe, multiple pricking, carborundum abrasion and scissor clipping method). Four different bacterial isolates of Xcc (WHRI 3811, 3971A, 1279A; SU) and their mixture were evaluated for the aggressiveness on ‘Cerox’ and ‘Sonja’ cultivars. On the basis of obtained results, breeding lines of head cabbage were inoculated by mixture of all tested isolates using multiple pricking method. The disease severity of inoculated seedlings proved high susceptibility of young plants to the Xcc infection. The disease incidence determined 75 and 105 days after sowing showed changes for 16 of tested lines and indicated that resistance testing should be observed until mature stage. The study revealed five breeding lines (DP25, T1, IT10, Kalibos and Avak1) with disease incidence lower than 20 % as perspective sources of resistance for further breeding.

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Colletotrichum lindemuthianum Races Prevalent on Dry Beans in North Dakota and Potential Sources of Resistance

Plant Disease ◽

10.1094/pdis-06-10-0429 ◽

2011 ◽

Vol 95 (4) ◽

pp. 408-412 ◽

Cited By ~ 5

Author(s):

Rubella S. Goswami ◽

Luis E. del Rio-Mendoza ◽

Robin S. Lamppa ◽

Jeff Prischmann

Keyword(s):

United States ◽

North Dakota ◽

Disease Incidence ◽

Genetic Resistance ◽

The United States ◽

Colletotrichum Lindemuthianum ◽

Sources Of Resistance ◽

Dry Bean ◽

New Races ◽

Major Resistance Genes

Anthracnose caused by Colletotrichum lindemuthianum is one of the most important diseases of dry edible beans in the major production areas worldwide. This pathogen is highly variable, with numerous races. Disease management relies heavily on genetic resistance and use of clean seed. Genetic resistance is controlled by major resistance genes conferring protection against specific races of the pathogen. Therefore, knowledge of the pathogen population in a region is essential for effective screening of germplasm. Surveys were conducted for more than 6 years in North Dakota, the largest dry-bean-growing state in the United States, and seed samples submitted for certification were assessed to identify the C. lindemuthianum races prevalent in the region. A collection of commercial cultivars from different market classes of dry bean was also screened for resistance to these races. Disease incidence was found to be low in most years. However, in addition to the previously reported races of anthracnose 7, 73, and 89, two new races, 1153 and 1161, previously never reported in the United States, were identified and the commercial cvs. Montcalm, Avalanche, Vista, and Sedona where found to possess resistance to these races.

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Field evaluation and components of peanut rust resistance of newly developed breeding lines

Peanut Science ◽

10.3146/ps18-4.1 ◽

2019 ◽

Vol 46 (1) ◽

pp. 22-36

Author(s):

I.L. Power ◽

B.L. Tillman ◽

T.B. Brenneman ◽

R.C. Kemerait ◽

K L. Stevenson ◽

...

Keyword(s):

Latent Period ◽

Rust Resistance ◽

Field Experiments ◽

The United States ◽

Growth Chamber ◽

Breeding Lines ◽

Plant Introductions ◽

Progress Curve ◽

Chamber Studies ◽

Growth Chamber Studies

ABSTRACT Field, greenhouse, and growth chamber experiments were conducted to determine the level of resistance to Puccinia arachidis Speg. in newly developed breeding lines of peanut (Arachis hypogaea L.). These lines were developed in the UF150 project of the Peanut Collaborative Research and Support Program (Peanut CRSP) as part of the United States Agency for International Development (USAID). Field experiments were carried out in Citra, FL and Tifton, GA from 2010 to 2013. Five genotypes Tifrust-10 and Tifrust-13, and CRSP breeding lines PTBOL3-3, 97x36-HO2-1-B2G-3-1-2-2, and BOL3-7 had the lowest standardized area under the disease progress curve and final disease severity score for rust. The CRSP breeding lines 97x36-HO2-1-B2G-3-1-2-2 and BOL3-7 also appeared to be highly resistant to late leaf spot, caused by Cercosporidium personatum (Berk & M. A. Curtis Deighton). In growth chamber studies, genotypes with longer latent periods generally had lower infection frequencies at 7, 11, and 16 d after inoculation, and smaller percent diseased areas. Latent period and percent diseased area were significantly correlated with stAUDPC. CRSP breeding lines 97x36-HO2-1-B2G-3-1-2-2 and BOL3-7, and plant introductions PI562530, PI568164, and PI298115, were among the genotypes with the lower scores for these components. Several genotypes with multiple disease resistance in different environments and under high disease pressure were identified in these studies. These results indicate sources of rust resistance in the CRSP breeding lines, including several genotypes that could be used as parents in peanut germplasm enhancement programs, and indicate that latent period, percent diseased area, and lesion diameter may be used as indicators for rust resistance in growth chamber studies.

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Development of Lettuce Breeding Lines Resistant to Bacterial Leaf Spot

HortScience ◽

10.21273/hortsci.40.4.1098a ◽

2005 ◽

Vol 40 (4) ◽

pp. 1098A-1098 ◽

Cited By ~ 1

Author(s):

Ryan J. Hayes ◽

Carolee T. Bull ◽

Polly H. Goldman ◽

Edward J. Ryder

Keyword(s):

Leaf Spot ◽

Xanthomonas Campestris ◽

Disease Incidence ◽

Field Trials ◽

Control Measures ◽

Bacterial Leaf Spot ◽

Sources Of Resistance ◽

Breeding Lines ◽

Overhead Irrigation ◽

Lettuce Breeding

Bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians (Xcv) is an important lettuce disease in California. No adequate control measures have been found, although resistance exists in several heirloom cultivars. Deployment of cultivars resistant to bacterial leaf spot will reduce these periodic and costly disease events. The objectives of this research were to 1) identify new sources of resistance within modern crisphead cultivars and 2) select for resistance in `Salad Crisp' × `Iceberg' progeny. Field plots were established and grown with overhead irrigation, and a three-strain mixture of Xcv was applied until runoff 1 week after thinning at 1 × 109 CFU/mL. Twenty-six crisphead cultivars were tested in unreplicated field trials and rated on a 1 (susceptible) to 4 (resistant) scale. Selection was carried out between and within families from the F2 to F4 generation. Sixteen F3 families were evaluated in unreplicated plots, and 12 F5 families were tested in replicated plots for disease incidence and severity. No usable levels of resistance were identified in the modern crisphead cultivars tested to date. All F3 families had resistance greater than `Iceberg', and 19 plants from eight families were selected for further breeding. Subsequently, 12 plants from two F4 families were selected. Replicated trials of 12 F5 families indicated that all lines have disease severity comparable to both parents. Breeding lines from crosses to `Salinas 88' are currently being developed.

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Screening and Mapping for Head Blast Resistance in a Panel of CIMMYT and South Asian Bread Wheat Germplasm

Frontiers in Genetics ◽

10.3389/fgene.2021.679162 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xinyao He ◽

Philomin Juliana ◽

Muhammad R. Kabir ◽

Krishna K. Roy ◽

Rabiul Islam ◽

...

Keyword(s):

South Asian ◽

Field Experiments ◽

Genome Wide Association Study ◽

Blast Resistance ◽

The United States ◽

Snp Markers ◽

Asian Countries ◽

Genome Wide ◽

A Genome ◽

Moderately Resistant

Wheat blast (WB) is a destructive disease in South America and its first outbreak in Bangladesh in 2016 posed a great risk to food security of South Asian countries. A genome wide association study (GWAS) was conducted on a diverse panel of 184 wheat genotypes from South Asia and CIMMYT. Phenotyping was conducted in eight field experiments in Bolivia and Bangladesh and a greenhouse experiment in the United States. Genotypic data included 11,401 SNP markers of the Illumina Infinium 15K BeadChip and four additional STS markers on the 2NS/2AS translocation region. Accessions with stable WB resistance across experiments were identified, which were all 2NS carriers. Nevertheless, a dozen moderately resistant 2AS lines were identified, exhibiting big variation among experiments. Significant marker-trait associations (MTA) were detected on chromosomes 1BS, 2AS, 6BS, and 7BL; but only MTAs on 2AS at the 2NS/2AS translocation region were consistently significant across experiments. The resistant accessions identified in this study could be used in production in South Asian countries as a preemptive strategy to prevent WB outbreak.

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