Evaluation of Aegilops tauschii (Coss.) germplasm for Karnal bunt resistance in a screen house with simulated environmental conditions

Karnal bunt (KB) of wheat, caused byTilletia indica(Mitra) Mundkur, adversely affects international wheat trading and the movement of germplasm between countries due to quarantine restrictions. Breeding for host plant resistance requires the identification of KB resistance sources. Accessions of the D genome progenitor of bread wheat,Aegilops tauschii, were screened in a specially designed screen-house, where the optimum environmental conditions conducive for KB development were simulated by controlling temperature, humidity, fogging and shading. The 183 accessions were subjected to artificial inoculation with a mixture of nine KB isolates, and seven proved highly resistant and four moderately resistant over three rounds of screening over 3 years.

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Effects of Host Plant Resistance and Fungicides on Severity of Cucumber Downy Mildew

HortScience ◽

10.21273/hortsci.48.1.53 ◽

2013 ◽

Vol 48 (1) ◽

pp. 53-59 ◽

Cited By ~ 12

Author(s):

Adam D. Call ◽

Todd C. Wehner ◽

Gerald J. Holmes ◽

Peter S. Ojiambo

Keyword(s):

Host Plant ◽

Downy Mildew ◽

Plant Resistance ◽

Host Plant Resistance ◽

Maximum Yield ◽

Plant Size ◽

High Yield ◽

High Yields ◽

A Minor ◽

Moderately Resistant

Cucurbit downy mildew caused by the oomycete Pseudoperonospora cubensis (Berk. And Curt) Rostov is a major disease of cucumber (Cucumis sativus L.) (Palti and Cohen, 1980) globally. Chemical control of downy mildew is necessary to achieve high yields in the absence of adequate host plant resistance. Most of the currently grown cultivars have some resistance to downy mildew. Before the resurgence of the disease in 2004, host plant resistance was sufficient to control the disease without fungicide use, and downy mildew was only a minor problem on cucumber. There are currently no cultivars that show resistance at a level equal to that observed before 2004. However, differences in resistance exist among cultivars, ranging from moderately resistant to highly susceptible. In this study, we evaluated the disease severity and yield of four cucumber cultivars that differed in disease resistance and were treated with fungicide programs representing a range of efficacy levels. The experiment was a split plot design with six replications and four years. Disease was evaluated as chlorosis, necrosis, and reduction in plant size on a 0 to 9 scale. Cultigen had a large effect in all four years. Fungicide has a smaller effect on resistance component traits and a larger effect on yield traits. The effects of cultivar resistance and fungicides appear to be additive until a threshold where maximum yield is reached. Highly resistant cultigens such as PI 197088 required only the least effective fungicides to achieve highest yields, whereas moderately resistant cultigens required a more effective fungicide to reach a similar level of yield. Susceptible cultigens did not achieve high yield even with the most effective fungicide treatments. It is likely that, even as highly resistant cultivars are released, growers will need to continue a minimal fungicide program to achieve maximum yield.

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Characterization of Strawberry Host Plant Resistance to Powdery Mildew caused by Podosphaera aphanis

Plant Health Progress ◽

10.1094/php-12-20-0107-rs ◽

2021 ◽

Author(s):

Michael Palmer ◽

Gerald Holmes

Keyword(s):

Powdery Mildew ◽

Host Plant ◽

Plant Resistance ◽

Host Plant Resistance ◽

Disease Incidence ◽

Strawberry Cultivar ◽

Plant Disease Management ◽

Relative Differences ◽

Moderately Resistant

Host plant resistance is an essential tool in plant disease management worldwide. Evaluations of strawberry cultivar resistance to powdery mildew were done previously in California, but many new cultivars have been released since the last evaluation in 1996 and merit evaluation for today’s growers. Two studies were conducted over the winter and summer of 2020, evaluating ten commonly grown cultivars. Powdery mildew-free plants were established in 3 L pots under high plastic tunnels and after three weeks (four- to five-leaf stage) moved into a powdery mildew-infested greenhouse. Disease incidence and severity ratings were taken weekly beginning at the first sign of disease. Ratings taken at 40 (winter) and 41 (summer) days after transfer to the greenhouse were used to make comparisons among cultivars. Significant differences were found in foliar disease severity among cultivars, but none were totally free of disease. Moderately resistant cultivars were ‘San Andreas’ and ‘Sweet Ann’. Highly susceptible cultivars were ‘BG 3.324’ and ‘Royal Royce’. Two field evaluations of the ten cultivars confirmed the observed relative differences in host resistance under field conditions. This information is valuable to California strawberry growers who select cultivars based in part on their susceptibility to economically important diseases such as powdery mildew.

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Host plant resistance and biological control: A test of the movement-risk hypothesis

10.1603/ice.2016.109191 ◽

2016 ◽

Author(s):

Cory Straub

Keyword(s):

Biological Control ◽

Host Plant ◽

Plant Resistance ◽

Host Plant Resistance

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Morphological and Chemical Factors Related to Western Flower Thrips Resistance in the Ornamental Gladiolus

Plants ◽

10.3390/plants10071384 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1384

Author(s):

Dinar S. C. Wahyuni ◽

Young Hae Choi ◽

Kirsten A. Leiss ◽

Peter G. L. Klinkhamer

Keyword(s):

Host Plant ◽

Plant Resistance ◽

Host Plant Resistance ◽

Frankliniella Occidentalis ◽

Western Flower Thrips ◽

Resistance Breeding ◽

Breeding Programs ◽

Triterpenoid Saponins ◽

Flower Thrips ◽

Highly Correlated

Understanding the mechanisms involved in host plant resistance opens the way for improved resistance breeding programs by using the traits involved as markers. Pest management is a major problem in cultivation of ornamentals. Gladiolus (Gladiolus hybridus L.) is an economically important ornamental in the Netherlands. Gladiolus is especially sensitive to attack by western flower thrips (Frankliniella occidentalis (Pergande) (Thysanoptera:Thripidae)). The objective of this study was, therefore, to investigate morphological and chemical markers for resistance breeding to western flower thrips in Gladiolus varieties. We measured thrips damage of 14 Gladiolus varieties in a whole-plant thrips bioassay and related this to morphological traits with a focus on papillae density. Moreover, we studied chemical host plant resistance to using an eco-metabolomic approach comparing the 1H NMR profiles of thrips resistant and susceptible varieties representing a broad range of papillae densities. Thrips damage varied strongly among varieties: the most susceptible variety showed 130 times more damage than the most resistant one. Varieties with low thrips damage had shorter mesophylls and epidermal cells, as well as a higher density of epicuticular papillae. All three traits related to thrips damage were highly correlated with each other. We observed a number of metabolites related to resistance against thrips: two unidentified triterpenoid saponins and the amino acids alanine and threonine. All these compounds were highly correlated amongst each other as well as to the density of papillae. These correlations suggest that papillae are involved in resistance to thrips by producing and/or storing compounds causing thrips resistance. Although it is not possible to distinguish the individual effects of morphological and chemical traits statistically, our results show that papillae density is an easy marker in Gladiolus-breeding programs targeted at increased resistance to thrips.

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Comparative TMT Proteomic Analysis Unveils Unique Insights into Helicoverpa armigera (Hübner) Resistance in Cajanus scarabaeoides (L.) Thouars

International Journal of Molecular Sciences ◽

10.3390/ijms22115941 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5941

Author(s):

Abigail Ngugi-Dawit ◽

Isaac Njaci ◽

Thomas J.V. Higgins ◽

Brett Williams ◽

Sita R. Ghimire ◽

...

Keyword(s):

Host Plant ◽

Helicoverpa Armigera ◽

Plant Resistance ◽

Host Plant Resistance ◽

Proteomic Analysis ◽

Artificial Diet ◽

Growth Stages ◽

Genetic Base ◽

Helicoverpa Armígera ◽

Helicoverpa Armigera Hubner

Pigeonpea [Cajanus cajan (L.) Millspaugh] is an economically important legume playing a crucial role in the semi-arid tropics. Pigeonpea is susceptible to Helicoverpa armigera (Hübner), which causes devastating yield losses. This pest is developing resistance to many commercially available insecticides. Therefore, crop wild relatives of pigeonpea, are being considered as potential sources of genes to expand the genetic base of cultivated pigeonpea to improve traits such as host plant resistance to pests and pathogens. Quantitative proteomic analysis was conducted using the tandem mass tag platform to identify differentially abundant proteins between IBS 3471 and ICPL 87 tolerant accession and susceptible variety to H. armigera, respectively. Leaf proteome were analysed at the vegetative and flowering/podding growth stages. H. armigera tolerance in IBS 3471 appeared to be related to enhanced defence responses, such as changes in secondary metabolite precursors, antioxidants, and the phenylpropanoid pathway. The development of larvae fed on an artificial diet with IBS 3471 lyophilised leaves showed similar inhibition with those fed on an artificial diet with quercetin concentrations with 32 mg/25 g of artificial diet. DAB staining (3,3’-diaminobenzidine) revealed a rapid accumulation of reactive oxygen species in IBS 3471. We conclude that IBS 3471 is an ideal candidate for improving the genetic base of cultivated pigeonpea, including traits for host plant resistance.

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