scholarly journals Assessment of Resistance to Witches'-Broom Disease in Clonal and Segregating Populations of Theobroma cacao

Plant Disease ◽  
2004 ◽  
Vol 88 (8) ◽  
pp. 797-803 ◽  
Author(s):  
S. Surujdeo-Maharaj ◽  
P. Umaharan ◽  
D. R. Butler
Keyword(s):  
Incubation Period ◽  
Theobroma Cacao ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Individual Plant ◽  
Germplasm Collections ◽  
Optimum Sample Size ◽  
Accuracy And Precision ◽  
Broom Disease ◽  
Highly Correlated

Fourteen clonal genotypes of cacao (Theobroma cacao) and their open-pollinated progenies were tested for their resistance to witches'-broom disease (Crinipellis perniciosa) using an agar-droplet inoculation method in separate, replicated greenhouse experiments. Nine measures of resistance were evaluated for precision, ability to discriminate between levels for resistance, and their correlation to field resistance. Correlations among the various measures of resistance were also ascertained. Data were re-examined to determine the accuracy and precision associated with individual plant measurement as well as the optimum sample size to assess segregating populations for resistance. The agar-droplet method was able to effectively discriminate various levels of resistance. Incubation period provided a precise, sensitive, valid, and heritable measure of resistance to C. perniciosa. Furthermore, incubation period was highly correlated with broom size and moderately correlated with broom frequency, two epidemiologically important components of resistance. The study also shows that 25 to 30 open-pollinated progeny are sufficient to provide a good estimate of a parent's resistance. The implications of the findings for identifying resistance among cacao germplasm collections as well as within segregating populations for resistance breeding are discussed.

scholarly journals Field Response of New Peanut Cultivar UF 91108 to Tomato Spotted Wilt Virus

Plant Disease ◽  
1997 ◽  
Vol 81 (12) ◽  
pp. 1410-1415 ◽  
Author(s):  
A. K. Culbreath ◽  
J. W. Todd ◽  
D. W. Gorbet ◽  
F. M. Shokes ◽  
H. R. Pappu
Keyword(s):  
Disease Incidence ◽  
Field Resistance ◽  
Individual Plant ◽  
Breeding Line ◽  
Oil Composition ◽  
Tomato Spotted Wilt ◽  
Progress Curve ◽  
Rating Method ◽  
Epidemic Development ◽  
Highly Correlated

Epidemics of spotted wilt, caused by tomato spotted wilt tospovirus (TSWV), were monitored in field plots of the new runner-type peanut (Arachis hypogaea) cv. UF 91108, in advanced breeding line F 84 × 9B-4-2-1-1-2-b2-B, in runner-type peanut cvs. Southern Runner and Florunner, and in Virginia-type cv. NC-V11 at two locations in 1994 and 1995. Epidemics of spotted wilt were suppressed in UF 91108 compared to the standard runner-type cv. Florunner. Final disease incidence, standardized area under the disease progress curve values, and final disease intensity ratings were lower in UF 91108 than in Florunner and were similar to those in the moderately resistant cv. Southern Runner. Results indicate that new cv. UF 91108 represents a new potential tool for management of spotted wilt in peanut production areas of the southeastern United States. UF 91108 is the first peanut cultivar in which an oil composition of approximately 65% oleic acid is combined with a moderate level of field resistance to TSWV. Epidemics of spotted wilt also were suppressed in breeding line F 84 × 9B-4-2-1-1-2-b2-B. Across the four tests, the effects of NC-V11 on epidemic development, final incidence, and spotted wilt intensity ratings were not consistent relative to the other genotypes. Use of final disease intensity ratings provided separation of the genotypes similar to use of final incidence of spotted wilt. Assessment values by these two methods were highly correlated. In three of four experiments, final disease intensity ratings were more closely correlated with pod yield than was final incidence. The new intensity rating method described in this paper requires much less time and effort than determining disease incidence and may be a practical alternative to individual plant assessment for characterization of genotype responses to TSWV.

scholarly journals Field and Growth Chamber Evaluation of Powdery Mildew Disease on Deciduous Azaleas

HortScience ◽  
2010 ◽  
Vol 45 (5) ◽  
pp. 784-789 ◽  
Author(s):  
Michael C. Long ◽  
Stephen L. Krebs ◽  
Stan C. Hokanson
Keyword(s):  
Powdery Mildew ◽  
Field Trial ◽  
Leaf Surface ◽  
Low Cost ◽  
Field Performance ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Growth Chamber ◽  
Leaf Surfaces ◽  
Highly Correlated

Forty-one deciduous azalea (Rhododendron subgen. Pentanthera G. Don) cultivars were assessed for powdery mildew (PM) resistance in a two-location, 3-year field trial. Disease severity (percent leaf area affected) on abaxial leaf surfaces was used to rate the level of field resistance. This measure was proportional to (r = 0.83) but higher than estimates from corresponding adaxial surfaces. Eleven of these cultivars (27%) appeared to be highly resistant under field conditions, i.e., evidence of PM on the leaves was zero or near zero. Twenty-three of the cultivars evaluated in the field experiment were also evaluated in a growth chamber experiment. In contrast to the field study, PM was more severe on the adaxial leaf surface in the growth chamber but still highly correlated with the abaxial response (r = 0.93). Based on adaxial disease scores, no cultivars in the growth chamber experiments were completely resistant. Growth chamber disease ratings based on either leaf surface were predictive of field performance (r2 = 0.62), suggesting use of the chambers could serve as a low-cost, off-season, early selection component of a deciduous azalea PM resistance breeding program.

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

Plants ◽  
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.

scholarly journals Search for Resistant Genotypes to Cuscuta campestris Infection in Two Legume Species, Vicia sativa and Vicia ervilia

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 738
Author(s):  
Eva María Córdoba ◽  
Mónica Fernández-Aparicio ◽  
Clara Isabel González-Verdejo ◽  
Carmela López-Grau ◽  
María del Valle Muñoz-Muñoz ◽  
...  
Keyword(s):  
Agricultural Production ◽  
Host Plants ◽  
Resistance Breeding ◽  
Parasitic Plants ◽  
Vicia Sativa ◽  
Common Vetch ◽  
Germplasm Collections ◽  
Bitter Vetch ◽  
Cuscuta Campestris ◽  
Resistant Genotypes

The dodders (Cuscuta spp.) are parasitic plants that feed on the stems of their host plants. Cuscuta campestris is one of the most damaging parasitic plants for the worldwide agricultural production of broad-leaved crops. Its control is limited or non-existent, therefore resistance breeding is the best alternative both economically and environmentally. Common vetch (Vicia sativa) and bitter vetch (Vicia ervilia) are highly susceptible to C. campestris, but no resistant genotypes have been identified. Thus, the aim of this study was to identify in V. sativa and V.ervilia germplasm collections genotypes resistant to C. campestris infection for use in combating this parasitic plant. Three greenhouse screening were conducted to: (1) identify resistant responses in a collection of 154 accessions of bitter vetch and a collection of 135 accessions of common vetch genotypes against infection of C. campestris; (2) confirm the resistant response identified in common vetch accessions; and (3) characterize the effect of C. campestris infection on biomass of V. sativa resistant and susceptible accessions. Most common vetch and bitter vetch genotypes tested were susceptible to C. campestris. However, the V. sativa genotype Vs.1 exhibited high resistance. The resistant phenotype was characterized by a delay in the development of C. campestris posthaustorial growth and a darkening resembling a hypersensitive-like response at the penetration site. The resistant mechanism was effective in limiting the growth of C. campestris as the ratio of parasite/host shoot dry biomass was more significantly reduced than the rest of the accessions. To the best or our knowledge, this is the first identification of Cuscuta resistance in V. sativa genotypes.

Genetic Diversity, Identification and Utilization of Novel Genetic Resources for Resistance to Meloidogyne incognita in Mulberry (Morus spp.)

Plant Disease ◽  
2021 ◽  
Author(s):  
Gondi S Arunakumar ◽  
Belaghihalli Nanjappa Gnanesh ◽  
Haniyambadi B Manojkumar ◽  
Doss S. Gandhi ◽  
Mogili Thallapally ◽  
...  
Keyword(s):  
Ssr Markers ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Infested Soil ◽  
Root Knot Nematode ◽  
Sources Of Resistance ◽  
Molecular Variance ◽  
Morus Spp ◽  
Principle Coordinate Analysis ◽  
Germplasm Accessions

Mulberry (Morus spp.) is an important crop in the sericulture industry as the leaves constitute the primary feed for the silkworm. The availability of diverse genetic sources of resistance to root- knot nematode (RKN; Meloidogyne spp.) are very scanty and therefore, a set of 415 varied exotic and indigenous germplasm accessions were screened under glasshouse conditions. Twenty one accessions were identified as highly resistant and 48 were resistant, the highest numbers of highly resistant/resistant accessions were found in Morus alba. Further, thirty accessions based on rooting ability were evaluated for field resistance at four different locations with infested soil. Finally, eight germplasm accessions; BR-8, Karanjtoli-1, Hosur-C8, Nagalur Estate, Tippu, Calabresa, Thai Pecah and SRDC-3 were identified as potential genetic sources in RKN resistance breeding programs or as resistant rootstock for the establishment of mulberry gardens. Sixteen SSR markers analyzed among the 77 resistant and susceptible accessions, generated 55 alleles, ranging from 2 to 5 with an average of 3.43 alleles per locus. Principle coordinate analysis grouped the accessions on the basis of RKN susceptible and resistant to a greater extent. The RKN susceptible accessions exhibited higher variability as compared to resistant accessions and they were more dispersed. Analysis of molecular variance showed that maximum molecular variance (78%) within the population and 22% between populations. Results of this study indicate that SSR markers are reliable for assessing genetic variability among the RKN resistant and susceptible mulberry accessions.

scholarly journals Identification of candidate genes involved in Witches’ broom disease resistance in a segregating mapping population of Theobroma cacao L. in Brazil

BMC Genomics ◽  
2016 ◽  
Vol 17 (1) ◽  
Author(s):  
Stefan Royaert ◽  
Johannes Jansen ◽  
Daniela Viana da Silva ◽  
Samuel Martins de Jesus Branco ◽  
Donald S. Livingstone ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Candidate Genes ◽  
Theobroma Cacao ◽  
Mapping Population ◽  
Broom Disease ◽  
Theobroma Cacao L

Identification of a major QTL in cocoa (Theobroma cacao L.) associated with resistance to witches’ broom disease

2003 ◽  
Vol 122 (3) ◽  
pp. 268-272 ◽  
Author(s):  
V. T. Queiroz ◽  
C. T. Guimarães ◽  
D. Anhert ◽  
I. Schuster ◽  
R. T. Daher ◽  
...  
Keyword(s):  
Theobroma Cacao ◽  
Broom Disease ◽  
Theobroma Cacao L ◽  
Major Qtl

scholarly journals Effect of powdery mildew (Erysiphe graminis f.sp. tritici) on spring wheat in Finland

1973 ◽  
Vol 45 (5) ◽  
pp. 461-467
Author(s):  
Oiva Nissinen
Keyword(s):  
Powdery Mildew ◽  
Spring Wheat ◽  
Relative Yield ◽  
Resistance Breeding ◽  
Field Resistance ◽  
Erysiphe Graminis ◽  
Grain Weight ◽  
Grain Yields ◽  
1000 Grain Weight

In 1970–72 the effect of powdery mildew on Finnish spring wheats with different field resistance was studied. For the mildew control 1 kg/ha Karathane WD (22.5 % Dinocap) was used. These investigations showed that mildew control increased grain yields in susceptible varieties by 2.4 to 6.6 %. The 1000-grain weight increased by 2.2 to 5.3 %, respectively. On the more field resistant spring wheats mildew control had no particular effect. Mildew control evened out the relative yield differences between the varieties. The paper includes notes on the occurrence of mildew in Finland while the need for resistance breeding is also discussed.

scholarly journals Screening of sweetpotato germplasm collections for sweetpotato weevil (Cylas spp.) resistance in Tanzania

2020 ◽  
pp. 1707-1714
Author(s):  
Filson Kagimbo ◽  
Hussein Shimelis ◽  
Julia Sibiya
Keyword(s):  
Durable Resistance ◽  
Resistance Breeding ◽  
Root Weight ◽  
Root Number ◽  
Storage Roots ◽  
Damage Score ◽  
Sweetpotato Weevil ◽  
Lattice Design ◽  
Germplasm Collections ◽  
Western Tanzania

Weevil damage caused by sweetpotato weevil (Cylas spp.) is a major constraint to sweetpotato production in Tanzania due to a lack of improved varieties with durable resistance. The objective of this study was to screen sweetpotato germplasm collections for weevil resistance and to select the best parents to be used in resistance breeding. Field studies involving 96 sweetpotato genotypes were conducted at two weevil hotspot sites in Western Tanzania using a 12 x 8 lattice design with three replications at each site. Data collected included yield and yield related traits, weevil reaction and weevil damage score. The tested genotypes differed significantly (P < 0.01) for sweetpotato storage root number, root weight, root infestation and root damage score. Weevil infestation on storage roots significantly (P ≤0.05) correlated with total root number (r = 0.38) and weevil damage score (r = 0.79). Marketable root weight and total root weight were significantly correlated with infested root weight each with r = 0.45. The study identified nine sweetpotato genotypes expressing resistance and 10 genotypes with moderate resistance to weevil. Five genotypes including Magunhwa, Chuchu ya Nesi, Rugomoka, Tumauma and New Kawogo were selected with weevil resistance and desirable yield and yield-related traits. These genotypes can be used in future weevil resistance breeding programs of sweetpotato in Western Tanzania or related agro-ecologies.

scholarly journals Spectroscopic Estimation of N Concentration in Wheat Organs for Assessing N Remobilization Under Different Irrigation Regimes

2021 ◽  
Vol 12 ◽  
Author(s):  
Wei Li ◽  
Xiaonan Zhou ◽  
Kang Yu ◽  
Zhen Zhang ◽  
Yang Liu ◽  
...  
Keyword(s):  
Low Cost ◽  
Resistance Breeding ◽  
Hyperspectral Data ◽  
Least Squares Regression ◽  
Irrigation Regimes ◽  
N Concentration ◽  
Organ Specific ◽  
Powder Samples ◽  
N Remobilization ◽  
Highly Correlated

Nitrogen (N) remobilization is a critical process that provides substantial N to winter wheat grains for improving yield productivity. Here, the remobilization of N from anthesis to maturity in two wheat cultivars under three irrigation regimes was measured and its relationship to organ N concentration was examined. Based on spectral data of organ powder samples, partial least squares regression (PLSR) models were calibrated to estimate N concentration (Nmass) and validated against laboratory-based measurements. Although spectral reflectance could accurately estimate Nmass, the PLSR-based Nmass-spectra predictive model was found to be organ-specific, organs at the top canopy (chaff and top three leaves) received the best predictions (R2 &gt; 0.88). In addition, N remobilization efficiency (NRE) in the top two leaves and top third internode was highly correlated with its corresponding N concentration change (ΔNmass) with an R2 of 0.90. ΔNmass of the top first internode (TIN1) explained 78% variation of the whole-plant NRE. This study provides a proof of concept for estimating N concentration and assessing N remobilization using hyperspectral data of individual organs, which offers a non-chemical and low-cost approach to screen germplasms for an optimal NRE in drought-resistance breeding.

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