Multi-trait and multi-environment QTL analyses of yield and a set of physiological traits in pepper
Alimi, N.A. ; Bink, M.C.A.M. ; Dieleman, J.A. ; Magán, J.J. ; Wubs, A.M. ; Palloix, A. ; Eeuwijk, F.A. van - \ 2013
Theoretical and Applied Genetics 126 (2013)10. - ISSN 0040-5752 - p. 2597 - 2625.
mixed-model approach - capsicum-annuum - complex traits - fruit size - loci - populations - barley - maize - covariables - regression
For many agronomic crops, yield is measured simultaneously with other traits across multiple environments. The study of yield can benefit from joint analysis with other traits and relations between yield and other traits can be exploited to develop indirect selection strategies. We compare the performance of three multi-response QTL approaches based on mixed models: a multi-trait approach (MT), a multi-environment approach (ME), and a multi-trait multi-environment approach (MTME). The data come from a multi-environment experiment in pepper, for which 15 traits were measured in four environments. The approaches were compared in terms of number of QTLs detected for each trait, the explained variance, and the accuracy of prediction for the final QTL model. For the four environments together, the superior MTME approach delivered a total of 47 regions containing putative QTLs. Many of these QTLs were pleiotropic and showed quantitative QTL by environment interaction. MTME was superior to ME and MT in the number of QTLs, the explained variance and accuracy of predictions. The large number of model parameters in the MTME approach was challenging and we propose several guidelines to help obtain a stable final QTL model. The results confirmed the feasibility and strengths of novel mixed model QTL methodology to study the architecture of complex traits.
Loss of Function in Mlo Orthologs Reduces Susceptibility of Pepper and Tomato to Powdery Mildew Disease Caused by Leveillula taurica
Zheng, Z. ; Nonomura, T. ; Appiano, M. ; Pavan, S.N.C. ; Matsuda, Y. ; Toyoda, H. ; Wolters, A.M.A. ; Visser, R.G.F. ; Bai, Y. - \ 2013
PLoS ONE 8 (2013)7. - ISSN 1932-6203 - 14 p.
real-time pcr - capsicum-annuum - subcellular-localization - nonhost resistance - gene-expression - oryza-sativa - cell-death - barley - family - identification
Powdery mildew disease caused by Leveillula taurica is a serious fungal threat to greenhouse tomato and pepper production. In contrast to most powdery mildew species which are epiphytic, L. taurica is an endophytic fungus colonizing the mesophyll tissues of the leaf. In barley, Arabidopsis, tomato and pea, the correct functioning of specific homologues of the plant Mlo gene family has been found to be required for pathogenesis of epiphytic powdery mildew fungi. The aim of this study was to investigate the involvement of the Mlo genes in susceptibility to the endophytic fungus L. taurica. In tomato (Solanum lycopersicum), a loss-of-function mutation in the SlMlo1 gene results in resistance to powdery mildew disease caused by Oidium neolycopersici. When the tomato Slmlo1 mutant was inoculated with L. taurica in this study, it proved to be less susceptible compared to the control, S. lycopersicum cv. Moneymaker. Further, overexpression of SlMlo1 in the tomato Slmlo1 mutant enhanced susceptibility to L. taurica. In pepper, the CaMlo2 gene was isolated by applying a homology-based cloning approach. Compared to the previously identified CaMlo1 gene, the CaMlo2 gene is more similar to SlMlo1 as shown by phylogenetic analysis, and the expression of CaMlo2 is up-regulated at an earlier time point upon L. taurica infection. However, results of virus-induced gene silencing suggest that both CaMlo1 and CaMlo2 may be involved in the susceptibility of pepper to L. taurica. The fact that overexpression of CaMlo2 restored the susceptibility of the tomato Slmlo1 mutant to O. neolycopersici and increased its susceptibility to L. taurica confirmed the role of CaMlo2 acting as a susceptibility factor to different powdery mildews, though the role of CaMlo1 as a co-factor for susceptibility cannot be excluded.
Detection and Quantification of Leveillula taurica Growth in Pepper Leaves
Zheng, Z. ; Nonomura, T. ; Bóka, K. ; Matsuda, Y. ; Visser, R.G.F. ; Toyoda, H. ; Kiss, L. ; Bai, Y. - \ 2013
Phytopathology 103 (2013)6. - ISSN 0031-949X - p. 623 - 632.
internal transcribed spacer - powdery-mildew - genus leveillula - capsicum-annuum - resistance - pcr - infections - sequences - fungi - dna
Leveillula taurica is an obligate fungal pathogen that causes powdery mildew disease on a broad range of plants, including important crops such as pepper, tomato, eggplant, onion, cotton, and so on. The early stage of this disease is difficult to diagnose and the disease can easily spread unobserved; for example, in pepper and tomato production fields and greenhouses. The objective of this study was to develop a detection and quantification method of L. taurica biomass in pepper leaves with special regard to the early stages of infection. We monitored the development of the disease to time the infection process on the leaf surface as well as inside the pepper leaves. The initial and final steps of the infection taking place on the leaf surface were consecutively observed using a dissecting microscope and a scanning electron microscope. The development of the intercellular mycelium in the mesophyll was followed by light and transmission electron microscopy. A pair of L. taurica-specific primers was designed based on the internal transcribed spacer sequence of L. taurica and used in real-time polymerase chain reaction (PCR) assay to quantify the fungal DNA during infection. The specificity of this assay was confirmed by testing the primer pair with DNA from host plants and also from another powdery mildew species, Oidium neolycopersici, infecting tomato. A standard curve was obtained for absolute quantification of L. taurica biomass. In addition, we tested a relative quantification method by using a plant gene as reference and the obtained results were compared with the visual disease index scoring. The real-time PCR assay for L. taurica provides a valuable tool for detection and quantification of this pathogen in breeding activities as well in plant-microbe interaction studies.
Genetic and QTL analyses of yield and a set of physiological traits in pepper
Alimi, N.A. ; Bink, M.C.A.M. ; Dieleman, J.A. ; Nicolaï, M. ; Wubs, M. ; Heuvelink, E. ; Magan, J. ; Voorrips, R.E. ; Jansen, J. ; Rodrigues, P.C. ; Heijden, G.W.A.M. van der; Vercauteren, A. ; Vuylsteke, M. ; Song, Y. ; Glasbey, C. ; Barocsi, A. ; Lefebvre, V. ; Palloix, A. ; Eeuwijk, F.A. van - \ 2013
Euphytica 190 (2013)2. - ISSN 0014-2336 - p. 181 - 201.
plant-breeding trials - cucumber mosaic-virus - capsicum-annuum - phytophthora-capsici - environment interactions - capsaicinoid content - mixed-model - fruit size - resistance - loci
An interesting strategy for improvement of a complex trait dissects the complex trait in a number of physiological component traits, with the latter having hopefully a simple genetic basis. The complex trait is then improved via improvement of its component traits. As first part of such a strategy to improve yield in pepper, we present genetic and QTL analyses for four pepper experiments. Sixteen traits were analysed for a population of 149 recombinant inbred lines, obtained from a cross between the largefruited pepper cultivar ‘Yolo Wonder’ (YW) and the small fruited pepper ‘Criollo de Morelos 334’(CM334). The marker data consisted of 493 markers assembled into 17 linkage groups covering 1,775 cM. The trait distributions were unimodal, although sometimes skewed. Many traits displayed heterosis and transgression. Heritabilities were high (mean 0.86, with a range between 0.43 and 0.96). A multiple QTL mapping approach per trait and environment yielded 24 QTLs. The average numbers of QTLs per trait was two, ranging between zero and six. The total explained trait variance by QTLs varied between 9 and 61 %. QTL effects differed quantitatively between environments, but not qualitatively. For stem-related traits, the trait-increasing QTL alleles came from parent CM334, while for leaf and fruit related traits the increasing QTL alleles came from parent YW. The QTLs on linkage groups 1b, 2, 3a, 4, 6 and 12 showed pleiotropic effects with patterns that were consistent with the genetic correlations. These results contribute to a better understanding of the genetics of yieldrelated physiological traits in pepper and represent a first step in the improvement of the target trait yield.
Functional analysis of H2O2-generating systems in Botrytis cinerea: the major Cu-Zn-superoxide dismutase (BCSOD1) contributes to virulence on French bean, whereas a glucose oxidase (BCGOD1) is dispensable
Rolke, Y. ; Liu, S. ; Quidde, T. ; Williamson, B. ; Schouten, A. ; Weltring, K.M. ; Siewers, V. ; Tenberge, K.B. ; Tudzynski, B. ; Tudzynski, P. - \ 2004
Molecular Plant Pathology 5 (2004)1. - ISSN 1464-6722 - p. 17 - 27.
claviceps-purpurea - saccharomyces-cerevisiae - infection mechanism - lipid-peroxidation - phaseolus-vulgaris - aspergillus-niger - capsicum-annuum - free-radicals - soft rots - gene
The oxidative burst, a transient and rapid accumulation of reactive oxygen species (ROS), is a widespread defence mechanism of higher plants against pathogen attack. There is increasing evidence that the necrotrophic fungal pathogen Botrytis cinerea itself generates ROS, and that this capability could contribute to the virulence of the fungus. Two potential H2O2-generating systems were studied with respect to their impact on the interaction of B. cinerea and its host plant Phaseolus vulgaris. A Cu-Zn-superoxide dismutase gene (bcsod1) and a putative glucose oxidase gene (bcgod1) were cloned and characterized, and deletion mutants were created using a gene-replacement methodology. Whereas the Deltabcgod1-mutants displayed normal virulence on bean leaves, the Deltabcsod1 mutants showed a significantly retarded development of lesions, indicating that the Cu-Zn SOD-activity is an important single virulence factor in this interaction system. Whether dismutation of (fungal or host) superoxide, or generation of H2O2 (or both), are important for pathogenesis in this system remains to be elucidated.
Evaluation of three gas chromatography and two direct mass spectrometry techniques for aroma analysis of dried red bell peppers
Ruth, S.M. van; Boscaini, E. ; Mayr, D. ; Pugh, J. ; Posthumus, M.A. - \ 2003
International Journal of Mass Spectrometry 223-224 (2003). - ISSN 1387-3806 - p. 55 - 65.
sniffing port analysis - beans phaseolus-vulgaris - rehydrated french beans - sensory evaluation - volatile constituents - capsicum-annuum - flavor release - breath - ms
Three gas chromatography methods and two direct mass spectrometry techniques were compared for the analysis of the aroma of rehydrated diced red bell peppers. Gas chromatography methods included systems with olfactometry detection (GC-O), flame ionisation detection (GC-FID) and mass spectrometry (GC-MS). The evaluated direct mass spectrometry techniques involved atmospheric pressure chemical ionisation-time-of-flight mass spectrometry (APCI-TOFMS) and proton transfer reaction-mass spectrometry (PTR-MS). The relevance of the aroma component of the flavour was shown by sensory analysis. High intensity scores were obtained for the aroma attributes 'bell pepper,' 'cooked vegetables' and 'grassy.' Sixty-three volatile compounds were identified in the headspace of the bell peppers by GC-MS. According to GC-O analysis, 11 compounds possessed odour activity. Consistently across all techniques, 3-methylbutanal was the most abundant odour active compound, followed by 2-methylbutanal. Compounds present at low concentrations were more affected by the methodology. Chromatography methods correlated strongly with each other (rho = 0.946), whereas the direct mass spectrometry methods showed less significant correlation (rho = 0.613). Examining differences across all methods, it appeared that the proportions of the odour active compounds were not significantly different for GC-MS, GC-FID and PTR-MS. Significant differences were observed for APCI-TOFMS and the other techniques (P <0.01). (C) 2002 Published by Elsevier Science B.V.