[PDF] Early Generation Testing In Bell Pepper Capsicum Annum L To Develop F1 Hybrids Resistant To Powdery Mildew eBook

Author : Li Jiang
Publisher :
Page : 308 pages
File Size : 47,74 MB
Release : 2015
Category : Capsicum annuum
ISBN :

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Chile peppers are one of the leading vegetables in the United States and worldwide. New Mexico is a major production region for chile peppers in the United States. Phytophthora blight disease caused by Phytophthora capsici, and Verticillium wilt cause by Verticillium dahliae are two economically important soilborn diseases affecting chile pepper production in the southwest. Host resistance to P. capsici is characterized as race-specific, and resistant sources are available in chile pepper. However, resistance inheritance to V. dahliae is not well defined due to the limitation of resistant accessions. Using 17 New Mexico recombinant inbred lines (designated NMRILs) developed from a cross of CM334 with Early Jahapeno, as differentials, the race structure in P. capsici populations in New Mexico was updated. A total of 12 new races were identified from 13 P. capsici isolates and designated as race 22 to Race 33 with race 25 (isolate PWB175) virulence of isolate was the highest. Its virulence was higher than Race 1 (PWB24) having the highest virulence. The virulence of race 25 was even higher than race 1 (PWB24), which is widely used as a highly virulent race for resistance testing of chile peppers in the United States. Race 25 may pose a potential risk for chile pepper production in New Mexico. Among the 17 NMRILs tested, 7 of them constituted a set of differentials to distinguish the 12 new races. NMRILs are stable and, hence, invaluable as P. capsci race differentials. A "resistance index" was developed for testing each NMRIL. It referred to the fraction of resistant reactions out of the total number of isolates used for challenging a specific NMRIL and represented the interaction of the susceptibilities of the host plants and the virulence of the isolates. The resistance indices of 15 NMRILs to races 1-13 and races 22-33 varied. The NMRIL-R had a low resistance index of 0.17, while NMRILs A, B, F, O, Z, demonstrated medium to high levels of resistance for the tested P. capsici isolates ranging from 0.75 to 0.89. These NMRILs are very good resistant sources for chile pepper breeding for resistance to P. capsici. The results from studies in this dissertation further show that multiple races of P. capsici can be found in a single production field. To assist breeding efforts, these results have elucidated the race structure in production fields in New Mexico and can assist in improving host resistance in chile peppers for New Mexico. Compared to Phytophthora blight disease resistance, resistance sources to Verticillium wilt are very limited in the chile pepper. Therefore, a molecular approach to finding resistance was undertaken. Using the tomato Ve1 and Ve2 gene sequence information, a contig containing Ve homolog was identified in the chile pepper CM334 WGS database in NCBI. The primary structure of the predicted protein of CpVe was similar to the tomato Ve2 gene. Based on predicted Ve gene sequence in the CM334 reference genome, the CpVe sequence with a 3423 bp was successfully sequenced from the susceptible line 14C107 and resistant line 14C661 to Verticillium wilt. With the CpVe gene sequences, 9 single nucleotide polymorphisms (SNPs) and 2 haplotypes were detected between 14C107 and 14C661. A homozygous haplotype was identified for the susceptible accession 14C107, whereas the putative resistant haplotype had mixed with the susceptible haplotype in the population of 14C661. A total of 14 commercially available restriction enzymes were selected for the detection of the SNPs on the two haplotypes, demonstrating that development of CpVe gene-targeted SNP or cleaved amplified polymorphic sequences (CAPS) markers are technically feasible. These molecular markers would provide promising tools to investigate Verticillium wilt resistance, and would improve the efficacy of the breeding program in the chile pepper. Cytoplasmic male-sterility (CMS) is an efficient and effective method to make F1 hybrids in chile peppers. Because most CMS cytoplasmic sources are identical for chile pepper, breeding disease resistance in CMS lines and isolation of new CMS cytoplasmic sources are essential in CMS hybrid breeding. Flower fertility phenotypes and genotyping by two CMS cytoplasm-specific markers were investigated among three accession groups: (1) Sixteen CMS lines under development at New Mexico State University, (2) Well defined CMS lines, F1, and F2 generations from China, and (3) Diverse germplasm accessions including 25 cultivars and CM334. Over all the three groups, the CMS cytoplasm specific SCAR130 marker was consistently associated with the sterile mitochondrial gene, but contradictory results were observed for the restorer gene (Rf) linked CRF-SCAR marker. It indicated that only one sterile cytoplasm type has been used in chile pepper. Two new lines, 14C905 and 14C906, with a New Mexican pod type were verified as stable CMS A-lines. The CMS breeding line 14C914 in a bell pepper pod type 'CalWonder' was shown to segregate for flower fertility and for the nucleus restorer fertility (Rf) gene locus in a BC3F2 generation. To develop a stable bell pepper CMS A-line from 14C914, a few more cycles of backcrossing followed by selfing in each backcross, to produce sterile segregants for further backcrossing, will be needed. Corresponding to these new CMS A-lines, New Mexico pod type 'Ortega', bell pepper pod type 'CalWonder', and 'Early Jalapeño' were identified as good CMS maintainer lines or maintainer candidates. However, all other tested varieties for development of maintaner lines including the seven lines that had resistance to P. capsici and V. dahlia, failed to maintain male sterility in testcrosses. In addition, CM334 and 'Cajamarca' (C. chinense) were detected to possess a sterile cytoplasm based on the presence of CMS cytoplasm-specific SCAR130 marker.

Author : Naveen Kumar
Publisher : LAP Lambert Academic Publishing
Page : 124 pages
File Size : 49,78 MB
Release : 2012-06
Category :
ISBN : 9783659143762

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Sweet pepper/Bell pepper (Capsicum annuum L. var. grossum Sendt.) is one of the most popular and widely grown off-season vegetables in many states of India including Himachal Pradesh. All the cultivars and hybrids being grown by the farmers are susceptible to bacterial wilt disease in varying proportion.Therefore present study was undertaken at the Research Farm of Department of Vegetable Science and Floriculture, CSKHPKV, Palampur, Himachal Pradesh, India during summer-rainy season 2007 & 2008 including some bacterial wilt resistant genotypes with the objectives to estimate the combining ability, gene action and heterosis on different yield components, quality, morphological traits and disease resistance in sweet pepper (Capsicum annuum L. Var. grossum Sendt.) following line x tester analysis.Some high yielding, bacterial wilt resistant F1 hybrids were developed which were likely to perform better in the bacterial wilt prone high rainfall areas of Himachal Pradesh.This book covers the genetic, breeding, disease resistance, morphological and yield components of bell pepper breeding programme. It is helpful for researchers, students & vegetable growers to understand the crop breeding

Author : John E. McCoy
Publisher :
Page : 66 pages
File Size : 12,75 MB
Release : 2018
Category :
ISBN :

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Since its introduction to New Mexico in the 1990s, powdery mildew, caused by Leveillula taurica (Lév), has been a major disease on chile peppers. Powdery mildew can lead to severe plant defoliation, resulting in significant quality and yield losses. Applications of fungicide can be effective in managing the disease; however, early detection and thorough coverage of the plant is required. The most economically and environmentally sustainable solution is breeding for resistance. The Chile Pepper Institute at New Mexico State University grows an annual Teaching Garden at the Fabian Garcia Science Center in Las Cruces, NM. During the 2017 growing season, environmental conditions were highly favorable for powdery mildew development, and severe infection was observed. Under natural infection, 152 accessions, including six Capsicum species, were evaluated for resistance. Of the 152 accession, 53 accessions would be considered resistant. When examining across species, 18 C. annuum accessions were resistant, as well as 11 C. baccatum, 16 C. chinense, 5 C. frutescens, 1 C. chacoense, and 1 C. rhomboideum accession. A disease index ranging from 0 to 5 was used to score individual leaves of the plant. Accessions were considered resistant if they scored a 0 or 1. In addition to the field study, characterization of a novel susceptibility gene, CaMlo2, was conducted in the resistant accession, HV-12, and the susceptible cultivar, Maor. A single nucleotide polymorphism (SNP) was identified and a marker was developed. Select accessions from the field study were screened with the developed marker. The marker identified all evaluated resistant accessions; however, was not accurate for all susceptible accessions. This study provides the first multiple species evaluation for powdery mildew resistance among Capsicum species in New Mexico. It also provides preliminary evidence for genetic control of resistance in Capsicum populations. The identified SNP can be used for early screening of resistant material. This study provides a valuable base for continued breeding efforts, especially in the more commercially significant, C. annuum.

Author : Manoj-Kumar Arthikala
Publisher : LAP Lambert Academic Publishing
Page : 296 pages
File Size : 30,42 MB
Release : 2014-10-28
Category :
ISBN : 9783659619908

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Powdery mildew is a serious fungal disease on bell pepper crops leading to heavy yield losses both under greenhouse and field conditions. Herein, we adopted 13 chemical fungicides and 8 biocontrol agents and 13 botanicals to manage powdery mildew disease under field conditions. Interestingly, dinocap, among chemical fungicides, Ampelomyces quisqualis among biocontrol agents and neem oil among botanicals reported minimum disease and the maximum yield compared to untreated controls. Next, these treatments were integrated in various combinations to minimize the use of fungicide applications under field conditions. By adopting integrated disease management package the yield increased to 232% compared to control plots. Finally, transgenic bell pepper plants have been developed by a tissue culture independent Agrobacterium tumefaciens-mediated in planta transformation procedure. This method resulted in 32.4% of stable transformants in bell pepper. Therefore, our studies should especially useful to those who researchers work in the area of agricultural pathology and transgenic technology for crop improvement and protection.