Genetic Resources of the Sunflower Crop Wild Relatives for Resistance to Sunflower Broomrape

Helia ◽  
2019 ◽  
Vol 42 (71) ◽  
pp. 127-143
Author(s):  
Gerald J. Seiler
Keyword(s):  
Resistance Genes ◽  
Genetic Resistance ◽  
Crop Wild Relatives ◽  
Wild Relatives ◽  
Perennial Species ◽  
Multiple Sources ◽  
Sources Of Resistance ◽  
Western Asia ◽  
Sunflower Broomrape ◽  
Sunflower Crop

AbstractOne of the most threatening holoparasitic plant species is Orobanche cumana Wallr. (sunflower broomrape), mainly distributed in the Mediterranean region and Western Asia where it exclusively parasitizes sunflowers. Sunflower broomrape (BR) is a very destructive parasitic weed causing significant yield losses under high infestations that can easily spread and is vulnerable to mutations. Broomrape is highly variable, controlled by vertical single dominant resistance genes leading to the rapid and frequent breakdown of resistance. This subsequently leads to the continuing need for new unique genes from multiple sources for controlling new emerging virulent races. The USDA-ARS, National Plant Germplasm System crop wild relatives (CWR) collection contains 2,519 accessions of 53 species with 14 annual species (1641 accessions) and 39 perennial species (878 accessions). This CWR collection provides a vast genetic resource for new BR resistance genes, especially in Europe and the Middle East. Sunflower CWR evaluations for new resistance genes for BR races have demonstrated that they are a substantial reservoir for existing and new emerging virulent races. Resistance to sunflower broomrape, including immunity, has been reported in seven annual and 32 perennial species. These sources discovered in the sunflower CWR confer resistance to new virulent broomrape races F, G, and H, and others that have not been assigned a race designation. Since several of the resistant CWR sources are annual and have the same chromosome number as cultivated sunflower, broomrape resistance genes can be incorporated into hybrid sunflower through interspecific hybridization. The diverse sources of resistance from the CWR provide breeders with the prospect for durable broomrape control through exploiting genetic resistance for existing and newly emerging races.

scholarly journals Screening Cultivated Eggplant and Wild Relatives for Resistance to Bacterial Wilt (Ralstonia solanacearum)

Agriculture ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 157 ◽  
Author(s):  
Namisy ◽  
Chen ◽  
Prohens ◽  
Metwally ◽  
Elmahrouk ◽  
...  
Keyword(s):  
High Temperatures ◽  
Resistance Genes ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Solanum Melongena ◽  
Wild Relatives ◽  
Sources Of Resistance ◽  
Race 1 ◽  
Moderately Resistant ◽  
Phylotype I

Bacterial wilt, caused by Ralstonia solanacearum, is highly diverse and the identification of new sources of resistance for the incorporation of multiple and complementary resistance genes in the same cultivar is the best strategy for durable and stable resistance. The objective of this study was to screen seven accessions of cultivated eggplant (Solanum melongena L.) and 40 accessions from 12 wild relatives for resistance to two virulent R. solanacearum strains (Pss97 and Pss2016; phylotype I, race 1, biovar 3). The resistant or moderately resistant accessions were further evaluated with Pss97 in a second trial under high temperatures (and also with Pss2016 for S. anguivi accession VI050346). The resistant control EG203 was resistant to Pss97, but only moderately resistant to Pss2016. One accession of S. sisymbriifolium (SIS1) and two accessions of S. torvum (TOR2 and TOR3) were resistant or moderately resistant to Pss97 in both trials. Solanum anguivi VI050346, S. incanum accession MM577, and S. sisymbriifolium (SIS1 and SIS2) were resistant to Pss2016 in the first trial. However, S. anguivi VI050346 was susceptible in the second trial. These results are important for breeding resistant rootstocks and cultivars that can be used to manage this endemic disease.

scholarly journals (13) Comparative Mapping of Early Blight Resistance QTLs and Candidate Resistance Genes in F2, F3, F4 and a RIL Population of Tomato

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1040B-1040
Author(s):  
Hamid Ashrafi ◽  
Arun Sharma ◽  
David Niño-Liu ◽  
Liping Zhang ◽  
Majid Foolad
Keyword(s):  
Resistance Genes ◽  
Early Blight ◽  
Genetic Resistance ◽  
Genetic Maps ◽  
Blight Resistance ◽  
Candidate Gene Approach ◽  
Sources Of Resistance ◽  
Resistance Qtls ◽  
Ril Population ◽  
Related Wild Species

Most cultivars of tomato (Lycopersiconesculentum) are susceptible to early blight (EB), a devastating fungal (Alternariasolani) disease of tomato in the northeast and eastern part of the U.S. The most economic and durable measure of disease control is by using genetic resistance. There is limited EB resistance within the cultivated tomato. However, genetic sources of resistance exist within the tomato-related wild species L. hirsutum and L. pimpinellifolium. Early blight resistance does not follow the gene-for-gene model of host–pathogen interaction. Mapping QTLs conferring horizontal resistance is an effective approach for studying complex resistance traits such as EB. We have developed F2, F3, F4, and an F2:7 derived RIL population of a L. esculentum× L. pimpinellifolium cross and evaluated them for EB resistance under field conditions. Genetic maps were constructed based on the F2 (including 256 RFLP, EST and RGA markers) as well as the RIL population (including over 220 RFLP and EST markers). In each of the F2, F3, and F4 population, an average of seven QTLs were identified for resistance, which were highly consistent across populations. Mapping of EB resistance QTLs in the RILs is underway. Co-localizations of QTLs with several ESTs and RGAs were observed, suggesting potential involvement of the latter markers with EB resistance. Furthermore, co-localizations were observed among QTLs, ESTs, and RGAs and several known tomato vertical disease resistance genes. Possible occurrence of such co-localization in the RIL population will be reported. It is speculated that candidate-gene approach is an effective way of identifying and mapping new R genes in tomato. This study may lead to the identification of genes underlying EB resistance in tomato.

scholarly journals Genome-Enabled Phylogeographic Investigation of the Quarantine Pathogen Ralstonia solanacearum Race 3 Biovar 2 and Screening for Sources of Resistance Against Its Core Effectors

2015 ◽  
Vol 105 (5) ◽  
pp. 597-607 ◽  
Author(s):  
Christopher R. Clarke ◽  
David J. Studholme ◽  
Byron Hayes ◽  
Brendan Runde ◽  
Alexandra Weisberg ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Ralstonia Solanacearum ◽  
Genetic Resistance ◽  
Brown Rot ◽  
The United States ◽  
South American ◽  
Sources Of Resistance ◽  
Quarantine Pathogen ◽  
Potato Brown Rot ◽  
Core Effectors

Phylogeographic studies inform about routes of pathogen dissemination and are instrumental for improving import/export controls. Genomes of 17 isolates of the bacterial wilt and potato brown rot pathogen Ralstonia solanacearum race 3 biovar 2 (R3bv2), a Select Agent in the United States, were thus analyzed to get insight into the phylogeography of this pathogen. Thirteen of fourteen isolates from Europe, Africa, and Asia were found to belong to a single clonal lineage while isolates from South America were genetically diverse and tended to carry ancestral alleles at the analyzed genomic loci consistent with a South American origin of R3bv2. The R3bv2 isolates share a core repertoire of 31 type III-secreted effector genes representing excellent candidates to be targeted with resistance genes in breeding programs to develop durable disease resistance. Toward this goal, 27 R3bv2 effectors were tested in eggplant, tomato, pepper, tobacco, and lettuce for induction of a hypersensitive-like response indicative of recognition by cognate resistance receptors. Fifteen effectors, eight of them core effectors, triggered a response in one or more plant species. These genotypes may harbor resistance genes that could be identified and mapped, cloned, and expressed in tomato or potato, for which sources of genetic resistance to R3bv2 are extremely limited.

Utilization of Sunflower Crop Wild Relatives for Cultivated Sunflower Improvement

Crop Science ◽  
2017 ◽  
Vol 57 (3) ◽  
pp. 1083-1101 ◽  
Author(s):  
Gerald J. Seiler ◽  
Lili L. Qi ◽  
Laura F. Marek
Keyword(s):  
Crop Wild Relatives ◽  
Wild Relatives ◽  
Sunflower Crop

scholarly journals Improvements in Hazelnuts in the United States

HortScience ◽  
2011 ◽  
Vol 46 (3) ◽  
pp. 343-344
Author(s):  
Jeff Olsen
Keyword(s):  
United States ◽  
Genetic Resistance ◽  
The United States ◽  
Management Program ◽  
Breeding Program ◽  
Eastern United States ◽  
Multiple Sources ◽  
Sources Of Resistance ◽  
Resistant Cultivars ◽  
Beneficial Traits

In the mid-1980s, eastern filbert blight (EFB) fungus, Anisogramma anomala (Peck) E. Müller, was discovered in Oregon's main hazelnut-producing region and now is present throughout the hazelnut-producing area. Oregon State University's (OSU) Hazelnut Breeding Program responded by developing EFB-resistant cultivars, the first of which was released in 2005. The breeding program has also selected for other beneficial traits such as uniform early nut maturation, larger kernel size, and improved kernel quality. A 2008 OSU economic study on the costs of establishing and producing hazelnuts showed that the EFB-resistant cultivars enhanced economic viability of orchards, increasing cumulative cash flow during the 12-year establishment period by $12,243 per hectare. Several completely resistant cultivars have been released from the OSU Hazelnut Breeding program, all of which have ‘Gasaway’ as a resistance source, which transmits a dominant allele at a single locus that provides resistance to EFB. Additional EFB-resistant genotypes have also been identified from a diversity of origins that are being integrated into the OSU breeding program to produce new cultivars expressing multiple sources of genetic resistance. Interest in growing hazelnuts is increasing in other parts of the United States; for example, the Arbor Day Foundation began the Hazelnut Research Project in 1996 in Nebraska. A Hybrid Hazelnut Consortium was formed to join the leading hazelnut researchers in the United States. The Consortium's goal is to create a world-leading research and breeding program to develop hazelnuts as a widely adapted, high-yielding, and low-input sustainable crop that is competitive with annual crops for food, feed, or bioenergy. At Rutgers University, there has been a program of breeding and research for hazelnuts for the eastern United States since 1996. The program currently has ≈11,000 hazelnut seedlings undergoing evaluation. The Rutgers program is also looking for winter-hardy genotypes. They have been working closely with OSU to assess the response of OSU hazelnut selections that are resistant to EFB in Oregon when they are exposed to EFB isolates collected from across the eastern United States. This work has demonstrated the need for cultivars to express multiple sources of resistance and has prompted quarantine on importation of hazelnut plants into Oregon from other states where EFB strains may differ. Rutgers is also searching for new sources of resistance to EFB from seedling populations from Europe with the goal of integrating these sources into American germplasm. More effective Integrated Pest Management for EFB-susceptible hazelnut cultivars has been developed by OSU scientists. They recommend a management program that integrates scouting for and pruning infected tissue, fungicidal sprays, and the use of more resistant cultivars. Advances in hazelnut fertilizer management have included descriptions of patterns of nitrogen uptake, distribution, and use using isotopically labeled nitrogen.

scholarly journals Inheritance of Resistance to Downy Mildew in Sweet Basil

2015 ◽  
Vol 140 (5) ◽  
pp. 396-403 ◽  
Author(s):  
Robert M. Pyne ◽  
Adolfina R. Koroch ◽  
Christian A. Wyenandt ◽  
James E. Simon
Keyword(s):  
Downy Mildew ◽  
Goodness Of Fit ◽  
Dominant Gene ◽  
Genetic Resistance ◽  
Severity Index ◽  
Inheritance Of Resistance ◽  
Multiple Sources ◽  
Sources Of Resistance ◽  
Gene Effects ◽  
Sweet Basil

Sweet basil (Ocimum basilicum) is one of the most economically important culinary herbs in the world, yet global production has become increasingly challenging due to the destructive disease downy mildew (Peronospora belbahrii). Although multiple sources of resistance have been identified, there are no resistant sweet basil cultivars with a commercially acceptable chemotype and phenotype available. The commercial basil cultivar Mrihani (MRI) was identified as resistant and crossed with a Rutgers University susceptible sweet basil inbred line (SB22) to generate a full-sibling family. To determine the mode of inheritance for resistance to downy mildew in basil, six related generations of the MRI × SB22 family were evaluated using a disease severity index (DSI) at northern and southern New Jersey locations over 2 years. All siblings in the F1 and BC1P2 generations were resistant (0.33 > DSI) providing strong evidence that inheritance of resistance from MRI was conferred by dominant alleles. Segregation ratios in the F2 and backcross to the susceptible parent (BCP1) generations demonstrated chi-square goodness of fit to the two-gene complementary (F2: P = 0.11, BC1P1: P = 0.04) and recessive epistatic (F2: P = 0.03, BC1P1: P = 0.63) models. Further analyses of gene effects using a weighted six-parameter scaling test provided evidence that nonallelic additive × additive and additive × dominant gene effects were highly significant (P < 0.001) and resistance reducing. This is the first report of heritable genetic resistance that can be introduced to sweet basil without the issue of sterility barriers. Plant breeding strategies using the MRI × SB22 family should exploit dominant gene action and remove recessive, resistance-reducing alleles from the population.

Crop wild relatives and their conservation strategies in China

2014 ◽  
Vol 21 (6) ◽  
pp. 750-757
Author(s):  
Yu Yanbo ◽  
Wang Qunliang ◽  
Kell Shelagh ◽  
Maxted Nigel ◽  
V. Ford-Lloyd Brian ◽  
...  
Keyword(s):  
Crop Wild Relatives ◽  
Wild Relatives ◽  
Conservation Strategies

scholarly journals Status of the Ex Situ and In Situ Conservation of Brazilian Crop Wild Relatives of Rice, Potato, Sweet Potato, and Finger Millet: Filling the Gaps of Germplasm Collections

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 638
Author(s):  
Marcelo B. Medeiros ◽  
José F. M. Valls ◽  
Aluana G. Abreu ◽  
Gustavo Heiden ◽  
Suelma Ribeiro-Silva ◽  
...  
Keyword(s):  
Finger Millet ◽  
Ex Situ Conservation ◽  
Gap Analysis ◽  
In Situ Conservation ◽  
Germplasm Collection ◽  
Crop Wild Relatives ◽  
Wild Relatives ◽  
Ex Situ ◽  
The Status

This study presents the status of ex situ and in situ conservation for the crop wild relatives of rice, potato, sweet potato, and finger millet in Brazil, and the subsequent germplasm collection expeditions. This research is part of a global initiative entitled “Adapting Agriculture to Climate Change: Collecting, Protecting, and Preparing Crop Wild Relatives” supported by the Global Crop Diversity Trust. Species of the primary, secondary, and tertiary gene pools with occurrences reported in Brazil were included: Oryza alta Swallen, O. grandiglumis (Döll) Prod., O. latifolia Desv., O. glumaepatula Steud., Eleusine tristachya (Lam.) Lam., E. indica (L.) Gaertn., Solanum commersonii Dunal, S. chacoense Bitter, Ipomoea grandifolia (Dammer) O’Donell, I. ramosissima (Poir.) Choisy, I. tiliacea (Willd.) Choisy, I. triloba L., and I. cynanchifolia Meisn. The status of the ex situ and in situ conservation of each taxon was assessed using the gap analysis methodology, and the results were used to plan 16 germplasm collection expeditions. Seeds of the collected material were evaluated for viability, and the protocols for seed germination and cryopreservation were tested. The final conservation score, resulting from the gap analysis and including the average of the ex situ and in situ scores, resulted in a classification of medium priority of conservation for all the species, with the exception of I. grandifolia (high priority). The total accessions collected (174) almost doubled the total accessions of these crop wild relatives incorporated in Embrapa’s ex situ conservation system prior to 2015. In addition, accessions for practically absent species were collected for the ex situ conservation system, such as Ipomoea species, Eleusine indica, and Solanum chacoense. The methods used for dormancy breaking and low temperature conservation for the Oryza, Eleusine, and Ipomoea species were promising for the incorporation of accessions in the respective gene banks. The results show the importance of efforts to collect and conserve ex situ crop wild relatives in Brazil based on previous gap analysis. The complementarity with the in situ strategy also appears to be very promising in the country.

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