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.

scholarly journals New Sources of Lettuce Aphid Resistance in Lettuce

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1109A-1109
Author(s):  
James D. McCreight
Keyword(s):  
Insect Pest ◽  
Dominant Gene ◽  
The United States ◽  
Inheritance Of Resistance ◽  
Sources Of Resistance ◽  
Lactuca Virosa ◽  
Nasonovia Ribisnigri ◽  
Lactuca Serriola ◽  
Salinas Valley ◽  
Greenhouse Tests

Lettuce aphid (Nasonovia ribisnigri Mosley) is a recent insect pest to lettuce (Lactuca sativa L.) production in the United States. The single dominant gene, Nr, conditions resistance to the lettuce aphid in Lactuca virosa accession IVT280 from The Netherlands and is available in a limited number of commercial lettuce cultivars. New and genetically unique sources of resistance are sought to broaden the genetic base for resistance to the lettuce aphid. About 1200 lettuce PI lines were evaluated for resistance to lettuce aphid in greenhouse tests using a strain of lettuce aphid obtained from commercial lettuce in Salinas Valley, Calif. In 2002, plants were individually infested with five 24-hour nymphs per plant (controlled protocol), and the numbers of aphids per plant were counted 10–14 days post-infestation (dpi). Beginning in 2003, plants were mass-infested (mass protocol) with nymphs and alates of various ages and numbers. Using the mass protocol, the number of aphids per plant 10–14 dpi were estimated and categorized using a 1–5 scale where 1 = 0 aphids per plant, 2 = 1–10 aphids per plant, 3 = 11–20 aphids per plant, 4 = 21–30 aphids per plant, and 5 = >30 aphids per plant. `Salinas' and `Barcelona' were included as susceptible and resistant controls, respectively. Most of the accessions were susceptible. A few accessions had a few plants with very low numbers of aphids after repeated infestation, but their progeny were susceptible. Two accessions were highly resistant: PI 491093, a Lactuca serriola accession from Turkey, and PI 274378, a L. virosa accession from France. Inheritance of resistance in these two accessions and their allelism to Nr remains to be determined.

scholarly journals Inheritance of Resistance to the Peanut Root-knot Nematode in Capsicum chinense

2000 ◽  
Vol 125 (5) ◽  
pp. 615-618
Author(s):  
Richard L. Fery ◽  
Judy A. Thies
Keyword(s):  
Resistance Gene ◽  
Dominant Gene ◽  
Inheritance Of Resistance ◽  
Capsicum Chinense ◽  
Root Knot Nematode ◽  
Sources Of Resistance ◽  
Resistant Parent ◽  
Backcross Populations ◽  
Race 1 ◽  
Allelism Tests

Greenhouse experiments determined the inheritance of resistance to the peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1] in Capsicum chinense Jacq. germplasm lines PA-353 and PA-426. Evaluation of parental, F1, F2, and backcross populations of the crosses PA-353 × PA-350 and PA-426 × PA-350 (PA-350 is a susceptible cultigen) indicated that resistance in both C. chinense germplasm lines was conditioned by a single dominant gene. Evaluation of the F1 × resistant parent backcross populations in the cytoplasm of their respective resistant and susceptible parents indicated that the cytoplasm of the resistant parent is not needed for full expression of resistance. Allelism tests indicated that the dominant resistance gene in both PA-353 and PA-426 is allelic to a resistance gene in C. annuum L. `Carolina Cayenne'. However, these allelism tests did not demonstrate conclusively that the M. arenaria race 1 resistance gene in C. chinense is the N gene that conditions resistance to the southern root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] in C. annuum. The ease and reliability of evaluating plants for resistance to root-knot nematodes and the availability of simply inherited sources of resistance makes breeding for peanut root-knot nematode resistance a viable objective in C. chinense breeding programs.

INHERITANCE OF RESISTANCE TO FRUIT FLY IN WATERMELON

1978 ◽  
Vol 20 (1) ◽  
pp. 31-34 ◽  
Author(s):  
R. C. Khandelwal ◽  
Prem Nath
Keyword(s):  
Citrullus Lanatus ◽  
Dominant Gene ◽  
Fruit Fly ◽  
Inheritance Of Resistance ◽  
Single Dominant Gene ◽  
Sources Of Resistance ◽  
Resistant Gene

Inheritance of resistance to the fruit fly Dacus cucurbitae Coq., was studied in intervarietal crosses of watermelon Citrullus lanatus (Thunb.) Mansf. Two sources of resistance J 18-1 and J 56-1 were used. The resistance of watermelon to the fruit fly was controlled by a single dominant gene. The symbol Fwr has been proposed to denote the resistant gene.

scholarly journals Transfer of Downy Mildew Resistance from Wild Basil (Ocimum americanum) to Sweet Basil (O. basilicum)

2018 ◽  
Vol 108 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Yariv Ben-Naim ◽  
Lidan Falach ◽  
Yigal Cohen
Keyword(s):  
Downy Mildew ◽  
Dominant Gene ◽  
Susceptible Parent ◽  
Backcross Generation ◽  
Sweet Basil ◽  
Resistant Varieties ◽  
Homeologous Chromosomes ◽  
Tetraploid Parent ◽  
Dominant Genes

Sweet basil (Ocimum basilicum) is susceptible to downy mildew caused by the oomycete foliar pathogen Peronospora belbahrii. No resistant varieties of sweet basil are commercially available. Here, we report on the transfer of resistance gene Pb1 from the highly resistant tetraploid wild basil O. americanum var. americanum (PI 500945, 2n = 4x = 48) to the tetraploid susceptible O. basilicum ‘Sweet basil’ (2n = 4x = 48). F1 progeny plants derived from the interspecific hybridization PI 500945 × Sweet basil were resistant, indicating that the gene controlling resistance (Pb1) is dominant, but sterile due to the genetic distance between the parents. Despite their sterility, F1 plants were pollinated with the susceptible parent and 115 first backcross generation to the susceptible parent (BCs1) embryos were rescued in vitro. The emerging BCs1 plants segregated, upon inoculation, 5:1 resistant/susceptible, suggesting that resistance in F1 was controlled by a pair of dominant genes (Pb1A and Pb1A’). Thirty-one partially fertile BCs1 plants were self-pollinated to obtain BCs1-F2 or were backcrossed to Sweet basil to obtain the second backcross generation to the susceptible parent (BCs2). In total, 1 BCs1-F2 and 22 BCs2 progenies were obtained. The BCs1-F2 progeny segregated 35:1 resistant/susceptible, as expected from a tetraploid parent with two dominant resistant genes. The 22 BCs2 progenies segregated 1:1 resistant/susceptible (for a BCs1 parent that carried one dominant gene for resistance) or 5:1 (for a BCs1 parent that carried two dominant genes for resistance) at a ratio of 4:1. The data suggest that a pair of dominant genes (Pb1A and Pb1A’) residing on a two homeologous chromosomes is responsible for resistance of PI 500945 against P. belbahrii.

scholarly journals Inheritance of resistance to downy mildew (Peronosclerospora maydis) in crossing of Madura Maize Plant (Zea mays L.)

2019 ◽  
Author(s):  
Achmad Amzeri ◽  
◽  
Kaswan Badami ◽  
Gita Pawana ◽  
◽  
...  
Keyword(s):  
Downy Mildew ◽  
Block Design ◽  
Dominant Gene ◽  
Genetic Resistance ◽  
Technology Study ◽  
Study Program ◽  
Randomized Block Design ◽  
Degree Of Dominance ◽  
Maize Genetic ◽  
Mdr 1

Hybridization of Back cross is one method to get varieties that are resistant to downy mildew. The purpose of this study was to obtain information on inheritance characteristics of downy mildew resistance. This research was conducted at the experiment center of Agro-Technology Study Program of Agriculture Faculty, University of Trunojoyo Madura. Research of Assessment of resistance to Downy Mildew used a randomized block design with 18 treatments (P1, P2, F1, F2, BC1P1 and BC1P2 in three sets of crosses, namely LGL x Mdr-3, T12 x Mdr-1 and E02 x Mdr-2) and three replications so there were 54 experimental units. Identification of polymorphic RAPD markers for endurance to downy mildew through Bulk Segregant Analysis (BSA) was done by amplifying the DNA in the resistant pool and susceptible pool. The random primers used were 120 primers from 6 operon groups, namely OPA, OPB, OPC, OPD, OPF and OPG. The results showed that the inheritance pattern of maize genetic resistance to downy mildew followed a segregation pattern of 3:1 with a degree of dominance between -1 and 0, and was controlled by incomplete partially negative dominant gene. OPC-07 was a marker that was linkage close to the resistance to downy mildew with a genetic distance of 1.9 cM.

scholarly journals New Sources of Resistance to Black rot in Crucifers and Inheritance of Resistance.

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1122f-1122
Author(s):  
Z. H. Guo ◽  
M. H. Dickson ◽  
J. E. Hunter
Keyword(s):  
Chinese Cabbage ◽  
Dominant Gene ◽  
Recessive Gene ◽  
Brassica Species ◽  
Black Rot ◽  
Inheritance Of Resistance ◽  
Quantitative Inheritance ◽  
Sources Of Resistance ◽  
Moderate Resistance ◽  
High Level

Resistance to Black rot was studied in B. oleracea, B. campestris and B. napus, using three different inoculation procedures. The results indicated that hydathode inoculation without wounding and the wound suspension technique were useful for differentiating levels of resistance found in B. oleracea and B. campestris, but not in B. napus. Only the wound colony method allowed differentiation between high and moderate resistance in B napus. B. napus, PI 199947 and PI 199949, exhibited the highest resistance found in cultivated Brassica species. In B. campestris, two chinese cabbage accessions showed quantitative inheritance for moderate levels of resistance. In B. napus, the high level of reistance was conferred by one dominant gene, to which the symbol Br was assigned, whereas the moderate resistance was due to one recessive gene bm.

scholarly journals CRISPR-Editing of Sweet Basil (Ocimum basilicum L.) Homoserine Kinase Gene for Improved Downy Mildew Disease Resistance

2021 ◽  
Vol 3 ◽  
Author(s):  
Xiaoyu Zhang ◽  
Yee Chen Low ◽  
Michael A. Lawton ◽  
James E. Simon ◽  
Rong Di
Keyword(s):  
Downy Mildew ◽  
Gene Editing ◽  
Susceptibility Gene ◽  
Genetic Resistance ◽  
Ocimum Basilicum ◽  
In Planta ◽  
Kinase Gene ◽  
Sweet Basil ◽  
Homoserine Kinase ◽  
Downy Mildew Disease

Sweet basil (Ocimum basilicum L.) downy mildew disease (DM) caused by Peronospora belbahrii is a worldwide threat to the basil industry due to the lack of natural genetic resistance in sweet basil germplasm collections. In this study, we used CRISPR-gene editing to modify the sweet basil DM susceptibility gene homoserine kinase (ObHSK). Gene-edited plants challenged with P. belbahrii displayed a significantly reduced susceptibility to DM, based on phenotypic disease indices and on in planta pathogen load. These results suggest that ObHSK plays a role in conditioning DM susceptibility, similar to that observed for the AtHSK gene in Arabidopsis. These results demonstrate the utility of CRISPR-gene editing in enhancing DM resistance and contributing to sweet basil breeding programs.

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 Basil Downy Mildew (Peronospora belbahrii): Discoveries and Challenges Relative to Its Control

2015 ◽  
Vol 105 (7) ◽  
pp. 885-894 ◽  
Author(s):  
Christian A. Wyenandt ◽  
James E. Simon ◽  
Robert M. Pyne ◽  
Kathryn Homa ◽  
Margaret T. McGrath ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Genetic Resistance ◽  
Significant Risk ◽  
Sweet Basil ◽  
The Past ◽  
Limited Success ◽  
The World ◽  
Important Disease ◽  
Efficacy Studies ◽  
Made In

Basil (Ocimum spp.) is one of the most economically important and widely grown herbs in the world. Basil downy mildew, caused by Peronospora belbahrii, has become an important disease in sweet basil (O. basilicum) production worldwide in the past decade. Global sweet basil production is at significant risk to basil downy mildew because of the lack of genetic resistance and the ability of the pathogen to be distributed on infested seed. Controlling the disease is challenging and consequently many crops have been lost. In the past few years, plant breeding efforts have been made to identify germplasm that can be used to introduce downy mildew resistance genes into commercial sweet basils while ensuring that resistant plants have the correct phenotype, aroma, and tastes needed for market acceptability. Fungicide efficacy studies have been conducted to evaluate current and newly developed conventional and organic fungicides for its management with limited success. This review explores the current efforts and progress being made in understanding basil downy mildew and its control.

Joint action of Pb1 and Pb2 provide dominant complementary resistance against new races of Peronospora belbahrii (Basil Downy Mildew)

2021 ◽  
Author(s):  
Yariv Ben-Naim ◽  
Michal Weitman
Keyword(s):  
Downy Mildew ◽  
Joint Action ◽  
Embryo Rescue ◽  
Dominant Gene ◽  
Signal Transduction Pathway ◽  
Sweet Basil ◽  
Complete Resistance ◽  
Race 1 ◽  
New Races ◽  
Common Signal

Sweet basil (Ocimum basilicum, 2n=4x=48) is susceptible to downy mildew caused by Peronospora belbahrii. Pb1 gene exhibit complete resistance to the disease. However, Pb1 became prone to disease due to occurrence of a new virulent races. Here we show that Zambian accession PI 500950 (O. americanum var pilosum) is highly resistant to the new races. From an interspecies backcross between PI 500950 and the susceptible cv ‘Sweet Basil’ we obtained, by embryo rescue, a population of 131 BC1F1 plants. This population segregated 73 Resistant: 58 Susceptible (1: 1, P=0.22), suggesting the resistance is controlled by one incompletely dominant gene called Pb2. To determine whether allelic relationship is existing between Pb1 and Pb2, we used two differential races, race-0, avirulent to both PI 500945 (Pb1) and PI 500950 (Pb2) and race-1, virulent to PI 500945 but avirulent to PI 500950. F1 plants obtained from ‘12-4-6’ (BC6F3 derived from PI 500945) and ‘56’ (BC3F3 derived from PI 500950) showed resistant superiority to both races due to dominant complementary interaction. F2 plants segregated to race-0 as follow; 12:3:1, immune: incomplete resistant: susceptible, as against to 9:3:4 to race-1, indicating Pb1 and Pb2 are not alleles. Since joint action is contributed in F1 plants and in advanced (BC3F3(56) x BC6F3(12-4-6) F4) populations who carrying both genes, it can be assumed that both accessions carry two unlinked genes but share a common signal transduction pathway which leading to dominant complementation superiority of the resistance against different races of BDM.

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