scholarly journals Identification of major quantitative trait loci controlling field resistance to downy mildew in cultivated lettuce (Lactuca sativa L.)

2020 ◽  
Author(s):  
Lorena B Parra ◽  
Ivan Simko ◽  
Richard Michelmore
Keyword(s):  
Downy Mildew ◽  
Lactuca Sativa ◽  
Quantitative Trait ◽  
Durable Resistance ◽  
Gene Pyramiding ◽  
Field Resistance ◽  
Significant Qtls ◽  
Resistant Cultivars ◽  
Lactuca Sativa L ◽  
Grand Rapids

Lettuce downy mildew caused by Bremia lactucae Regel is the most economically important foliar disease of lettuce (Lactuca sativa L.). The deployment of resistant cultivars carrying dominant resistance genes (Dm genes) plays a crucial role in integrated downy mildew disease management; however, high variability in pathogen populations leads to the defeat of plant resistance conferred by Dm genes. Some lettuce cultivars exhibit field resistance that is only manifested in adult plants. Two populations of recombinant inbred lines (RILs), originating from crosses between the field resistant cultivars Grand Rapids and Iceberg and susceptible cultivars Salinas and PI491224, were evaluated for downy mildew resistance under field conditions. One hundred and sixty RILs from the Iceberg × PI491224 and 88 RILs from the Grand Rapids × Salinas RIL populations were genotyped using genotyping by sequencing, which respectively generated 906 and 746 high quality markers that were used for quantitative trait locus (QTL) analysis. We found a QTL in Chromosome 4 that is present in both Grand Rapids × Salinas and Iceberg × PI491224 populations that has a major effect on field resistance. We also found two additional significant QTLs in Chromosomes 2 and 5 in the Iceberg × PI491224 RIL population. Marker-assisted gene pyramiding of multiple Dm genes in combination with QTLs for field resistance provides the opportunity to develop cultivars with more durable resistance to B. lactucae.

scholarly journals Resistance to Downy Mildew in Lettuce ‘La Brillante’ is Conferred by Dm50 Gene and Multiple QTL

2015 ◽  
Vol 105 (9) ◽  
pp. 1220-1228 ◽  
Author(s):  
Ivan Simko ◽  
Oswaldo E. Ochoa ◽  
Mathieu A. Pel ◽  
Cayla Tsuchida ◽  
Carolina Font i Forcada ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Field Experiments ◽  
Field Resistance ◽  
Phenotypic Variance ◽  
Lactuca Sativa L ◽  
Trait Locus ◽  
Group 2 ◽  
High Level ◽  
Harvest Maturity ◽  
Multiple Field

Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar ‘La Brillante’ has a high level of field resistance to the disease in California. Testing of a mapping population developed from a cross between ‘Salinas 88’ and La Brillante in multiple field and laboratory experiments revealed that at least five loci conferred resistance in La Brillante. The presence of a new dominant resistance gene (designated Dm50) that confers complete resistance to specific isolates was detected in laboratory tests of seedlings inoculated with multiple diverse isolates. Dm50 is located in the major resistance cluster on linkage group 2 that contains at least eight major, dominant Dm genes conferring resistance to downy mildew. However, this Dm gene is ineffective against the isolates of B. lactucae prevalent in the field in California and the Netherlands. A quantitative trait locus (QTL) located at the Dm50 chromosomal region (qDM2.2) was detected, though, when the amount of disease was evaluated a month before plants reached harvest maturity. Four additional QTL for resistance to B. lactucae were identified on linkage groups 4 (qDM4.1 and qDM4.2), 7 (qDM7.1), and 9 (qDM9.2). The largest effect was associated with qDM7.1 (up to 32.9% of the total phenotypic variance) that determined resistance in multiple field experiments. Markers identified in the present study will facilitate introduction of these resistance loci into commercial cultivars of lettuce.

scholarly journals Introgression of Big Vein Tolerance from Lactuca virosa L. into Cultivated Lettuce (Lactuca sativa L.)

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 881C-881 ◽  
Author(s):  
Ryan J. Hayes* ◽  
Ed Ryder ◽  
Bert Robinson
Keyword(s):  
Great Lakes ◽  
Lactuca Sativa ◽  
Infested Soil ◽  
Hybrid Progeny ◽  
Developmental Processes ◽  
Resistant Cultivars ◽  
Lactuca Virosa ◽  
Lactuca Sativa L ◽  
Congruity Backcrossing ◽  
Linkage Of Genes

Big vein (BV) disease of lettuce is caused by soil borne fungal vectored viruses, and reduces marketability through head deformation. Tolerant cultivars reduce BV frequency, but no resistant cultivars exist. L. virosa L. is highly resistance. The objectives were to 1) determine if L. virosa P.I.s exhibit variation for resistance, and 2) determine if resistance is transferable to lettuce. Seedlings were inoculated with root macerate of BV infected plants, transplanted to BV infested soil, and greenhouse grown for 3 months. Twelve plants in each of 1,2, or 3 reps of Great Lakes 65 (GL65-susceptible), Pavane (Pav-tolerant), L. virosa (11 accessions), and BC1 F2 through F5 families of lettuce cultivars x L. virosa accession IVT280 were tested. The percentage of BV afflicted plants was recorded. In hybrid families, BV free plants from tolerant families were selected and advanced. No BV was found in L. virosa. Variation for tolerance was observed in BC1 F2 and F3 families; 33% had greater tolerance than Pav (17% afflicted). Additional tests identified 11 BC1 F3 families (14%) with greater tolerance than Pav (42% afflicted). Subsequent BC1 F4 and F5 generations however, were more susceptible than Pav. Lactuca virosa is highly resistant, but resistance did not transfer to hybrid progeny. Variation for tolerance was observed in BC1 F2 and F3 families, but later generations were susceptible. Interactions or linkage of genes for developmental processes and BV resistance may hinder introgression. Introgression will continue using congruity backcrossing and a greater diversity of L. virosa.

scholarly journals Penggunaan AB Mix dan Media Tanam terhadap Viabilitas Tanaman Selada (Lactuca sativa L. Var. New Grand Rapids) dalam Hydroponic Wick System

2020 ◽  
Vol 5 (1) ◽  
pp. 14-19
Author(s):  
Imam Safir Alwan Nurza ◽  
Diliviva Venesia
Keyword(s):  
Lactuca Sativa ◽  
Agricultural Sector ◽  
Growth And Yield ◽  
Lactuca Sativa L ◽  
Data Collection And Analysis ◽  
Grand Rapids ◽  
Wet Weight ◽  
Number Of Leaves ◽  
Resource Wealth ◽  
Natural Resource Wealth

Indonesia is a country that has abundant natural resources. One of the natural resource wealth is in the agricultural sector. The agricultural sector has a variety of agricultural commodities found in Indonesia. One of them is horticulture. Lettuce (Lactuca sativa L.) is a horticultural commodity. The purpose of this study was to determine the use of ab mix and planting media on lettuce (Lactuca sativa L. var New Grand Rapids) in increasing growth and yield after 40 Days After Planting (HST). This research method is an experiment with statistical data collection and analysis techniques. The results of this study are the number of leaves, plant height, and wet weight in the ab mix is ​​higher than aquades (control) because the ab mix provides nutrients for plant growth so that the plant becomes tall and enlarged with its leaves looking wide. However, the number of seeds germinated and plant viability in aquades (control) was higher than ab mix because there was an inorganic salt in ab mix that inhibited seed germination so that the seed membrane in absorbing water became impermeable.

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