Towards new sources of resistance to the currant-lettuce aphid (Nasonovia ribisnigri)

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.

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New sources of resistance to hazardous organisms in pea in the eastern forest steppe of Ukraine

Plant Breeding and Seed Production ◽

10.30835/2413-7510.2014.42054 ◽

2014 ◽

Vol 0 (105) ◽

pp. 70-76

Author(s):

Т. В. Сокол

Keyword(s):

Forest Steppe ◽

Sources Of Resistance

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RESISTANCE TO MILDEW OF SELECTION FAMILY OF RED CURRANT THE BELAYA POTAPENKO × № 1426-21-80

Vestnik of the Russian agricultural science ◽

10.30850/vrsn/2020/4/38-40 ◽

1970 ◽

pp. 38-40

Author(s):

O. O. Kalinina ◽

O. D. Golyaeva ◽

O. V. Panfilova ◽

А. V. Pikunova

Keyword(s):

Powdery Mildew ◽

Field Resistance ◽

Disease Development ◽

Artificial Infection ◽

Sources Of Resistance ◽

Climate Conditions ◽

High Productivity ◽

Local Soil ◽

The Family ◽

Red Currant

Powdery mildew is one of the most harmful fungal diseases that causes economically significant damage to berry plantations. The disease is common in all areas of currant cultivation in the Russian Federation. In this regard, in modern conditions of intensive berry growing, the problem of breeding cultivars that are highly resistant to diseases and pests becomes urgent. Breeders have a difficult task to combine the adaptive potential of the cultivar with its annual high productivity and resistance to biotic environmental factors. When studying the adaptability of introduced cultivars of red currant and selected forms of the Institute to local soil and climate conditions, the following cultivars were identified as sources of economic and useful characteristics and involved in selection: ‘Belaya Potapenko’ as a complex source of resistance powdery mildew and high marketable and taste qualities of berries; SS 1426-21-80 as a source of high productivity and long racemes (raceme length 11-13 cm; up to 20 berries in the raceme). On their base the selection family of red currant has been developed: Belaya Potapenko × ♂SS 1426-21-80. The study of data on the destruction of hybrid seedlings of the selection family by powdery mildew showed that in epiphytotic conditions, the percentage of intensity of the disease development varies over the periods of screening from 0.2% in May to 20.4% in June. Such indicators served as a prerequisite for conducting a comparative test of breeding material in the field under artificial infection with powdery mildew. After artificial infection on the background of epiphytosis, the rate of intensity of the disease development increased slightly and amounted to 35.6% for the family. There were 30 highly resistant seedlings in the family, 10 of which have remained stable and highly resistant since 2018. In these plants we can assume the presence of the so-called field resistance, controlled by polygens, each of which does not give a visible effect of stability, but with different combinations determines one or another of its degree. Highly resistant seedlings will be used in further breeding studies to identify new sources of resistance to powdery mildew.

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Resistance to Lettuce Infectious Yellows Virus in Melon

HortScience ◽

10.21273/hortsci.33.3.534b ◽

1998 ◽

Vol 33 (3) ◽

pp. 534b-534

Author(s):

James D. McCreight

Keyword(s):

Cucumis Melo ◽

Dominant Gene ◽

Field Tests ◽

Single Dominant Gene ◽

Limited Data ◽

Sweetpotato Whitefly ◽

Sources Of Resistance ◽

Lettuce Infectious Yellows Virus ◽

Greenhouse Tests

Yellowing of melon (Cucumis melo L.) incited by lettuce infectious yellows virus (LIYV) reduces yield and fruit quality of infected plants. LIYV is transmitted only by the sweetpotato whitefly (Bemisia tabaci Genn.). Two naturally infected field tests indicated several potential sources of resistance to LIYV. PI 124112 and `Snake Melon' had mild symptoms in both field tests whereas PI 313970 was asymptomatic in the test in which it was included. In greenhouse tests using controlled inoculation, PI 313970 was asymptomatic, had negative ELISA assays for LIYV, and was negative for LIYV in serial transfers to Chenopodium. `Top Mark' and `PMR 5' were symptomatic, had positive ELISA assays for LIYV, and were positive for LIYV in serial transfers to Chenopodium in these greenhouse tests. Limited data indicate that resistance in PI 313970 is conditioned by a single, dominant gene.

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