2005 RESEARCH REPORT
California Pepper Improvement Foundation/
California Pepper Commission
Title: Breeding for CMV tolerance for bell peppers adapted for California production
Principal Investigator: Molly Jahn (firstname.lastname@example.org), Professor, Dept. of Plant Breeding & Genetics, Cornell University, Ithaca, NY 14853
Personnel: George Moriarty, Research Support Specialist
Duration: May 1, 2005 – April 30, 2006
Requested Funds: $25,000
At the request of the CPIF/CPC, we revived our breeding program focused in the improvement of tolerance to cucumber mosaic virus resistance in bell peppers adapted for open field production in California. We have used the two leading sources of CMV resistance (CMR): C. annuum 'French Perennial', a Perennial line obtained from INRA, France that compared favorably with other versions of Perennial for stability and uniformity of CMR and a selection from this source (CMR 3990); and C. frutescens 'BG2814-6'. At the direction of the CPIF, we are using ëBaroní as the recurrent parent in this phase of the breeding program. Our disease screening protocol involves a cotyledon stage mechanical inoculation followed by two or more subsequent inoculations on older leaves and rouguing of all symptomatic plants until after fruit set. Resistance or tolerance derived from both the C. annuum and the C. frutescens sources refers to the failure to develop symptoms. Although virus titer appears to be substantially reduced in tolerant genotypes relative to fully susceptible genotypes, virus is generally present at levels that are slightly higher than uninoculated controls. To reflect this, we refer to materials we are developing as "tolerant" to CMV. We still feel that the combination of Perennial and the C. frutescens sources gives the highest frequency of symptomless progeny.
We now routinely run F3 progeny screens in order to confirm the tolerance of F2 plants used for backcrossing, since selected tolerant F2 plants give occasionally give low percentages of tolerant offspring. We have virtually no escapes of susceptible check plants (a couple of plants out of many hundreds). We hypothesized that the relatively low numbers of resistant individuals from resistant F2 plants may be due to some incompletely penetrant tolerance to the disease (i.e., the tolerance may be exhibited in the F2 but may fail to be expressed in a genotypically similar plant). We also see incomplete penetrance of CMV tolerance in the C. frutescens source and occasionally in Perennial.
When notice came about the California pepper commissionís renewed interest in CMV resistance we already had a program in place for an early maturing red bell with CMV resistance for the Northeast. We were using King of the North and a selection from Early Red Sweet as recurrent parents. For this program, we used best material from the original work with CalPep in the 1990s which was planted and re-screened for resistance. The variety Baron was crossed into both the CalPep and the Northeast populations. Selections from both populations were sent to Bob Heisey for testing and crossing as well. The list of pedigrees for the newly generated populations is below.
Populations generated in 04-05 in Ithaca
Resistant plants X Baron
|K.O.N. X [Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-2]F2 X CMR3990)F4 X Baron|
|[Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F3] X K.O.N. F4 X BARON)F1|
|[Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F2 X CMR 3990 F2 x KON Bc1F2) X BARON)F1|
|K.O.N. X [Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-2]F2 X CMR 3990 F1)F2 X KON}Bc1 F2 X BARON)F1|
|K.O.N. X [Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F3)F4 X BARON)F1|
|K.O.N. X [Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F3)F2 X E.R.S)F2. X BARON)F1|
|K.O.N. X [Gad x (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-11]F2 X CMR 3990 F1) F2 X Yankee Bell)F2 X BARON)F1|
|[Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F3] X K.O.N.) F2 X E.R.S.)F2 X BARON)F1|
|[Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F3] X K.O.N. F2 X KON X BARON)F1|
KON (King of the North)
ERS (Early Red Sweet selection from Minnesota)
All 31 F1 populations generated in Ithaca were planted in the field in 2005 without virus pressure and selected for earliness, habit and large blocky fruit. Out of these populations 29 individual plant selections were made for F2 populations to be tested in the 05-06 winter greenhouse plantings. Several of the Northeast breeding lines were also sent to Bob Heisey for testing and crosses to "Baron". The F1s were increased in the greenhouse and F2s were sent to Ithaca for winter virus testing.
Populations generated in 04-05 by Bob Heisey
|K.O.N. X [Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F3)F4 X Baron|
|[Gad X (Ver X (Ver X (Jup X (14-6 X F.Per))-18)F2-4)F2-4]F3] X K.O.N. F4 X Baron|
For the 05–06 winter screens 50+ seed of each of the F2 families (82 families total) were planted in seedling flats. All plants were inoculated the first time in the cotyledon stage and again one week later. Two weeks post-inoculation all plants were classified, symptomatic plants were discarded and all symptomless plants were transplanted to 72 cell trays for further development. Resistant individuals will be selfed and crossed to Baron to develop F3 and BC1 F1 populations. The F3 populations will be inoculated and transplanted to the field for selection. BC1 F1 lines will be planted without inoculation and selected for type. A few F1 populations between Baron and CMR3990 are being selfed to generate F2 populations that will be included in the spring screens and field plantings.
Initial results are below.
|Row #||pedigree||# resistant||# susc||Total plants||% resistant|
Populations developed in Ithaca (pedigrees 1–9) had to be restarted and inoculated due to virus culture contamination. These populations have not been classified yet.