|NOTICE OF RELEASE OF FC301 MONOGERM, O-TYPE SUGARBEET GERMPLASM WITH RESISTANCE TO RHIZOMANIA AND CERCOSPORA LEAF SPOT|
The USDA Agricultural Research Service (ARS), in cooperation with the Beet Sugar Development Foundation (BSDF), announces the release of FC301 sugarbeet germplasm. This germplasm was developed in the breeding programs of Drs. Lee Panella and R. T. Lewellen, USDA-ARS, Fort Collins, Colorado, and Salinas, California. FC301 is a germplasm with a moderate frequency of the Rz allele conferring resistance to rhizomania caused by Beet necrotic yellow vein virus. It has been selected for resistance to cercospora leaf spot caused by Cercospora beticola Sacc., and has moderate resistance to black root caused by Aphanomyces cochlioides Drechsl., and the Beet curly top virus (BCTV). FC301 is a population from which to select disease resistant, monogerm, O-type parents to infuse multiple disease resistance on the female side of hybrids. There is no CMS equivalent. FC301 is released from Salinas seed production 01-FC123, and has been tested as 00-FC123 and 01-FC123.
FC301 is an O-type germplasm segregating for hypocotyl color (94% R-) and for monogerm (90% mm). Two crosses were made. The first cross was 'C890'aa x two pollen donors B ' FC607' and 'FC604' (approximately 50 F1 plants) bulked with the cross 'C859'aa x the same two pollen donors (approximately 50 F1 plants). Seed from both F1 populations was combined for bulk increase of the F2 after germination testing to make the parental contribution equal from both female parents. The F2 seed was planted in Fort Collins and 90 mother roots were harvested and selfed. Seventy-five selfed families were produced and planted in the cercospora leaf spot nursery in Fort Collins, and in the BCTV nursery in Kimberly, ID. Based on performance in these nurseries, three populations were developed B two containing the best five families for leaf spot resistance and BCTV resistance and one population containing the five families that had the best performance in both nurseries. Mother roots were dug from the Fort Collins cercospora leaf spot nursery and seed was produced in the greenhouse.
These three populations were sent to Salinas, where, combined, selections were made for rhizomania resistance; resistance to Erwinia root rot caused by E. carotovora betavasculorum Thomsen et al.; powdery mildew caused by Erysiphe polygoni DC, agronomic performance; and percent sucrose. The selected roots from these three populations were inter-pollinated, and monogerm and multigerm seed was separated forming two populations 99-1,2,3 M and 99-1,2,3 m. Seed from the monogerm population was either sent to Oregon for steckling production or planted in the Salinas rhizomania nursery. Stecklings were obtained from Oregon in June, 2002, and male-fertile, high quality monogerm plants were selected near anthesis and individually selfed to produce S1 progeny, while being crossed simultaneously an annual male-sterile tester. The F1 hybrids were indexed for O-type in December, 2000, and found to be uniformly male-sterile, suggesting that fertility restorer genes were present at only a low frequency, and O-type selection was unnecessary. Seed of the population and the S1 progenies was planted the Oregon steckling nursery and the Salinas rhizomania nursery in August, 2000. From the Salinas rhizomania nursery, S1 plants from within S1 progenies and plants from the population were selected for resistance to rhizomania. Concurrently, during this time, seed from the original Fort Collins population, which had been selected strictly for leaf spot resistance and then re-selected for leaf spot resistance using the leaf disc method, was planted also in the Salinas rhizomania nursery and Oregon steckling nursery. In March 2001, induced, selected plants from Salinas and stecklings from Oregon were pooled and recombined through the male-sterile plants from all three phases. There was nearly equal representation from the new Fort Collins cercospora leaf spot population, the S1 lines, and the population selected for resistance to rhizomania. Seed from the male-sterile plants was harvested separately and the composite called 01-FC123. 01-FC123 seed was released as FC301. Half-sib family grow outs indicated that the male-sterility was mixed genetic male-sterility (aa) and genetic-cytoplasmic male-sterility (CMS). Progeny testing could be used to identify and separate genetic sterility from CMS, and to isolate a near equivalent CMS counterpart to the male-fertile, O-type.
In a greenhouse test for resistance to sugar beet root aphid (Pemphigus sp.) at Shakopee, MN, in 2003, the population was not different from the susceptible control although there were a number of roots which were scored as 1 (1 = free from aphids to 4 = heavily infested with aphids). When tested in Fort Collins, CO, and Rosemount, MN, in 2002 and 2003 for resistance to cercospora leaf spot in an artificial epiphytotic, the scores were either intermediate (significantly more resistant than the susceptible check and significantly less resistant than the resistant check) or not significantly different from the resistant check. The same level of resistance was seen when tested at Shakopee, MN, in 2003 for resistance to Aphanomyces root rot. In the BSDF curly top nursery at Kimberly, ID, in 2003 FC301 had a DI of 4.3 over three replications (not statistically analyzed) compared to US H11 with a DI of 3.3 and Monohikari with a DI of 7.0 (1 = no damage to 9 = plant dead). When tested at Fort Collins, CO, in 2003 for resistance to rhizoctonia root rot under strong disease pressure the FC301 population was not significantly different from the susceptible check.
In observation and evaluation tests at Salinas in 2002 B 2003, FC301 was moderately susceptible to powdery mildew; intermediate in reaction to Erwinia root rot with 50 B 65% resistant plants; and moderately resistant to intermediate for bolting tendency in fall plantings. Sucrose concentration was moderately low in comparison to a group of monogerm populations and inbred lines.
Breeder seed of FC301 is maintained by USDA-ARS and will be provided in quantities sufficient for reproduction upon written request to Sugarbeet Research, USDA-ARS, Crops Research Laboratory, 1701 Center Ave., Fort Collins, CO 80526-2083. Genetic material of this release will be deposited in the National Plant Germplasm System where it will be available for research purposes, including development and commercialization of new varieties/cultivars. We request that appropriate recognition be made of the source when this germplasm contributes to a new cultivar. U.S. plant variety protection will not be requested for FC301.
Acknowledgement: Tests at Shakopee and Rosemount, MN were run by Betaseed, Inc. by M. Rekoske and J. Miller, and reaction to BCTV was tested in the BSDF nursery at Kimberly, ID.