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United States Department of Agriculture

Agricultural Research Service

Title: Registration of Fc720, Fc722, and Fc722cms Monogerm Sugarbeet Germplasm Resistant to Rhizoctonia Root Rot and Moderately Resistant to Cercospora Leaf Spot.

Authors
item Panella, Leonard
item Hanson, Linda

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 8, 2005
Publication Date: March 28, 2006
Citation: Panella, L.W., Hanson, L.E. 2006. Registration of FC720, FC722, and FC722CMS onogerm Sugarbeet Germplasm resistant to Rhizoctonia Root Rot and moderately resistant to Cercospora Leaf Spot. Crop Science.

Interpretive Summary: Sugarbeet germplasms FC720, FC722, and FC722CMS (PI 636335, PI 636336, and PI 636337) were developed by the USDA-ARS, at Fort Collins, CO, in cooperation with the Beet Sugar Development Foundation (BSDF), Denver, CO. FC720 has good resistance to rhizcotonia root rot and good to moderate resistance to cercospora leaf spot, but is not resistant to curly top (BCTV). FC722 has good resistance to rhizcotonia root rot and good to moderate resistance to cercospora leaf spot, but is BCTV susceptible. FC720 and FC722 are populations from which to select rhizoctonia and cercospora resistant, monogerm, O-type parents to infuse some rhizoctonia and leaf spot resistance on the female side of hybrids, and FC722CMS provides a CMS female with these characteristics. FC720 is released from Fort Collins seed production 20001017, FC722 from 19961010HO, and FC722CMS from 19961010HO1. Both FC720 and FC722 germplasm have FC708, a rhizoctonia- and cercospora-resistant monogerm O-type release from the Fort Collins program as one parent. The other parent, C718, is a germplasm released from the USDA-ARS sugarbeet improvement program in Salinas, CA, and is moderately susceptible to virus yellows, moderately resistant to bolting, and moderately resistant to BCTV; it has very good combining ability for root and gross sugar yield.

Technical Abstract: Sugarbeet (Beta vulgaris L.) germplasms FC720, FC722, and FC722CMS (PI 636335, PI 636336, and PI 636337) were developed by the USDA-ARS, at Fort Collins, CO, in cooperation with the Beet Sugar Development Foundation (BSDF), Denver, CO. FC720 has good resistance to root-rotting strains (AG-2-2) of Rhizoctonia solani Kühn and good to moderate resistance to cercospora leaf spot caused by Cercospora beticola Sacc., but is not resistant to the Beet curly top virus (BCTV). FC722 has good resistance to root-rotting strains (AG-2-2) of Rhizoctonia solani and good to moderate resistance to cercospora leaf spot caused by Cercospora beticola, but is BCTV susceptible. FC720 and FC722 are populations from which to select rhizoctonia and cercospora resistant, monogerm, O-type parents to infuse some rhizoctonia and leaf spot resistance on the female side of hybrids, and FC722CMS provides a CMS female with these characteristics. FC720 is an O-type germplasm with 73% green (rr) hypocotyls (26 plants counted) and is segregating for monogerm (mm) and self-sterility (Ss). FC722 is an O-type germplasm with 15% green hypocotyls (rr) (59 plants counted) and is segregating for monogerm (mm) and self-sterility (Ss). Both germplasm have ‘FC708’ (PI 590845), a rhizoctonia- and cercospora-resistant monogerm O-type release from the Fort Collins program as one parent. The other parent, ‘C718’ (PI 590849), is a germplasm released from the USDA-ARS sugarbeet improvement program in Salinas, CA, and is moderately susceptible to virus yellows, moderately resistant to bolting, and moderately resistant to BCTV; it has very good combining ability for root and gross sugar yield. FC720 is a product of six generations of mass selection for rhizoctonia resistance within the cross (C718//(C718/FC708)). The initial population had 25% of its genes from FC708 and 75% from C718. FC722 also is a product of six generations of cyclic mass selection for rhizoctonia root rot resistance. The source population was the cross C718/FC708; and the initial population had 50% of its genes from FC708 and 50% from C718. FC722CMS is the genetic-cytoplasmic male sterile (CMS) equivalent of FC722 backcrossed nine times. The original cross was C718CMS/FC708. It was backcrossed continually to the populations, from which FC722 was derived, and went through five generations of cyclic mass selection for rhizoctonia root rot resistance.

Last Modified: 7/28/2014
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