Broomrape (Orobanche cumana Wallr.) resistance breeding utilizing wild Helianthus species

Authors: Jan, Chao-Chien; LIU, ZHAO - North Dakota State University; Seiler, Gerald; VELASCO, LEONARDO - Institute For Sustainable Agriculture; PEREZ-VICH, BEGONA - Institute For Sustainable Agriculture; FERNANDEZ-MARTINEZ, JOSE - Institute For Sustainable Agriculture

Submitted to: Helia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2014
Publication Date: 12/1/2014
Citation: Jan, C.C., Liu, Z., Seiler, G.J., Velasco, L., Perez-Vich, B., Fernandez-Martinez, J. 2014. Broomrape (Orobanche cumana Wallr.) resistance breeding utilizing wild Helianthus species. Helia. 37(61):141-150.

Interpretive Summary: Sunflower broomrape is a holoparasitic plant, which parasitizes sunflower roots and constrains sunflower production in many countries. Since broomrape is a highly variable parasite, the breakdown of resistance is a frequent phenomenon, and multiple sources of resistance are needed to control the emerging races. Historically, sunflower breeders have been successful in developing broomrape resistant cultivars, but breeding programs are often based on a few dominant genes, and resistance breakdown caused by the appearance of new virulent races has occurred frequently in recent decades. These rapid race shifts of broomrape since the mid-1990s sent an alarming message to the sunflower community and all sunflower breeders that they lacked critically needed resistance genes to the new races. Wild sunflower species possess valuable resistance genes for sunflower broomrape, especially the 39 largely under-utilized perennial species. Resistance to broomrape race F has been transferred into cultivated background via bridging of interspecific amphiploids from wild perennial species. More recently, a single dominant resistance gene to race G was identified in the annual slow-flowering sunflower and transferred into cultivated HA 89. Interspecific crosses between wild annual species with cultivated lines are relatively easy compared to those involving wild perennial species, which was made easier only after the development of embryo rescue techniques and the subsequent improvement of backcross seed set. Breeding for broomrape resistance is a never ending battle. Since we have a good reservoir of resistance genes in the wild species and tools to mine and transfer them to cultivated sunflower, all that is needed now is a good breeding strategy and a consortium of international collaborators.

Technical Abstract: Wild Helianthus species possess valuable resistance genes for sunflower broomrape (Orobanche cumana Wallr.), especially the 39 largely under-utilized perennial species. Resistance to race F has been transferred into cultivated background via bridging of interspecific amphiploids. More recently, a single dominant resistance gene to race G was identified in annual H. debilis ssp. tardiflorus and transferred into cultivated HA 89. Interspecific crosses between wild annual Helianthus species with cultivated lines are relatively easy compared to those involving wild perennial species, which was made easier only after the development of embryo rescue techniques. Interspecific amphiploids resulting from colchicine treatment of F1 hybrids provides bridging materials for transferring genes without relying on embryo rescue. Among the diploid, tetraploid, and hexaploid perennial species, the speed of gene utilization follows the ploidy level of diploids, tetraploids, and hexaploids due to the time consuming backcrosses required to eliminate the extra chromosomes in the latter two groups. In the development of pre-breeding materials, the retention rate of genetic materials of the wild species is another concern with each additional backcross. For crosses involving tetraploid and hexaploid wild perennials, the use of 2n=51 chromosome F1 or BC1F1 generation as pollen source could accelerate chromosome reduction to 2n=34 in BC1F1 or BC2F1, resulting in useful materials with fewer backcrosses for trait selection.