Basic Information - Genetics, Genomics and Breeding of Crop Plants - page 33

subset contains two ornamental accessions, seven breeding lines, 12
landraces, and 91 cultivars. Researchers may initially use the core collection
to determine traits of interest and, pending the results of their research,
request additional accessions from one or more clusters to explore indepth
at a later date.
1.5.5 Wild Species Utilization
1.5.5.1 Pathogen Resistance
Wild sunflower species have been a valuable source of resistance genes for
many of the common pathogens of cultivated sunflower. Helianthus annuus ,
H. petiolaris , and H. praecox are the major sources of genes for Verticillium
wilt resistance (Hoes et al. 1973). These species plus H. argophyllus are also
the major sources of resistance genes for downy mildew and rust in cultivated
sunflower. Resistance genes for these pathogens occur frequently in the
wild annual species (Tan et al. 1992; Quresh et al. 1993). Resistance to
broomrape has been observed in most of the wild perennial species
(Fernández-Martínez et al. 2000). Early reports of broomrape resistance were
from the FSU where they developed cultivars Progress and Novinka using
the “Group Immunity” breeding approach (Pustovoit and Gubin 1974).
Phoma black stem ( Phoma macdonaldii ) resistance has been reported in several
perennial species, H. decapetalus , H. eggertii , H. hirsutus , H. resinosus and H.
tuberosus (Skoric 1985). Phomopsis stem canker ( Phomopsis helianthi Munt-
Cvet. et al.) resistance has been found in perennials H. maximiliani , H.
pauciflorus , H. hirsutus , H. resinosus , H. mollis , and H. tuberosus (Skoric 1985;
Dozet 1990). Alternaria leaf spot [ Alternaria helianthi (Hansf.) Tubaki and
Nishihara] resistance was observed in perennials H. hirsutus, H. pauciflorus ,
and H . tuberosus (Morris et al. 1983). Rhizopus head rot ( Rhizopus arrhizus
Fischer) resistance was observed in perennials H. divaricatus , H. hirsutus , H.
resinosus , and H. x laetiflorus (Yang et al. 1980) . Powdery mildew ( Erysiphe
cichoracearum ) resistance was observed in annuals H. debilis ssp. debilis , H.
bolanderi , and H. praecox (Saliman et al. 1982; Jan and Chandler 1985).
Sclerotinia head rot ( Sclerotinia sclerotiorum ) tolerance was observed in
perennials H. resinosus, H. tuberosus, H. decapetalus , H. grosseserratus , H.
nuttallii , and H. pauciflorus (Pustovoit and Gubin 1974; Mondolot-Cosson
and Andary 1994; Ronicke et al. 2004). Sclerotinia root rot tolerance was
observed in perennials H. mollis , H . nuttallii , H . resinosus , and H. tuberosus
(Skoric 1987). Sclerotinia stalk rot tolerance was observed in annual H. praecox ,
and perennials H. pauciflorus , H. giganteus , H. maximiliani , H . resinosus , and
H . tuberosus (Skoric 1987). Stalk rot resistance has been identified in hexaploid
perennial H . californicus and is being transferred into cultivated sunflower
(Feng et al. 2006). Five interspecific amphiploids derived from perennial