Articles
SCREENING LEUCOSPERMUM HYBRIDS FOR TOLERANCE TO PHYTOPHTHORA CINNAMOMI
Article number
602_15
Pages
113 – 117
Language
English
Abstract
The goal of the University of Hawaii College of Tropical Agriculture and Human Resources (CTAHR) Leucospermumí breeding program is the development of hybrids with improved horticultural traits, including disease resistance. CTAHR hybrids selected for desirable floral and foliar characteristics were screened for their resistance to the soil-borne fungal pathogen Phytophthora cinnamomi (Pc), which causes a serious root and crown disease on Leucospermum in Hawaii.
Cultivars from South Africa and L. cuneiforme lines from Hawaii were also evaluated for resistance to Pc. Potted Leucospermum cuttings were inoculated with isolates of Pc collected from Maui, Hawaii fields.
Five of the 28 CTAHR hybrids screened were highly sensitive to Pc, with plant death occurring within four months of inoculation.
Eight CTAHR hybrids are tentatively categorized as moderately sensitive, with inoculated plants showing depressed vigor compared to uninoculated controls.
Twelve CTAHR hybrids were not affected by inoculation after six months.
Several of the hybrids were sensitive to a foliar disorder that obscured the results of the Phytophthora screening.
The South African cultivars and L. cuneiforme plants had varied responses to inoculation with Phytophthora. The relative tolerance to Pc among the CTAHR hybrids may be influenced by their genealogies.
Certain parent lines including Leucospermum Spider appear to confer a measure of Pc tolerance to their progeny, while other lines may confer sensitivity. This screening identifies hybrids that deserve more rigorous testing of their tolerance to P. cinnamomi.
Cultivars from South Africa and L. cuneiforme lines from Hawaii were also evaluated for resistance to Pc. Potted Leucospermum cuttings were inoculated with isolates of Pc collected from Maui, Hawaii fields.
Five of the 28 CTAHR hybrids screened were highly sensitive to Pc, with plant death occurring within four months of inoculation.
Eight CTAHR hybrids are tentatively categorized as moderately sensitive, with inoculated plants showing depressed vigor compared to uninoculated controls.
Twelve CTAHR hybrids were not affected by inoculation after six months.
Several of the hybrids were sensitive to a foliar disorder that obscured the results of the Phytophthora screening.
The South African cultivars and L. cuneiforme plants had varied responses to inoculation with Phytophthora. The relative tolerance to Pc among the CTAHR hybrids may be influenced by their genealogies.
Certain parent lines including Leucospermum Spider appear to confer a measure of Pc tolerance to their progeny, while other lines may confer sensitivity. This screening identifies hybrids that deserve more rigorous testing of their tolerance to P. cinnamomi.
Publication
Authors
P. Nakao, K. Leonhardt, N. Nagata, P. Shingaki
Keywords
Protea, Proteaceae, pincushion flower, disease resistance, disease tolerance, inoculation
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