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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Crop Germplasm Research » Research » Publications at this Location » Publication #331129

Research Project: Pecan Improvement through Breeding and Genetics

Location: Crop Germplasm Research

Title: Characterization of partial resistance to black spot disease of Rosa spp.

Author
item Dong, Qianni - Texas A&M University
item Wang, Xinwang
item Byrne, David - Texas A&M University
item Ong, Kevin - Texas A&M University

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: Black spot (BS) is one of the most serious diseases of garden roses. There are no completely effective chemicals to control this disease in the rose nursery. Although this disease can be visible at the adult stage of the rose growth, it is necessary to diagnose it at the early stage of the rose growth in order to decrease the BS damage for rose production. To accurately diagnose the BS, both lab (detached leaf assay, DLA) and field (whole plant inoculation, WPI) detection methods were compared. The results showed both DLA and WPI are good to detect the BS disease at the early growth stage, with the DLA being a simple, fast method for use in the rose nursery and industry.

Technical Abstract: Black spot disease (BSD) is one of the most serious diseases of garden roses. Both complete (vertical) resistance and partial (horizontal) resistance have been identified in 16 rose genotypes using two laboratory assays, the detached leaf assay (DLA) and the whole plant inoculation (WPI) approaches. The results indicated that these two approaches were well correlated in the characterization of the BSD resistance in the given genotypes. Thus either method could be used to assess the resistance of the plants to the BSD. Fifteen diploid hybrid populations from 10 parents segregating for black spot partial (horizontal) resistance were assessed for black spot resistance by quantifying the percentage of the leaf area with symptoms (LAS) and lesion length (LL) measured by the diameter of the largest lesion in detached leaf assays. Nine of these populations were also evaluated in field trials by rating the incidence of damage due to the fungal infection. The narrow sense heritability of partial resistance to black spot as measured by LAS and LL data of DLA was estimated from 0.3 to 0.4 when calculated with a genetic variance analysis and from 0.7 to 0.9 when generated from mid-parent offspring regression.