Solanum lycopersicoides is a valuable genetic resource for tomato (Lycopersicon esculentum) genetic improvement. However, there are few reports on its agronomic traits such as disease resistance and cold tolerance. In this paper, the resistance to cucumber mosaic virus (CMV) and leaf mold (Cladosporium fulvum Cooke) and cold tolerance of five lines of S. lycopersicoides were studied through investigation of disease inoculation and electrolyte leakage analysis. The results showed that S. lycopersicoides was highly resistant or immune to CMV and leaf mold and more tolerant to low temperature than L. esculentum. This study is helpful for the genetic improvement of tomato by using S. lycopersicoides as breeding materials.
Lingxia Zhao, Chengxiang Qiu, Jingfu Li, Yourong Chai, Guoyin Kai, Zhugang Li, Xiaofen Sun and K.X. Tang
Stephen R. King, Angela R. Davis, Wenge Liu and Amnon Levi
can sometimes be a solution on its own for soilborne diseases and can often be part of an integrated solution. Some researchers have even found grafting to be an advantage over methyl bromide as a result of comparable disease resistance, reduced
Shawn A. Mehlenbacher
55 COLLOQUIUM 2 (Abstr. 995-999) Classical and Molecular Approaches to Breeding Horticultural Plants for Disease Resistance
Gayle M. Volk, Christopher M. Richards, Ann A. Reilley, Adam D. Henk, Patrick A. Reeves, Philip L. Forsline and Herb S. Aldwinckle
particularly damaging to apple crops. Some resistant cultivars are available to breeding programs, but additional sources of resistance are desirable. Phenotypic screening is the primary source of disease resistance data for Malus collections, but specific
Thomas G. Beckman, Philip A. Rollins, James Pitts, Dario J. Chavez and Jose X. Chaparro
-29’ has moved into commercial production and is now being offered by several nurseries in Tennessee, Florida, and California. The testing of the disease resistance and other attributes of ‘MP-29’ has continued in researcher and grower trials. The
D.J. Norman, R.J. Henny and J.M.F. Yuen
Twenty commonly grown Dieffenbachia cultivars were tested for their resistance to diseases affecting production caused by the following bacterial and fungal pathogens: Xanthomonas campestris pv. dieffenbachiae (McCulloch and Pirone) Dye, Erwinia chrysanthemi Burk, Fusarium solani Sacc, and Myrothecium roridum Tode ex Fr. Two isolates of each pathogen were used to compare heterogenic pathogen populations to the relatively homogenetic asexually produced cultivars. Cultivars having horizontal resistance toward tested pathogens could then easily be identified. The cultivars Camille, Compacta, and Parachute showed the broadest horizontal resistance, with resistance toward three of the four pathogen groups tested. Disease resistance identified in this research permits the selection of plants to be used in breeding, and also creates a baseline to compare resistance of newly developed cultivars.
Karen R. Harris, W. Patrick Wechter and Amnon Levi
genetic markers linked to resistance genes have been identified in watermelon ( Harris et al., 2009 ; Ling et al., 2009 ; Xu et al., 1999 ). Disease resistance genes (R-genes) have been cloned from several model plant species (reviewed in McHale et al
Linda Gombert, Mark Windham and Susan Hamilton
Fifty-seven cultivars of zinnia (Zinnia elegans Jacq.) were studied for 17 weeks to determine their resistance to alternaria blight (Alternaria zinniae Pape), powdery mildew (Erysiphe cichoracearum DC ex Merat) and bacterial leaf & flower spot [Xanthomonas campestris pv. zinniae (syn. X. nigromaculans f. sp. zinniae Hopkins & Dowson)]. A disease severity scale was used to determine acceptability for landscape use. At week 4, all cultivars were acceptable. At week 10, eleven cultivars were acceptable. At week 17, all cultivars were unacceptable. Ten cultivars had been killed by one or more pathogens by week 17. Only two cultivars showed any tolerance to any disease (powdery mildew) at week 17.
Zhanyuan Zhang, D.P. Coyne and A. Mitra
Gene transfer can provide plants with a novel source of disease resistance. Two different antibacterial peptides, Shiva-1 and lactoferrin, were tested in vitro for antibacterial activity. The former is from cecropin B in insects, and the latter from human or mammal fluids such as milk. Both peptides exhibited high antibacterial activity against all tested gram-negative phytopathogenic bacterial strains. Lactoferrin was more lethal than Shiva-1. A particular lactoferrin domain showed a much higher activity against bacterial strains. A gene encoding lactoferrin was then transferred to Nicotinia tabacum L. xanthi-nc to evaluate the gene expression using Agrobacterium. Stable transformation was confirmed by Southern, Northern, and Western blot analysis. Delayed wilting of the transgenic plants inoculated with Pseudomonas solanacearum was observed. A significant positive relationship between the gene expression levels and resistance was also found by either Northern or Western blotting. Biolistic transformation using a gene gun is currently underway to transfer this novel gene to common beans.
J.M. Sherman, K.S. Reddy, S.E. Newman and J.A. Spencer
Most modern roses are highly susceptible to the disease blackspot caused by the fungus Diplocarpon rosae. This contrasts to species roses that are resistant to the disease. To gain information on the biochemical factors in this resistance mechanism, we are studying the involvement of proteins. Soluble proteins of modern roses and species roses were extracted and analyzed by SDS-PAGE. When healthy leaves were examined, there were no distinct differences in the protein patterns, indicating that there are no constitutive proteins involved in the disease resistance mechanism. There were no differences between healthy and infected leaves of resistant genotypes. When detached leaves of some susceptible types were infected with the fungus new proteins seemed to appear in the healthy region surrounding the blackspot lesion. These proteins may be involved in resisting the spread of the pathogen.