Resistance studies in pepper (Capsicum spp.) and melon (Cucumis melo)

Four independent resistance studies are described. Translation initiation factors eIF4E and eIF(iso)4E have been shown to interact with the multifunctional potyvirus protein NIa, and to be critical host factors in potyviral infection. We show that mutations in the eIF4E homolog eIF4E-687 result in broad-spectrum potyvirus resistance conferred by the Capsicum resistance gene pvr1. Two other resistance genes with narrower resistance spectra, pvr21 and pvr22, were determined to be alleles at the pvr1 locus, and were re-designated pvr11 and pvr12. Mutations in pvr1, pvr11 and pvr12 grouped to similar regions of the gene, and were predicted by protein homology models to cause conformational shifts in the encoded proteins. Disruption in NIa binding was evident for all three resistance alleles, while cap-binding was also disrupted for the pvr1 allele. Interaction assays suggest, however, that potyvirus resistance is not correlated with disruption of NIa-binding or cap-binding ability of eIF4E-687.; Inheritance and allelism studies demonstrate that five distinct genes in melon confer monogenic resistance to foliar infection by the fungal pathogen Didymella bryoniae, otherwise known as gummy stem blight. Resistance in (Cucumis melo) accessions PI 482398 and PI 482399 was determined to be monogenic dominant and monogenic recessive, respectively. Allelism studies among four sources of monogenic dominant resistance to gummy stem blight (PI 157082, PI 511890, PI 482398 and PI 140471) indicated that these four genes segregate independently.; Greenhouse screening for resistance to green peach aphid (GPA) ( Myzus persicae) found significant differences among Capsicum accessions for damage rating, number of aphids/plant and number of aphids/leaf. Reported sources of aphid resistance supported high levels of GPA colonization and damage. High levels of tolerance were observed, however, among several C. annuum commercial varieties and sources of virus resistance.; Greenhouse screening for resistance to European corn borer (ECB) ( Ostrinia nubilalis) conducted among Capsicum accessions found that resistance to fruit damage was associated with increasing pungency level, with two notable exceptions. The pungent cultivar ‘Large Red Thick Cayenne’ was significantly more damaged than many of the other pungent accessions tested, while the sweet pepper ‘Corno di Toro’ showed significantly lower percent fruit damage than other non-pungent peppers.