Abstract
Russian wheat aphid, Diuraphis noxia (Kurdjumov), is a severe pest of wheat, Triticum aestivum L., throughout the world. Resistant cultivars are viewed as the most economical and environmentally viable control available. Studies to identify molecular markers to facilitate resistance breeding started in the 1990s, and still continue. This paper reviews and discusses the literature pertaining to the D. noxia R-genes on chromosome 7D, and markers reported to be associated with them. Individual plants with known phenotypes from a panel of South African wheat accessions are used as examples. Despite significant inputs from various research groups over many years, diagnostic markers for resistance to D. noxia remain elusive. Factors that may have impeded critical investigation, thus blurring the accumulation of a coherent body of information applicable to Dn resistance, are discussed. This review calls for a more fastidious approach to the interpretation of results, especially considering the growing evidence pointing to the complex regulation of aphid resistance response pathways in plants. Appropriate reflection on prior studies, together with emerging knowledge regarding the complexity and specificity of the D. noxia–wheat resistance interaction, should enable scientists to address the challenges of protecting wheat against this pest in future.
Highlights
The Russian wheat aphid (RWA; Diuraphis noxia (Kurdjumov), (Homoptera: Aphididae)) has been known as a severe pest of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) since devastating losses were reported in the Crimea in 1901 [1], as quoted by [2]
The mean phenotypic damage rating for the five example plants from each accession was used to rank them, from most resistant to least resistant to biotype RWASA2, and calculate the standard error of means, which is presented in Table 2 together with postulated potential genes in the accession
The examples presented in this paper indicate that the markers tested did not meet the required level of reliability and repeatability across a panel of resistant and susceptible South African accessions
Summary
The Russian wheat aphid (RWA; Diuraphis noxia (Kurdjumov), (Homoptera: Aphididae)) has been known as a severe pest of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) since devastating losses were reported in the Crimea in 1901 [1], as quoted by [2]. This atypical grain aphid appears throughout the world [3,4,5,6,7,8,9,10,11,12,13,14], following the 2016 report of its arrival in Australia [15]. Climate change and increased crop pest dispersal make finding tools for breeding resistant cultivars so as to control D. noxia more important than ever before
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