Patterns of resistance to three cereal aphids among wheats in the genus Triticum (Poaceae)

Abstract

Forty-one accessions of wild and cultivated wheats belonging to 19 Triticum species were tested in the field for resistance to three species of aphids, Rhopalosiphum padi Linnaeus, Sitobion avenae Fabricius and Schizaphis graminum Rondani. Antibiotic resistance was estimated by the increase in biomass of aphids over 21 days on adult plants. Overall resistance was estimated by the plant biomass lost due to aphid infestation. All three species of aphids survived and reproduced on all wheats, and reduced spike biomass compared to uninfested controls. The level of antibiosis varied among wheat species and among accessions, with accessions from three, five and one species showing antibiosis to R. padi, S. avenae and S. graminum, respectively. Overall resistance to the three aphid species was observed in five to seven accessions per aphid species. Resistance was usually specific to one aphid species. The frequency of accessions with antibiosis or overall resistance was associated with the ploidy level of the plant species. Except for overall resistance to R. padi, resistance was highest for diploid species and lowest for hexaploid species. No consistent relationship between resistance and level of domestication was detected. Accessions of the wild wheats, Triticum boeoticum Bois, Triticum tauschii (Coss.) Schmal. and Triticum araraticum Jakubz. exhibited high levels of resistance to aphids, as did Triticum monococcum L. which is derived from T. boeoticum. Nevertheless, individual susceptible or resistant accessions occurred at all levels within the evolutionary tree of wheat.

Triticum monococcumlines with distinct metabolic phenotypes and phloem-based partial resistance to the bird cherry-oat aphidRhopalosiphum padi

“…Ancient diploid wheat genotypes have been shown to have the highest resistance to cereal aphid pests, including R. padi , Sitobion avenae (F.), Schizaphis graminum (Rondani) and Diuraphis noxia (Kurdjumov) (Deol et al , 1995; Di Pietro et al , 1998; Migui & Lamb, 2003; Elek et al , 2012; Crespo‐Herrera et al , 2013) and provide a useful source of material in the search for resistance mechanisms that ultimately may be utilised in hexaploid breeding programmes. Triticum monococcum (L.) lines, in particular, have shown evidence of complete or partial resistance to pathogens and aphids (Spiller & Llewellyn, 1986; Migui & Lamb, 2004; Jing et al , 2007; Elek et al , 2012).…”

Maize landraces recruit egg and larval parasitoids in response to egg deposition by a herbivore

“…1998; Dicke & van Loon 2000; Heil 2008). However, these naturally occurring defence responses may have been lost whilst selective breeding favoured other traits such as yield (Sotelo 1997; Migui & Lamb 2003; Köllner et al. 2008).…”

“…Directly, they produce toxins, digestion inhibitors and herbivore-induced plant volatiles (HIPVs) repellent to phytophagous insects (Duffey & Stout 1996;De Moraes et al 2001;Kessler & Baldwin 2001); indirectly, they use HIPVs to attract natural enemies antagonistic to the herbivores (Turlings et al 1990;Loughrin et al 1995;De Moraes et al1998;Dicke & van Loon 2000;Heil 2008). However, these naturally occurring defence responses may have been lost whilst selective breeding favoured other traits such as yield (Sotelo 1997;Migui & Lamb 2003;Köllner et al 2008). Landraces comprise locally adapted crop germplasm maintained by farmers rather than by breeders.…”

Searching for wheat resistance to aphids and wheat bulb fly in the historical Watkins and Gediflux wheat collections

“…We did not, however, see a difference in average performance of R. padi and S. avenae between the two collections, suggesting that during modern plant breeding, where improvements have focussed mainly on maximising yield, the plant effect on these aphid species has not been altered. In fact it could be inferred that a general loss of resistance traits happened before the rise of landraces, as resistance to aphid species has been reported in a number of diploid ancestors of wheat (Lamb & Migui, 2003; Migui & Lamb, 2004; Radchenko, 2011; Elek et al , 2013). …”