Feeding Behavior of Russian Wheat Aphid (Hemiptera: Aphididae) Biotype 2 in Response to Wheat Genotypes Exhibiting Antibiosis and Tolerance Resistance

Abstract

In this study, wheat, Triticum aestivum L. (em Thell), genotypes containing the Dnx, Dn7, Dn6, and Dn4 genes for resistance to the Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae), along with Dn0, a susceptible control, were assessed to determine the categories of D. noxia biotype 2 (RWA2) resistance in each genotype and RWA2 feeding behaviors on Dnx and Dn0 plants by using the electronic penetration graph technique. At 14 d postinfestation, Dn0 plants exhibited intense chlorosis and leaf rolling, and all test genotypes expressed some degree of chlorosis and leaf rolling, except Dn7, which was not damaged. Both Dn7 and Dnx expressed antibiosis effects, significantly reducing the numbers of aphids on plants and the intrinsic rate of aphid increase. Dn6 plants seemed to contain tolerance, exhibiting tolerance index measurements for leaf and root dry weight and plant height that were significantly lower than those of the susceptible Dn0 plants. Principal component analyses indicated that antibiosis and leaf rolling data explained 80% of the variance among genotypes. Electronic penetration graph analysis demonstrated contrasting results between RWA1 and RWA2 phloem sieve element phase feeding events, but results indicated that Dnx resistance factors are present in the sieve element cells or phloem sap. Plants containing Dnx exhibit antibiosis resistance to D. noxia RWA2 similar to that in plants containing the Secale cereale L. (rye)-based Dn7 gene without the negative baking quality traits associated with Dn7.

Wheat Gene Expression is Differentially Affected by a Virulent Russian Wheat Aphid Biotype

“…However, results of Lazzari et al (2009) indicated that sustained ingestion of wheat phloem by D. noxia occurs within 1 h after initiation of feeding probes during compatible interactions and within 2 h after the beginning of feeding in incompatible interactions. Couldridge et al (2007) demonstrated the expression of Arabidopsis esterase and extracellular glycoproteins in compatible interactions with the green peach aphid, Myzus persicae (Sulzer) at 2 hpi.…”

“…This event was designated as the zero time point. Results of previous EPG experiments indicate that there are no significant differences between D. noxia resistant-and susceptible plants for the mean time until initiation of the first D. noxia probe or the mean interval from the first probe to the first sieve element phase feeding event (Lazzari et al, 2009).…”

“…During compatible interactions with D. noxia, susceptible wheat plants react to saliva injection by failing to unfurl leaves longitudinally around the main leaf vein, thus forming a tubular refuge that protects D. noxia from predators; plants suffer extensive leaf chlorophyll and carotenoid loss (Burd and Elliot, 1996;Heng-Moss et al, 2003). During incompatible interactions involving resistant plants, chlorophyll loss is minor, and D. noxia population growth is significantly reduced (Khan et al, 2009;Lazzari et al, 2009). Although several D. noxia resistance genes exist in barley and wheat, virulent D. noxia populations occur on all continents except Australia .…”

Comparative gut transcriptome analysis reveals differences between virulent and avirulent Russian wheat aphids, Diuraphis noxia

“…This result suggests that RWA2 gut transcriptome diversity may be related to the increased survival of RWA2 known to occur on RWA1-resistant wheat plants containing the Dn4 resistance gene (Haley et al 2004;Weiland et al 2008;Lazzari et al 2009). …”

“…Other than differential plant foliar damage (Burd et al 2006, Haley et al 2004 and related differences in the feeding behavior, growth and survival of different D. noxia biotypes (Khan et al 2009, Lazzari et al 2009), little is known about the ecological and genetic factors underlying the development of D. noxia biotypes. Therefore, we investigated alterations in the D. noxia gut transcriptome that may identify genes involved in D. noxia-wheat interactions.…”