Virus-Induced Gene Silencing Suggests (1,3;1,4)-β-glucanaseIs a Susceptibility Factor in the Compatible Russian Wheat Aphid–Wheat Interaction

Abstract

The Russian wheat aphid (RWA), Diuraphis noxia (Kurdjumov), is a significant insect pest of wheat (Triticum aestivum L.) and has a major economic impact worldwide, especially on winter wheat in the western United States. The continuing emergence of new RWA biotypes virulent to existing resistance genes reinforces the need for more durable resistance. Studies have indicated that resistance in previously susceptible plants can be produced by knock-down of susceptibility genes or other genes involved in host plant susceptibility. Therefore, investigation into genes involved in compatible RWA-wheat interactions could be a feasible approach to achieving durable RWA resistance. The objective of this study was to test whether silencing (1,3;1,4)-β-glucanase, previously observed to be highly induced in susceptible compared with resistant wheat during aphid infestation, would confer resistance to a susceptible wheat genotype. Barley stripe mosaic virus-mediated virus-induced gene silencing was employed to test whether (1,3;1,4)-β-glucanase is involved in the susceptible reaction of 'Gamtoos-S' (GS). Controlled infestation with U.S. biotype RWA2 was done to assess aphid reproduction and host symptom development. Aphids on (1,3;1,4)-β-glucanase-silenced plants reproduced less per day and had longer prenymphipositional periods than those on control GS plants. Furthermore, the (1,3;1,4)-β-glucanase-silenced plants exhibited less chlorosis and greater dry weight compared with GS. Aphid reproduction and host plant symptom development showed linear relationships with (1,3;1,4)-β-glucanase transcript levels. Our results suggest that (1,3;1,4)-β-glucanase is required for successful infestation by the RWA and may be a susceptibility factor that could be exploited as a potential target for RWA resistance breeding.

OXI1 kinase plays a key role in resistance of Arabidopsis towards aphids (Myzus persicae)

“…These findings are in keeping with Anderson et al (2014) who suggest a role for (1,3;1,4)-b-glucanase in susceptibility of wheat to Russian wheat aphid. This hypothesis could be tested using RNAi.…”

The constitutive expression and induction of three β-1,3-glucanases by bird cherry-oat aphid in relation to aphid resistance in 15 barley breeding lines

“…A possible mode of action of b-1,3-glucanases in susceptibility toward phloem feeders might be in the breakdown of induced callose in the sieve tube, as was shown in the interaction between the brown plant hopper and rice (Hao et al 2008). In the case of b-1,3;1,4-glucanases, they may facilitate aphid probing and feeding by cell wall degradation as suggested by Anderson et al (2014). We have results suggesting that b-1,3-glucanase sequences in barley might be susceptibility factors in the interaction with R. padi.…”

“…A b-1,3-glucanase transcript was induced in sorghum upon infestation by greenbug (Schizaphis graminum Rondani) (ZhuSalzman et al 2004;Park et al 2006). Three reports on wheat indicate that b-glucanases might be susceptibility factors in the interactions with greenbug (Reddy et al 2013) or RWA (Botha et al 2010;Anderson et al 2014). A possible mode of action of b-1,3-glucanases in susceptibility toward phloem feeders might be in the breakdown of induced callose in the sieve tube, as was shown in the interaction between the brown plant hopper and rice (Hao et al 2008).…”

Cryptic Virulence and Avirulence Alleles Revealed by Controlled Sexual Recombination in Pea Aphids

“…Such susceptibility genes would need to override the very strong resistance conferred by RAP1. In other insect-plant systems, dominant host susceptibility loci have been reported recently that enable compatibility with Russian wheat aphid or hessian fly (Liu et al 2013;Anderson et al 2014).Additional explanations need to be advanced for the few clones that show opposite changes i.e., decreased virulence on the rNIL host compared with A17. The enhanced resistance shown by rNIL hosts to these clones could relate to genes from DZA315.16 that interact with RAP1-dependent resistance processes.…”

“…Such susceptibility genes would need to override the very strong resistance conferred by RAP1. In other insect-plant systems, dominant host susceptibility loci have been reported recently that enable compatibility with Russian wheat aphid or hessian fly (Liu et al 2013;Anderson et al 2014).…”