The Resistant Soybean-Aphis glycines Interaction: Current Knowledge and Prospects

Abstract

Soybean aphids (Aphis glycines Matsumura) are invasive insect pests of soybean, and they cause significant yield losses. Resistance to soybean aphids is conferred by Resistance to Aphis glycines (Rag) genes. Since the first discovery of aphid-resistant soybean genotypes in 2004, several studies have attempted to characterize Rag genes from aphid-resistant soybean genotypes. To date, 12 Rag genes and four quantitative trait loci for aphid resistance have been reported on soybean chromosomes 07, 08, 13, 16, and 17. Although candidate genes have been proposed for several discovered Rag loci, additional studies are needed to pinpoint, validate, and further explain the potential mechanisms of Rag gene action. A major challenge to utilizing host plant resistance is the discovery of virulent aphid biotypes that can colonize aphid-resistant soybean. This occurrence suggests the need for additional studies to devise strategies to enhance the effectiveness of aphid-resistant soybean. In this mini review, we discuss current knowledge on the resistant soybean-Aphis glycines interaction, potential mechanisms of Rag gene action, opportunities to discover new Rag genes, and prospects for utilization of host plant resistance to manage soybean aphids. A clearer understanding of host plant resistance to soybean aphids will guide researchers on strategies for developing soybean varieties with more durable aphid resistance, reducing the present challenge of virulent aphid biotypes.

Transcriptome analysis of aphid-resistant and susceptible near isogenic lines reveals candidate resistance genes in cowpea (Vigna unguiculata)

“…Other aphid resistance genes identified are linked to both antibiosis and antixenosis components, such as the Rag genes in soybean (Glycine max) that confer resistance to the soybean aphid (Aphis glycines). Of the12 Rag genes identified, Rag1 and Rag5 are two R genes that mediate antibiosis and antixenosis components [30][31][32][33].…”

Soybean (Glycine max L Merr) host-plant defenses and resistance to the two-spotted spider mite (Tetranychus urticae Koch)

“…The association of aphid resistance in soybean with phytochemical defenses is not as common as it is with 5 resistance genes ( Rag 1 - Rag 5 ) that are correlated with negative effects to biology and behaviour [ 31 ]. A recent review of the potential mechanisms of Rag gene action summarized that the induction of these genes is related to secondary metabolite production, but the metabolites (isoflavonoids, phenolics, and others) levels were not correlated with changes in aphid feeding behavior in order to advance knowledge on host plant resistance [ 32 ]. Currently, there is no known genetic association with resistance to TSSM so the cultivars screened in the present research were compared by leaf chemistry.…”

The Source of Rag5-Mediated Resistance to Soybean Aphids Is Located in the Stem

“…The use of detached leaves has been proposed as a more rapid and practical assay to screen germplasm for resistance to aphids. Several studies have shown no significant differences in aphid performance on detached leaves than intact plants, but these studies used only susceptible plants (MacKinnon, 1961;Nam and Hardie, 2012;Soffan and Aldawood, 2014;Li and Akimoto, 2018). When detached leaf assays are performed with resistant plants, contrasting results are observed.…”