TY - JOUR
T1 - Defence gene expression and phloem quality contribute to mesophyll and phloem resistance to aphids in wild barley
AU - Leybourne, Daniel J.
AU - Valentine, Tracy A.
AU - Robertson , Jean A. H .
AU - Pérez-Fernández, Estefania
AU - Main , Angela M .
AU - Karley, Alison J.
AU - Bos, Jorunn I. B.
N1 - D.J.L was funded by the James Hutton Institute and the Universities of Aberdeen and Dundee through a Scottish Food Security Alliance (Crops) PhD studentship. A.J.K, T.A.V, A.H.J.R, A.M.M, and E.P-F were supported by the strategic research programme funded by the Scottish Government’s Rural and Environment Science and Analytical Services Division. J.I.B.B. was supported by the European Research Council (310190-APHIDHOST). We would like to thank Dr Freddy Tjallingii (EPG Systems, The Netherlands), Professor Alberto Fereres (CSIC, Spain) and Professor Gregory Walker (University of California, Riverside, USA) for providing EPG training and Gaynor Malloch (James Hutton Institute) for kindly providing COI barcoding primers.
PY - 2019/8/1
Y1 - 2019/8/1
N2 - Aphids, including the bird cherry-oat aphid (Rhopalosiphum padi), are significant agricultural pests. The wild relative of barley, Hordeum spontaneum 5 (Hsp5), has been described to be partially resistant to R. padi, with this resistance proposed to involve higher thionin and lipoxygenase gene expression. However, the specificity of this resistance to aphids and its underlying mechanistic processes are unknown. In this study, we assessed the specificity of Hsp5 resistance to aphids and analysed differences in aphid probing and feeding behaviour on Hsp5 and a susceptible barley cultivar (Concerto). We found that partial resistance in Hsp5 to R. padi extends to two other aphid pests of grasses. Using the electrical penetration graph technique, we show that partial resistance is mediated by phloem- and mesophyll-based resistance factors that limit aphid phloem ingestion. To gain insight into plant traits responsible for partial resistance, we compared non-glandular trichome density, defence gene expression, and phloem composition of Hsp5 with those of the susceptible barley cultivar Concerto. We show that Hsp5 partial resistance involves elevated basal expression of thionin and phytohormone signalling genes, and a reduction in phloem quality. This study highlights plant traits that may contribute to broad-spectrum partial resistance to aphids in barley.
AB - Aphids, including the bird cherry-oat aphid (Rhopalosiphum padi), are significant agricultural pests. The wild relative of barley, Hordeum spontaneum 5 (Hsp5), has been described to be partially resistant to R. padi, with this resistance proposed to involve higher thionin and lipoxygenase gene expression. However, the specificity of this resistance to aphids and its underlying mechanistic processes are unknown. In this study, we assessed the specificity of Hsp5 resistance to aphids and analysed differences in aphid probing and feeding behaviour on Hsp5 and a susceptible barley cultivar (Concerto). We found that partial resistance in Hsp5 to R. padi extends to two other aphid pests of grasses. Using the electrical penetration graph technique, we show that partial resistance is mediated by phloem- and mesophyll-based resistance factors that limit aphid phloem ingestion. To gain insight into plant traits responsible for partial resistance, we compared non-glandular trichome density, defence gene expression, and phloem composition of Hsp5 with those of the susceptible barley cultivar Concerto. We show that Hsp5 partial resistance involves elevated basal expression of thionin and phytohormone signalling genes, and a reduction in phloem quality. This study highlights plant traits that may contribute to broad-spectrum partial resistance to aphids in barley.
KW - Amino acid composition
KW - Hordeum spontaneum
KW - Rhopalosiphum padi
KW - Sitobion avenae
KW - Utamphorophora humboldti
KW - defence gene expression
KW - electrical penetration graph (EPG)
KW - partial resistance
UR - http://www.scopus.com/inward/record.url?scp=85071346696&partnerID=8YFLogxK
U2 - 10.1093/jxb/erz163
DO - 10.1093/jxb/erz163
M3 - Article
C2 - 31173098
SN - 0022-0957
VL - 70
SP - 4011
EP - 4026
JO - Journal of Experimental Botany
JF - Journal of Experimental Botany
IS - 15
ER -