title: Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.
abstract: The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter aphid fecundity in water stresses plants.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Huijuan
authors.initials: H
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China sunyc@ioz.ac.cn gef@ioz.ac.cn.
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Sun
authors.affiliation: College of Agronomy, Jiangxi Agricultural University, Nanchang, China.
authors.forename: Xinhong
authors.initials: X
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Qinyang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Entomology, Texas A & M University, College Station, TX 77843, USA.
authors.forename: Marvin
authors.initials: M
authors.lastname: Harris
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China sunyc@ioz.ac.cn gef@ioz.ac.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Ge
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D065567:Absorption, Physiological / Q000187:drug effects; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001042:Aphids / Q000502:physiology*; D055864:Droughts; D005247:Feeding Behavior / Q000187:drug effects; D005740:Gases / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006458:Hemolymph / Q000187:drug effects / Q000378:metabolism; D046913:Medicago truncatula / Q000187:drug effects / Q000235:genetics / Q000469:parasitology / Q000502:physiology; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism; D009994:Osmolar Concentration; D064587:Osmoregulation / Q000187:drug effects; D052585:Phloem / Q000187:drug effects / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D014867:Water / Q000378:metabolism; D052584:Xylem / Q000187:drug effects / Q000502:physiology*
chemical_list: D000596:Amino Acids; D005740:Gases; D010937:Plant Growth Regulators; D014867:Water; D000040:Abscisic Acid; D009584:Nitrogen; D020156:Salicylic Acid
keywords: Abscisic acid; Acyrthosiphon pisum; Medicago truncatula; drought; feeding behavior; jasmonic acid; osmoregulation; resistance; salicylic acid; xylem absorption.