TY - JOUR

T1 - Endophytic Colonization of Onions Induces Resistance Against Viruliferous Thrips and Virus Replication

AU - Muvea, Alexander Mutua

AU - Subramanian, Sevgan

AU - Maniania, Nguya Kalemba

AU - Poehling, Hans Michael

AU - Ekesi, Sunday

AU - Meyhöfer, Rainer

N1 - Funding information: The authors kindly acknowledge the receipt of polyclonal anti-NSs antibodies for IYSV from Dr. Hanu Pappu, Washington State University, Pullman. The authors thank Regina Malit for technical assistance during ELISA experiments and Peris Kariuki for screenhouse help. Funding. This study was funded by BMZ (The German Federal Ministry for Economic Cooperation and Development) through GIZ (Deutsche Gesellschaft für Internationale Zusammenarbeit) through a project grant entitled “Implementation of integrated thrips and tospovirus management strategies in small-holder vegetable cropping systems of Eastern Africa” (Project No. 11.7860.7-001.00, Contract No. 81141840) for which we are grateful. Core funding provided to icipe by United Kingdom Aid from the United Kingdom Government, Swedish International Development Cooperation Agency (Sida), the Swiss Agency for Development and Cooperation (SDC), Federal Ministry for Economic Cooperation and Development (BMZ), and Germany and the Kenyan Government. The publication of this article was funded by the Open Access fund of Leibniz Universität Hannover.

PY - 2018/12

Y1 - 2018/12

N2 - In agricultural ecosystems, insect pests, pathogens, weather patterns, and reduced soil fertility pose major challenges to crop productivity and are responsible for significant yield losses worldwide. Iris yellow spot virus (IYSV) vectored by Thrips tabaci Lindeman, is a major hindrance to onion production in eastern Africa. Control measures often rely on insecticides with deleterious effects. Endophytes are one key alternative as they can play important roles in mediating induced systemic resistance. Hence, we examined the potential effect of endophytic fungus Hypocrea lixii (F3ST1) on feeding and replication of IYSV on endophyte-colonized (E+) and endophyte-free (E-) onion plants. For more precise assessment, replication was also tested using leaf disk bioassays and individual thrips. The number of feeding punctures was significantly lower in E+ as compared to E- plants. Disease level was significantly lower in E+ as compared to E- plants for four weeks post-exposure to thrips. IYSV replication was reduced by 2.5-fold in endophytic treatment on both whole plant and leaf disk assays. Thrips tabaci showed 2 times higher feeding activities on endophyte-free onion leaf disks as compared to the endophyte-inoculated leaf disks. Our results suggest potential utility of the endophytes to reduce feeding damage and virus infection on onion plants. Further studies should be conducted to elucidate the secondary metabolites involved in such endophyte-thrips-virus mediated interaction and determine whether the interactions extend for this and other onion varieties and viruses under field conditions.

AB - In agricultural ecosystems, insect pests, pathogens, weather patterns, and reduced soil fertility pose major challenges to crop productivity and are responsible for significant yield losses worldwide. Iris yellow spot virus (IYSV) vectored by Thrips tabaci Lindeman, is a major hindrance to onion production in eastern Africa. Control measures often rely on insecticides with deleterious effects. Endophytes are one key alternative as they can play important roles in mediating induced systemic resistance. Hence, we examined the potential effect of endophytic fungus Hypocrea lixii (F3ST1) on feeding and replication of IYSV on endophyte-colonized (E+) and endophyte-free (E-) onion plants. For more precise assessment, replication was also tested using leaf disk bioassays and individual thrips. The number of feeding punctures was significantly lower in E+ as compared to E- plants. Disease level was significantly lower in E+ as compared to E- plants for four weeks post-exposure to thrips. IYSV replication was reduced by 2.5-fold in endophytic treatment on both whole plant and leaf disk assays. Thrips tabaci showed 2 times higher feeding activities on endophyte-free onion leaf disks as compared to the endophyte-inoculated leaf disks. Our results suggest potential utility of the endophytes to reduce feeding damage and virus infection on onion plants. Further studies should be conducted to elucidate the secondary metabolites involved in such endophyte-thrips-virus mediated interaction and determine whether the interactions extend for this and other onion varieties and viruses under field conditions.

KW - Host plant resistance

KW - Hypocrea lixii

KW - Iris yellow spot virus

KW - Multi-trophic interactions

KW - Onions

KW - Systemic

KW - Thrips tabaci

UR - http://www.scopus.com/inward/record.url?scp=85058781842&partnerID=8YFLogxK

U2 - 10.3389/fpls.2018.01785

DO - 10.3389/fpls.2018.01785

M3 - Article

C2 - 30574155

AN - SCOPUS:85058781842

VL - 9

JO - Frontiers in Plant Science

JF - Frontiers in Plant Science

SN - 1664-462X

M1 - 1785

ER -