%0 Journal Article
%@ 2045-2322
%A Tamiru, A
%A Paliwal, R
%A Manthi, S J
%A Odeny, D A
%A Midega, C A O
%A Khan, Z R
%A Pickett, J A
%A Bruce, T J A
%D 2020
%F icrisat:11548
%I Nature Research
%J Scientific Reports (TSI)
%K Genomics, Maize
%N 1
%T Genome wide association analysis of a stemborer egg induced “call-for-help” defence trait in maize
%U http://oar.icrisat.org/11548/
%V 10
%X Tritrophic interactions allow plants to recruit natural enemies for protection against herbivory. Here  we investigated genetic variability in induced responses to stemborer egg-laying in maize Zea mays  (L.) (Poaceae). We conducted a genome wide association study (GWAS) of 146 maize genotypes  comprising of landraces, inbred lines and commercial hybrids. Plants were phenotyped in bioassays  measuring parasitic wasp Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) attraction  to volatiles collected from plants exposed to stemborer Chilo partellus (Swinhoe) (Lepidoptera:  Crambidae) eggs. Genotyping-by-sequencing was used to generate maize germplasm SNP data for  GWAS. The egg-induced parasitoid attraction trait was more common in landraces than in improved  inbred lines and hybrids. GWAS identified 101 marker-trait associations (MTAs), some of which were  adjacent to genes involved in the JA-defence pathway (opr7, aos1, 2, 3), terpene biosynthesis (fps3,  tps2, 3, 4, 5, 7, 9, 10), benzoxazinone synthesis (bx7, 9) and known resistance genes (e.g. maize insect  resistance 1, mir1). Intriguingly, there was also association with a transmembrane protein kinase  that may function as a receptor for the egg elicitor and other genes implicated in early plant defence  signalling. We report maize genomic regions associated with indirect defence and provide a valuable  resource for future studies of tritrophic interactions in maize. The markers identified may facilitate  selection of indirect defence by maize breeders.
%Z This Research was supported by BBSRC grant BB/J011371/1. We gratefully acknowledge the financial support  for icipe research by European Union, UK’s Department for International Development (DFID); Swedish International  Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC);  Federal Democratic Republic of Ethiopia and the Kenyan Government. We thank CIMMYT and Prof Mathews  Dida of Maseno University for supplying seed. We thank Amos Gadi and Silas Ouko for assistance with insect  rearing and screen house operations.