The role of jasmonate signalling in quinolizidine alkaloid biosynthesis, wounding and aphid predation response in narrow-leafed lupin
Karen M. Frick A B C E , Rhonda C. Foley B , Kadambot H. M. Siddique
C , Karam B. Singh B C D and Lars G. Kamphuis B C D F
+ Author Affiliations
- Author Affiliations
A UWA School of Agriculture and Environment, The University of Western Australia, LB 5005, Perth, WA 6001, Australia.
B CSIRO Agriculture and Food, 147 Underwood Avenue, Floreat, WA 6014, Australia.
C The UWA Institute of Agriculture, The University of Western Australia, LB 5005, Perth, WA 6001, Australia.
D Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia.
E Present address: Section for Plant Biochemistry, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark.
F Corresponding author. Email: lars.kamphuis@csiro.au
Functional Plant Biology 46(5) 443-454 https://doi.org/10.1071/FP18278
Submitted: 22 October 2018 Accepted: 17 January 2019 Published: 25 February 2019
Journal Compilation © CSIRO 2019 Open Access CC BY-NC-ND
Abstract
Quinolizidine alkaloids (QAs) are toxic secondary metabolites produced in lupin species that protect the plant against insects. They form in vegetative tissues and accumulate to a different extent in the grains: high levels in ‘bitter’ narrow-leafed lupin (NLL) and low levels in ‘sweet’ NLL. Grain QA levels vary considerably, and sometimes exceed the industry limit for food and feed purposes. We hypothesised that jasmonates regulate QA biosynthesis in response to environmental stresses such as wounding and aphid predation, which may explain non-genetic variability in grain QA levels. Methyl jasmonate (MeJA)-inducible genes were identified and verified in NLL. Exogenous MeJA application-induced expression of QA biosynthetic genes and QA levels for bitter, but not sweet NLL. Although MeJA-inducible genes responded to wounding, the expression of QA biosynthetic genes was not induced for bitter and sweet NLL. We assessed the effect of aphid predation on QA production for two cultivars – one moderately resistant and one susceptible to aphid predation. Although MeJA-inducible genes responded to aphid predation, no change in QA levels was found for either cultivar. These findings offer insights into the regulation of QA biosynthesis in bitter and sweet NLL and concludes that aphids are not a concern for increasing grain QAs in NLL cultivars.
Additional keywords: biotic stress, grain quality, green-peach aphid, Myzus persicae, plant defence, plant defense, secondary metabolism.
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