The role of jasmonate signalling in quinolizidine alkaloid biosynthesis, wounding and aphid predation response in narrow-leafed lupin

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.

A pan‐genome and chromosome‐length reference genome of narrow‐leafed lupin (Lupinus angustifolius) reveals genomic diversity and insights into key industry and biological traits

“…While NLL is emerging as a human health food, toxic specialised metabolites of the quinolizidine alkaloids class are required to remain below a 0.02% threshold in the grain for it to be used for food or feed purposes (Frick et al., 2017). A picture is emerging in which environmental stresses cause an increase in alkaloids in the NLL leaves and grain (Frick et al., 2018; Frick et al., 2019), but independent studies have identified different candidate genes for the key alkaloid regulatory locus iucundus (Kroc et al., 2019b; Wang et al., 2021).…”

Spatial and Temporal Dynamics of Electrical and Photosynthetic Activity and the Content of Phytohormones Induced by Local Stimulation of Pea Plants

“…In particular, Ca 2+ can activate enzyme LOX6, which participates in the JA synthesis [ 41 ]. Additionally, stimulation of the JA production after mechanical damage [ 42 ] can be caused changes in activity of the phospholipase D [ 43 ]; it is known that this enzyme is activated by Ca 2+ influx [ 44 ]. Ways of influence of other signal molecules (ROS, H + ) on the phytohormones production are not clear; however, their effects can be potentially related to interactions between Ca 2+ , ROS and pH signal ways [ 45 ].…”

Genomic resources for lupins are coming of age

“…Both drought and high temperature stress as well as their interaction could affect alkaloid content in the NLL grain, albeit in a genotype specific matter (Frick et al, 2018). In contrast aphid predation using the green peach aphid ( Myzus persicae ) did not exhibit changes in QA biosynthetic gene expression or grain QA content (Frick et al, 2019). In conclusion, a number of genes that contribute to QA biosynthesis and regulation have been identified (Frick et al, 2018, 2019; Kroc et al, 2019; Yang et al, 2017).…”

“…In contrast aphid predation using the green peach aphid ( Myzus persicae ) did not exhibit changes in QA biosynthetic gene expression or grain QA content (Frick et al, 2019). In conclusion, a number of genes that contribute to QA biosynthesis and regulation have been identified (Frick et al, 2018, 2019; Kroc et al, 2019; Yang et al, 2017).…”