Genetic and environmental variation impact the cuticular hydrocarbon metabolome on the stigmatic surfaces of maize

Authors: DENNISON, TESIA - Iowa State University; QIN, WENMIN - Iowa State University; LONEMAN, DEREK - Iowa State University; CONDON, SAMPSON - Iowa State University; Lauter, Nicholas; NIKOLAU, BASIL - Iowa State University; YANDEAU-NELSON, MARNA - Iowa State University

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2019
Publication Date: 10/17/2019
Citation: Dennison, T., Qin, W., Loneman, D.M., Condon, S.G., Lauter, N.C., Nikolau, B.J., Yandeau-Nelson, M.D. 2019. Genetic and environmental variation impact the cuticular hydrocarbon metabolome on the stigmatic surfaces of maize. Biomed Central (BMC) Plant Biology. 19. https://doi.org/10.1186/s12870-019-2040-3.
DOI: https://doi.org/10.1186/s12870-019-2040-3

Interpretive Summary: Linear hydrocarbons accumulate in discrete regions of the environment including within bacteria, algae, and the outer surfaces of plants and insects, where they are known to protect against environmental stresses. The outer surfaces of maize silks are rich in linear hydrocarbons and provide an opportunity to study these biologically interesting metabolites in detail. This study reveals that the composition of metabolites in the silk is primarily governed by genetic factors that can be identified using quantitative genetic approaches. Such studies will clarify how linear hydrocarbons and other metabolites are produced. Understanding the diversity and complexity of these metabolites will improve our understanding of their role in protection against environmental stress.

Technical Abstract: Extracellular surface hydrocarbon accumulation on husk-encased silks and silks that have emerged from the husk leaves was surveyed among 32 genetically diverse maize inbred lines, including founders of the Nested Association Mapping population. Total hydrocarbon accumulation varied ~10-fold among these inbred lines, and up to 5-fold between emerged and husk-encased silks from specific genotypes. Alkene composition varied from 5% to 60% of the surface hydrocarbon metabolome, and the majority of observed alkenes were monoenes with a double bond at either the 7th or 9th position in the alkyl chain. Total accumulation was impacted to similar degrees by both genotype and husk-encasement status, whereas genotype predominantly affected alkene composition. Only minor changes in the metabolome were observed for silks that were emerged into the external environment for 3- or 6-day periods. The surface hydrocarbon metabolomes of inbred lines grown in two growing seasons, one of which was warmer and significantly wetter, were impacted by environment, with some inbred lines grown in the drier year accumulating up to 2-fold more hydrocarbons and an increased percentage of alkenes. In summary, the silk surface hydrocarbon metabolome is affected primarily by genotype and husk encasement status, with smaller but significant impacts by environment and genotype-by-environment interactions.