Structure-activity relationship of volatile compounds that induce defense-related genes in maize seedlings

ABSTRACT

Volatile organic compounds mediate plant-to-plant communication, and plants receiving volatile cues can acquire greater defenses against attackers. It has been expected that volatiles are received by factors that eventually lead to the induction of defense-related gene expression; however, the nature of these factors remain unclear. Structure-activity relationship analysis of gene expression induction by volatiles should provide insights into the nature of these factors. We conducted a structure-activity relationship study using maize seedlings and (Z)-3-hexen-1-yl acetate (Z3HAC) as the lead compound. The acid portion of Z3HAC was not essential, and (Z)-3-hexen-1-ol (Z3HOL), which is formed after the hydrolysis of Z3HAC, is likely the structure essential for the upregulation of the genes. The double bond of Z3HOL is essential; however, its geometry is indistinguishable. Strict specificity was detected regarding the length of the methylene chain on the α- and ω-sides of the double bond, and therefore, the 3-hexen-1-ol structure was found to be the ultimate structure. This finding provides insight into the nature of the factors that interact with a volatile compound and subsequently activate signaling pathways, leading to the upregulation of a subset of defense genes.

KEYWORDS:

• Green leaf volatiles
• Zea mays
• plant communication
• RT-qPCR
• defense-gene induction

Authors contribution

K.M. designed and coordinated the entire project. Y.T., K.F., and M.D. performed experiment and data analysis. Y.T., K.F. and K. M. wrote the manuscript. B.W. synthesized the chemicals. All authors read and approved the manuscript.

Acknowledgments

This work was partly the result of using research equipment shared in MEXT Project for promoting public utilization of advanced research infrastructure (Program for supporting construction of core facilities, Grant Number JPMXS0440400021). Some of the experimental measurements were carried out using the JEOL JNM-ECA600 spectrometer at the Joint Usage/Research Center (JURC) at the Institute for Chemical Research (ICR) of Kyoto University, Japan.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15592324.2023.2234115

Additional information

Funding

The research was partly supported by JSPS KAKENHI Grant Numbers 19H02887 and 23H02140, and by Yamaguchi University Research Hub Project, Plant Robustness against Environmental Changes.