In situ detection of methyl jasmonate using plant-wearable sensors to quantify genotype-dependent herbivory resistance

Authors: HARIDASS, VIGNESH KUMAR - Iowa State University; ELANGO, DINAKARAN - Oak Ridge Institute For Science And Education (ORISE); Abel, Craig; Lopez, Miriam; Woolfolk, Sandra; SINGH, ARTI - Iowa State University; DONG, LIANG - Iowa State University

Submitted to: Biosensors and Bioelectronics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2026
Publication Date: 3/17/2026
Citation: Haridass, V.T., Elango, D., Abel, C.A., Lopez, M.D., Woolfolk, S.W., Singh, A., Dong, L. 2026. In situ detection of methyl jasmonate using plant-wearable sensors to quantify genotype-dependent herbivory resistance. Biosensors and Bioelectronics. https://doi.org/10.1016/j.bios.2026.118624.
DOI: https://doi.org/10.1016/j.bios.2026.118624

Interpretive Summary: Understanding how plants defend from pest injury greatly improves our ability to develop crop varieties that are productive during insect infestations. Traditional methods used to gain this knowledge involved collecting tissue from plants during pest injury to analyze the biochemicals that confer plant defense. These methods are useful but limited to measurements at specific time points as the collection of tissue for analysis is injurious and often destructive to the plant. We developed minimally invasive sensors to measure a plant hormone that regulates pest defense (methyl jasmonate) in real time while pest injury was occurring to corn plants. The sensor is novel and uses molecularly imprinted polymer technology integrated with microneedle electrode arrays. We tested the sensors on corn plants that were infested with fall armyworm, an economically important pest. Fall armyworm resistant lines Mp708 and BS39 were compared to susceptible lines GEMN-0131 and Tx601. The corn plants were infested at the seven-leaf stage with ten fall armyworm larvae per plant. Our sensors were applied to the plants and methyl jasmonate levels were monitored over ten days (200 hours). The resistant corn lines (Mp708 and BS39) exhibited significantly higher methyl jasmonate production at early time points (4-, 8-, and 12-hours post-infestation with fall armyworm), peaking at 20-hours post infestation, followed by a gradual decline. In contrast, the susceptible corn lines (Tx601 and GEMN-0131) showed delayed methyl jasmonate production, with notable increases only after 72-hours post infestation. Non-infested Mp708 plants maintained consistently low methyl jasmonate levels, confirming stress-specific induction. Validation studies, including hormone interference and reproducibility assessments, confirmed the sensor's reliability for methyl jasmonate detection and quantification. This novel sensor will lead to the development of additional sensors that will be used to acquire a complete understanding of plant response to defend against pest injury. This information will improve our fundamental knowledge of plant biology which will enhance crop breeding efforts.

Technical Abstract: Methyl jasmonate (MeJA) is a key phytohormone regulating plant responses to herbivory and environmental stress. While conventional analytical techniques, such as liquid chromatography-mass spectrometry, provide high accuracy, their application is often limited by labor-intensive workflows, high costs, and complex sample preparation requirements. In this study, we present a wearable electrochemical sensor for the in situ monitoring of MeJA in maize (Zea mays L.) under fall armyworm (FAW; Spodoptera frugiperda [J.E. Smith]) herbivory. The sensor employs an array of microneedles functionalized with a MeJA-specific molecularly imprinted polymer (MIP). This work presents the in situ monitoring of MeJA levels within intact plant tissues using a MeJA-specific MIP integrated with a microneedle-based sensor, and demonstrates, for the first time, the use of a plant-wearable sensor to quantify genotype-dependent herbivory resistance. The sensor exhibited considerable sensitivity and selectivity, with a detection limit of 0.18 µ M. Sensor performance was validated in four maize genotypes with varying levels of resistance to FAW (Mp708, BS39:0043, Tx601, GEMN0131). Time-course measurements revealed that resistant genotypes exhibited earlier and stronger MeJA induction following infestation, whereas susceptible genotypes showed delayed and attenuated responses. Sensor measurements demonstrated a strong correlation with conventional measurement data. Statistical analysis using a randomized complete block design confirmed that genotype, detection methodology, and infestation status significantly influence MeJA variability. These findings highlight the potential of the present wearable sensor as a powerful tool for studying plant defense mechanisms and advancing precision agriculture through direct monitoring of phytohormonal signaling.