Root-TRAPR: a modular plant growth device to visualize root development and monitor growth parameters, as applied to an elicitor response of Cannabis sativa

Abstract

Background Plant growth devices, for example, rhizoponics, rhizoboxes, and ecosystem fabrication (EcoFAB), have been developed to facilitate studies of plant root morphology and plant-microbe interactions in controlled laboratory settings. However, several of these designs are suitable only for studying small model plants such as Arabidopsis thaliana and Brachypodium distachyon and therefore require modification to be extended to larger plant species like crop plants. In addition, specific tools and technical skills needed for fabricating these devices may not be available to researchers. Hence, this study aimed to establish an alternative protocol to generate a larger, modular and reusable plant growth device based on different available resources. Results Root-TRAPR (Root-Transparent, Reusable, Affordable three-dimensional Printed Rhizo-hydroponic) system was successfully developed. It consists of two main parts, an internal root growth chamber and an external structural frame. The internal root growth chamber comprises a polydimethylsiloxane (PDMS) gasket, microscope slide and acrylic sheet, while the external frame is printed from a three-dimensional (3D) printer and secured with nylon screws. To test the efficiency and applicability of the system, industrial hemp (Cannabis sativa) was grown with or without exposure to chitosan, a well-known plant elicitor used for stimulating plant defense. Plant root morphology was detected in the system, and plant tissues were easily collected and processed to examine plant biological responses. Upon chitosan treatment, chitinase and peroxidase activities increased in root tissues (1.7- and 2.3-fold, respectively) and exudates (7.2- and 21.6-fold, respectively). In addition, root to shoot ratio of phytohormone contents were increased in response to chitosan. Within 2 weeks of observation, hemp plants exhibited dwarf growth in the Root-TRAPR system, easing plant handling and allowing increased replication under limited growing space. Conclusion The Root-TRAPR system facilitates the exploration of root morphology and root exudate of C. sativa under controlled conditions and at a smaller scale. The device is easy to fabricate and applicable for investigating plant responses toward elicitor challenge. In addition, this fabrication protocol is adaptable to study other plants and can be applied to investigate plant physiology in different biological contexts, such as plant responses against biotic and abiotic stresses.

Effects of chitin and chitosan on root growth, biochemical defense response and exudate proteome ofCannabis sativa

“…Root morphology was imaged using the WinRHIZO Arabidopsis 2019 software (Regent Instruments, Canada). Root length and root surface area were calculated using the same protocol as previously described (Suwanchaikasem et al ., 2022). Briefly, root region was manually assigned, and root were automatically detected by the software based on image contrast where the root is brighter than the background.…”

“…Phytohormone contents were measured from shoot and root tissues using a targeted LC-MS/MS method with slight modification from the previous protocol (Suwanchaikasem et al ., 2022). Approximately 100 mg tissue was weighed in a 1.5-ml microcentrifuge tube and extracted with 400 µl of 70% methanol, supplied with 500 ng ml -1 of six internal standards ([ 2 H 5 ]zeatin, [ 2 H 2 ]indole-3-acetic acid, [ 2 H 7 ]cinnamic acid, [ 2 H 4 ]salicylic acid, [ 2 H 6 ]abscisic acid and dihydro-jasmonic acid).…”

“…How these elicitors impact root systems is less well understood due to the physical challenges of studying roots and difficulty in investigating secretion of plant products into the surrounding soil (Lopez-Moya et al ., 2017). We recently developed an in vitro plant growth device, Root-TRAPR system, for imaging and sampling root material, making it possible to explore the impact of different environmental inputs on root system (Suwanchaikasem et al ., 2022).…”

RhizoPot platform: A high-throughput in situ root phenotyping platform with integrated hardware and software

“…Automatic image acquisition is completed by setting relevant parameters of AutoScan (scanning time and resolution). This platform is more efficient and flexible than individual culture vessels, such as RhizoTubes ( Jeudy et al., 2016 ), RhizoChamber-Monitor ( Wu et al., 2018 ), and root-TRAPR ( Suwanchaikasem et al., 2022 ).…”

“…The change characteristics of root phenotype, such as root growth rate, root diameter change rate, and net root growth per unit volume, were calculated based on the time of in situ root image collection. This can enhance research on the growth rate and change characteristics of the root system in response to environmental changes ( Suwanchaikasem et al., 2022 ).…”