Wounding rapidly alters transcription factor expression, hormonal signaling, and phenolic compound metabolism in harvested sugarbeet roots

Authors: Fugate, Karen; FINGER, FERNANDO - Universidade Federal De Vicosa; LAFTA, ABBAS - North Dakota State University; Dogramaci, Munevver; KHAN, MOHAMED - North Dakota State University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2022
Publication Date: 1/6/2023
Citation: Fugate, K.K., Finger, F.L., Lafta, A.M., Dogramaci, M., Khan, M.F. 2023. Wounding rapidly alters transcription factor expression, hormonal signaling, and phenolic compound metabolism in harvested sugarbeet roots. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2022.1070247.
DOI: https://doi.org/10.3389/fpls.2022.1070247

Interpretive Summary: Injuries sustained by sugarbeet roots during harvest and piling operations seriously reduce the quantity of white sugar that is recovered from stored roots. Although healing postharvest injuries is critical for successful storage of sugarbeet roots, knowledge of (1) the signals that trigger and (2) the changes that initiate wound healing is limited. To better understand the internal factors that signal and initiate wound healing in sugarbeet roots, research was carried out to identify the genetic and metabolic changes that occur in sugarbeet roots following injury. In the first 24 hours after injury, extensive molecular changes occurred in wounded roots, indicating a major reorientation of metabolism within the root due to injury. A multitude of genetic elements that are involved in alerting cells to root developmental or environmental changes increased in both type and number in wounded roots and included genetic elements associated with the plant hormones, ethylene and jasmonic acid. Genetic elements involved in ethylene biosynthesis and signaling were especially notable for the extent and duration of their increase after injury which suggested a central role in signaling and initiating wound healing responses for this plant hormone. Additionally, genetic elements and enzymes involved in producing barriers that seal off wound sites were elevated during the first 24 hours after wounding, indicating that wound healing began within the first day after injury. Combined, these results provide sugarbeet researchers with new molecular tools that could be used to enhance wound healing in this important commercial crop.

Technical Abstract: Injuries sustained by sugarbeet (Beta vulgaris L.) roots during harvest and postharvest operations seriously reduce the yield of white sugar produced from stored roots. Although wound healing is critically important to reduce losses, knowledge of these processes is limited for this crop as well as for roots in other species. To better understand the metabolic signals and changes that occur in wounded roots, dynamic changes in gene expression were determined by RNA sequencing and the activity of products from key genes identified in this analysis were determined in the 0.25 to 24 h following injury. Nearly five thousand differentially expressed genes that contribute to a wide range of cellular and molecular functions were identified in wounded roots. Highly upregulated genes included transcription factor genes, as well as genes involved in ethylene and jasmonic acid (JA) biosynthesis and signaling and phenolic compound biosynthesis and polymerization. Enzyme activities for key genes in ethylene and phenolic compound biosynthesis and polymerization also increased due to wounding. Results indicate that wounding causes a major reallocation of metabolism in sugarbeet taproots. Although both ethylene and JA are likely involved in triggering wound responses, the greater and more sustained upregulation of ethylene biosynthesis and signaling genes relative to those of JA, suggest a preeminence of ethylene signaling in wounded sugarbeet roots. Changes in gene expression and enzymes involved in phenolic compound metabolism additionally indicate that barriers synthesized to seal off wounds, such as suberin or lignin, are initiated within the first 24 h after injury.