Overexpression of Pennisetum purpureum CCoAOMT Contributes to Lignin Deposition and Drought Tolerance by Promoting the Accumulation of Flavonoids in Transgenic Tobacco

Abstract

Elephant grass (Pennisetum purpureum) is a fast-growing and low-nutrient demand plant that is widely used as a forage grass and potential energy crop in tropical and subtropical regions of Asia, Africa, and the United States. Transgenic tobacco with the PpCCoAOMT gene from Pennisetum purpureum produces high lignin content that is associated with drought tolerance in relation to lower accumulation of reactive oxygen species (ROS), along with higher antioxidant enzyme activities and osmotic adjustment. In this study, transgenic tobacco plants revealed no obvious cost to plant growth when expressing the PpCCoAOMT gene. Metabolomic studies demonstrated that tobacco plants tolerant to drought stress accumulated flavonoids under normal and drought conditions, which likely explains the observed tolerance phenotype in wild-type tobacco. Our results suggest that plants overexpressing PpCCoAOMT were better able to cope with water deficit than were wild-type controls; metabolic flux was redirected within primary and specialized metabolism to induce metabolites related to defense to drought stress. These results could help to develop drought-resistant plants for agriculture in the future.

Physiological, Photosynthetic, and Transcriptomics Insights into the Influence of Shading on Leafy Sweet Potato

“…In addition, the first oxidation reaction to generate ρ-coumaric acid in flavonoids synthesis were catalyzed by C4H [55,59]. CCoAOMT and DFR contributed to the accumulation of flavonoids and enhanced plant stress resistance, while GPT2 was necessary for photodynamic domestication [60][61][62]. These findings suggested that 50% shading induced a high expression of enzyme genes, which might increase the content of total flavonoids and total phenolic compounds.…”

A Transcriptomic Analysis Sheds Light on the Molecular Regulation of Wood Formation in Populus trichocarpa during Drought Stress

“…Transgenic Morus alba, expressing the gene encoding cinnamyl-alcohol dehydrogenase (CAD), which catalyzes the final step of monolignol biosynthesis, revealed that the MaCAD family members are responsible for the formation of various monolignols in lignin biosynthesis under drought stress [23]. Overexpression of the Pennisetum purpureum PpCCoAOMT gene promotes lignin accumulation, which is associated with drought tolerance and reduced accumulation of reactive oxygen species [24]. The phytohormones auxin [25,26], cytokinin [27], gibberellin [28,29], brassinosteroids [30], ethylene [31], and abscisic acid [32,33] form a complex regulatory network that controls both vascular cell development during wood formation and plant responses to drought [34].…”