Morphophysiological and Biochemical Responses of Lippia grata Schauer (Verbenaceae) to Water Deficit

• Published in: Journal of plant growth regulation 2020-03, Vol.39 (1), p.26-40
• Main Authors: Palhares Neto, Luiz, de Souza, Lindomar Maria, de Morais, Marciana Bizerra, Arruda, Emília, de Figueiredo, Regina Célia Bressan Queiroz, de Albuquerque, Cynthia Cavalcanti, Ulisses, Cláudia
• Format: Article
• Language: English
• Subjects: Agriculture; Biochemistry; Biomedical and Life Sciences; Bundles; Carbohydrates; Carbon dioxide; Carotenoids; Cellular structure; Chlorophyll; Drought; Gas exchange; Hydrogen peroxide; Irrigation; Irrigation water; Life Sciences; Lippia; Moisture content; Parameters; Physiology; Plant Anatomy/Development; Plant growth; Plant Physiology; Plant Sciences; Proteins; Reduction; Rehydration; Soil improvement; Soil water; Structural damage; Superoxide dismutase; Trichomes; Water absorption; Water content; Water deficit; Water regimes; Water stress; Water use; Xylem
• ISSN: 0721-7595; 1435-8107
• DOI: 10.1007/s00344-019-09961-6

In the present study, we investigated the morphophysiological and biochemical responses of the species Lippia grata Schauer to water deficit. Plants from cuttings were submitted to two water regimes, irrigation (control) and suspended irrigation (stress) for 15 days and were then rehydrated for 10 days. During water regimes, we performed physiological (gas exchange, growth parameters, and biochemical) and anatomical analyses. The water deficit negatively affected growth of the aerial part of the plant with reduction of approximately 72%. On the contrary, root system growth was stimulated by water deficit (increase of 205%). The drought caused a reduction in the physiological parameters ( gs , E , and A ), while leaf temperature and internal and external CO 2 concentration ratio ( Ci/Ca ) increased. Plants subjected to drought had higher intrinsic efficiency of water use on the 10th day of deficit ( A/g s ). The levels of total chlorophyll, carotenoids, and soluble carbohydrates increased on the 10th and 15th days of water suspension. The levels of H 2 O 2 , proteins, and MDA were high in plants on the 15th day of water deficit. The levels of H 2 O 2 in the control plants increased on the 20th and 25th day of rehydration, along with the activation of some enzymes of the antioxidative system SOD, CAT and APX. Plants under water deficit increased SOD activity on the 10th day and CAT on the 10th and 15th day under stress. Plants submitted to water deficit showed reduction of mesophilic thickness, smaller epidermal cells, reduction of intercellular spaces, more vascular bundles, greater lignification of xylem cells, morphological modification of cortical cells, and have more glandular trichomes in the abaxial face compared to plants always irrigated. During rehydration, the plants submitted to the water deficit recovered in all variables analyzed and have a higher density of glandular and the tector trichomes in both epidermises, adaxial and abaxial. We conclude that the rapid recovery of the parameters evaluated for Lippia grata are related to the absence of irreversible damage in the cellular structures, due to the efficiency of the antioxidative system, and metabolic processes involved with the dissipation of the excess energy because of the imposed water stress. In addition, other important morphophysiological strategies such as increased root growth, increased vascular bundles and density of trichomes improved soil water absorption and maintained the cellu