Accumulation of trehalose increases soluble sugar contents in rice plants conferring tolerance to drought and salt stress

Abstract

Trehalose is a nonreducing sugar composed of two glucose units linked in an a,a-1,1-glycosidic linkage. Present in a wide variety of organisms, this sugar may serve as a source of energy and carbon and as a protective molecule against abiotic stresses. In this study, trehaloseproducing transgenic rice plants (Oryza sativa) expressing a bifunctional fusion enzyme TPSP (Ubi1:TPSP) were utilized to dissect the enigmatic role of trehalose in conferring stress tolerance to plants. Grown under normal conditions, the Ubi1:TPSP plants produced high amounts of soluble sugars (glucose, fructose and sucrose), ranging from 1.5-to 3.5-fold over NT controls. In the time course of drought treatment, the transcripts for the drought degradable-marker genes (RbcS, FBPase, and PBZ1) persisted for two more days in Ubi1:TPSP plants before being completely degraded relative to those in NT plants, confirming the tolerance of the transgenic plants to drought. This was further supported by a delayed increase in transcript levels of the stress-inducible genes SalT, Dip1, and Wsi18 during drought stress. Similarly, Ubi1:TPSP plants showed tolerance to salt levels of up to 150 mM NaCl, as evidenced by the seedling growth and the delayed decay in RbcS and delayed increase in SalT transcript levels. The growth of NT plants was found to be slightly affected by exogenous trehalose feeding, whereas Ubi:TPSP plants remained resistant, validating the protective role of internally produced trehalose. These results suggest that the elevated production of trehalose in rice, through TPSP overexpression, increases the soluble sugar contents and enhances tolerance to both drought and salt stress.

Comparative Metabolome Profile between Tobacco and Soybean Grown under Water-Stressed Conditions

“…Trehalose is a well-studied metabolite associated with abiotic stress and the subject of various metabolic engineering efforts to enhance drought tolerance in plants. Overexpression of genes involved in trehalose metabolism increased drought tolerance in rice [41] and tomato [42]. …”

Contribution of trehalose biosynthetic pathway to drought stress tolerance of Capparis ovata Desf

“…Trehalose and trehalose biosynthesis are important contributors to several physiological processes, including protection against stressors, not only in plants but also in animals, yeasts and bacteria (Jang et al 2003;Redillas et al 2012). Different approaches have been used to address and understand this pathway, such as overexpressing endogenous and exogenous genes encoding enzymes responsible for biosynthesis and hydrolysis of trehalose.…”

“…In plant cells degradation of trehalose is facilitated by the trehalase enzyme, which also contributes to the stability of this molecule and inhibits trehalose over-accumulation (Goddijn & Van Dun 1999). To date, several functional roles, such as osmoprotection, desiccation tolerance, storage energy (carbon) source, thermotolerance, regulation of growth and development and sugar signalling, have been attributed to trehalose and trehalose metabolism (Jang et al 2003;Veyres et al 2008;Redillas et al 2012;O'Hara et al 2013).…”

Use of MSAP Markers to Analyse the Effects of Salt Stress on DNA Methylation in Rapeseed (Brassica napus var. oleifera)

“…Trehalose has also been reported to act as a free radical scavenger, thus helping the plant to reduce the cellular damages induced by stress-induced reactive oxygen species [63,64]. Besides its protective functions, trehalose may also act as an elicitor of genes involved in abiotic stress response [64], and it was shown to confer a high level of salt tolerance in rice, primarily through causing an increase in the synthesis of other soluble sugars [67]. It is noteworthy that Pace et al [44] recently reported that the level of soluble sugars in rapeseed correlated with tolerance of salinity stress.…”