Functional screening of a cDNA library from the desiccation-tolerant plant Selaginella lepidophylla in yeast mutants identifies trehalose biosynthesis genes of plant and microbial origin

Abstract

Trehalose is a non-reducing disaccharide that accumulates to large quantities in microbial cells, but in plants it is generally present in very low, barely-detectible levels. A notable exception is the desiccation-tolerant plant Selaginella lepidophylla, which accumulates very high levels of trehalose in both the hydrated and dehydrated state. As trehalose is known to protect membranes, proteins, and whole cells against dehydration stress, we have been interested in the characterization of the trehalose biosynthesis enzymes of S. lepidophylla; they could assist in engineering crop plants towards better stress tolerance. We previously isolated and characterized trehalose-6-phosphate synthases from Arabidopsis thaliana (desiccation sensitive) and S. lepidophylla (desiccation tolerant) and found that they had similar enzymatic characteristics. In this paper, we describe the isolation and characterization of trehalose-6-phosphate phosphatase from S. lepidophylla and show that its catalytic activities are also similar to those of its homolog in A. thaliana. Screening of an S. lepidophylla cDNA library using yeast trehalose biosynthesis mutants resulted in the isolation of a large number of trehalose biosynthesis genes that were of microbial rather than plant origin. Thus, we suggest that the high trehalose levels observed in S. lepidophylla are not the product of the plant but that of endophytes, which are known to be present in this plant. Additionally, the high trehalose levels in S. lepidophylla are unlikely to account for its desiccation tolerance, because its drought-stress-sensitive relative, S. moellendorffii, also accumulated high levels of trehalose.Electronic supplementary materialThe online version of this article (doi:10.1007/s10265-014-0663-x) contains supplementary material, which is available to authorized users.

Invertebrate Trehalose-6-Phosphate Synthase Gene: Genetic Architecture, Biochemistry, Physiological Function, and Potential Applications

“…It is found ubiquitously as a metabolite in various bacteria, fungi, slime molds, protozoa, plants, and invertebrates (Kern et al, 2012 ; Tang et al, 2012a , b , 2014a , b , 2016 ; Lyu et al, 2013 ). Trehalose functions not only as a reserve carbohydrate, but also as an important stress-protecting molecule in different organisms (Elbein et al, 2003 ; Pampurova et al, 2014 ). Trehalose has been shown to serve as a mobile energy source for flight, and its levels in the blood have been reported to control the expenditure of flight energy in insects (Clegg and Evans, 1961 ; Cui and Xia, 2009 ).…”

Against All Odds: Trehalose-6-Phosphate Synthase and Trehalase Genes in the Bdelloid Rotifer Adineta vaga Were Acquired by Horizontal Gene Transfer and Are Upregulated during Desiccation

“…In Archaebacteria an accumulation of trehalose occurs in response to stress suggesting that the protective role of trehalose during cell dehydration might be an ancient adaptation that is evolutionary preserved [ 19 , 20 ]. Accumulation of high levels of trehalose was also observed in desiccated cysts of Artemia fransiscana and the desiccation tolerant chironomid larvae up to 15% and 20% respectively of dry body mass [ 10 , 21 ].…”

“…Despite the presence of trehalose anabolytic and catabolytic enzymes in the whole plant kingdom, high amounts of trehalose (up to 12% of dry weight) were only detected in few desiccation-tolerant plants [ 20 , 26 ]. Surprisingly, attempts to improve drought tolerance by engineering genetically modified plants accumulating trehalose resulted in plants that were less tolerant to drought than wild-type strains [ 27 ].…”

“…Instead, sucrose is hypothesized to take over the role of trehalose as a protective sugar during desiccation in plants [ 26 , 28 ]. Even in a highly desiccation-tolerant plant such as Selaginella lepidophylla , a recent publication suggested that the high level of trehalose detected is synthetized by plant endophytes and not by the plant itself [ 20 ]. The widespread occurrence and evolutionary conservation of genes involved in trehalose metabolism in the plant kingdom suggests their possible implication in something else than mere desiccation or drought resistance by trehalose accumulation.…”

Functional Characterization of Class I Trehalose Biosynthesis Genes in Physcomitrella patens

“…In most vascular plants, only minute amounts of trehalose are detected, which implies that trehalose could not act as an osmoprotectant during stress conditions, as seen in stressresistant species such as Selaginella lepidophylla, where trehalose accumulates to high amounts (Vogel et al, 2001;Fernandez et al, 2010;Pampurova et al, 2014). Therefore, several initiatives were taken to increase trehalose levels by expressing microbial TPS and TPP genes in plants.…”