Functional Characterization of Class I Trehalose Biosynthesis Genes in Physcomitrella patens

Abstract

The function of trehalose metabolism in plants during growth and development has been extensively studied, mostly in the eudicot Arabidopsis thaliana. So far, however, not much is known about trehalose metabolism in the moss Physcomitrella patens. Here, we show that in P. patens, two active trehalose-6-phosphate synthase enzymes exist, PpTPS1 and PpTPS2. Expression of both enzymes in Saccharomyces cerevisiae can complement the glucose-growth defect of the yeast tps1Δ mutant. Truncation of N-terminal extension in PpTPS1 and PpTPS2 resulted in higher TPS activity and high trehalose levels, upon expression in yeast. Physcomitrella knockout plants were generated and analyzed in various conditions to functionally characterize these proteins. tps1Δ and tps2Δ knockouts displayed a lower amount of caulonema filaments and were significantly reduced in size of gametophores as compared to the wild type. These phenotypes were more pronounced in the tps1Δ tps2Δ mutant. Caulonema formation is induced by factors such as high energy and auxins. Only high amounts of supplied energy were able to induce caulonema filaments in the tps1Δ tps2Δ mutant. Furthermore, this mutant was less sensitive to auxins as NAA-induced caulonema development was arrested in the tps1Δ tps2Δ mutant. In contrast, formation of caulonema filaments is repressed by cytokinins. This effect was more severe in the tps1Δ and tps1Δ tps2Δ mutants. Our results demonstrate that PpTPS1 and PpTPS2 are essential for sensing and signaling sugars and plant hormones to monitor the balance between caulonema and chloronema development.

A fundamental developmental transition in Physcomitrium patens is regulated by evolutionarily conserved mechanisms

“…Sugar sensing is not completely abolished in tps1∆ tps2∆ mutants, but these mutants are less responsive to glucose and sucrose treatment than wild type and indeed tps1∆ mutants. Collectively, these findings demonstrate that PpTPS1 and PpTPS2 are required for the perception of both sugars and hormones, but likely act with other factors such as Class II TPS enzymes or SNF1‐related kinases (SnRKs) (Phan et al, 2020). This is in line with reports of a link between Tre‐6P concentration and sugar availability, as well as Tre‐6P mediated inhibition of SnRK1 in Arabidopsis (Lunn et al, 2006; Y. Zhang et al, 2009).…”

“…Comparative analyses of Tre‐6P levels between these mutants suggest that PpTPS1 is likely to be more active than PpTPS2 , since the concentration of Tre‐6P is significantly lower in tps1∆ mutants than in tps2 ∆ mutants. Interestingly, low levels of Tre‐6P are detectable in tps1∆tps2∆ mutants, but this is likely due to a basal level of TPS activity exhibited by the Class II TPS proteins (Phan et al, 2020).…”

“…Tre‐6P is required for carbohydrate utilization, and glucose and sucrose induce caulonema formation in wild type P. patens (Phan et al, 2020; Schluepmann et al, 2003). Sugar sensing is not completely abolished in tps1∆ tps2∆ mutants, but these mutants are less responsive to glucose and sucrose treatment than wild type and indeed tps1∆ mutants.…”

“…Interestingly, snf1a snf1b double mutants exhibit increased sensitivity to auxin and reduced sensitivity to cytokinin (Thelander et al, 2005). The opposite is true for both tps1∆ mutants and tps1∆tps2∆ mutants, which exhibit reduced sensitivity to auxin treatment and increased sensitivity to cytokinin (Phan et al, 2020). Thus, the developmental phenotypes observed in these mutants are likely due to perturbations in the underlying auxin‐cytokinin crosstalk.…”

Transcriptomics Analysis of Primordium Formation in Pleurotus eryngii

“…Trehalose is a non-reducing sugar composed of two glucose molecules with 1,1-glycosidic bonds [ 41 ], and can be used as a source of carbohydrates, in addition to a typical stress protectant to maintain cell homeostasis [ 42 ]. Previous research has shown that trehalose can improve the antifreeze performance of L. edodes and P. ostreatus , and the growth of mycelia on medium containing trehalose is better than that on medium containing glucose [ 43 ].…”