Trehalose metabolism is important for heat stress tolerance and spore germination of Botrytis cinerea

Abstract

To analyse the role of trehalose as stress protectant and carbon storage compound in the grey mould fungus Botrytis cinerea, mutants defective in trehalose-6-phosphate synthase (TPS1) and neutral trehalase (TRE1) were constructed. The Dtps1 mutant was unable to synthesize trehalose, whereas the Dtre1 mutant showed elevated trehalose levels compared to the wild-type and was unable to mobilize trehalose during conidial germination. Both mutants showed normal vegetative growth and were not affected in plant pathogenicity. Growth of the Dtps1 mutant was more heat sensitive compared to the wild-type. Similarly, Dtps1 conidia showed a shorter survival under heat stress, and their viability at moderate temperatures was strongly reduced. In germinating wild-type conidia, rapid trehalose degradation occurred only when germination was induced in the presence of nutrients. In contrast, little trehalose breakdown was observed during germination on hydrophobic surfaces in water. Here, addition of cAMP to conidia induced trehalose mobilization and accelerated the germination process, probably by activation of TRE1. In accordance with these data, both mutants showed germination defects only in the presence of sugars but not on hydrophobic surfaces in the absence of nutrients. The data indicate that in B. cinerea trehalose serves as a stress protectant, and also as a significant but not essential carbon source for germination when external nutrients are low. In addition, evidence was obtained that trehalose 6-phosphate plays a role as a regulator of glycolysis during germination.

Trehalose Is an Important Mediator of Cap1p Oxidative Stress Response in Candida albicans

“…19,20) The nonreducing disaccharide trehalose is found in many organisms, in which it accumulates dramatically under stress conditions. [21][22][23][24] We demonstrate here a relationship between trehalose and Cap1p. Our results showed that trehalose was an important mediator of Cap1p oxidative stress response in C. albicans.…”

The Botrytis cinerea hexokinase, Hxk1, but not the glucokinase, Glk1, is required for normal growth and sugar metabolism, and for pathogenicity on fruits

“…Fructose is taken up by B. cinerea conidia by a fructose transporter (Frt1) and probably by a variety of hexose transporters (Doehlemann et al, 2005). Nevertheless, germinating conidia also use endogenous carbon sources such as lipids, glycogen and trehalose (Thines et al, 2000;Doehlemann et al, 2006b). The preferential metabolism of the storage compounds might be the reason for the higher fructose tolerance of germinating spores as compared to the growing mycelium.…”

“…This implies that trehalose 6-phosphate plays a role in sugar metabolism also in B. cinerea. A B. cinerea Dtps1 mutant disrupted in trehalose-6-phosphate synthase was found to grow normally, but to be defective in fructose-and glucose-induced germination (Doehlemann et al, 2006b). This was interpreted as an indication that trehalose 6-phosphate is particularly important during germination for regulating the glycolytic flux via Hxk1.…”

Transcriptome Profiling of Botrytis cinerea Conidial Germination Reveals Upregulation of Infection-Related Genes during the Prepenetration Stage

“…In the presence of carbon sources, germ tube outgrowth is preceded by rapid turnover of the disaccharide trehalose, which serves as a carbohydrate reserve and as an osmoprotectant (28). Based on the germination phenotypes of mutants, two signaling pathways have been described that are involved in the control of germination induction.…”