Mycorrhiza formation enhances adaptive response of hybrid poplar to drought

Mycorrhized and nonmycorrhized plants of hybrid poplar (Populus tremula L. x Populus tremuloides Mich) were cultivated in petri dishes until the amount of water became limiting (detected by a decrease of photosynthetic yield). RNA was isolated from both main and fine roots and used for analysis of water channel (aquaporin) gene expression by semiquantitative RT-PCR. For three of five investigated aquaporin genes, expression did not differ between mycorrhized and nonmycorrhized plants. However, expression of the two other aquaporin genes was more pronounced in fine roots of mycorrhized plants, indicating that the root-fungus symbiosis may improve the water transport capacity under conditions of reduced water availability.