Influence of evaporative demand on aquaporin expression and root hydraulics of hybrid poplar

Adriana M. ALMEIDA-RODRIGUEZ, Uwe G. HACKE and Joan LAUR

Résumé:

When light levels and evaporative demand increase, dynamic physiological changes in roots may be required to restore the water balance at the whole plant level. We hypothesized that a dynamic increase in root hydraulic conductance (L_P) and aquaporin (AQP) expression could moderate the transpiration-induced drop in water potential (Ψ), allowing continued gas exchange in hybrid poplar (Populus trichocarpa × deltoides) saplings. Fifty-six AQPs have been identified in poplar, but little information about their expression patterns in roots is available, especially from a whole-plant water relations perspective. We measured AQP expression and L_P in plants subjected to different levels of light and evaporative demand. Shaded plants had only one-tenth the root area of plants growing at higher light levels. Shade-grown saplings experiencing a sudden increase in light exhibited a threefold higher L_P than plants remaining in shade. This dynamic increase in L_P corresponded with increased transcript abundance of 15 AQPs out of a total of 33 genes simultaneously assessed by quantitative RT-PCR. The tissue-level localization of transcripts of four AQPs was studied with in situ hybridization. Comprehensive expression profiling in conjunction with physiological and morphological measurements is a valuable reference for future studies on AQP function in poplar.

Revue:

Plant, Cell & Environment

Lien:

https://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2011.02331.x/full