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Mycorrhiza (2016) 26:311323 DOI 10.1007/s00572-015-0670-3
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Aquaporin gene expression and physiologicalresponses of Robinia pseudoacacia L. to the mycorrhizal fungus Rhizophagus irregularis and drought stress
Fei He1 & Haoqiang Zhang1 & Ming Tang1
Received: 10 September 2015 /Accepted: 13 November 2015 /Published online: 21 November 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract The influence of arbuscular mycorrhiza (AM) and drought stress on aquaporin (AQP) gene expression, water status, and photosynthesis was investigated in black locust (Robinia pseudoacacia L.). Seedlings were grown in potted soil inoculated without or with the AM fungus Rhizophagus irregularis, under well-watered and drought stress conditions. Six full-length AQP complementary DNAs (cDNAs) were isolated from Robinia pseudoacacia, named RpTIP1;1, RpTIP1;3, RpTIP2;1, RpPIP1;1, RpPIP1;3, and RpPIP2;1. A phylogenetic analysis of deduced amino acid sequences demonstrated that putative proteins coded by these RpAQP genes belong to the water channel protein family. Expression analysis revealed higher RpPIP expression in roots while RpTIP expression was higher in leaves, except for RpTIP1;3. AM symbiosis regulated host plant AQPs, and the expression of RpAQP genes in mycorrhizal plants depended on soil water condition and plant tissue. Positive effects were observed for plant physiological parameters in AM plants, which had higher dry mass and lower water saturation deficit and electrolyte leakage than non-AM plants. Rhizophagus irregularis inoculation also slightly increased leaf net photosynthetic rate and stomatal conductance under well-watered and drought
stress conditions. These findings suggest that AM symbiosis can enhance the drought tolerance in Robinia pseudoacacia plants by regulating the expression of RpAQP genes, and by improving plant biomass, tissue water status, and leaf photo-synthesis in host seedlings.
Keywords Arbuscular mycorrhiza . Rhizophagus irregularis . Robinia pseudoacacia . Aquaporins . Drought stress
AbbreviationsAM Arbuscular mycorrhizaNM Non-mycorrhizal plantsAQP AquaporinRpAQP Robinia pseudoacacia aquaporin genePIPs Plasma membrane intrinsic proteinsTIPs Tonoplast intrinsic proteinsNIPs NOD26-like MIPs or NOD26-like intrinsic proteinsSIPs Small basic intrinsic proteinsXIPs Newly identified X (or uncategorized) intrinsic proteinsWW Well-wateredDS Drought stressWSD Water saturation deficitEL Electrolyte leakageEC Electrical conductivityPn Net photosynthetic rate
Gs Stomatal conductance Tr Transpiration rate
Ci Intercellular CO2 concentration WUE Water use efficiency
Electronic supplementary material The online version of this article (doi:http://dx.doi.org/10.1007/s00572-015-0670-3
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