First cloning and characterization of two functional aquaporin genes from an arbuscular mycorrhizal fungus Glomus intraradices

Abstract

SummaryArbuscular mycorrhizal (AM) symbiosis is known to stimulate plant drought tolerance. However, the molecular basis for the direct involvement of AM fungi (AMF) in plant water relations has not been established.Two full-length aquaporin genes, namely GintAQPF1 and GintAQPF2, were cloned by rapid amplification of cDNA 5′-and 3′-ends from an AMF, Glomus intraradices. Aquaporin localization, activities and water permeability were examined by heterologous expression in yeast. Gene expression during symbiosis was also analyzed by quantitative real-time polymerase chain reaction.GintAQPF1 was localized to the plasma membrane of yeast, whereas GintAQPF2 was localized to both plasma and intracellular membranes. Transformed yeast cells exhibited a significant decrease in cell volume on hyperosmotic shock and faster protoplast bursting on hypoosmotic shock. Polyethylene glycol (PEG) stimulated, but glycerol inhibited, the aquaporin activities. Furthermore, the expression of the two genes in arbuscule-enriched cortical cells and extraradical mycelia of maize roots was also enhanced significantly under drought stress.GintAQPF1 and GintAQPF2 are the first two functional aquaporin genes from AMF reported to date. Our data strongly support potential water transport via AMF to host plants, which leads to a better understanding of the important role of AMF in plant drought tolerance.

Molecular characterization of microbial communities in the rhizosphere soils and roots of diseased and healthy Panax notoginseng

“…AM fungi that belong to Glomeromycota associate with more than 80 % of vascular land plants and play an important role in natural ecosystems (Vigo et al 2000). AM fungi benefit plants by supplying mineral nutrients especially phosphorus (Al-Karaki 2006), helping transport water to ease drought stress (Li et al 2013) and increasing plant resistance to soil borne diseases locally or/and systemically (Hao et al 2012). However, the effect of AM fungi on root-rot of P. notoginseng is still unclear.…”

Presidential address: recent advance of mycorrhizal research in China

“…In the mycorrhizal molecular biology, Li et al (2013) firstly cloned and identified two aquaporin genes of GintAQPF1 and GintAQPF2 from AM fungus Glomus intraradices (syn. Rhizophagus intraradices ) and confirmed their function under drought stress.…”

“…For example, AM fungi can efficiently improve crop growth, biomass, and productivity particularly in extremely P-limited soil (Hu et al 2009), due to enhanced nutritional assimilation of plant as well as improved soil organic matter content and total nitrogen (Wu et al 2005). AM fungi can enhance plant resistance to drought (Li et al 2013; Liu et al 2015) and heavy metals (Dong et al 2008; Zhang et al 2009). AM fungus Glomus mosseae (syn.…”

Potential role of D-myo-inositol-3-phosphate synthase and 14-3-3 genes in the crosstalk between Zea mays and Rhizophagus intraradices under drought stress

“…It has been well established that AMF not only supply host plants with water and nutrients (Augé 2001;Li et al 2013Li et al , 2014, but also improve their photosynthesis (Ruíz-Sánchez et al 2011) and modulate metabolic processes like ABA synthesis (Herrera-Medina et al 2007). According to GeneChip data comparing the transcriptional profiles of mycorrhizal and non-mycorrhizal roots (García Garrido et al 2010), five genes encoding enzymes relevant to ABA biosynthesis were up-regulated in mycorrhizal roots.…”

“…Additionally, as one of the AMF strategies in helping plants cope with water deficit, the extraradical mycelium of AMF can enter fine soil pores and enhance water transport to plants (Khalvati et al 2005). Our previous work has suggested that the functional aquaporins (GintAQPF1 and GintAQPF2) potentially mediated water uptake by host plants (Li et al 2013). An AMF 14-3-3 protein may be involved in signaling pathways in AMF (Porcel et al 2006b) and activities of GintAQPF1 and GintAQPF2.…”