Relative importance of an arbuscular mycorrhizal fungus (Rhizophagus intraradices) and root hairs in plant drought tolerance

Abstract

Both arbuscular mycorrhizal (AM) fungi and root hairs play important roles in plant uptake of water and mineral nutrients. To reveal the relative importance of mycorrhiza and root hairs in plant water relations, a bald root barley (brb) mutant and its wild type (wt) were grown with or without inoculation of the AM fungus Rhizophagus intraradices under well-watered or drought conditions, and plant physiological traits relevant to drought stress resistance were recorded. The experimental results indicated that the AM fungus could almost compensate for the absence of root hairs under drought-stressed conditions. Moreover, phosphorus (P) concentration, leaf water potential, photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency were significantly increased by R. intraradices but not by root hairs, except for shoot P concentration and photosynthetic rate under the drought condition. Root hairs even significantly decreased root P concentration under drought stresses. These results confirm that AM fungi can enhance plant drought tolerance by improvement of P uptake and plant water relations, which subsequently promote plant photosynthetic performance and growth, while root hairs presumably contribute to the improvement of plant growth and photosynthetic capacity through an increase in shoot P concentration.

Chromium immobilization by extra- and intraradical fungal structures of arbuscular mycorrhizal symbioses

“…AMF provides host plants with mineral nutrients (such as phosphorus) and in return receive carbohydrates from plants. AMF can also enhance plant resistance to various biotic and abiotic stresses, such as drought [5], salinity [6], pathogen infection [7], and heavy metal contamination [8][9][10][11], etc. It has been documented that arbuscular mycorrhizal (AM) symbiosis also takes an active part in relieving plant Cr toxicity [12,13].…”

Chromium immobilization by extraradical mycelium of arbuscular mycorrhiza contributes to plant chromium tolerance

“…AMF obtain carbohydrates from their host plants and in return they provide plants with mineral nutrients such as phosphorus (P), nitrogen (N), etc (Smith and Read, 2008). Additionally, AMF can relieve plant drought stress (Li et al, 2014), protect host plants from pathogens (Singh et al, 2013b), improve soil structure (Rillig and Steinberg, 2002), and even play an important role in maintaining plant biodiversity and ecosystem stability (van der Heijden et al, 1998). Various studies have demonstrated that AM symbiosis take an active part in plant resistance to heavy metal contamination including As, Cd, Cu and Cr etc (Chen et al, 2007a(Chen et al, ,b, 2005Davies et al, 2001;Wu et al, 2014).…”

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

“…The relative water content was determined according to Ruiz-Lozano and Azcon (1997). One gram fresh weight of roots from each compartment was used for root staining and determination of mycorrhizal colonization rates (Li et al 2014). In brief, roots were cleared in 10 % KOH and stained with 0.05 % trypan blue in lactic acid (v/v) to confirm the presence of fungal structures (intraradical mycelia, vesicles, and arbuscules).…”

“…Based on the 14-3-3 gene screened from the genome of R. irregularis DAOM 197198 (Lin et al 2014), Ri 14-3-3 was cloned from R. intraradices AH01. The similarity of the amplified fragments between R. intraradices AH01 and R. irregularis DAOM 197198 was 98 %, which was confirmed by sequencing.…”

“…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.…”