Contribution of six arbuscular mycorrhizal fungal isolates to water uptake by Lactuca sativa plants under drought stress

Abstract

It is currently accepted that, along with nutrients, arbuscular mycorrhizal (AM) fungi also transport water to their host plant. However, the quantity of water supplied and its significance for plant water relations remain controversial. The objective of this work was to evaluate and compare the ability of six AM fungi to alter rates of root water uptake under drought stress conditions. Soil drying rates of uninoculated control plants of comparable size and nutritional status and mycorrhizal plants were recorded daily. Lactuca sativa plants colonized by Glomus coronatum, G. intraradices, G. claroideum and G. mosseae depleted soil water to a higher extent than comparably sized uninoculated control plants or plants colonized by G. constrictum or G. geosporum. The differences ranged from 0.6% volumetric soil moisture for G. mosseaecolonized plants to 0.95% volumetric soil moisture for G. intraradices-colonized plants. These differences in soil moisture were equivalent to 3-4.75 ml plant À1 day À1 , respectively, and could not be ascribed to differences in plant size, but to the activity of AM fungi. The AM fungi tested in this study differed in their effectiveness to enhance plant water uptake from soil. This ability seems to be related to the amount of external mycelium produced by each AM fungus and to the frequency of root colonization in terms of live and active fungal structures.

Arbuscular mycorrhizae and soil/plant water relations

“…Water uptake by AM hyphae (Faber et al 1991;Ruiz-Lozano and Azcón 1995) and/or increased water uptake related to AM changes in root morphology (Kothari et al 1990) or root fineness (Price et al 1989) could conceivably allow mycorrhizal plants in drying soil to sustain higher g s and leaf turgor by effectively providing roots access to more of the soil water reservoir. Recent comparisons among six AM species revealed significant contributions by extraradical hyphae to mycorrhizal root water uptake (Marulanda et al 2003).…”

“…Bethlenfalvay and colleagues had suggested earlier that, theoretically, colonization of soil by hyphae might be expected to have as great (or greater) influence on host behavior during drought as colonization of roots (e.g., Bethlenfalvay and Linderman 1992). Others recently reported that, among six AM species tested, effectiveness in enhancing plant water uptake from soil appeared related to the amount of external mycelium produced by each AM fungus as well as to the frequency of root colonization in terms of live and active fungal structures (Marulanda et al 2003).…”

Arbuscular mycorrhizal networks: process and functions. A review

“…In fact, AM plants are frequently more tolerant to drought and salt stresses than non-AM plants (Rosendahl and Rosendahl, 1991;Khalvati et al, 2005;Al-Karaki, 2006;Porcel et al, 2006;Aroca et al, 2007). AM plants are able to take up more water from the soil than non-AM plants under waterdeficient conditions (Marulanda et al, 2003;Khalvati et al, 2005). However, this capacity depends on the fungal species, Glomus intraradices being one of the most efficient AM fungi in enhancing plant water uptake from the soil among six fungi tested (Marulanda et al, 2003).…”

“…AM plants are able to take up more water from the soil than non-AM plants under waterdeficient conditions (Marulanda et al, 2003;Khalvati et al, 2005). However, this capacity depends on the fungal species, Glomus intraradices being one of the most efficient AM fungi in enhancing plant water uptake from the soil among six fungi tested (Marulanda et al, 2003). Aroca et al (2007) evaluated how AM symbiosis influences root hydraulic properties, aquaporin expression and abundance in roots of Phaseolus vulgaris L. plants under drought, cold or salinity conditions.…”

Efficient Strategies for Elimination of Phenolic Compounds During DNA Extraction from Roots of Pistacia vera L.

“…Several studies have investigated the role of endophytic microorganisms -for instance arbuscular mycorrhiza (AM)-in protection of plants against salt stress by various mechanisms (Marulanda, Azcón, & Ruiz-Lozano, 2003;Marulanda, Porcel, Barea, & Azcón, 2007;Wu, Zou, Xia, & Wang, 2007;Wang & Liu 2001).…”