Physiological parameters of desert truffle mycorrhizal Helianthemun almeriense plants cultivated in orchards under water deficit conditions

Abstract

Physiological parameters of mycorrhizal symbiosis by Helianthemum almeriense and Terfezia claveryi in orchards were characterized under water deficit conditions. Our orchard included 40 mycorrhizal and 40 nonmycorrhizal plants. Only mycorrhizal plants survived at the beginning of the experimental period, indicating dependency on fungal symbionts in roots for survival. Drought stress significantly affected the mycorrhizal colonization percentage which was 70% in nonirrigated mycorrhizal and 48% in irrigated mycorrhizal plants. No significant differences in plant growth were observed between nonirrigated and irrigated mycorrhizal plants before and after drought stress. Stomatal conductance was more sensitive to water stress than shoot water potential. It decreased more than two-fold under drought-stress compared to control mycorrhizal plants under irrigation/light saturating conditions, indicating important stomatal closure with water deficit. Plants' water use efficiency improved with drought with stomatal conductance values below 0.3 molm −2 s −1 . The ability to maintain open stomata and photosynthesis under drought increased carbon supply for growth, and ascocarp fruiting which requires current photosynthates. Basically, H. almeriense shows a conservative water use strategy based mainly on avoiding drought stress by reducing stomatal conductance as soil water potential decreases and atmospheric conditions dry. The results show that mycorrhizal H. almeriense plants maintain good physiological parameters with low soil matric potentials, thus making them an alternative agricultural crop in arid/semi-arid areas.

Two new Terfezia species from Southern Europe

“…However, most of the biogeographical and evolutionary studies that address Cistaceae colonization in the Mediterranean (Civeyrel et al 2011, Falchi et al 2009, Guzmán et al 2009, Guzmán & Vargas 2009a did not approach the possible interaction of the mycorrhizal character of these Cistaceae species with their distribution pattern. A high mycorrhizal dependence has been observed in some Cistaceae species (Morte et al 2010, Honrubia et al 2014, which depend on the presence of a fungal symbiont in their root for survival. Therefore, studies combining evolutionary studies on mycorrhizal fungi and their host plants are needed and they could help to explain the success of new species in different Mediterranean areas.…”

Expression Analysis of Aquaporins from Desert Truffle Mycorrhizal Symbiosis Reveals a Fine-Tuned Regulation Under Drought

“…Fine frozen roots from three plants, randomly selected within each water treatment, were sectioned as previously described (Morte et al 2010). All root sections were observed under an Olympus BH2 microscope and classified into one of the following M types: "ectomycorrhiza", with intercellular hyphae; "ectendomycorrhiza", with intracellular hyphae and intercellular hyphae; or "endomycorrhiza", when only intracellular hyphae were observed (Gutiérrez et al 2003).…”

“…A and g s were measured as previously described (Morte et al 2010). WUE intrinsic was calculated as A/g s .…”

“…In a recent 10-year cultivation trial, carpophores fructified yearly and production increased in time because of suitable land management techniques and irrigation (Morte et al 2008(Morte et al , 2009). In contrast, in conditions of overwatering, plants do not lose their leaves in summer and truffle harvesting does not occur (Morte et al 2010). These phenomena do not occur in natural populations or in plantations under dry conditions, which receive only deficit irrigation.…”

“…T. claveryi has become an alternative agricultural crop in semiarid areas because of the low water input required for its cultivation (Morte et al 2009). Although the association is well adapted to semiarid climates (Morte et al 2000(Morte et al , 2010Navarro-Ródenas et al 2011), the fungus requires localized outbreaks of rain to develop and fructify (Honrubia et al 2007; Navarro- Ródenas et al 2011). In a recent 10-year cultivation trial, carpophores fructified yearly and production increased in time because of suitable land management techniques and irrigation (Morte et al 2008(Morte et al , 2009).…”