Glomus intraradices causes differential changes in amino acid and starch concentrations of in vitro strawberry subjected to water stress

Abstract

The effect of colonization of tissue‐cultured strawberry (Fragaria×ananassa Duch. cv. Kent) plantlets in vitro by the arbuscular mycorrhizal fungus (AMF) Glomus intraradices on plantlet response to poly(ethylene glycol) (PEG)‐8000‐induced water stress was investigated. The plantlets were inoculated axenically and co‐cultured with the AMF for 4 wk, then transferred to 15% PEG‐8000 solutions for 4, 8 and 12 h. Relative water content, water potential, osmotic potential, leaf conductance for water vapour diffusion and photosynthetic efficiency as estimated by chlorophyll a fluorescence were all affected by the PEG treatment and its duration but not by the presence of the intraradical phase of the AMF. However, distinct differences in PEG‐induced changes in amino acid content were observed between nonmycorrhizal and mycorrhizal plantlets. In the latter, the treatment with PEG caused a substantial decrease in asparagine levels in leaves that was accompanied by a marked increase in asparagine concentration in roots. The opposite was observed in nonmycorrhizal plantlets. Furthermore, concentrations of aspartic acid, serine, threonine, amino‐N‐butyric acid, alanine and starch increased in roots of mycorrhizal and decreased in nonmycorrhizal plantlets. Our results suggest the presence of a mobile pool of asparagine that can be translocated from leaves to roots or vice versa in response to PEG‐induced water stress, depending on the mycorrhizal status of the plantlets. These opposite patterns suggest different strategies of mycorrhizal and nonmycorrhizal plantlets to water stress, which seem to involve different adjustments in nitrogen and carbon metabolism.

Response of the cherry rootstock to water stress induced in vitro

“…The relative chlorophyll content in leaf tissue of explants was significantly decreased due to increased PEG concentration (Table 1). This effect of water stress on chlorophyll content was also reported in vitro cultures of other plants (Hernandez-Sebastia et al 2000, Brito et al 2003). In addition, water stress caused physiological disorders in explants and the severity of this injury increased with the elevated concentration of PEG (Table 1).…”

Nitrogen availability drives the effect of Glomus intraradices on the growth of strawberry (Fragaria x ananassa Duch.) plants

“…On strawberry plants, AMF have demonstrated a positive effect on the production of dry matter, as well as of flowers, fruit and runners; the rate of photosynthesis; and the production of amino acids 14–17. Nevertheless, most of these studies have been made using in vitro plants and information about the effect of this symbiosis and N accumulation on strawberry plants in the productive stage under non‐limiting N conditions, is not yet available.…”

Integration of mycorrhization and photoautotrophic micropropagation in vitro: feasibility analysis for mass production of mycorrhizal transplants and inoculants of arbuscular mycorrhizal fungi

“…The earliest PM system was the large culture vessel, which used forced ventilation to import pure CO 2 or airenriched CO 2 . Culture vessels range in volume from about several liters to 180 l (Kozai 1991a;Xiao and Kozai 2004;Guan 2007). Two practical models of culture vessels, with holes sealed with filters (Kozai 1991a) or with a top-seal film (Tanaka et al 1988a, b), were developed as experimental tools used for in vitro culture in large culture vessels.…”

“…In addition, relative humidity in the culture system (vessel, room and chamber) can be controlled automatically using a water-absorbent device and humidifier. In order to decrease the frequency of renewing the absorbent materials in the water-absorbent device, a membrane-cover technique was developed to keep water in the substratum (Guan 2007). The higher quality of plantlets and the economic advantages of commercial applications of PM systems over conventional methods have been demonstrated for calla lily (Zantedeschia elliottiana) and China fir (Cunninghamia lanceolata) plantlet production, using the large culture vessels (120 l) (Xiao and Kozai 2004).…”

“…Most importantly, symbiotic formation in vitro can take advantage of the interaction benefits between AMF and controllable environmental factors to improve the growth and development of plantlets synergistically. Guan (2007) first demonstrated mycorrhization in vitro with prerooting plantlets of the Chinese flowering crabapple (Malus pruniolia var ringo) in a PM system (a 180 l large vessel with a control device and forced air ventilation importing controllably pure CO 2 ) with 1500 ± 50 lmol mol -1 CO 2 concentration. The results showed that mycorrhizal symbiosis was well established, and the growth and photosynthetic parameters of the plantlets, such as stomatal resistances, stomatal conductance, chlorophyll content and CO 2 fixation, and photosynthesis rate, were promoted by mycorrhizal colonization.…”