Effect of arbuscular mycorrhizal symbiosis and methyl jasmonate on photosynthetic pigments content under water deficit stress

The arbuscular mycorrhizal (AM) symbiosis enhances plant tolerance to water deficit. Hormonal regulation and symbiotic relationships provide benefits for plants to overcome stress conditions. Methyl jasmonate (MeJA) is a phytohormone related to multiple developmental and growth processes, which might play an important role in the mycorrhizal symbiosis. The aim of this study was to evaluate the effects of exogenous MeJA application and AM symbiosis on photosynthetic pigments content of alfalfa (Medicago sativa L.) under drought. A combined factorial design was performed with three factors: (1) plants inoculated or not (NI) with the AM fungi Rhizophagus intraradices, (2) untreated plants and plants treated with 0, 50 and 100 μm MeJA, and (3) soil moisture levels including field soil capacity (FC) and 55% FC. All plants (inoculated or non-inoculated) received a MeJA treatment through the foliar spray. Drought treatment was applied one week after hormone applying for four weeks. MeJA application and AM symbiosis enhanced biomass, Chl a, Chl b and total Chl content at FC in comparison with NI plants. Moreover, MeJA treatment induced an increase in Clh a, Chl b and total Chl content at both soil moisture levels in comparison with not treated plants. Also, AM symbiosis increased biomass, Clh a, Chl b and total Chl content at 55% FC in comparison with NI plants. But carotenoids content was not affected significantly by water deficit stress, fungus and MeJA interactions. According to these results, we can speculate that MeJA application and AM symbiosis could improve host plant responses to water deficit stress.

کلیدواژه ها:

Alfalfa ، Arbuscular mycorrhiza ، Photosynthetic pigments ، Methyl jasmonate ، Water stress