Evaluating the effects of Funneliformis mosseae on expression of dehydrin during drought stress on Iranian pistachio (Pistacia vera L.)

Arbuscular mycorrhizal fungi are one of the most important and the most abundant micro-organisms in soil. The fungi have symbiotic relation with 80 to 90 percent of plant species. Arbuscular mycorrhizal symbiosis is able to alter pattern of dehydrin expression under drought stress. During period of drought acclimation that causes dehydration of cells, dehydrin proteins accumulate inside cells and protect membranes and macromolecules structures. All seedlings were irrigated three times per week during two years then were exposed to severe drought stress for nine days until wilt symptoms appeared on their leaves, then irrigated normally. It was evaluated whether Funneliformis mosseae is able to alter expression functions of dehydrin in the mycorrhiza seedlings of Pistacia vera under drought stress. Results showed that mycorrhizal colonization percentage in roots of P. vera declined significantly due to water stress treatments. The result revealed that the expression of dehydrin was increased significantly in non-mycorrhizal seedlings at 9 days exposure to the drought stress compared to the mycorrhizal seedlings, but the levels of dehydrin accumulation in mycorrhizal treatment subjected to drought were considerably lower than that of corresponding non-mycorrhiza seedlings, indicating that the accumulation of dehydrin proteins is not a mechanism by which the mycorrhizal symbiosis protects their host seedlings and suggesting that mycorrhizal seedlings were less strained by drought due to primary drought-avoidance mechanisms