Exogenous application of trehalose induced H2O2 production and stomatal closure in Vicia faba

Trehalose can reduce stomatal aperture by a hydrogen-peroxide-dependent pathway in Vicia faba L. (cv. Daqingpi) resulting in significantly lower values of net photosynthetic rate (P_N), stomatal conductance (g_s), and transpiration rate (E). At 8 and 24 h, the lower P_N in trehalose-treated plants was accompanied by significant decrease in intercellular CO₂ concentration (c_i) suggesting that the reduction of P_N was caused by stomatal limitation. At 48 and 72 h, trehalose decreased apparent carboxylation efficiency (P_N/c_i) and did not decrease c_i and g_s compared with controls; therefore the reduction in photosynthesis was caused by non-stomatal limitation. Trehalose treatment resulted in significantly higher effective photochemical efficiency of PS II (Φ_PSII) and did not affect maximum photochemical efficiency of PS II (F_v/F_m). At 24, 48, and 72 h, trehalose decreased non-photochemical quenching (NPQ) and increased photochemical quenching (qP). Our results suggest that trehalose did not damage photosynthetic reaction centers.