Plasticity of photosynthesis after the 鈥榬ed light syndrome鈥?in cucumber

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• 作者：Govert Trouwborst¹ ; Sander W. Hogewoning¹ ; Olaf van Kooten ; Jeremy Harbinson ; Wim van Ieperen ; ^{Wim.vanIeperen@wur.nl" class="auth_mail" title="E-mail the corresponding author}
• 关键词：A100 ; net photosynthetic rate at growth irradiance ; An ; net photosynthetic rate ; Amg ; maximum gross photosynthetic rate ; Amax ; maximum net photosynthetic rate ; CF ; chlorophyll fluorescence ; Ci ; internal CO2 concentration ; ETR ; electron transport rate ; Fv/Fm ; maximum quantum efficiency of PSII photochemistry in the dark ; Fv&prime ; /Fm&prime ; maximum quantum efficiency of PSII photochemistry in the light ; gs ; stomatal conductance ; Jmax ; maximum electron transport rate ; LMA ; leaf mass per area ; Nor
• 刊名：Environmental and Experimental Botany
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：121
• 期：Complete
• 页码：75-82
• 全文大小：704 K

文摘

The quantum efficiency of photosynthesis of leaves is wavelength dependent and peaks in red (620–670 nm). However when cucumber plants are raised under pure red light, leaf photosynthesis becomes severely impaired. This “red light syndrome” has been characterized before by a low F_v/F_m, unresponsive stomatal conductance (g_s), and a low photosynthetic capacity (A_max). It is not known if the syndrome also occurs in fully developed leaves that are exposed to pure red light after reaching maturity and if initially injured leaves can recover from the syndrome. This study investigates the plasticity leaf photosynthetic apparatus after inducing or releasing the “red light syndrome” in leaves of young cucumber plants. The plants were grown under pure red (R) or mixed red/blue (RB; 70%R) LED light and subsequently exposed to RB (R/RB) and R (RB/R) light (100 渭mol PPFD m⁻² s⁻¹, 16 h photoperiod) or kept at their initial growth spectrum (R/R) and (RB/RB). Acclimation of fully developed leaves was monitored with gas exchange and chlorophyll fluorescence (CF) over a period of 8–10 days after the shift. After switching to RB, R injured leaves recovered from photodamage within 4 days. Photosynthetic capacity (A_max) and g_s partly recovered, but did not restrict the net CO₂ assimilation rate at growth irradiance (A₁₀₀), which increased to the same level as in healthy (RB/RB) leaves. After imposing injurious R to healthy mature leaves, they transiently developed signs of the red light-syndrome: a slightly decreased F_v/F_m and more severely reduced A_max and g_s. However, A₁₀₀ did not significantly decrease. CF quenching analysis revealed an potentially harmful increased quantum yield of non-regulated non-photochemical energy loss in PSII under R, which was higher in leaves that developed under R than in leaves that were exposed to R after reaching maturity. We conclude that exposure to pure red light is harmful to photosynthetic systems in both developing and developed leaves of cucumber, but the effect on CO₂ assimilation rate and F_v/F_m is much more severe in developing leaves than in mature leaves at low growth irradiance. Chloroplasts of previously R light injured leaves can recover within a few days after releasing from R light, while stomatal conductance and other (partial) morphologically determined leaf factors do not completely acclimate.