Departamento de Biologia and Centro de Investigação e de Tecnologias Agro-ambientais e Biológicas, Universidade do Minho, Braga, Portugal.
Photochem Photobiol. 2013 May-Jun;89(3):579-85. doi: 10.1111/php.12046. Epub 2013 Mar 15.
Grape berry development and ripening depends mainly on imported photosynthates from leaves, however, fruit photosynthesis may also contribute to the carbon economy of the fruit. In this study pulse amplitude modulated chlorophyll fluorescence imaging (imaging-PAM) was used to assess photosynthetic properties of tissues of green grape berries. In particular, the effect of the saturation pulse (SP) intensity was investigated. A clear tissue-specific distribution pattern of photosynthetic competence was observed. The exocarp revealed the highest photosynthetic capacity and the lowest susceptibility to photoinhibition, and the mesocarp exhibited very low fluorescence signals and photochemical competence. Remarkably, the seed outer integument revealed a photosynthetic ability similar to that of the exocarp. At a SP intensity of 5000 μmol m(-2) s(-1) several photochemical parameters were decreased, including maximum fluorescence in dark-adapted (F(m)) and light-adapted (F'(m)) samples and effective quantum yield of PSII (Φ(II)), but the inner tissues were susceptible to a SP intensity as low as 3200 μmol m(-2) s(-1) under light-adapted conditions, indicating a photoinhibitory interaction between SP and actinic light intensities and repetitive exposure to SP. These results open the way to further studies concerning the involvement of tissue-specific photosynthesis in the highly compartmentalized production and accumulation of organic compounds during grape berry development.
葡萄浆果的发育和成熟主要依赖于叶片导入的光合作用产物，但果实的光合作用也可能为果实的碳经济做出贡献。本研究采用脉冲振幅调制叶绿素荧光成像（imaging-PAM）技术评估了绿色葡萄浆果组织的光合特性。特别研究了饱和脉冲（SP）强度的影响。观察到了具有组织特异性的光合能力分布模式。外果皮表现出最高的光合能力和最低的光抑制敏感性，而中果皮表现出非常低的荧光信号和光化学能力。值得注意的是，种皮外种皮表现出类似于外果皮的光合能力。在 5000 μmol m(-2) s(-1) 的 SP 强度下，几个光化学参数降低，包括暗适应（F(m))和光适应（F'（m））时的最大荧光以及 PSII 的有效量子产量（Φ(II)))，但在光适应条件下，内部组织对 3200 μmol m(-2) s(-1)的 SP 强度也很敏感，这表明 SP 和光强之间存在光抑制相互作用以及对 SP 的重复暴露。这些结果为进一步研究组织特异性光合作用在葡萄浆果发育过程中高度分隔的有机化合物的产生和积累中的作用开辟了道路。
