Saito Akihiro, Shinjo Shotaro, Ito Daiki, Doi Yuko, Sato Akira, Wakabayashi Yuna, Honda Juma, Arai Yuka, Maeda Tsubasa, Ohyama Takuji, Higuchi Kyoko
Laboratory of Biochemistry in Plant Productivity, Department of Agricultural Chemistry, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan.
Plants (Basel). 2021 Jan 25;10(2):234. doi: 10.3390/plants10020234.
Leaf iron (Fe) contents in Fe-deficiency-tolerant plants are not necessarily higher than that in Fe-deficiency-susceptible ones, suggesting an unknown mechanism involved in saving and allowing the efficient use of minimal Fe. To quantitatively evaluate the difference in Fe economy for photosynthesis, we compared the ratio of CO assimilation rate to Fe content in newly developed leaves as a novel index of photosynthetic iron-use efficiency (PIUE) among 23 different barley ( L.) varieties. Notably, varieties originating from areas with alkaline soil increased PIUE in response to Fe-deficiency, suggesting that PIUE enhancement is a crucial and genetically inherent trait for acclimation to Fe-deficient environments. Multivariate analyses revealed that the ability to increase PIUE was correlated with photochemical quenching (qP), which is a coefficient of light energy used in photosynthesis. Nevertheless, the maximal quantum yield of photosystem II (PSII) photochemistry, non-photochemical quenching, and quantum yield of carbon assimilation showed a relatively low correlation with PIUE. This result suggests that the ability of Fe-deficiency-tolerant varieties of barley to increase PIUE is related to optimizing the electron flow downstream of PSII, including cytochrome and photosystem I.
缺铁耐受性植物叶片中的铁（Fe）含量不一定高于缺铁敏感性植物，这表明存在一种未知机制参与节省和有效利用微量铁。为了定量评估光合作用中铁经济的差异，我们比较了23个不同大麦（Hordeum vulgare L.）品种新发育叶片中二氧化碳同化率与铁含量的比值，将其作为光合铁利用效率（PIUE）的新指标。值得注意的是，来自碱性土壤地区的品种在缺铁时PIUE增加，这表明PIUE增强是适应缺铁环境的关键且遗传固有的特性。多变量分析表明，增加PIUE的能力与光化学猝灭（qP）相关，光化学猝灭是光合作用中光能利用的系数。然而，光系统II（PSII）光化学的最大量子产率、非光化学猝灭和碳同化量子产率与PIUE的相关性相对较低。这一结果表明，大麦缺铁耐受性品种增加PIUE的能力与优化PSII下游的电子流有关，包括细胞色素b6f和光系统I。
