Horiguchi Genki, Nemoto Kyosuke, Yokoyama Tomomi, Hirotsu Naoki
Graduate School of Life Sciences, Toyo University, Itakura-machi, Oura-gun, Gunma, Japan.
Faculty of Life Sciences, Toyo University, Itakura-machi, Oura-gun, Gunma, Japan.
AoB Plants. 2019 Feb 27;11(2):plz009. doi: 10.1093/aobpla/plz009. eCollection 2019 Apr.
, a heterophyllous amphibious plant, develops serrated or dissected leaves when grown in terrestrial or submerged conditions, respectively. In this study, we tested whether submerged leaves and ethylene-induced leaves of the heterophyllous, amphibious plant have improved photosynthetic ability under submerged conditions. Also, we investigated how this amphibious plant photosynthesizes underwater and whether a HCO transport system is present. We have analysed leaf morphology, measured underwater photosynthetic rates and HCO affinity in to determine if there are differences in acclimation ability dependent on growth conditions: terrestrial, submerged, terrestrial treated with ethylene and submerged treated with an ethylene inhibitor. Moreover, we measured time courses for changes in leaf anatomical characteristics and underwater photosynthesis in terrestrial leaves after submersion. Compared with the leaves of terrestrially grown plants, leaf thickness of submerged plants was significantly thinner. The stomatal density on the abaxial surface of submerged leaves was also reduced, and submerged plants had a significantly higher O evolution rate. When the leaves of terrestrially grown plants were treated with ethylene, their leaf morphology and underwater photosynthesis increased to levels comparable to those of submerged leaves. Underwater photosynthesis of terrestrial leaves was significantly higher by 5 days after submersion. In contrast, leaf morphology did not change after submergence. Submerged leaves and submerged terrestrial leaves were able to use bicarbonate but submerged terrestrial leaves had an intermediate ability to use HCO that was between terrestrial leaves and submerged leaves. Ethoxyzolamide, an inhibitor of intracellular carbonic anhydrase, significantly inhibited underwater photosynthesis in submerged leaves. This amphibious plant acclimates to the submerged condition by changing leaf morphology and inducing a HCO utilizing system, two processes that are regulated by ethylene.
一种叶形多变的两栖植物，在陆地或水下生长时分别长出锯齿状或深裂的叶子。在本研究中，我们测试了这种叶形多变的两栖植物的水下叶片和乙烯诱导的叶片在水下条件下是否具有更高的光合能力。此外，我们研究了这种两栖植物在水下如何进行光合作用以及是否存在HCO运输系统。我们分析了叶片形态，测量了水下光合速率和HCO亲和力，以确定是否存在取决于生长条件（陆地、水下、用乙烯处理的陆地、用乙烯抑制剂处理的水下）的适应能力差异。此外，我们测量了陆地叶片浸没后叶片解剖特征和水下光合作用变化的时间进程。与陆地生长的植物叶片相比，水下植物的叶片厚度明显更薄。水下叶片背面的气孔密度也降低了，水下植物的O释放速率明显更高。当用乙烯处理陆地生长的植物叶片时，其叶片形态和水下光合作用增加到与水下叶片相当的水平。陆地叶片浸没5天后水下光合作用显著提高。相比之下，浸没后叶片形态没有变化。水下叶片和浸没的陆地叶片能够利用碳酸氢盐，但浸没的陆地叶片利用HCO的能力介于陆地叶片和水下叶片之间。乙氧唑胺，一种细胞内碳酸酐酶抑制剂，显著抑制水下叶片的水下光合作用。这种两栖植物通过改变叶片形态和诱导利用HCO的系统来适应水下条件，这两个过程受乙烯调节。
