College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China.
Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China.
Int J Mol Sci. 2022 Sep 14;23(18):10694. doi: 10.3390/ijms231810694.
Root-zone CO is essential for plant growth and metabolism. However, the partitioning and assimilation processes of CO absorbed by roots remain unclear in various parts of the oriental melon. We investigated the time at which root-zone CO enters the oriental melon root system, and its distribution in different parts of the plant, using C stable isotopic tracer experiments, as well as the effects of high root-zone CO on leaf carbon assimilation-related enzyme activities and gene expressions under 0.2%, 0.5% and 1% root-zone CO concentrations. The results showed that oriental melon roots could absorb CO and transport it quickly to the stems and leaves. The distribution of C in roots, stems and leaves increased with an increase in the labeled root-zone CO concentration, and the δC values in roots, stems and leaves increased initially, and then decreased with an increase in feeding time, reaching a peak at 24 h after C isotope labeling. The total accumulation of C in plants under the 0.5% and 1% CO concentrations was lower than that in the 0.2% CO treatment. However, the distributional proportion of C in leaves under 0.5% and 1% CO was significantly higher than that under the 0.2% CO concentration. Photosynthetic carbon assimilation-related enzyme activities and gene expressions in the leaves of oriental melon seedlings were inhibited after 9 days of high root-zone CO treatment. According to these results, oriental melon plants' carbon distribution was affected by long-term high root-zone CO, and reduced the carbon assimilation ability of the leaves. These findings provide a basis for the further quantification of the contribution of root-zone CO to plant communities in natural field conditions.
根区 CO 对植物生长和代谢至关重要。然而，在东方甜瓜的不同部位，根部吸收的 CO 的分配和同化过程尚不清楚。我们使用 C 稳定同位素示踪实验研究了根区 CO 进入东方甜瓜根系的时间及其在植物不同部位的分布，以及在 0.2%、0.5%和 1%根区 CO 浓度下，高根区 CO 对叶片碳同化相关酶活性和基因表达的影响。结果表明，东方甜瓜根系能够吸收 CO 并迅速将其运输到茎和叶片。根、茎和叶中 C 的分布随标记根区 CO 浓度的增加而增加，根、茎和叶中的 δC 值最初增加，然后随喂养时间的增加而减少，在 C 同位素标记后 24 小时达到峰值。在 0.5%和 1% CO 浓度下，植物中 C 的总积累量低于 0.2% CO 处理。然而，在 0.5%和 1% CO 下，叶片中 C 的分布比例明显高于 0.2% CO 浓度。经过 9 天的高根区 CO 处理后，东方甜瓜幼苗叶片中与光合作用碳同化相关的酶活性和基因表达受到抑制。根据这些结果，长期高根区 CO 影响了东方甜瓜植物的碳分配，降低了叶片的碳同化能力。这些发现为进一步量化根区 CO 对自然田间条件下植物群落的贡献提供了依据。
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