Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, Zhengzhou 45000, China.
Institute of Geographical Sciences and Natural Resource Research, Chinese Academy of Sciences, Beijing 100101, China.
Sci Total Environ. 2022 Aug 10;833:155217. doi: 10.1016/j.scitotenv.2022.155217. Epub 2022 Apr 14.
Cadmium (Cd) is an element of global concern in agricultural fields owing to its high bioavailability and its risk to human health via the consumption of wheat products. However, whether wheat leaves can directly absorb atmospheric Cd and transport them to the grains along with the contribution of leaves to Cd accumulation in the grains is not clear. We evaluated this mechanism through three comparative treatments: 1) exposure to atmospheric deposition (CK), 2) no exposure to atmospheric deposition (T1), and 3) exposure to atmospheric deposition with leaf cutting (T2). The Cd accumulation rate of grains in the CK, T1, and T2 groups all showed an increasing trend, followed by a decreasing trend, which was consistent with the trend of filling rate. Moreover, the critical period for leaf Cd accumulation in the grains was the early filling period, and its contribution decreased gradually as filling progressed. The contribution of the leaves to grain Cd reached 31.73% at maturity, with the reactivation of stored Cd in leaves pre-flowering and the newly absorbed atmospheric Cd by leaves post-flowering contributing 19.76% and 11.97% to Cd accumulation in grains, respectively, at maturity. Sub-microstructure analysis of the leaves further confirmed that the direct Cd absorption by leaves from atmospheric deposition through stomata contributed to Cd accumulation in wheat grains. Therefore, controlling the sources of atmospheric Cd pollution and reducing Cd absorption by leaves during grain filling can effectively control Cd pollution of wheat grains. This study provides significant insights on how to more effectively control the Cd content of edible part of wheat and ensure food security.
镉（Cd）是农业领域中受到全球关注的元素，因为它的生物可利用性高，而且通过食用小麦产品会对人类健康造成风险。然而，小麦叶片是否可以直接从大气中吸收 Cd，并将其与叶片对籽粒中 Cd 积累的贡献一起运输到籽粒中尚不清楚。我们通过三种对比处理来评估这种机制：1）暴露于大气沉降（CK），2）不暴露于大气沉降（T1），3）暴露于大气沉降并切除叶片（T2）。CK、T1 和 T2 组的籽粒 Cd 积累率均表现出先增加后减少的趋势，这与灌浆速率的趋势一致。此外，叶片中 Cd 在籽粒中积累的关键时期是早期灌浆期，随着灌浆的进行，其贡献逐渐减少。叶片对籽粒 Cd 的贡献率在成熟时达到 31.73%，其中开花前叶片中储存的 Cd 的再活化和开花后叶片中新吸收的大气 Cd 分别对籽粒中 Cd 积累的贡献为 19.76%和 11.97%。叶片的亚微观结构分析进一步证实了叶片通过气孔直接从大气中吸收 Cd 有助于小麦籽粒中 Cd 的积累。因此，控制大气 Cd 污染的来源并减少灌浆期间叶片对 Cd 的吸收可以有效地控制小麦籽粒的 Cd 污染。本研究为如何更有效地控制小麦可食用部分的 Cd 含量，确保食品安全提供了重要的见解。
