Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha, China.
Sci Rep. 2021 Nov 11;11(1):22045. doi: 10.1038/s41598-021-00322-6.
Abscisic acid (ABA) is known as an important hormone regulating plant stress resistance, such as salt, drought and heavy metal resistance. However, the relationship between ABA and cadmium (Cd) enrichment in ramie (Boehmeria nivea L.) is still unclear to date. This study aimed to reveal the effect of ABA on Cd enrichment in ramie, and we received the following results: (1) Under Cd treatment, the Cd uptake of ramie increased with the increase of Cd concentration, but the chlorophyll content decreased. Under Cd treatment, the ABA content was highest in roots of ramie, followed by that in old leaves, and lowest in new leaves. Long-time treatment of high Cd concentration reduced the ability of endogenous ABA biosynthesis. (2) Spraying ABA on ramie plants (SORP) and adding ABA directly to the culture solution (ADCS) with low concentration can promote the growth of ramie and increase the amount of Cd uptake, and the effect of SORP is better. (3) The molecular reason for the decrease of chlorophyll content due to Cd stress, may be resulted from the down-regulated expression of the chlorophyll synthesis genes (BnPAO and BnNYC1) and the up-regulated expression of the chlorophyll degradation genes (BnCHLH, BnCHLG, BnHAP3A and BnPPR1). The elevated ABA content in ramie plants may due to the up-regulated expression of the ABA synthesis related genes (BnABA1, BnNCED3, and BnNCED5) and the genes (BnABCG40, BnNFXL2, BnPYL9, BnGCR2, BnGTG1, BnBGLU1, BnUTG1, BnVHAG1 and BnABI5) that encoding ABA transport and response proteins, which was consistent with the enhance the Cd uptake in ramie. Our study revealed the relationship between ABA and Cd uptake in ramie, which provided a reference for improving the enrichment of Cd in ramie.
脱落酸（ABA）是一种重要的激素，可调节植物的抗逆性，如盐、干旱和重金属抗性。然而，ABA 与苎麻（Boehmeria nivea L.）中镉（Cd）富集的关系至今仍不清楚。本研究旨在揭示 ABA 对苎麻中 Cd 富集的影响，我们得到了以下结果：（1）在 Cd 处理下，苎麻对 Cd 的吸收随 Cd 浓度的增加而增加，但叶绿素含量下降。在 Cd 处理下，ABA 含量在苎麻根中最高，其次是老叶，在新叶中最低。长时间高浓度 Cd 处理降低了内源 ABA 生物合成的能力。（2）在苎麻植株上喷施 ABA（SORP）和在低浓度的培养液中直接添加 ABA（ADCS）可以促进苎麻的生长，增加 Cd 的吸收量，且 SORP 的效果更好。（3）由于 Cd 胁迫导致叶绿素含量下降的分子原因，可能是由于叶绿素合成基因（BnPAO 和 BnNYC1）的下调表达和叶绿素降解基因（BnCHLH、BnCHLG、BnHAP3A 和 BnPPR1）的上调表达所致。苎麻中 ABA 含量的升高可能是由于 ABA 合成相关基因（BnABA1、BnNCED3 和 BnNCED5）和编码 ABA 转运和响应蛋白的基因（BnABCG40、BnNFXL2、BnPYL9、BnGCR2、BnGTG1、BnBGLU1、BnUTG1、BnVHAG1 和 BnABI5）的上调表达所致，这与增强苎麻对 Cd 的吸收一致。本研究揭示了 ABA 与苎麻中 Cd 吸收的关系，为提高苎麻对 Cd 的富集提供了参考。
