A novel microRNA IamiR-4-3p from water spinach (Ipomoea aquatica Forsk.) increased Cd uptake and translocation in Arabidopsis thaliana

Shen, Chuang; Huang, Ying-Ying; Xin, Jun-Liang; He, Chun-Tao; Yang, Zhong-Yi

A novel microRNA IamiR-4-3p from water spinach (Ipomoea aquatica Forsk.) increased Cd uptake and translocation in Arabidopsis thaliana

2022

Shen, Chuang | Huang, Ying-Ying | Xin, Jun-Liang | He, Chun-Tao | Yang, Zhong-Yi

MicroRNAs (miRNAs) play important roles in plant response to Cd stress. In our previous study, we observed significant differences in the expression levels of IamiR-4-3p between high-Cd and low-Cd cultivars of water spinach. The function of IamiR-4-3p was investigated by using wild type Arabidopsis (WT), Arabidopsis transfected with empty vector pCambia1302 (CK), and Arabidopsis transfected with IamiR-4-3p + vector pCambia1302 (p35S::miR-4-3p) in this study. In p35S::miR-4-3p Arabidopsis, the expression levels of GST3 and AWPM19-like were reduced by 20% and 24%. Under Cd treatment, higher root and shoot Cd concentrations were detected in the transgenic p35S::miR-4-3p Arabidopsis. MDA and H₂O₂ concentrations were positively correlated with the Cd concentrations in all Arabidopsis. The elevated GSH pool in p35S::miR-4-3p Arabidopsis should compensate for its restricted GST3 expression in response to Cd-induced oxidative stress. Lower F1 (cell wall) and higher F2 (organelle) and F3 (soluble fraction) Cd concentrations were observed along with the reduced ABA level in p35S::miR-4-3p Arabidopsis, which could induce a weakened apoplastic barrier and higher Cd accumulation and translocation in roots. It is suggested that IamiR-4-3p is able to reduce the expression levels of GST3 and AWPM19-like, resulting in higher Cd uptake and translocation in Arabidopsis.

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