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Abstract Plants have developed mechanisms that allow them to tolerate different abiotic stresses. Among these mechanisms, the accumulation of specific proteins such as dehydrins (DHNs) and aquaporins (AQPs) can protect other proteins from damage during dehydration and may allow the control of water loss, respectively. Although both types of proteins are involved in plant protection against dehydration stress, a direct interaction between them has not been explored. A previous screen to identify potential OpsDHN1 protein interactions revealed an aquaporin as a possible candidate. Here, we used the Bimolecular Fluorescence Complementation (BiFC) approach to investigate the direct interaction of the cactus OpsDHN1 protein with the Arabidopsis plasma membrane PIP family aquaporin AtPIP2B (At2G37170). Since AtPIP2B is a membrane protein and OpsDHN1 is a cytosolic protein that may be peripherally associated with membranes, we propose that OpsDHN1/AtPIP2B interaction takes place at cellular membranes. Furthermore, we also demonstrate the interaction of AtPIP2B with the three Arabidopsis dehydrins COR47 (AT1G20440), ERD10 (At1g20450), and RAB18 (At5g66400). Highlights • This study constitutes the first report of a membrane protein target of the dehydrin OpsDHN1. • The COR47, ERD10, and RAB18 Arabidopsis dehydrins are able to interact with AtPIP2B in planta. • DHN-PIP2B proteins interactions across plant species suggest a common stress response mechanism. [ABSTRACT FROM AUTHOR]

Abstract Arabidopsis amiR: ADC -L2 is a non-lethal line with several developmental defects, it is characterized by a drastic reduction in free polyamine content. Herein, we found that catalase application had growth-promoting effects in amiR: ADC -L2 and parental Ws seedlings. Differences in ROS content between amiR: ADC -L2 and Ws seedlings were detected. Increased H 2 O 2 levels were found in the amiR: ADC -L2, as well as low AtCAT2 gene expression and reduced catalase activity. Estimation of polyamine oxidase activity in amiR: ADC -L2 line indicated that the over-accumulation of H 2 O 2 is independent of polyamine catabolism. However, increments in NADPH oxidase activity and O 2 •− content could be associated to the higher H 2 O 2 levels in the amiR: ADC -L2 line. Our data suggest that low polyamine levels in Arabidopsis seedlings are responsible for the accumulation of ROS, by altering the activities of enzymes involved in ROS production and detoxification. Highlights • ROS content and CAT activity is deregulated in a non-lethal line (amiR: ADC -L2) with low polyamine levels. • Catalase exogenous treatment induces a promoting growth in A. thaliana. • Accumulation of ROS in amiR: ADC -L2 line is independent of PA catabolism. [ABSTRACT FROM AUTHOR]