Contents lists available at ScienceDirect Plant Science journal homepage: www.elsevier.com/locate/plantsci Investigation of the interaction of DAD1-LIKE LIPASE 3 (DALL3) with Selenium Binding Protein 1 (SBP1) in Arabidopsis thaliana Irene Dervisi a , Chrysanthi Valassakis a , Adamantia Agalou b,1 , Nikolaos Papandreou c , Varvara Podia a , Kosmas Haralampidis a , Vassiliki A. Iconomidou c , Vassili N. Kouvelis d , Herman P. Spaink b , Andreas Roussis a, * a Department of Botany, Faculty of Biology, National & Kapodistrian University of Athens, 15784, Athens, Greece b Institute of Biology, Leiden University, Leiden, the Netherlands c Department of Cell Biology and Biophysics, Faculty of Biology, National & Kapodistrian University, 15784, Athens, Greece d Department of Genetics and Biotechnology, Faculty of Biology, National & Kapodistrian University of Athens, 15784, Athens, Greece ARTICLE INFO Keywords: SBP1 Selenium Binding Protein 1 DALL3 Phospholipase ABSTRACT Phospholipase PLA 1 -Iγ2 or otherwise DAD1-LIKE LIPASE 3 (DALL3) is a member of class I phospholipases and has a role in JA biosynthesis. AtDALL3 was previously identified in a yeast two-hybrid screening as an inter- acting protein of the Arabidopsis Selenium Binding Protein 1 (SBP1). In this work, we have studied AtDALL3 as an interacting partner of the Arabidopsis Selenium Binding Protein 1 (SBP1). Phylogenetic analysis showed that DALL3 appears in the PLA1-Igamma1, 2 group, paired with PLA1-Igammma1. The highest level of expression of AtDALL3 was observed in 10-day-old roots and in flowers, while constitutive levels were maintained in seedlings, cotyledons, shoots and leaves. In response to abiotic stress, DALL3 was shown to participate in the network of genes regulated by cadmium, selenite and selenate compounds. DALL3 promoter driven GUS assays revealed that the expression patterns defined were overlapping with the patterns reported for AtSBP1 gene, indicating that DALL3 and SBP1 transcripts co-localize. Furthermore, quantitative GUS assays showed that these com- pounds elicited changes in activity in specific cells files, indicating the differential response of DALL3 promoter. GFP::DALL3 studies by confocal microscopy demonstrated the localization of DALL3 in the plastids of the root apex, the plastids of the central root and the apex of emerging lateral root primordia. Additionally, we confirmed by yeast two hybrid assays the physical interaction of DALL3 with SBP1 and defined a minimal SBP1 fragment that DALL3 binds to. Finally, by employing bimolecular fluorescent complementation we demonstrated the in planta interaction of the two proteins. 1. Introduction Phospholipases are a group of enzymes that hydrolyze phospholi- pids and are categorized based on their positional specificity toward phospholipid substrates. In plants, it is known that there are phospho- lipases A (PLA), C (PLC) and D (PLD) while phospholipases B have not been identified [1,2]. These enzymes are involved in a wide range of cellular functions such as cellular regulation, lipid metabolism, mem- brane homeostasis, stress responses and cell signaling [1,2]. The PLA superfamily contains a broad range of enzymes that are designated with Greek letters and have been classified into three sub- types: PLA 1 and PLA 2 , which hydrolyse acyl groups from the sn-1 and sn-2 positions of phospholipids respectively, and patatin-like PLAs (PAT-PLA) all exhibiting activity towards both positions [1]. Further- more, the molecules mediated by PLAs act as secondary signal mes- sengers that mediate cell elongation, gravitropism, anther dehiscence, biosynthesis of jasmonic acid and defense [3]. It is noteworthy that these enzymes play a significant role in important applications of food and biotechnology industries, such as degumming of vegetable oils, diary, baking or egg yolk treatment and biodiesel production [4,5]. Specifically, PLA 1 proteins hydrolyze phospholipids and produce 2- acyl-lysophospholipids and fatty acids [6] and they are involved in a wide range of cellular functions including jasmonic acid biosynthesis [7,8], defense signaling induced by ultraviolet (UV) radiation [9], cell and tissue growth [10], onset of senescence [11], storage lipid accu- mulation [11,12] and shoot gravitropism [13]. All PLA 1 proteins https://doi.org/10.1016/j.plantsci.2019.110357 Received 26 June 2019; Received in revised form 18 November 2019; Accepted 21 November 2019 ⁎ Corresponding author. E-mail address: aroussis@biol.uoa.gr (A. Roussis). 1 Current address: Developmental Biology, Biomedical Research Foundation Academy of Athens, Soranou Ephessiou 4, 11527, Athens, Greece. Plant Science 291 (2020) 110357 Available online 23 November 2019 0168-9452/ © 2019 Elsevier B.V. All rights reserved. T