Identification and Expression Analysis of Stress-Associated Proteins (SAPs) Containing A20/AN1 Zinc Finger in Cucumber

Abstract

Stress-associated proteins (SAPs) are a class of zinc finger proteins that confer tolerance to a variety of abiotic and biotic stresses in diverse plant species. However, in cucumber (Cucumis sativus L.), very little is known about the roles of SAP gene family members in regulating plant growth, development, and stress responses. In this study, a total of 12 SAP genes (named as CsSAP1-CsSAP12) were identified in the cucumber genome, which were unevenly distributed on six chromosomes. Gene duplication analysis detected one tandem duplication and two segmental duplication events. Phylogenetic analysis of SAP proteins from cucumber and other plants suggested that they could be divided into seven groups (sub-families), and proteins in the same group generally had the same arrangement of AN1 (ZnF-AN1) and A20 (ZnF-A20) domains. Most of the CsSAP genes were intronless and harbored a number of stress- and hormone-responsive cis-elements in their promoter regions. Tissue expression analysis showed that the CsSAP genes had a broad spectrum of expression in different tissues, and some of them displayed remarkable alteration in expression during fruit development. RT-qPCR results indicated that all the selected CsSAP genes displayed transcriptional responses to cold, drought, and salt stresses. These results enable the first comprehensive description of the SAP gene family in cucumber and lay a solid foundation for future research on the biological functions of CsSAP genes.

Characterization of Germin-like Proteins (GLPs) and Their Expression in Response to Abiotic and Biotic Stresses in Cucumber

“…The chromosomal locations of the CsGLP genes were analyzed by MapGene2Chrom (http://mg2c.iask.in/mg2c_v2.0/, 15 March 2021), a tool for the online reconstruction of the gene chromosome position map. Tandem and segmental duplication events were identified using the MCScanX software based on previously published criteria [32].…”

“…Total RNA was isolated using the Eastep Super Total RNA Extraction Kit (Promega, Madison, WI, USA), and cDNA synthesis was performed using the M-MLV reverse transcriptase (Invitrogen, USA) according to the protocols. qRT-PCR was performed with the Roche Lightcyler 480II PCR System using the TB Green Premix Ex TaqII Kit (TaKaRa, Dalian, China) under the guidelines, as previously described [32]. Three biological replicates were performed for each experiment.…”

“…Three biological replicates were performed for each experiment. The CsAct3 gene was used as a control for qRT-PCR analysis with the 2 −∆∆Ct relative quantitative method [32].…”

Differential Functions of Pepper Stress-Associated Proteins in Response to Abiotic Stresses

“…Stress-associated proteins (SAPs) are a group of zinc-fingertype proteins that are reportedly associated with abiotic stress responses, immunity, and development (Mukhopadhyay et al, 2004;Dixit et al, 2018;Dong et al, 2018;Liu et al, 2019c;Wang et al, 2019;Zhao et al, 2020). Since the discovery of the first SAP gene, the OsiSAP1 (OsSAP1) gene in rice, others have been characterized in various plant species as genome sequencing technology has advanced (Mukhopadhyay et al, 2004;Vij and Tyagi, 2006;Solanke et al, 2009;Giri et al, 2013;Dong et al, 2018;Liu et al, 2019a;Zhang et al, 2019;Ben Saad et al, 2020;Lai et al, 2020;Wang et al, 2021). However, no SAP genes have been isolated from pepper plant.…”

Cloning and Characterization of TaSAP7-A, a Member of the Stress-Associated Protein Family in Common Wheat

“…Stress-associated proteins (SAPs) are a class of zinc finger proteins including A20/AN1 domains. SAP genes are widely distributed in many plant species, such as rice, maize, tomato, soybean, cucumber, Arabidopsis , Medicago truncatula , Aeluropus littpralis , and Sorghum bicolor ( Vij and Tyagi, 2006 ; Solanke et al, 2009 ; Gimeno Gilles et al, 2011 ; Xuan et al, 2011 ; Wang et al, 2013 ; Zhang et al, 2019 ; Lai et al, 2020 ). SAP genes are known to play important roles in stress responses in plants, and majority of them have been reported to be stress inducible.…”