Functional characterization of tomato membrane-bound NAC transcription factors

Abstract

Genome-wide analysis was carried out to identify and analyze differential expression pattern of tomato membrane bound NAC transcription factors (SlNACMTFs) during stresses. Two biotic-stress-related SlNACMTFs have been characterized to elucidate their regulatory function. NAC transcription factors are known regulators of stress-related gene expression. As Stresses are perceived and transmitted by membrane-bound proteins, functional characterization of membrane-associated NAC transcription factors in tomato can reveal valuable insight about membrane-mediated stress-signalling. Tomato genome encodes 13 NAC genes which have predicted transmembrane domain(s) (SlNACMTFs). mRNA of 12 SlNACMTFs were readily detected in multiple tissues, and also in polysome isolated from leaf, confirming active transcription and translation from these genes occur under normal physiological condition. Additionally, most of the SlNACMTFs were differentially regulated during stresses and stress-related transcription factor binding sites are prevalent in their promoters. SlNACMTF3 and 8 were majorly regulated in biotic and abiotic stresses. Like other MTFs, SlNACMTF3 was translocated to the plasma membrane, whereas the C-terminus truncated (ΔC) form localized in the cytoplasm and the nucleus. Accordingly, the ΔC forms significantly influenced the activity of promoters harbouring NAC binding sites (NACbs). Furthermore, the NAC domain of these transcription factors could directly interact with an NACbs, and the proteins failed to regulate a promoter lacking a crucial NACbs. Interestingly, the type of influence to an NACbs containing promoter was dependent on the context of the NACbs, as the same SlNACMTF showed an alternative mode of regulation on different promoters, as well as the same promoter activity was oppositely regulated by two different SlNACMTF. Finally, both SlNACMTFs demonstrated the differential regulatory effect on the expression of several stress-related genes by interacting with the putative NACbs in their promoter region, suggesting their direct role in plant stress response.

Comprehensive analysis of NAC transcription factors uncovers their roles during fiber development and stress response in cotton

“…Membrane-bound transcription factors (MTF) are located in the membrane itself and are activated upon receiving of specific signal, and this regulation mode is considered to be accurate, such as membrane release [ 10 ]. Membrane-bound NAC transcription factors have been extensively identified and involved in many biological processes in different plant species [ 9 , 11 , 49 , 50 ]. In this study, we firstly identified 68 predicted membrane-bound NAC transcription factors in four cotton species and members are mainly distributed in the same subfamily, and these genes appear to be conserved during evolution.…”

“…Some NAC proteins have a transmembrane (TM) motif in the C-terminus, and show subcellular localization at the plasma membrane or endoplasmic reticulum; these proteins may be regulated by post-translational regulation under specific conditions [ 6 – 8 ]. Several species have membrane-bound NAC transcription factors, with 13 in Arabidopsis , 13 in tomato, 11 in soybean and 5 in rice, and most are induced by abiotic stresses [ 1 , 9 – 12 ].…”

Distinct transcriptional and processing regulations control miR167a level in tomato during stress

“…Therefore, we performed transient expression studies of the transcription factors in ¡316/C72 transgenic plant to appreciate their role in the promoter regulation. One of the tomato NAC proteins, SlNACMTF3 lacking the C-terminus domain, 23 slightly but significantly augmented the ¡316/C72 promoter activity ( Figure S8D). The predicted DREBbs has high level of homology with the similar CRT/DRE sites found in other stress-responsive genes (Fig.…”

Elucidation and functional characterization of CsPSY and CsUGT promoters in Crocus sativus L.

“…The ABRE element has earlier been identified in the PSY promoter of Oryza sativa and Zea mays [ 26 , 27 , 28 ]. Besides, ABRE has been reported to play a crucial role in the regulation of NAC TFs under stressed condition [ 29 ]. The phytohormones play significant role in development and defense and hence presence of these elements in CsPSYp and CsUGTp point towards the possibility of their phytohormone mediated regulation.…”