Over-expression of Topoisomerase II Enhances Salt Stress Tolerance in Tobacco

Abstract

Topoisomerases are unique enzymes having an ability to remove or add DNA supercoils and untangle the snarled DNA. They can cut, shuffle, and religate DNA strands and remove the torsional stress during DNA replication, transcription or recombination events. In the present study, we over-expressed topoisomerase II (TopoII) in tobacco (Nicotiana tabaccum) and examined its role in growth and development as well as salt (NaCl) stress tolerance. Several putative transgenic plants were generated and the transgene integration and expression was confirmed by PCR and Southern blot analyses, and RT-PCR analysis respectively. Percent seed germination, shoot growth, and chlorophyll content revealed that transgenic lines over-expressing the NtTopoIIα-1 gene exhibited enhanced tolerance to salt (150 and 200 mM NaCl) stress. Moreover, over-expression of TopoII lead to the elevation in proline and glycine betaine levels in response to both concentrations of NaCl as compared to wild-type. In response to NaCl stress, TopoII over-expressing lines showed reduced lipid peroxidation derived malondialdehyde (MDA) generation. These results suggest that TopoII plays a pivotal role in salt stress tolerance in plants.

Modulation of cell cycle progression and chromatin dynamic as tolerance mechanisms to salinity and drought stress in maize

“…Immunostaining data revealed a lower DNA methylation pattern in response to abiotic stress. Furthermore, the expression level of DNA topoisomerases was upregulated in response to both salinity and drought stress, which is corroborated by other studies (Hettiarachchi et al, 2005; John et al, 2016). High level of the DNA topoisomerase in maize seedlings exposed to abiotic stresses reflects that abiotic stress induces DNA damage (Huang et al, 2003; Morotomi‐Yano et al, 2018), cell cycle arrest, and apoptosis (Wang et al, 2016).…”

“…CDK/CYC complex activation is also altered by the upregulation of WEE1 kinase, which is associated with the stress response. Red background color refers to strongly upregulated genes and green background color refers to strongly downregulated genes, whereas black backgrounds indicate no transcription changes drought stress, which is corroborated by other studies (Hettiarachchi et al, 2005;John et al, 2016). High level of the DNA topoisomerase in maize seedlings exposed to abiotic stresses reflects that abiotic stress induces DNA damage (Huang et al, 2003;Morotomi-Yano et al, 2018), cell cycle arrest, and apoptosis (Wang et al, 2016).…”

Physiological and Transcriptome Analysis of Sugar Beet Reveals Different Mechanisms of Response to Neutral Salt and Alkaline Salt Stresses

“…DNA replication is the biological process by which can exact copy of a DNA molecule is created and genetic information is faithfully transmitted in all living organisms. It is evident that salinity stress affects the cellular molecules involved in DNA replication including helicases, DNA polymerase and DNA replication licensing factor (Sanan-Mishra et al, 2005;John et al, 2016). In our study, transcriptomic analysis also showed that several DEG S required for DNA replication process were only up-regulated in the leaves of sugar beet treated with high neutral salt.…”

Physiological and transcriptomic analyses reveal novel insights into the cultivar-specific response to alkaline stress in alfalfa (Medicago sativa L.)

“…To date, ve DDR pathways (base combination repair (BER), nucleotide recombination repair (NER), mismatch repair (MMR), homologous recombination repair (HR), and nonhomologous end-joining (NHEJ) have been reported (Chatterjee and Walker 2017;Nisa et al 2019). It has been demonstrated that salinity stress affects the cellular processes involved in DNA replication (Geng et al 2020;John et al 2016;Sanan-Mishra et al 2005). Our study observed that the CAR gene (MS.gene031323.t1) required for DNA replication, mismatch repair, nucleotide excision repair and homologous recombination was down-regulated in GN but signi cantly up-regulated in AG (Table 1).…”