NAC transcription factor JUNGBRUNNEN1 enhances drought tolerance in tomato
Saturday, 2017/08/12 | 06:24:06
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VP Thirumalaikumar, V Devkar, N Mehterov, S Ali, R Ozgur, I Turkan, B Mueller-Roeber, S Balazadeh Plant Biotechnology Journal; First published: 4 August 2017; DOI: 10.1111/pbi.12776 SummaryWater deficit (drought stress) massively restricts plant growth and the yield of crops; reducing the deleterious effects of drought is therefore of high agricultural relevance. Drought triggers diverse cellular processes including the inhibition of photosynthesis, the accumulation of cell-damaging reactive oxygen species and gene expression reprogramming, besides others. Transcription factors (TF) are central regulators of transcriptional reprogramming and expression of many TF genes is affected by drought, including members of the NAC family. Here, we identify the NAC factor JUNGBRUNNEN1 (JUB1) as a regulator of drought tolerance in tomato (Solanum lycopersicum). Expression of tomato JUB1 (SlJUB1) is enhanced by various abiotic stresses, including drought. Inhibiting SlJUB1 by virus-induced gene silencing drastically lowers drought tolerance concomitant with an increase in ion leakage, an elevation of hydrogen peroxide (H2O2) levels and a decrease in the expression of various drought-responsive genes. In contrast, overexpression of AtJUB1 from Arabidopsis thaliana increases drought tolerance in tomato, alongside with a higher relative leaf water content during drought and reduced H2O2 levels. AtJUB1 was previously shown to stimulate expression of DREB2A, a TF involved in drought responses, and of the DELLA genes GAI and RGL1. We show here that SlJUB1 similarly controls the expression of the tomato orthologs SlDREB1, SlDREB2 and SlDELLA. Furthermore, AtJUB1 directly binds to the promoters of SlDREB1, SlDREB2 and SlDELLA in tomato. Our study highlights JUB1 as a transcriptional regulator of drought tolerance and suggests considerable conservation of the abiotic stress-related gene regulatory networks controlled by this NAC factor between Arabidopsis and tomato.
See http://onlinelibrary.wiley.com/doi/10.1111/pbi.12776/full
Figure 1: SlJUB1 encodes a nuclear protein and is induced by various abiotic stresses. (a) Confocal microscope image showing nuclear localization of SlJUB1-GFP fusion protein upon transient expression in N. benthamiana leaf cells. Scale bar, 5 μm. (b–d) SlJUB1 expression upon treatment with (b) H2O2 (5 mm), (c) NaCl (200 mm), (d) PEG 6000 (20% [w/v]). Three-week-old tomato seedlings were subjected to the stress treatments and harvested at the time points indicated at the x-axes. (e) SlJUB1 expression upon dehydration treatment. Terminal leaflets (of leaf 2) were detached and subjected to 2 h and 3 h of desiccation, respectively. Transcript levels were measured using qRT-PCR; numbers at the y-axis indicate fold change (FCh; log2 basis) compared to controls (unstressed plants). Data represent means ± SD (two independent biological replications with three technical replications per assay). |
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