Global gene expression analysis using RNA-seq uncovered a new role for SR1/CAMTA3 transcription factor in salt stress

Abstract

Abiotic and biotic stresses cause significant yield losses in all crops. Acquisition of stress tolerance in plants requires rapid reprogramming of gene expression. SR1/CAMTA3, a member of signal responsive transcription factors (TFs), functions both as a positive and a negative regulator of biotic stress responses and as a positive regulator of cold stress-induced gene expression. Using high throughput RNA-seq, we identified ~3000 SR1-regulated genes. Promoters of about 60% of the differentially expressed genes have a known DNA binding site for SR1, suggesting that they are likely direct targets. Gene ontology analysis of SR1-regulated genes confirmed previously known functions of SR1 and uncovered a potential role for this TF in salt stress. Our results showed that SR1 mutant is more tolerant to salt stress than the wild type and complemented line. Improved tolerance of sr1 seedlings to salt is accompanied with the induction of salt-responsive genes. Furthermore, ChIP-PCR results showed that SR1 binds to promoters of several salt-responsive genes. These results suggest that SR1 acts as a negative regulator of salt tolerance by directly repressing the expression of salt-responsive genes. Overall, this study identified SR1-regulated genes globally and uncovered a previously uncharacterized role for SR1 in salt stress response.

Plant immunity in signal integration between biotic and abiotic stress responses

“…Massive immune activation in camta3‐ knockout plants (at 19–21°C) led to the notion that CAMTAs act as negative regulators of immunity (Du et al ., ; Nie et al ., ). camta3‐ knockout plants constitutively express multiple biotic/abiotic stress‐responsive genes (except cold‐responsive genes) and exhibit salt tolerance (Prasad et al ., ). Virus‐induced gene silencing of CAMTAs in tomato also results in constitutive defense activation and enhanced pathogen resistance, albeit at the cost of drought tolerance (Li et al ., ).…”

CALMODULIN-BINDING TRANSCRIPTION ACTIVATOR 6: A Key Regulator of Na+ Homeostasis during Germination

“…CAMTA6 (SR3) transcript levels were reported to be enhanced by salt in 3-week-old Col-0 plants (Yang and Poovaiah, 2002). Prasad et al (2016) suggested that CAMTA3 (SR1) acts as a negative regulator of salt tolerance. However, the expression pattern during the early stages of germination, under control and salt stress conditions, has not been reported.…”

The Transcription Factor MYB29 Is a Regulator of ALTERNATIVE OXIDASE1a

“…To further validate the intermediate TF network that regulates RAO7/MYB29-affected genes, we gathered published microarray studies on loss-and/or gain-offunction mutants for ATAF2, ATWRKY11, WRKY15, WRKY33, WRKY40, and SR1 (Delessert et al, 2005;Journot-Catalino et al, 2006;Birkenbihl et al, 2012;Vanderauwera et al, 2012;Van Aken et al, 2013;Prasad et al, 2016). For each TF, DE genes were split into groups of up-and down-regulated genes under control and stress conditions.…”