The Protein Phosphatase RCF2 and Its Interacting Partner NAC019 Are Critical for Heat Stress–Responsive Gene Regulation and Thermotolerance in Arabidopsis

Abstract

Heat stress is a major environmental constraint for crop production worldwide. To respond to and cope with heat stress, plants synthesize heat shock proteins (HSPs), which are often molecular chaperones and are under the control of heat stress transcription factors (HSFs). Very little is known about the upstream regulators of HSFs. In a forward genetic screen for regulators of C-REPEAT BINDING FACTOR (CBF) gene expression (RCFs), we identified RCF2 and found that it is allelic to CPL1/FIERY2, which encodes a homolog of C-terminal domain phosphatase. Our results also showed that, in addition to being critical for cold stress tolerance, RCF2 is required for heat stress-responsive gene regulation and thermotolerance, because, compared with the wild type, the rcf2-1 mutant is hypersensitive to heat stress and because the reduced thermotolerance is correlated with lower expression of most of the 21 HSFs and some of the HSPs in the mutant plants. We found that RCF2 interacts with the NAC transcription factor NAC019 and that RCF2 dephosphorylates NAC019 in vivo. The nac019 mutant is more sensitive to heat stress than the wild type, and chromatin immunoprecipitation followed by quantitative PCR analysis revealed that NAC019 binds to the promoters of HSFA1b, HSFA6b, HSFA7a, and HSFC1. Overexpression of RCF2 or NAC019 in Arabidopsis thaliana increases thermotolerance. Together, our results suggest that, through dephosphorylation of NAC019, RCF2 is an integrator of high-temperature signal transduction and a mechanism for HSF and HSP activation.

A Genome-Wide Chronological Study of Gene Expression and Two Histone Modifications, H3K4me3 and H3K9ac, during Developmental Leaf Senescence

“…In agreement with this observation, our list of SURGs that displayed a gain of H3K4me3 (K4-SURGs) includes four WRKY and six NAC transcription factors. Of these WRKY and NAC genes, mutant analysis has shown that WRKY75 , NAC016 (Kim et al, 2013), and NAC019 (Guan et al, 2014) are positive regulators of senescence, whereas WRKY54 (Besseau et al, 2012) is a negative regulator of senescence. Thus, numerous important primary regulators of senescence do display a concomitant change in H3K4me3 marks and gene expression.…”

Overexpression of receptor-like kinase ERECTA improves thermotolerance in rice and tomato

“…Plants respond to temperature changes by reprogramming their growth and development [4][5][6][7][8] , and progress has been made towards genetic modification of plants to increase their tolerance to heat stress. However, these studies have mainly been restricted to the model plant Arabidopsis [9][10][11][12][13][14] . Many studies have shown that expression of heat shock proteins (HSPs) can improve the tolerance of transgenic plants to heat shock (short exposure to high temperatures) 15 .…”

Direct Repression of Evening Genes by CIRCADIAN CLOCK-ASSOCIATED1 in the Arabidopsis Circadian Clock

“…Because eGO terms indicate a relationship to TF, we further focused on the TF set of genes ( (Pruneda-Paz et al, 2009;Dai et al, 2011). DREB2A and DREB2B are drought stress response proteins (Liu et al, 1998), DREB2C, AKS2, and ABI5 are involved in ABA signaling (Finkelstein and Lynch, 2000;Lee et al, 2010;Takahashi et al, 2013), DREB2C is also in heat stress response (Lim et al, 2007), DEWAX is involved in wax biosynthesis regulation (Go et al, 2014), ARF6 is required for flower maturation (Nagpal et al, 2005), AIF1 and MYBL2 are brassinosteroid signaling proteins (Wang et al, 2009;Ye et al, 2012), MYBL2 is important for anthocyanin biosynthesis (Matsui et al, 2008), BIB is involved in root development (Long et al, 2015), SNF-YB2 helps control flowering time (Cai et al, 2007), SCL13 is a part of red light signaling (Torres-Galea et al, 2006), RVE7 regulates cotyledon opening and flowering time (Kuno et al, 2003), NAC019 is a water stress regulator (Tran et al, 2004), and HSFC1 responds to heat stress (Guan et al, 2014). These data imply that CCA1 influences diverse physiological processes partly through regulating this set of TFs.…”