Multiple roles of the transcription factor AtMYBR1/AtMYB44 in ABA signaling, stress responses, and leaf senescence

Abstract

BackgroundThe transcription factor AtMYBR1 (MYB44) is a member of the MYB family of transcription factors and is expressed throughout the plant life cycle and especially in senescing and wounded leaves. It has previously been shown to be involved in responses to abiotic stress and is regulated by phosphorylation.ResultsWhen MYBR1 was over-expressed under the control of the constitutive 35S promoter in Arabidopsis thaliana (OxMYBR1), leaf senescence was delayed. In contrast loss-of-function mybr1 plants showed more rapid chlorophyll loss and senescence. The MYBR1 promoter strongly drove β-GLUCURONIDASE reporter gene expression in tissues immediately after wounding and many wounding/pathogenesis genes were downregulated in OxMYBR1. OxMYBR1 plants were more susceptible to injury under water stress than wildtype, which was correlated with suppression of many ABA inducible stress genes in OxMYBR1. Conversely, mybr1 plants were more tolerant of water stress and exhibited reduced rates of water loss from leaves. MYBR1 physically interacted with ABA receptor PYR1-LIKE8 (PYL8) suggesting a direct involvement of MYBR1 in early ABA signaling. MYBR1 appears to exhibit partially redundant functions with AtMYBR2 (MYB77) and double mybr1 X mybr2 mutants exhibited stronger senescence and stress related phenotypes than single mybr1 and mybr2 mutants.ConclusionsMYBR1 is a negative regulator of ABA, stress, wounding responses and blocks senescence. It appears to have a homeostatic function to maintain growth processes in the event of physical damage or stress.

Central Metabolic Responses to Ozone and Herbivory Affect Photosynthesis and Stomatal Closure

“…MYB44 overexpression in Arabidopsis mutants increases drought tolerance by modifying the regulation of stomatal closure (Jung et al, 2008). However, MYB44 also negatively regulates ABA responses (Jaradat et al, 2013;Li et al, 2014) involved in stomatal closure, leaf senescence, and ROS scavenging (Persak and Pitzschke, 2014). In our study, MYB44 expression correlated positively with glycerol levels and negatively with the expression of NOGC1, a nitric oxide-dependent guanylyl cyclase involved in stomatal closure via Ca 2+ signaling (Mulaudzi et al, 2011;Joudoi et al, 2013).…”

Stress-Related Gene Expression Reflects Morphophysiological Responses to Water Deficit

“…9A), it was relatively strong, but insignificant, under MWD conditions (r = 0.45, P = 0.064). MYB44 codes for a transcription factor previously associated with ABA signaling, stomatal movement, and transpiration processes (Jaradat et al, 2013). By contrast, transpiration rate and the response of ANN2 expression were significantly correlated under both MWD (r = 0.63, P = 0.005) and SWD (r = 0.50, P = 0.034) conditions (Fig.…”

“…We also identified three accessions (An-1, Est-1, and Ga-0) that displayed minimal reductions in shoot size under WD conditions; thus, they can be considered as WD tolerant. Besseau et al, 2007;Székely et al, 2008;Harb et al, 2010;Colebrook et al, 2014), response to sugar starvation (N-MYC DOWNREGULATED-LIKE1 [NDL1] and CYTOCHROME P450 [P450]; Mudgil et al, 2009Mudgil et al, , 2013Hummel et al, 2010) Li et al, 2008;Alexandersson et al, 2010;Jaradat et al, 2013), and calcium fluxes (ANN1 and ANN2; Cantero et al, 2006;Konopka-Postupolska et al, 2009;Wang et al, 2015). Reference genes for quantitative PCR (qPCR) analyses were chosen from the set of superior genes for transcript normalization proposed by Czechowski et al (2005), and four genes (PROTEIN PHOSPHATASE2A SUBUNIT A3, PEROXIN4 [PEX4], UBIQUITIN-PROTEIN LIGASE7, and YELLOW-LEAF-SPECIFIC GENE8) were finally selected for normalization of transcript levels.…”

Isolation and Characterization of a Basic Leucine Zipper Gene in Poplar (Populus alba × P. glandulosa)

“…최근 유전체학 기술의 발전을 바탕으로 식물의 환경 스트레스 내성을 조절하는 유전자에 대한 연구가 많이 이루어지고 있다 (Ballen-Taborda et al, 2013;Gong et al, 2010;Luo et al, 2010;Wang et al, 2013). 특히 유전자의 전 사조절 부위에 특이적으로 결합하여 그 유전자의 전사를 활성화시키거나 억제시키는 단백질인 전사인자에 대한 연 구가 활발하다 (Jaradat et al, 2013;Riano-Pachon et al, 2007;Xu et al, 2013 (Jeong et al, 2012;Lindemose et al, 2013).…”