GBF1 differentially regulates CAT2 and PAD4 transcription to promote pathogen defense in Arabidopsis thaliana

Abstract

G-BOX BINDING FACTOR 1 (GBF1) influences light-regulated seedling development in Arabidopsis, and inhibits CATALASE 2 (CAT2) expression during senescence. CAT2 functions as a scavenger of hydrogen peroxide. The role of GBF1 in the defense response is not known. We report here that GBF1 positively influences the defense against virulent and avirulent strains of Pseudomonas syringae. The gbf1 mutants are susceptible, whereas GBF1 over-expresser transgenic plants are resistant to bacterial pathogens. GBF1 negatively regulates pathogen-induced CAT2 expression and thereby positively regulates the hypersensitive response. In addition to CAT2 promoter, GBF1 binds to the G-box-like element present in the intron of PHYTOALEXIN DEFICIENT 4 (PAD4). This association of GBF1 with PAD4 intron is enhanced upon pathogenesis. GBF1 positively regulates PAD4 transcription in an intron-dependent manner. GBF1-mediated positive regulation of PAD4 expression is also evident in gbf1 mutant and GBF1 over-expression lines. Similar to pad4 mutants, pathogen-induced camalexin and salicylic acid (SA) accumulation, and expression of SA-inducible PATHOGENESIS RELATED1 (PR1) gene are compromised in the gbf1 mutant. Exogenous application of SA rescues the loss-of-defense phenotypes of gbf1 mutant. Thus, altogether, our results demonstrate that GBF1 is an important component of the plant defense response that functions upstream of SA accumulation and, by oppositely regulating CAT2 and PAD4, promotes disease resistance in Arabidopsis.

Fusarium graminearum ATP-Binding Cassette Transporter Gene FgABCC9 Is Required for Its Transportation of Salicylic Acid, Fungicide Resistance, Mycelial Growth and Pathogenicity towards Wheat

“…EDS1 and PAD4 as part of a central regulator complex contribute to the positive feedback loop of SA accumulation [28]. PR1 is one of the genes that is induced by SA and often used as the marker for SA signaling [29]. Unexpectedly, only the expression of NPR1 was affected, which indicated that transgenic expression of FgABCC9 did not activate SA signaling.…”

Genetic Network between Leaf Senescence and Plant Immunity: Crucial Regulatory Nodes and New Insights

“…In addition to NAC and WRKY TF families, other TF family members have also been reported to regulate leaf senescence and plant immunity (Table 1). GBF1, a bZIP protein, controls leaf senescence by directly regulating PAD4 [76] and binding the promoter of CAT2 to suppress its transcription, thus resulting in the decreased H 2 O 2 -scavenging activity [75]. Accordingly, the gbf1 mutant shows a decreased H 2 O 2 level and delayed senescence phenotypes [75].…”

“…Accordingly, the gbf1 mutant shows a decreased H 2 O 2 level and delayed senescence phenotypes [75]. The GBF1 overexpressing plants are more resistant, whereas gbf1 is susceptible, to Pst pathogens when compared to Col-0 [76]. The circadian clock pathway is known to regulate leaf senescence and plant innate immunity [77,96].…”

Peroxisomes: versatile organelles with diverse roles in plants

“…In Arabidopsis, CAT1 and CAT2 gene expression can be regulated by physiological signals and transcription factors, for example Abscisic acid insensitive 5 (ABI5) in seed germination and G-box binding factor 1 (GBF1) in leaf senescence and pathogen defense (Smykowski et al, 2010;Bi et al, 2017;Giri et al, 2017). In Arabidopsis, CAT1 and CAT2 gene expression can be regulated by physiological signals and transcription factors, for example Abscisic acid insensitive 5 (ABI5) in seed germination and G-box binding factor 1 (GBF1) in leaf senescence and pathogen defense (Smykowski et al, 2010;Bi et al, 2017;Giri et al, 2017).…”

“…CAT appears to be a key target for various regulatory mechanisms. In Arabidopsis, CAT1 and CAT2 gene expression can be regulated by physiological signals and transcription factors, for example Abscisic acid insensitive 5 (ABI5) in seed germination and G-box binding factor 1 (GBF1) in leaf senescence and pathogen defense (Smykowski et al, 2010;Bi et al, 2017;Giri et al, 2017). The expression of rice OsCATA, OsCATB, and OsCATC is induced by different abiotic stresses through cis-elements in their promoters (Vighi et al, 2016).…”