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ACT001, derived from traditional herbal medicine, is a novel compound with effective anticancer activity in clinical trials. However, little is known regarding its role in pituitary adenomas. Here, we demonstrated that ACT001 suppressed cell proliferation and induced cell death of pituitary tumor cells in vitro and in vivo. ACT001 was also effective in suppressing the growth of different subtypes of human pituitary adenomas. The cytotoxic mechanism ACT001 employed was mainly related to autophagic cell death (ACD), indicated by autophagosome formation and LC3-II accumulation. In addition, ACT001-mediated inhibitory effect decreased when either ATG7 was downregulated or cells were cotreated with autophagy inhibitor 3-methyladenine (3-MA). RNA-seq analysis showed that mitogen-activated protein kinase (MAPK) pathway was a putative target of ACT001. Specifically, ACT001 treatment promoted the phosphorylation of JNK and P38 by binding to mitogen-activated protein kinase kinase 4 (MEK4). Our study indicated that ACT001-induced ACD of pituitary tumor cells via activating JNK and P38 phosphorylation by binding with MEK4, and it might be a novel and effective anticancer drug for pituitary adenomas.

Small cysteine-rich (SCR) proteins, including fungal avirulence proteins, play important roles in pathogen–plant interactions. SCR protein-encoding genes have been discovered in the genomes of Phytophthora pathogens but their functions during pathogenesis remain obscure. Here, we report the characterization of one Phytophthora capsici SCR protein (namely, SCR82) with similarity to Phytophthora cactorum phytotoxic protein PcF. The scr82 gene has 10 allelic sequences in the P. capsici population. Homologs of SCR82 were not identified in fungi or other organisms but in Phytophthora relative species. Initially, scr82 was weakly expressed during the mycelium, sporangium, and zoospore stages but quickly upregulated when the infection initiated. Both ectopic expression of SCR82 and recombinant yeast-expressed protein (rSCR82) caused cell death on tomato leaves. Upon treatment, rSCR82 induced plant defense responses, including the induction of defense gene expression, reactive oxygen species burst, and callose deposition. Knockout of scr82 in P. capsici by CRISPR/Cas9 severely impaired its virulence on host plants and significantly reduced its resistance against oxidative stress. Inversely, its overexpression increased the pathogen’s virulence and tolerance to oxidative stress. Our results collectively demonstrate that SCR82 functions as both an important virulence factor and plant defense elicitor, which is conserved across Phytophthora spp. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Nitrate-dependent anaerobic oxidation of methane (AOM) is a new pathway to reduce methane emissions from paddy ecosystems. The elevated atmospheric CO硝酸盐型甲烷厌氧氧化(AOM)是控制稻田甲烷排放的一种新途径,大气CO

Currently, the influence of elevated atmospheric CO

To examine the influence of widely used protein affinity tags and the tobacco PR1a signal peptide (SP) on detection, purification and bioactivity analyses of the small oomycete apoplastic effector SCR96 in planta.Through agroinfiltration, the phytotoxic effector SCR96 of Phytophthora cactorum was expressed in Nicotiana benthamiana leaf apoplast as a fusion protein carrying single affinity tag (His, HA or FLAG) at either C- or N-terminus. Leaf necrosis caused by different affinity-tagged SCR96 varied among tags and replicates. All of tagged proteins can be detected by antibodies against SCR96. All of SCR96 fusions except N-terminally fused 6His-tagged protein were detected using tag antibodies, indicating that 6His tag may be degraded when fused at N-terminus. Interestingly, C-terminal His- and FLAG-tagged SCR96 maintained the biological activity after purification. In the substitution assay of SCR96 SP, we observed that PR1a SP can lead chimeric SCR96 expression in N. benthamiana, but the replacement totally disrupted its bioactivity.C-terminal His or FLAG tag, along with its original SP, is efficient enough to enable detection and purification of functional SCR96 from N. benthamiana leaf apoplast, which would facilitate plant-pathogen interaction studies.

Paddy fields are one of the most important methane sources, which have great impacts on climate change. The nitrite-dependent anaerobic methane oxidation, by NC10 phylum bacteria-稻田是温室气体甲烷的重要排放源之一,对全球气候变化具有重要影响。由隶属于NC10门的

Candidatus Methanoperedens-like archaea, which can use multiple electron acceptors (nitrate, iron, manganese, and sulfate) for anaerobic methane oxidation, could play an important role in reducing methane emissions from freshwater wetlands. Currently, very little is known about the distribution and community composition of Methanoperedens-like archaea in freshwater wetlands, particularly based on their alpha subunit of methyl-coenzyme M reductase (mcrA) genes. Here, the community composition, diversity, and abundance of Methanoperedens-like archaea were investigated in a freshwater wetland through high-throughput sequencing and quantitative PCR on their mcrA genes. A large number of Methanoperedens-like mcrA gene sequences (119,250) were recovered, and a total of 31 operational taxonomic units (OTUs) were generated based on 95% sequence similarity cut-off. The majority of Methanoperedens-like sequences can be grouped into three distinct clusters that were closely associated with the known Methanoperedens species which can couple anaerobic methane oxidation to nitrate or iron reduction. The community composition of Methanoperedens-like archaea differed significantly among different sampling sites, and their mcrA gene abundance was 1.49 × 10

Nitrite-dependent anaerobic methane oxidation (n-damo) catalyzed by Candidatus Methylomirabilis oxyfera (M. oxyfera)-like bacteria is a new pathway for the regulation of methane emissions from paddy fields. Elevated atmospheric CO

The elevated atmospheric CO

Squamosa promoter binding protein (SBP)-box genes are plant-specific transcription factors involved in plant growth and development, morphogenesis and biotic and abiotic stress responses. However, these genes have been understudied in pepper, especially with respect to defense responses to Phytophthora capsici infection. CaSBP11 is a SBP-box family gene in pepper that was identified in our previous research. Silencing CaSBP11 enhanced the defense response of pepper plants to Phytophthora capsici. Without treatment, the expression of defense-related genes (CaBPR1,CaPO1,CaSAR8.2 and CaDEF1) increased in CaSBP11-silenced plants. However, the expression levels of these genes were inhibited under transient CaSBP11 expression. CaSBP11 overexpression in transgenic Nicotiana benthamiana decreased defense responses, while in Arabidopsis, it induced or inhibited the expression of genes in the salicylic acid and jasmonic acid signaling pathways. CaSBP11 overexpression in sid2-2 mutants induced AtNPR1, AtNPR3, AtNPR4, AtPAD4, AtEDS1, AtEDS5, AtMPK4 and AtNDR1 expression, while AtSARD1 and AtTGA6 expression was inhibited. CaSBP11 overexpression in coi1-21 and coi1-22 mutants, respectively, inhibited AtPDF1.2 expression and induced AtPR1 expression. These results indicate CaSBP11 has a negative regulatory effect on defense responses to Phytophthora capsici. Moreover, it may participate in the defense response of pepper to Phytophthora capsici by regulating defense-related genes and the salicylic and jasmonic acid-mediated disease resistance signaling pathways.

Little information is available on the role of Squamosa promoter binding protein (SBP)-box genes in pepper plants. This family of genes is known to have transcription characteristics specific to plants and to regulate plant growth, development, stress responses, and signal transduction. To investigate their specific effects in pepper (Capsicum annuum), we screened pepper SBP-box family genes (CaSBP genes) for Phytophthora capsici (P. capsici) resistance genes using virus-induced gene silencing. CaSBP08, CaSBP11, CaSBP12, and CaSBP13, which are associated with plant defense responses against P. capsici, were obtained from among fifteen identified CaSBP genes. The function of CaSBP08 was identified in pepper defense response against P. capsici infection in particular. CaSBP08 protein was localized to the nucleus. Silencing of CaSBP08 enhanced resistance to P. capsici infection. Following P. capsici inoculation, the malondialdehyde content, peroxidase activity, and disease index percentage of the CaSBP08-silenced plants decreased compared to the control. Additionally, the expression levels of other defense-related genes, especially those of CaBPR1 and CaSAR8.2, were more strongly induced in CaSBP08-silenced plants than in the control. However, CaSBP08 overexpression in Nicotiana benthamiana enhanced susceptibility to P. capsici infection. This work provides a foundation for the further research on the role of CaSBP genes in plant defense responses against P. capsici infection.

Coastal wetlands are critical in the global carbon budget while vulnerable to plant invasion. Spartina alterniflora (S. alterniflora), a typical invasive plant species, has rapidly expanded in China’s coastal area since 1979, which disturbed the carbon cycle of the coastal wetland ecosystems. However, until now, the effect and underlying mechanisms of S. alterniflora invasion on methanotrophs are poorly known in coastal wetlands. Here, a large-scale investigation of the activity, abundance and community structure of methanotrophs was conducted in seven wetlands under both native (dominated by Phragmites australis, Kandelia candel or Avicennia marina) and invasive plants (dominated by S. alterniflora) across the southeast coast of China. Compared with the native community, S. alterniflora invasion led to a significant (p

The elevated atmospheric CO2 concentration (eCO2) has a great impact on soil microbial communities and their functions; however, how the activity and communities of methanotrophs respond to eCO2 in paddy ecosystem is poorly known. Here, we examined the effects of a 4-year exposure to eCO2 (EC; ambient + 200 ppm) in open top chambers on the potential activity, abundance and community composition of methanotrophs in paddy fields in Nanjing City, China. The potential activity was measured in a slurry incubation under aerobic condition, and the community composition and abundance of methanotrophs were analyzed through Illumina Miseq sequencing and quantitative PCR of pmoA genes. The results demonstrated that EC significantly increased (p

The AP2/ERF family is one of the largest transcription factor families in the plant kingdom. AP2/ERF genes contributing to various processes including plant growth, development, and response to various stresses have been identified. In this study, 175 putative AP2/ERF genes were identified in the latest pepper genome database and classified into AP2, RAV, ERF, and Soloist subfamilies. Their chromosomal localization, gene structure, conserved motif, cis-acting elements within the promoter region, and subcellular locations were analyzed. Transient expression of CaAP2/ERF proteins in tobacco revealed that CaAP2/ERF064, CaAP2/ERF109, and CaAP2/ERF127 were located in the nucleus, while CaAP2/ERF171 was located in the nucleus and cytoplasm. Most of the CaAP2/ERF genes contained cis-elements within their promoter regions that responded to various stresses (HSE, LTR, MBS, Box-W1/W-box, and TC-rich repeats) and phytohormones (ABRE, CGTCA-motif, and TCA-element). Furthermore, RNA-seq analysis revealed that CaAP2/ERF genes showed differential expression profiles in various tissues as well as under biotic stresses. Moreover, qRT-PCR analysis of eight selected CaAP2/ERF genes also showed differential expression patterns in response to infection with Phytophthora capsici (HX-9) and in response to phytohormones (SA, MeJA, and ETH). This study will provide basic insights for further studies of the CaAP2/ERF genes involved in the interaction between pepper and P. capsici.

Nitrite-dependent anaerobic methane oxidation (n-damo) catalyzed by Candidatus Methylomirabilis oxyfera (M. oxyfera)-like bacteria is a new pathway for the regulation of methane emissions from paddy fields. Elevated atmospheric CO2 concentrations (e[CO2]) can indirectly affect the structure and function of microbial communities. However, the response of M. oxyfera-like bacteria to e[CO2] is currently unknown. Here, we investigated the effect of e[CO2] (ambient CO2 + 200 ppm) on community composition, abundance, and activity of M. oxyfera-like bacteria at different depths (0–5, 5–10, and 10–20 cm) in paddy fields across multiple rice growth stages (tillering, jointing, and flowering). High-throughput sequencing showed that e[CO2] had no significant effect on the community composition of M. oxyfera-like bacteria. However, quantitative PCR suggested that the 16S rRNA gene abundance of M. oxyfera-like bacteria increased significantly in soil under e[CO2], particularly at the tillering stage. Furthermore, 13CH4 tracer experiments showed potential n-damo activity of 0.31–8.91 nmol CO2 g−1 (dry soil) d−1. E[CO2] significantly stimulated n-damo activity, especially at the jointing and flowering stages. The n-damo activity and abundance of M. oxyfera-like bacteria increased by an average of 90.9% and 50.0%, respectively, under e[CO2]. Correlation analysis showed that the increase in soil dissolved organic carbon content caused by e[CO2] had significant effects on the activity and abundance of M. oxyfera-like bacteria. Overall, this study provides the first evidence for a positive response of M. oxyfera-like bacteria to e[CO2], which may help reduce methane emissions from paddy fields under future climate change conditions.

The elevated atmospheric CO2 concentration is well known to have an important effect on soil nutrient cycling. Ammonia oxidation, mediated by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), is the rate-limiting step in soil nitrification, which controls the availability of two key soil nutrients (ammonium and nitrate) for crops. Until now, how the AOA and AOB communities in paddy soils respond to elevated CO2 remains largely unknown. Here, we examined the communities of AOA and AOB and nitrification potential at both surface (0–5 cm) and subsurface (5–10 cm) soil layers of paddy fields under three different CO2 treatments, including CK (ambient CO2 concentration), LT (CK + 160 ppm of CO2) and HT (CK + 200 ppm of CO2). The elevated CO2 was found to have a greater impact on the community structure of AOB than that of AOA in surface soils as revealed by high-throughput sequencing of their amoA genes. However, no obvious variation of AOA or AOB communities was observed in subsurface soils among different CO2 treatments. The abundance of AOA and AOB, and nitrification potential were significantly increased in surface soils under elevated CO2. The variation of AOB abundance correlated well with the variation of nitrification potential. The soil water content and dissolved organic carbon content had important impacts on the dynamic of AOB communities and nitrification potential. Overall, our results showed different responses of AOA and AOB communities to elevated CO2 in paddy ecosystems, and AOB were more sensitive to the rising CO2 concentration.

Nitrite-dependent anaerobic oxidation of methane (AOM), which is mediated by Candidatus Methylomirabilis oxyfera (M. oxyfera)-like bacteria, has the great potential to reduce methane emissions from paddy ecosystems. Fertilization, a necessary practice for increasing crop yields, could greatly affect nitrite-dependent AOM process. Here, we investigated the abundance, community composition and activity of M. oxyfera-like bacteria at different layers (0–10, 20–30 and 40–50 cm) of paddy soils under three fertilization treatments, including unfertilized control (CK), chemical fertilization (CF) and organic fertilization (OF). The 16S rRNA gene abundance of M. oxyfera-like bacteria in soils under CF (6.1 × 106–2.2 × 107 copies g−1 dry soil) and OF (8.9 × 106–1.8 × 107 copies g−1 dry soil) treatments was higher than that under CK treatment (5.0 × 106–1.5 × 107 copies g−1 dry soil). An obvious separation of M. oxyfera-like bacterial communities was observed between different fertilization treatments, and a higher diversity of these bacteria was detected in CF and OF soils. The nitrite-dependent AOM activity was increased in soils under CF (3.6–11.5 nmol CO2 g−1 (dry soil) d−1) and OF (3.4–7.2 nmol CO2 g−1 (dry soil) d−1) treatments as compared to CK (1.6–4.4 nmol CO2 g−1 (dry soil) d−1) treatment, particularly at the layer of 20–30 cm. Overall, our results demonstrated that the communities and activity of M. oxyfera-like bacteria responded positively to both chemical and organic fertilization, which expanded our knowledge of the role of nitrite-dependent AOM in regulating methane emissions from paddy ecosystems.

Candidatus Methanoperedens nitroreducens (M. nitroreducens)-like archaea, catalyzing anaerobic methane oxidation coupled with nitrate reduction, could play an important role in reducing methane emissions from paddy ecosystems. Currently, the spatial and temporal variations of the communities of M. nitroreducens-like archaea and the factors regulating their distribution in paddy soils are poorly known. Here, we examined the diversity, community composition and abundance of these anaerobic methanotrophs at four representative depths (0–10, 10–20, 20–30 and 30–40 cm) of paddy soils across four rice growth stages (tillering, jointing, flowering and milky stages). High-throughput sequencing of M. nitroreducens-like archaeal mcrA genes showed that their community structure varied among different depths. In contrast, the community structure of these archaea remained relatively stable across rice growth stages. Further, both soil depth and rice growth stage had a significant impact on the abundance of mcrA genes. The gene abundance varied from 7.6 × 105 to 5.0 × 106 copies g−1 dry soil with higher values in 20–30 cm soils, and the abundance was found to be decreased from tillering to milky stages. The soil organic carbon content and ammonium content were the key factors affecting the community structure of these archaea. Our results indicated that both soil depth and crop growth stage greatly affected the abundance of M. nitroreducens-like archaea, while their community structure seemed to be more responsive to soil depth. Taken together, both space and time scales should be considered for better understanding the role of M. nitroreducens-like archaea reducing methane emissions from paddy ecosystems.

SBP-box (Squamosa-promoter binding protein) genes are a type of plant-specific transcription factor and play important roles in plant growth, signal transduction, and stress response. However, little is known about the role of pepper SBP-box transcription factor genes in response to abiotic stress. Here, one of the pepper SBP-box gene, CaSBP12, was selected and isolated from pepper genome database in our previous study. The CaSBP12 gene was induced under salt stress. Silencing the CaSBP12 gene enhanced pepper plant tolerance to salt stress. The accumulation of reactive oxygen species (ROS) of the detached leaves of CaSBP12-silenced plants was significantly lower than that of control plants. Besides, the Na+, malondialdehyde content, and conductivity were significantly increased in control plants than that in the CaSBP12-silenced plants. In addition, the CaSBP12 over-expressed Nicotiana benthamiana plants were more susceptible to salt stress with higher damage severity index percentage and accumulation of ROS as compared to the wild-type. These results indicated that CaSBP12 negatively regulates salt stress tolerance in pepper may relate to ROS signaling cascades.

Little information is available on the role of Squamosa promoter binding protein (SBP)-box genes in pepper plants. This family of genes is known to have transcription characteristics specific to plants and to regulate plant growth, development, stress responses, and signal transduction. To investigate their specific effects in pepper (Capsicum annuum), we screened pepper SBP-box family genes (CaSBP genes) for Phytophthora capsici (P. capsici) resistance genes using virus-induced gene silencing. CaSBP08, CaSBP11, CaSBP12, and CaSBP13, which are associated with plant defense responses against P. capsici, were obtained from among fifteen identified CaSBP genes. The function of CaSBP08 was identified in pepper defense response against P. capsici infection in particular. CaSBP08 protein was localized to the nucleus. Silencing of CaSBP08 enhanced resistance to P. capsici infection. Following P. capsici inoculation, the malondialdehyde content, peroxidase activity, and disease index percentage of the CaSBP08-silenced plants decreased compared to the control. Additionally, the expression levels of other defense-related genes, especially those of CaBPR1 and CaSAR8.2, were more strongly induced in CaSBP08-silenced plants than in the control. However, CaSBP08 overexpression in Nicotiana benthamiana enhanced susceptibility to P. capsici infection. This work provides a foundation for the further research on the role of CaSBP genes in plant defense responses against P. capsici infection.

Phytophthora blight is one of the most destructive diseases of pepper (Capsicum annuum L.) globally. The APETALA2/Ethylene Responsive Factors (AP2/ERF) genes play a crucial role in plant response to biotic stresses but, to date, have not been studied in the context of Phytophthora resistance in pepper. Here, we documented potential roles for the pepper CaAP2/ERF064 gene in inducing cell death and conferring resistance to Phytophthora capsici (P. capsici) infection. Results revealed that the N-terminal, AP2 domain, and C-terminal of CaAP2/ERF064 protein is responsible for triggering cell death in Nicotiana benthamiana (N. benthamiana). Moreover, the transcription of CaAP2/ERF064 in plant is synergistically regulated by the Methyl-Jasmonate (MeJA) and ethephon (ET) signaling pathway. CaAP2/ERF064 was found to regulate the expression of CaBPR1, which is a pathogenesis-related (PR) gene of pepper. Furthermore, the silencing of CaAP2/ERF064 compromised the pepper plant resistance to P. capsici by reducing the transcript level of defense-related genes CaBPR1, CaPO2, and CaSAR82, while the ectopic expression of CaAP2/ERF064 in N. benthamiana plant elevated the expression level of NbPR1b and enhanced resistance to P. capsici. These results suggest that CaAP2/ERF064 could positively regulate the defense response against P. capsici by modulating the transcription of PR genes in the plant.

SBP-box (Squamosa-promoter binding protein) genes are a type of plant-specific transcription factor and play important roles in plant growth, signal transduction and stress response. However, little is known about the SBP-box genes in pepper (CaSBP), especially in the process of Phytophthora capsici infection. In this study, a novel gene (CaSBP12) was selected from the CaSBP gene family, which was isolated from the pepper genome database in our previous study. The CaSBP12 gene was located in the nucleus of the cell and its silencing in the pepper plant enhanced the defense response against Phytophthora capsici infection. After inoculation with Phytophthora capsici, the root activity of the CaSBP12-silenced plants is compared to control plants, while malondialdehyde (MDA) content is compared viceversa. Additionally, the expression of defense related genes (CaPO1, CaSAR8.2, CaBPR1, and CaDEF1) in the silenced plants were induced to different degrees and the peak of CaSAR8.2 and CaBPR1 were higher than that of CaDEF1. The CaSBP12 over-expressed Nicotiana benthamiana plants were more susceptible to Phytophthora capsici infection with higher EC (electrical conductivity) and MDA contents as compared to the wild-type. The relative expression of defense related genes (NbDEF, NbNPR1, NbPR1a, and NbPR1b) in transgenic and wild-type Nicotiana benthamiana plants were induced, especially the NbPR1a and NbPR1b. In conclusion, these results indicate that CaSBP12 gene negative regulates the defense response against Phytophthora capsici infection which suggests their potentially significant role in plant defense. To our knowledge, this is the first report on CaSBP gene which negative regulate defense response.

The dirigent (DIR and DIR-like) proteins involved in lignification, play a pivotal role against biotic and abiotic stresses in plants. However, no information is available about DIR gene family in pepper (Capsicum annuum L.). In this study, 24 putative dirigent genes (CaDIRs) were identified, their gene structure, genome location, gene duplication and phylogenetic relationship were elucidated. Tissue-specific expression analysis displayed the highest transcription levels in flower, stem and leaf. Some CaDIRs were up-regulated by virulent (CaDIR2, 3, 6, 7, 11, 14, 16, 22 and 23) and avirulent (CaDIR3, 5, 7, 16, 20, 22, 23 and 24) Phytophthora capsici strains, as well as by Methyl jasmonate, salicylic acid, NaCl and mannitol stresses. Acid-soluble lignin content increased (103.21%) after P. capsici inoculation (48-hour). Silencing of CaDIR7 weakened plant defense by reducing (~50%) root activity and made plants more susceptible (35.7%) to P. capsici and NaCl (300 mM). Leaf discs of the CaDIR7:silenced plants exposed to NaCl and mannitol (300 mM each), exhibited a significant decrease (56.25% and 48% respectively) in the chlorophyll content. These results suggested that CaDIR7 is involved in pepper defense response against pathogen and abiotic stresses and the study will provide basic insights for future research regarding CaDIRs.

Opening the porphyrin macrocycle of pheophorbide a and forming the primary fluorescent chlorophyll catabolites are key steps in the chlorophyll catabolism pathway. These steps are catalyzed by pheophorbide a oxygenase and red chlorophyll catabolite reductase (RCCR). In this study, a novel RCCR gene, CaRCCR, was isolated from the pepper (Capsicum annuum L.). The full-length CaRCCR complementary DNA is comprised of 1173 bp, contains an open reading frame of 945 bp, and encodes a 314-amino acid protein. This deduced protein belongs to the ferredoxin-dependent bilin reductase family. Amino acid sequence alignment showed that CaRCCR shared a high homology to other higher plant RCCR proteins. CaRCCR expression, as determined by quantitative real-time polymerase chain reaction, was higher in the leaves than the roots, stems, flowers, and immature fruits. CaRCCR expression was almost constant during all phases of leaf development. It was upregulated by abscisic acid, methyl jasmonate, and salicylic acid. Moreover, CaRCCR was induced by high salinity and drought stress treatments; it was also slightly regulated by Phytophthora capsici. Taken together, these results suggest that CaRCCR is involved in defense responses to various stresses.

Phytophthora blight is one of the most destructive diseases of pepper (Capsicum annuum L.) globally. The APETALA2/Ethylene Responsive Factors (AP2/ERF) genes play a crucial role in plant response to biotic stresses but, to date, have not been studied in the context of Phytophthora resistance in pepper. Here, we documented potential roles for the pepper CaAP2/ERF064 gene in inducing cell death and conferring resistance to Phytophthora capsici (P. capsici) infection. Results revealed that the N-terminal, AP2 domain, and C-terminal of CaAP2/ERF064 protein is responsible for triggering cell death in Nicotiana benthamiana (N. benthamiana). Moreover, the transcription of CaAP2/ERF064 in plant is synergistically regulated by the Methyl-Jasmonate (MeJA) and ethephon (ET) signaling pathway. CaAP2/ERF064 was found to regulate the expression of CaBPR1, which is a pathogenesis-related (PR) gene of pepper. Furthermore, the silencing of CaAP2/ERF064 compromised the pepper plant resistance to P. capsici by reducing the transcript level of defense-related genes CaBPR1, CaPO2, and CaSAR82, while the ectopic expression of CaAP2/ERF064 in N. benthamiana plant elevated the expression level of NbPR1b and enhanced resistance to P. capsici. These results suggest that CaAP2/ERF064 could positively regulate the defense response against P. capsici by modulating the transcription of PR genes in the plant.

SQUAMOSA promoter binding protein (SBP)-box genes encode plant-specific transcription factors that are extensively involved in many physiological and biochemical processes, including growth, development, and signal transduction. However, pepper (Capsicum annuum L.) SBP-box family genes have not been well characterized. We investigated SBP-box family genes in the pepper genome and characterized these genes across both compatible and incompatible strain of Phytophthora capsici, and also under different hormone treatments. The results indicated that total 15 members were identified and distributed on 7 chromosomes of pepper. Phylogenetic analysis showed that SBP-box genes of pepper can be classified into six groups. In addition, duplication analysis within pepper genome, as well as between pepper and Arabidopsis genomes demonstrated that there are 4 pairs of homology of SBP-box genes in the pepper genome and 10 pairs between pepper and Arabidopsis genomes. Tissue-specific expression analysis of the CaSBP genes demonstrated their diverse spatiotemporal expression patterns. The expression profiles were similarly analyzed following exposure to P. capsici inoculation and hormone treatments. It was shown that 9 of the CaSBP genes (CaSBP01, 02, 03, 04, 05, 06, 11, 12 and 13) exhibited a dramatic up-regulation after compatible HX-9 strain (P. capsici) inoculation, while CaSBP09 and CaSBP15 were down-regulated. In case of PC strain (P. capsici) infection six of the CaSBP genes (CaSBP02, 05, 06, 11, 12 and 13) were arose while CaSBP14 was down regulated. Furthermore, Salicylic acid (SA), Methyl jasmonate (MeJA) and their biosynthesis inhibitors treatment indicated that some of the CaSBP genes are potentially involved in these hormone regulation pathways. This genome-wide identification, as well as characterization of evolutionary relationships and expression profiles of the pepper CaSBP genes, will help to improve pepper stress tolerance in the future.

Ethylene-responsive factors (ERF) are usually considered to play diverse roles in plant response to biotic and abiotic stresses. In this study, an ERF gene CaPTI1 was isolated from pepper transcriptome database. CaPTI1 contains an open reading frame (ORF) of 543bp, which encodes a putative polypeptide of 180 amino acids with a theoretical molecular weight of 20.30 kDa. Results of expression profile showed that CaPTI1 had a highest expression level in roots and this gene could not only response to the infection of Phytophthora capsici and the stresses of cold and drought, but also be induced by the signaling molecule (salicylic acid (SA), Methyl Jasmonate (MeJA), Ethephon (ETH) and hydogen peroxide (H2O2)). Furthermore, virus-induce gene silencing (VIGS) of CaPTI1 in pepper weakened the defense response significantly by reducing the expression of defense related genes CaPR1, CaDEF1 and CaSAR82 and also the root activity. These results suggested that CaPTI1 is involved in the regulation of defense response to P. capsici in pepper.