Identification and Analysis of the AP2 Subfamily Transcription Factors in the Pecan (Carya illinoinensis)

The AP2 transcriptional factors (TFs) belong to the APETALA2/ ethylene-responsive factor (AP2/ERF) superfamily and regulate various biological processes of plant growth and development, as well as response to biotic and abiotic stresses. However, genome-wide research on the AP2 subfamily TFs in the pecan (Carya illinoinensis) is rarely reported. In this paper, we identify 30 AP2 subfamily genes from pecans through a genome-wide search, and they were unevenly distributed on the pecan chromosomes. Then, a phylogenetic tree, gene structure and conserved motifs were further analyzed. The 30 AP2 genes were divided into euAP2, euANT and basalANT three clades. Moreover, the cis-acting elements analysis showed many light responsive elements, plant hormone-responsive elements and abiotic stress responsive elements are found in CiAP2 promoters. Furthermore, a qPCR analysis showed that genes clustered together usually shared similar expression patterns in euAP2 and basalANT clades, while the expression pattern in the euANT clade varied greatly. In developing pecan fruits, CiAP2-5, CiANT1 and CiANT2 shared similar expression patterns, and their expression levels decreased with fruit development. CiANT5 displayed the highest expression levels in developing fruits. The subcellular localization and transcriptional activation activity assay demonstrated that CiANT5 is located in the nucleus and functions as a transcription factor with transcriptional activation activity. These results help to comprehensively understand the pecan AP2 subfamily TFs and lay the foundation for further functional research on pecan AP2 family genes.

Genome-wide identification and expression analysis of ethylene responsive factor family transcription factors in Juglans regia

Background Walnut is an important economic tree species with prominent economic value and ecological functions. However, in recent years, walnuts have become susceptible to drought stress, resulting in a decline in comprehensive benefits. Therefore, it is necessary to identify the regulatory molecular mechanism associated with walnut response to drought. In many plants, ethylene responsive factor (ERF) gene family plays important roles in response to biotic and abiotic stress, especial drought. Therefore, the identification and characterisation of walnut ERF genes will benefit walnut with regard to the clarification of drought response mechanism as well as the management, production, and quality of plantations. Methods ‘ERF’ was compared against the walnut transcriptome, and the JrERFs with a complete open reading frame (ORF) were identified by ORF Finder. The molecular weights, amino acid residues, and theoretical isoelectric point (pI) were predicted by ExPASy. The distribution of JrERFs in chromosome locations was determined based on walnut genome data from NCBI. The intron-exon structures and conserved domains were analysed using Gene Structure Display Server 2.0 and CD-Search, accordingly. Multi-sequence alignment and a phylogenetic tree were constructed by ClustalX2.1 and MEGA7, respectively. The conserved motifs were acquired using MEME. Total RNA was isolated using the cetyltrimethylammonium ammonium bromide (CTAB) method (Yang et al., 2018). Gene expression was determined by using real-time quantitative polymerase chain reaction (qRT-PCR) analysis and calculated according to the 2−ΔΔCT method (Livak & Schmittgen, 2001). Results A total of 44 JrERFs were identified from the walnut transcriptome, whose ORFs were 450–1,239 bp in length. The molecular weights of the JrERF proteins (consisting 149–412 amino acids) were 16.81–43.71 kDa, with pI ranging from 4.8 (JrERF11) to 9.89 (JrERF03). The JrERFs can be divided into six groups (B1–B6), and among the groups, B6 contained the most number of members. Each JrERF contained 1–6 motifs and each motif comprised 9–50 amino acids. Among the motifs, motif1, motif2, and motif3 were the most abundant. More than 40% of JrERFs were up-regulated continuously when subjected to ethephon (ETH), PEG6000, and PEG6000+ETH treatments. Of all the JrERFs, JrERF11 showed the highest expression. Therefore, we conclude that walnut ERF genes are highly conserved and involved in the regulation of drought response in the presence of ETH. JrERFs are possibly important candidate genes for molecular breeding; hence, the findings of this study provides the theoretical basis for further investigation of ERF genes in walnut and other species.

A novel ERF transcription factor, CmERF12, negatively influences chrysanthemum embryo development

Embryo abortion often occurs during distant hybridization events. Apetala 2/ethylene-responsive factor (AP2/ERF) proteins are key transcription factor (TF) regulators of plant development and stress resistance, but their roles in hybrid embryo development are poorly understood. We isolated a novel AP2/ERF TF, CmERF12, from chrysanthemum and showed that it adversely affects embryo development during distant hybridization. Transcriptome and real-time quantitative PCR data demonstrated that CmERF12 is expressed at significantly higher levels in aborted ovaries compared with normal ovaries. CmERF12 localizes to the cell nucleus and contains a conserved EAR motif that mediates its transcription repressor function in yeast and plant cells. We generated an amiR-CmERF12 transgenic Chrysanthemum morifolium (C.m.) var. ‘Yuhualuoying’ and conducted distant hybridization with the wild-type tetraploid, Chrysanthemum nankingense (C.n.), revealing that CmERF12 knockdown significantly promoted embryo development and increased the seed setting rates during hybridization. The expression of various embryo development-related genes was up-regulated in developing ovaries from the ♀amiR-CmERF12-C.m. × ♂C.n. cross. Furthermore, CmERF12 directly interacted with CmSUF4 and significantly reduced its ability to activate its target gene CmEC1. Overall, we invented an original method to overcome plant distant hybridization barriers and unraveled the mechanism by which CmERF12 negatively affects chrysanthemum embryo development.

Orchestration of plant development and defense by indirect crosstalk of SA and BR signaling through a transcription factor GhTINY2

Salicylic acid (SA) and brassinosteroids (BRs) are well known to regulate diverse processes of plant development and stress responses, but the mechanisms by which these phytohormones mediate the growth-defense trade-off is largely unclear. In addition, little is known about the roles of DEHYDRATION RESPONSIVE ELEMENT BINDING (DREB) transcription factors, especially in biotic stress and plant growth. Here, we identified a cotton (Gossypium hirsutum) APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF) gene GhTINY2 which is strongly induced by Verticillium dahliae. Overexpression of GhTINY2 in cotton and Arabidopsis (Arabidopsis thaliana) enhanced tolerance to V. dahliae, while knockdown of GhTINY2 expression increased cotton susceptibility to the pathogen. By directly activating WRKY51 expression, GhTINY2 promoted SA accumulation and SA signaling transduction. Moreover, GhTINY2-overexpressing cotton and Arabidopsis showed growth retardation, increased sensitivity to inhibitors of BR biosynthesis and downregulation of several BR-induced genes and upregulation of BR-repressed genes, while GhTINY2-RNAi cotton showed the opposite results. We further demonstrate that GhTINY2 negatively regulates BR signaling by interacting with BRASSINAZOLE-RESISTANT 1 (BZR1) and restraining its transcriptional activation of the expression of INDOLE-3-ACETIC ACID INDUCIBLE 19 (IAA19). These findings indicate that GhTINY2 fine-tunes the immunity-growth trade-off via an indirect crosstalk between WRKY51-mediated SA biosynthesis and BZR1-IAA19-regulated BR signaling.

Carbon Dioxide Pretreatment and Cold Storage Synergistically Delay Tomato Ripening through Transcriptional Change in Ethylene-Related Genes and Respiration-Related Metabolism

The effects of CO2 pretreatment before cold storage on tomato quality were investigated using physicochemical and transcriptome changes. Harvested tomatoes were treated with 30% or 60% CO2 for 3 h before storage at 4 °C for 14 d (cold storage), followed by transfer to 20 °C for 8 d (ambient conditions). The CO2-treated fruits were firmer with a better appearance than untreated fruits, even after being transferred from 4 °C storage to 20 °C for 8 d. CO2 pretreatment coupled with cold storage synergistically delayed tomato ripening by reducing respiration and lowering lycopene production. The tomatoes treated with 30% and 60% CO2 had fewer pits than untreated fruits after cold storage, even after being transferred to ambient conditions. Moreover, the 60% CO2 treatment significantly suppressed the decay rate. Transcriptome and metabolome functional enrichment analyses commonly showed the involvement of CO2-responsive genes or metabolites in sucrose and starch metabolism, as well as biosynthesis of secondary metabolites—in particular, glycolysis reduction. The most frequently detected domain was the ethylene-responsive factor. These results indicate that altered ethylene biosynthesis and ethylene signaling, via ethylene-responsive transcription factors and respiration-related pathways, appear to control CO2-induced fruit quality.

Carbon Dioxide Pretreatment on Tomatoes Before Cold Storage Synergistically Delays Ripening Through Transcriptional Change of Ethylene-Related Genes and Respiration-Related Metabolisms

The effect of CO2 pre-treatments on tomato quality prior to cold storage was investigated using physiochemical and transcriptome changes. Three hours CO2 treated fruits were firmer than untreated fruits and had a good appearance even after being transferred from 4°C storage to 20°C for 8 d. CO2 pretreatment with cold storage showed a synergistic effect on delayed ripening through reduced respiration; these tomatoes exhibited a lower lycopene content than untreated fruit under cold storage. Tomatoes treated with 30% CO2 had fewer pits than untreated fruits subjected to chilling temperatures, even after being transferred to 20°C for 8 d. Functional enrichment analyses from transcriptome and metabolome commonly showed that CO2-responsive genes or metabolites were involved in the sucrose and starch and biosynthesis of secondary metabolisms. The most frequently detected domain, ethylene-responsive factor domain and reduced glycolysis provide insights into the mechanism that CO2 regulates tomato quality.

GENETIC MODIFICATION FOR SALT AND DROUGHT TOLERANCE IN PLANTS THROUGH SODERF3

Plants constitute the major part of the ecosystem and maintain balance through their different roles in the stability of the environment. As plants have an impact over environment; in the same manner environment interacts with plants. These interactions bring some productive results or sometimes may cause serious issues to plants. The environment poses some serious threats to plants as it is changing drastically over the course of years. Plants have been resistant to many of biotic and abiotic stresses naturally but now it is getting challenging. The major issues faced by plants are drought, high salt concentration, temperature and many other factors. These issues can be compensated by engineering plants with such novel genes which cause the release of ethylene responsive factor in the case of drought and salt intolerance. There are various studies to engineer the stress sensitive plants with SodERF3, a novel sugarcane ethylene responsive factor which causes promising tolerance in transgenic plants.

Systematic analysis of the Capsicum ERF transcription factor family: identification of regulatory factors involved in the regulation of species-specific metabolites

Background: ERF transcription factors (TFs) belong to the Apetala2/Ethylene responsive Factor (AP2/ERF) TF family and play a vital role in plant growth and development processes. Capsorubin and capsaicinoids have relatively high economic and nutritional value, and they are specifically found in Capsicum. However, there is little understanding of how ERFs participate in the regulatory networks of capsorubin and capsaicinoids biosynthesis. Results: In this study, a total of 142 ERFs were identified in the Capsicum annuum genome. Subsequent phylogenetic analysis allowed us to divide ERFs into DREB (dehydration responsive element binding proteins) and ERF subfamilies, and further classify them into 11 groups with several subgroups. Expression analysis of biosynthetic pathway genes and CaERFs facilitated the identification of candidate genes related to the regulation of capsorubin and capsaicinoids biosynthesis; the candidates were focused in cluster C9 and cluster C10, as well as cluster L3 and cluster L4, respectively. The expression patterns of CaERF82, CaERF97, CaERF66, CaERF107 and CaERF101, which were found in cluster C9 and cluster C10, were consistent with those of accumulating of carotenoids (β-carotene, zeaxanthin and capsorubin) in the pericarp. In cluster L3 and cluster L4, the expression patterns of CaERF102, CaERF53, CaERF111 and CaERF92 were similar to those of the accumulating capsaicinoids. Furthermore, CaERF92, CaERF102 and CaERF111 were found to be potentially involved in temperature-mediated capsaicinoids biosynthesis. Conclusion: This study will provide an extremely useful foundation for the study of candidate ERFs in the regulation of carotenoids and capsaicinoids biosynthesis in peppers.