Arabidopsis CPR5 Plays a Role in Regulating Nucleocytoplasmic Transport of mRNAs in Ethylene Signaling Pathway

The ETR1 receptor plays a predominant role in ethylene signaling in Arabidopsis thaliana. Previous studies showed that both RTE1 and CPR5 can directly bind to the ETR1 receptor and regulate ethylene signaling. RTE1 was suggested to promote the ETR1 receptor signaling by influencing its conformation, but little is known about the regulatory mechanism of CPR5 in ethylene signaling. In this study, we presented data showing that both RTE1 and CPR5 bound to the N-terminal domains of ETR1, and regulated ethylene signaling via the ethylene receptor. On the other hand, the research provided evidence indicating that CPR5 could act as a nucleoporin to regulate the ethylene-related mRNAs export out of the nucleus, while RTE1 or its homolog (RTH) had no effect on the nucleocytoplasmic transport of mRNAs. Nuclear qRT-PCR analysis and poly(A)-mRNA in situ hybridization showed that defect of CPR5 restricted nucleocytoplasmic transport of mRNAs. These results advance our understanding of the regulatory mechanism of CPR5 in ethylene signaling.

Nanopore-Based Comparative Transcriptome Analysis Reveals the Potential Mechanism of High-Temperature Tolerance in Cotton (Gossypium hirsutum L.)

Extreme high temperatures are threatening cotton production around the world due to the intensification of global warming. To cope with high-temperature stress, heat-tolerant cotton cultivars have been bred, but the heat-tolerant mechanism remains unclear. This study selected heat-tolerant (‘Xinluzao36′) and heat-sensitive (‘Che61-72′) cultivars of cotton treated with high-temperature stress as plant materials and performed comparative nanopore sequencing transcriptome analysis to reveal the potential heat-tolerant mechanism of cotton. Results showed that 120,605 nonredundant sequences were generated from the raw reads, and 78,601 genes were annotated. Differentially expressed gene (DEG) analysis showed that a total of 19,600 DEGs were screened; the DEGs involved in the ribosome, heat shock proteins, auxin and ethylene signaling transduction, and photosynthesis pathways may be attributed to the heat tolerance of the heat-tolerant cotton cultivar. This study also predicted a total of 5118 long non-coding RNAs (lncRNAs)and 24,462 corresponding target genes. Analysis of the target genes revealed that the expression of some ribosomal, heat shock, auxin and ethylene signaling transduction-related and photosynthetic proteins may be regulated by lncRNAs and further participate in the heat tolerance of cotton. This study deepens our understandings of the heat tolerance of cotton.

Ethylene signaling increases reactive oxygen species accumulation to drive root hair initiation in Arabidopsis thaliana

Root hair initiation is a highly regulated aspect of root development. The plant hormone, ethylene, and its precursor, 1-amino-cyclopropane-1-carboxylic acid (ACC), induce formation and elongation of root hairs. We asked whether elevated ethylene induced root hair formation by increasing reactive oxygen species (ROS) synthesis in hair cells. Using confocal microscopy paired with redox biosensors and dyes, we demonstrated that treatments that elevate ethylene levels led to increased ROS accumulation in hair cells prior to root hair formation. In two ethylene-insensitive mutants, etr1-3 and ein3/eil1, there was no increase in root hair number or ROS accumulation. Conversely, etr1-7, a constitutive ethylene signaling receptor mutant, has increased root hair formation and ROS accumulation similar to ethylene-treated wild type seedlings. The rhd2-6 mutant, with a defect in the gene encoding a ROS synthesizing Respiratory Burst Oxidase Homolog C (RBOHC), showed impaired ethylene-dependent ROS synthesis and root hair formation and decreased RBOH enzyme activity compared to Col-0. To identify additional proteins that drive ROS induced root hair formation, we examined a time course root transcriptomic dataset examining Col-0 grown in the presence of ACC and identified PRX44 and other positively regulated transcripts that encode class III peroxidases (PRXs). The prx44-2 mutant has decreased root hair initiation and ROS accumulation when treated with ACC compared to Col-0 and pPRX44::GFP fluorescence is increased in response to ACC treatment. Together, these results support a model in which ethylene increases ROS accumulation through RBOHC and PRX44 to drive root hair formation.

Overexpression of Galactinol Synthase 1 From Solanum Commersonii (ScGolS1) Confers Freezing Tolerance In Transgenic Potato

Potato (Solanum tuberosum L.) is the fourth largest food crop in the world. Low temperature causes serious damage to potato plants every year, and freezing tolerance has become a hot spot in potato research. Galactinol synthase (GolS) is a key enzyme in the synthesis of raffinose family oligosaccharides (RFOs), and plays an important role in the response of plants to abiotic stress. In this study, the ScGolS1 gene from S. commersonii was cloned and introduced into the S. tuberosum cultivars ‘Atlantic’ and ‘Desiree’ via Agrobacterium-mediated transformation. Phenotyping assay showed that overexpression of the ScGolS1 could significantly improve freezing tolerance in transgenic potato plants. Further physiological and biochemical results showed that the relative conductivity, malondialdehyde (MDA) content, and 3,3'-Diaminobenzidine (DAB) staining of the transgenic lines decreased, and the plant survival rate increased compared with wild type (WT). Moreover, CBF1, CBF2, CBF3, CBF downstream cold responsive genes COR413, COR47 and ERF transcription factor genes ERF3, ERF4, ERF6 in the ethylene signaling pathway were all induced by freezing treatment, while higher levels were observed in ScGolS1 overexpression lines compared with WT. In addition, other genes such as MIPS, STS and RS genes from RFO metabolic pathway and some sugars content were altered in response to freezing treatment. This indicates that overexpression of the ScGolS1 gene induced both the regulation of the ethylene signaling pathway and the metabolism of raffinose series oligosaccharides, regulating the balance of sugar composition and improved anti-peroxidation capacity, and thereby improved freezing tolerance in potato. These results provide theoretical support and genetic resources for freezing tolerance breeding in potato.