Knockout of SlbZIP68 reduces late blight resistance in tomato.

Tomato (Solanum lycopersicum) is one of the most widely cultivated vegetable crop species in the world. Tomato late blight caused by Phytophthora infestans is a severe disease, which can cause serious losses in tomato production. In this study, tomato SlbZIP68 was identified as a transcription factor that can be induced by P. infestans, salicylic acid (SA) and jasmonic acid (JA). Knockout of SlbZIP68 via clustered, regularly interspaced, short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) technology revealed a significant decrease in tomato resistance to P. infestans. Furthermore, knockout of SlbZIP68 reduced the activity of defense enzymes and increased the accumulation of reactive oxygen species (ROS). Our findings also indicated that SlbZIP68 can activate the expression of the PR genes and enhance resistance to P. infestans. In addition, SlbZIP68 can bind to the PR3 and PR5 promoters and induce gene expression, as revealed by yeast one-hybrid (Y1H) and dual-luciferase (LUC) assays. These findings not only elucidate the mechanisms of response to P. infestans but also enable targeted breeding strategies for tomato resistance to P. infestans.

Genome-Wide Identification of PEBP Gene Family in Solanum lycopersicum.

The PEBP gene family is crucial for the growth and development of plants, the transition between vegetative and reproductive growth, the response to light, the production of florigen, and the reaction to several abiotic stressors. The PEBP gene family has been found in numerous species, but the SLPEBP gene family has not yet received a thorough bioinformatics investigation, and the members of this gene family are currently unknown. In this study, bioinformatics was used to identify 12 members of the SLPEBP gene family in tomato and localize them on the chromosomes. The physicochemical characteristics of the proteins encoded by members of the SLPEBP gene family were also examined, along with their intraspecific collinearity, gene structure, conserved motifs, and cis-acting elements. In parallel, a phylogenetic tree was built and the collinear relationships of the PEBP gene family among tomato, potato, pepper, and Arabidopsis were examined. The expression of 12 genes in different tissues and organs of tomato was analyzed using transcriptomic data. It was also hypothesized that SLPEBP3, SLPEBP5, SLPEBP6, SLPEBP8, SLPEBP9, and SLPEBP10 might be related to tomato flowering and that SLPEBP2, SLPEBP3, SLPEBP7, and SLPEBP11 might be related to ovary development based on the tissue-specific expression analysis of SLPEBP gene family members at five different stages during flower bud formation to fruit set. This article's goal is to offer suggestions and research directions for further study of tomato PEBP gene family members.

Genome-Wide Identification and Expression Analysis of Cysteine-Rich Polycomb-like Protein (CPP) Gene Family in Tomato.

The cysteine-rich polycomb-like protein (CPP) gene family is a class of transcription factors containing conserved cysteine-rich CRC structural domains that is involved in the regulation of plant growth and stress tolerance to adversity. Relative to other gene families, the CPP gene family has not received sufficient attention. In this study, six SlCPPs were identified for the first time using the most recent genome-wide identification data of tomato. Subsequently, a phylogenetic analysis classified SlCPPs into four subfamilies. The analysis of cis-acting elements in the promoter indicates that SlCPPs are involved in plant growth and development and also stress response. We present for the first time the prediction of the tertiary structure of these SlCPPs proteins using the AlphaFold2 artificial intelligence system developed by the DeepMind team. Transcriptome data analysis showed that SlCPPs were differentially expressed in different tissues. Gene expression profiling showed that all SlCPPs except SlCPP5 were up-regulated under drought stress; SlCPP2, SlCPP3 and SlCPP4 were up-regulated under cold stress; SlCPP2 and SlCPP5 were up-regulated under salt stress; all SlCPPs were up-regulated under inoculation with Cladosporium fulvum; and SlCPP1, SlCPP3, and SlCPP4 were up-regulated under inoculation with Stemphylium lycopersici. We performed a virus-induced gene silencing experiment on SlCPP3, and the results indicated that SlCPP3 was involved in the response to drought stress. Finally, we predicted the interaction network of the key gene SlCPP3, and there was an interaction relationship between SlCPP3 and 10 genes, such as RBR1 and MSI1. The positive outcome showed that SlCPPs responded to environmental stress. This study provides a theoretical and empirical basis for the response mechanisms of tomato in abiotic stresses.

Transcriptome Analysis and Screening of Genes Associated with Flower Size in Tomato (Solanum lycopersicum).

Flower development is not only an important way for tomato reproduction but also an important guarantee for tomato fruit production. Although more and more attention has been paid to the study of flower development, there are few studies on the molecular mechanism and gene expression level of tomato flower development. In this study, RNA-seq analysis was performed on two stages of tomato flower development using the Illumina sequencing platform. A total of 8536 DEGs were obtained by sequencing, including 3873 upregulated DEGs and 4663 down-regulated DEGs. These differentially expressed genes are related to plant hormone signaling, starch and sucrose metabolism. The pathways such as pentose, glucuronate interconversion, and Phenylpropanoid biosynthesis are closely related and mainly involved in plant cellular and metabolic processes. According to the enrichment analysis results of DEGs, active energy metabolism can be inferred during flower development, indicating that flower development requires a large amount of energy and material supply. In addition, some plant hormones, such as GA, may also have effects on flower development. Combined with previous studies, the expression levels of Solyc02g087860 and three of bZIPs were significantly increased in the full flowering stage compared with the flower bud stage, indicating that these genes may be closely related to flower development. These genes were previously reported in Arabidopsis but not in tomatoes. Our next work will conduct a detailed functional analysis of the identified bZIP family genes to characterize their association with tomato flower size. This study will provide new genetic resources for flower formation and provide a basis for tomato yield breeding.

Variability of coherent and incoherent features of internal tides in the north South China Sea.

The coherent and incoherent features of internal tides (ITs) in the north South China Sea (SCS) are investigated based on observations and numerical simulations. The 11-month (from May 2011 to March 2012) moored current observations indicate that coherent semidiurnal ITs are obviously amplified, which can be attributed to the interference of ITs. Interference enhances coherent motions of semidiurnal ITs, but weakens those of diurnal ITs. Moreover, observations also show that semidiurnal ITs are more incoherent than diurnal ITs. Variations of vertical stratification and surface tide forcing can hardly affect the incoherence of ITs. The increase of incoherent signal is largely due to the influence of mesoscale eddies. Mesoscale eddies affect both amplitude and phase of ITs, making them more incoherent. Mesoscale eddies not only increase the intensity of background currents, but also induce horizontal variations of density. Variations of horizontal density and the influence of background currents lead to the increase of incoherent signals. And semidiural ITs are more sensitive to the influence of mesoscale eddies, making them more incoherent than diurnal counterparts. Incoherent ITs, which induce strong current shear, play essential roles in cascading tidal energy to small-scale motions, and contribute to turbulent mixing eventually. The findings help to better understand ITs and may offer reference for the improvement of parameterization of ocean turbulent mixing in the northern SCS.

Application of the Orthogonal Polynomial Fitting Method in Estimating PM2.5 Concentrations in Central and Southern Regions of China.

Sufficient and accurate air pollutant data are essential to analyze and control air contamination problems. An orthogonal polynomial fitting (OPF) method using Chebyshev basis functions is introduced to produce spatial distributions of fine particle (PM2.5) concentrations in central and southern regions of China. Idealized twin experiments (IE1 and IE2) are designed to validate the feasibility of the OPF method. IE1 is designed in accordance with the most common distribution of PM2.5 concentrations in China, whereas IE2 represents a common distribution in spring and autumn. In both idealized experiments, prescribed distributions are successfully estimated by the OPF method with smaller errors than kriging or Cressman interpolations. In practical experiments, cross-validation is employed to assess the interpolation results. Distributions of PM2.5 concentrations are well improved when OPF is applied. This suggests that errors decrease when the fitting order increases and arrives at the minimum when both orders reach 6. Results calculated by the OPF method are more accurate than kriging and Cressman interpolations if appropriate fitting orders are selected in practical experiments.