Identification and characterization of the CRK gene family in the wheat genome and analysis of their expression profile in response to high temperature-induced male sterility.

Cysteine-rich receptor-like kinases (CRKs) play many important roles during plant development, including defense responses under both biotic and abiotic stress, reactive oxygen species (ROS) homeostasis, callose deposition and programmed cell death (PCD). However, there are few studies on the involvement of the CRK family in male sterility due to heat stress in wheat (Triticum aestivum L.). In this study, a genome-wide characterization of the CRK family was performed to investigate the structural and functional attributes of the wheat CRKs in anther sterility caused by heat stress. A total of 95 CRK genes were unevenly distributed on 18 chromosomes, with the most genes distributed on chromosome 2B. Paralogous homologous genes with Ka/Ks ratios less than 1 may have undergone strong purifying selection during evolution and are more functionally conserved. The collinearity analysis results of CRK genes showed that wheat and Arabidopsis (A. thaliana), foxtail millet, Brachypodium distachyon (B. distachyon), and rice have three, 12, 15, and 11 pairs of orthologous genes, respectively. In addition, the results of the network interactions of genes and miRNAs showed that five miRNAs were in the hub of the interactions map, namely tae-miR9657b-5p, tae-miR9780, tae-miR9676-5p, tae-miR164, and tae-miR531. Furthermore, qRT-PCR validation of the six TaCRK genes showed that they play key roles in the development of the mononuclear stage anthers, as all six genes were expressed at highly significant levels in heat-stressed male sterile mononuclear stage anthers compared to normal anthers. We hypothesized that the TaCRK gene is significant in the process of high-temperature-induced sterility in wheat based on the combination of anther phenotypes, paraffin sections, and qRT-PCR data. These results improve our understanding of their relationship.

SlbHLH152, a bHLH transcription factor positively regulates iron homeostasis in tomato.

The maintain of iron (Fe) homeostasis is essential for plant survival. In tomato, few transcription factors have been identified as regulators of Fe homeostasis, among which SlbHLH068 induced by iron deficiency, plays an important role. However, the upstream regulator(s) responsible for activating the expression of SlbHLH068 remain(s) unknown. In this study, the bHLH (basic helix-loop-helix) transcription factor SlbHLH152 was identified as an upstream regulator of SlbHLH068 using yeast one-hybrid screening. Deletion of SlbHLH152 led to a significant decline in Fe concentration, which was accompanied by reduced expression of Fe-deficiency-responsive genes. In contrast, SlbHLH152 overexpression plants displayed tolerance to iron deficiency, increased Fe accumulation, and elevated expression of Fe-deficiency-responsive genes. Further analysis indicated that SlbHLH152 directly activates the transcription of SlbHLH068. Taken together, our results suggest that SlbHLH152 may be involved in the regulation of iron homeostasis by directly activating the transcription of SlbHLH068 in tomato.

Comparative Transcriptome Analysis of Male Sterile Anthers Induced by High Temperature in Wheat (Triticum aestivum L.).

Global warming will have a negative effect on agricultural production as high temperature (HT) stress can seriously threaten plant growth and reproduction. Male sterility caused by HT may be exploited by the creation of a male-sterile line, which has great potential for application in crop heterosis. Therefore, it is important to understand the molecular mechanisms of anther abortion induced by HT in wheat, which remain unclear at present. In this study, we performed phenotype improve language in the abstract and comparative transcriptome analysis of the male sterile anthers induced by HT in wheat. Compared with Normal anthers, the cytological analysis indicated that HT-induced male sterile anthers were smaller and had no starch accumulation in pollen grains, which is consistent with the results observed by scanning electron microscopy (SEM). The 9601 differentially expressed genes (DEGs) identified by transcriptome sequencing compared with the Normal anthers were noticeably involved in the following pathways: starch and sucrose metabolism, phosphatidylinositol (PI) signaling system, peroxidase activity and response to oxidative stress, and heme binding. In addition, TUNEL assays were performed and the results further confirmed the excessive accumulation of reactive oxygen species (ROS) in sterile anthers. Moreover, a total of 38 hub genes were obtained from the protein-protein interaction network analysis of these pathways, including genes, for example, heat shock protein 90 (HSP90), thioredoxin-like protein 1, peroxidase (POD), calreticulin, UDP glucose pyrophosphorylase (UGPase), sucrose synthase, phosphatidylinositol-4-phosphate 5-Kinase (PIP5K), cytochrome c, and Cystathionine beta-synthase X6-like (CBSX6-like). These findings provide insights for predicting the functions of the candidate genes, and the comprehensive analysis of our results is helpful for studying the abortive interaction mechanism induced by HT in wheat.

Chromatin Architectures Are Associated with Response to Dark Treatment in the Oil Crop Sesamum indicum, Based on a High-Quality Genome Assembly.

Eukaryotic chromatin is tightly packed into hierarchical structures, allowing appropriate gene transcription in response to environmental and developmental cues. Here, we provide a chromosome-scale de novo genome assembly of sesame with a total length of 292.3 Mb and a scaffold N50 of 20.5 Mb, containing estimated 28,406 coding genes using Pacific Biosciences long reads combined with a genome-wide chromosome conformation capture (Hi-C) approach. Based on this high-quality reference genome, we detected changes in chromatin architectures between normal growth and dark-treated sesame seedlings. Gene expression level was significantly higher in 'A' compartment and topologically associated domain (TAD) boundary regions than in 'B' compartment and TAD interior regions, which is coincident with the enrichment of H4K3me3 modification in these regions. Moreover, differentially expressed genes (DEGs) induced by dark treated were enriched in the changed TAD-related regions and genomic differential contact regions. Gene Ontology (GO) enrichment analysis of DEGs showed that genes related to 'response to stress' and 'photosynthesis' functional categories were enriched, which corresponds to dark treatment. These results suggested that chromatin organization is associated with gene transcription in response to dark treatment in sesame. Our results will facilitate the understanding of regulatory mechanisms in response to environmental cues in plants.

Improved expression and purification of recombinant human serum albumin from transgenic tobacco suspension culture.

Most human serum albumin (HSA) for medical applications is derived from human plasma due to the lack of suitable heterologous expression systems for recombinant HSA (rHSA). To determine whether plant cell cultures could provide an alternative source, we employed the hyper-translatable cowpea mosaic virus protein expression system (CPMV-HT) to stably express rHSA in tobacco Bright Yellow-2 (BY-2) cells. rHSA was stably produced with yield up to 11.88µg/ml in the culture medium, accounting for 0.7% of total soluble protein, in a 25-ml flask. Cultivation of transgenic cells in modified Murashige and Skoog medium with a pH of 8.0 improved the yield of rHSA two-fold, which may be the result of reduced proteolytic activity in the modified medium. A simple purification scheme was developed to purify the rHSA from culture medium, resulting in a recovery of 48.41% of the secreted rHSA. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and N-terminal sequence analysis of the purified rHSA revealed that plant cell-derived rHSA is identical to that of the plasma-derived HSA. Our results show that the CPMV-HT system, which was originally developed as a transient expression system for use in whole plants, can also be used for high-level expression of rHSA, a protein highly susceptible to proteolysis, in transgenic tobacco cells.