Comprehensive Evolutionary Analysis of CPP Genes in Brassica napus L. and Its Two Diploid Progenitors Revealing the Potential Molecular Basis of Allopolyploid Adaptive Advantage Under Salt Stress

Genome-Wide Analysis of CPP Transcription Factor Family in Endangered Plant Phoebe bournei and Its Response to Adversity

The CPP gene family comprises transcription factor genes containing a conserved CRC domain, which is mainly involved in plant development and evolution. Although CPP genes have been widely studied in many plants, little is known about them in woody plants, especially in the endangered species Phoebe bournei (Hemsl.). In the genome of Phoebe bournei, we identified 11 PbCPP genes (PbCPP1-PbCPP11) distributed on four chromosomes, with large differences in the number of amino acids. They encode both acidic and alkaline proteins. A phylogenetic analysis showed that these PbCPP genes can be divided into three subfamilies, A, B, and C, which contain seven, two, and two genes, respectively. Through an interspecific collinearity analysis, we identified homologous PbCPP genes. A promoter cis-acting element analysis revealed that PbCPPs contain a variety of elements that respond to plant hormones, stress signals, and light and play a role in growth and development, and most PbCPP genes (except PbCPP3 and PbCPP8) contain MYB binding site elements that regulate drought-induced stress responses, indicating that they play an important role in plant drought resistance. An expression analysis showed that PbCPP3 and PbCPP4 expression was high in the roots and stems and lower in the leaves, whereas the expression of most of the other genes was low in the roots, stems, and leaves. In addition, six representative PbCPP genes were detected using qRT-PCR. The results show significant differences in the expression of PbCPP genes under abiotic stress conditions (drought, cold, and salt), indicating that they play an important role in stress responses. This study preliminarily verified the role of the PbCPP gene family in different abiotic stress responses, which is of great significance for understanding its mechanism in plant growth and development and stress adaptation.

Decryption of the survival "black box": gene family expansion promotes the encystment in ciliated protists

BACKGROUND

Encystment is an important survival strategy extensively employed by microbial organisms to survive unfavorable conditions. Single-celled ciliated protists (ciliates) are popular model eukaryotes for studying encystment, whereby these cells degenerate their ciliary structures and develop cyst walls, then reverse the process under more favorable conditions. However, to date, the evolutionary basis and mechanism for encystment in ciliates is largely unknown. With the rapid development of high-throughput sequencing technologies, genome sequencing and comparative genomics of ciliates have become effective methods to provide insights into above questions.

RESULTS

Here, we profiled the MAC genome of Pseudourostyla cristata, a model hypotrich ciliate for encystment studies. Like other hypotrich MAC genomes, the P. cristata MAC genome is extremely fragmented with a single gene on most chromosomes, and encodes introns that are generally small and lack a conserved branch point for pre-mRNA splicing. Gene family expansion analyses indicate that multiple gene families involved in the encystment are expanded during the evolution of P. cristata. Furthermore, genomic comparisons with other five representative hypotrichs indicate that gene families of phosphorelay sensor kinase, which play a role in the two-component signal transduction system that is related to encystment, show significant expansion among all six hypotrichs. Additionally, cyst wall-related chitin synthase genes have experienced structural changes that increase them from single-exon to multi-exon genes during evolution. These genomic features potentially promote the encystment in hypotrichs and enhance their ability to survive in adverse environments during evolution.

CONCLUSIONS

We systematically investigated the genomic structure of hypotrichs and key evolutionary phenomenon, gene family expansion, for encystment promotion in ciliates. In summary, our results provided insights into the evolutionary mechanism of encystment in ciliates.

Identification of the High-Affinity Potassium Transporter Gene Family (HKT) in Brassica U-Triangle Species and Its Potential Roles in Abiotic Stress in Brassica napus L

Members of the high-affinity potassium transporter (HKT) protein family regulate the uptake and homeostasis of sodium and potassium ions, but little research describes their roles in response to abiotic stresses in rapeseed (Brassica napus L.). In this study, we identified and characterized a total of 36 HKT genes from the species comprising the triangle of U model (U-triangle species): B. rapa, B. nigra, B. oleracea, B. juncea, B. napus, and B. carinata. We analyzed the phylogenetic relationships, gene structures, motif compositions, and chromosomal distributions of the HKT family members of rapeseed. Based on their phylogenetic relationships and assemblage of functional domains, we classified the HKT members into four subgroups, HKT1;1 to HKT1;4. Analysis of the nonsynonymous substitutions (Ka), synonymous substitutions (Ks), and the Ka/Ks ratios of HKT gene pairs suggested that these genes have experienced strong purifying selective pressure after duplication, with their evolutionary relationships supporting the U-triangle theory. Furthermore, the expression profiles of BnaHKT genes varies among potassium, phytohormone and heavy-metal treatment. Their repression provides resistance to heavy-metal stress, possibly by limiting uptake. Our results systematically reveal the characteristics of HKT family proteins and their encoding genes in six Brassica species and lay a foundation for further exploration of the role of HKT family genes in heavy-metal tolerance.