摘要：
BackgroundPolycomb group (PcG) proteins play important roles in animal and plant development and stress response. Polycomb repressive complex 1 (PRC1) and PRC2 are the key epigenetic regulators of gene expression, and are involved in almost all developmental stages. PRC1 catalyzes H2A monoubiquitination resulting in transcriptional silencing or activation. The PRC1 components in the green lineage were identified and evolution and conservation was analyzed by bioinformatics techniques. RING Finger Protein 1 (RING1), B lymphoma Mo-MLV insertion region 1 homolog (BMI1), Like Heterochromatin Protein 1 (LHP1) and Embryonic Flower 1 (EMF1) are the PRC1 core components and Vernalization 1 (VRN1), VP1/ABI3-Like 1/2/3 (VAL1/2/3), Alfin-like 1-7 (AL1-7), Inhibitor of growth 1/2 (ING1/2), and Early Bolting in Short Days (EBS) / Short Life (SHL) are the associated factors.ResultsEach PRC1 subunit possesses special domain organizations, such as RING and the ring finger and WD40-associated ubiquitin-like (RAWUL) domains for RING1 and BMI1, chromatin organization modifier (CHROMO) and chromo shadow (ChSh) domains for LHP1, one or two B3 DNA binding domain(s) for VRN1, B3 and zf-CW domains for VAL1/2/3, Alfin and Plant HomeoDomain (PHD) domains for AL1-7, ING and PHD domains for ING1/2, Bromoadjacent homology (BAT) and PHD domains for EBS/SHL. Six new motifs are uncovered in EMF1.The PRC1 core components RING1 and BMI1, and the associated factors VAL1/2/3, AL1-7, ING1/2, and EBS/SHL exist from alga to higher plants, whereas LHP1 only occurs in higher plants. EMF1 and VRN1 are present only in eudicots. PRC1 components undergo duplication in the plant evolution. Most of plants carry the homologous core component LHP1, the associated factor EMF1, and several homologs in RING1, BMI1, VRN1, AL1-7, ING1/2/3, and EBS/SHL. Cabbage, cotton, poplar, orange and maize often exhibit more gene copies than other species. Domain organization analysis shows that duplicated gene functions may be of diverse.ConclusionsThe PRC1 core components RING1 and BMI1, and the associated factors VAL1/2/3, AL1-7, ING1/2, and EBS/SHL originate from algae. The core component LHP1 is from moss and the associated factors EMF1 and VRN1 are from dicotyledon. PRC1 components are of functional redundancy and diversity in evolution.
摘要：
Sulfotransferases (SOTs; EC 2.8.2.-), which are widespread from prokaryotes to eukaryotes, constitute a multi-protein family that plays crucial roles in plant growth, development and stress adaptation. However, this family has not been systemically investigated in Brassica rapa. Here, a genome-wide systemic analysis of SOT genes in B. rapa subsp. pekinensis, a globally cultivated vegetable, were conducted. We identified 56 SOT genes from the whole B. rapa genome using Arabidopsis SOT sequences as queries and classified them into nine groups, rather than the eight groups of previous research. 56 B. rapa SOT genes (BraSOTs) were distributed on all 10 chromosomes except for chromosome 5. Of these, 27 BraSOTs were distributed in seven clusters on five chromosomes (ChrA01, ChrA02, Chr03, ChrA07, and Chr09). Among the BraSOT proteins, 48 had only one SOT_1 domain and 6 had two, while 2 had one SOT_3 domain. Additionally, 47 BraSOT proteins contained only known SOT domains. The remaining nine proteins, five in group-VIII and two in group-IX, contained additional transmembrane domains. Specific motif regions I and IV for 3'-phosphoadenosine 5'-phosphosulfate binding were found in 41 BraSOT proteins. Introns were present in only 18 BraSOT genes, and all seven BraSOT genes in groups VIII and IX had more than three introns. To identify crucial SOTs mediating the response to abiotic stress in B. rapa, expression changes in 56 BraSOT genes were determined by quantitative RT-PCR after drought, salinity, and ABA treatments, and some BraSOT genes were associated with NaCl, drought and ABA stress, e.g. Bra017370, Bra009300, Bra027880.
摘要：
Priming for better defense performance is an important strategy in acclimation to the ever-changing environment. In the present study, defense priming induced by sodium chloride at the seedling stage significantly increased the expression of defense gene VSP2, the content of total glucosinolates and the level of the reactive oxygen species in mature Arabidopsis thaliana plants after transferred into the stress-free environment. The previously primed plants could effectively resist the feeding of Spodoptera litura (Fabricius) larvae. Salt-priming enhanced defense of Arabidopsis plants in the absence of either MYC2 or AOS, which encodes a critical transcription factor in JA-signaling and an important enzyme in JA biosynthesis, respectively. Our results supported the JA-independent defense primed by sodium chloride, as well as the elevated ROS and glucosinolate level in primed plants. In addition, the feasibility of using mild salt-priming to improve crop performance in field was proposed.
摘要：
<jats:title>Summary</jats:title><jats:p>Although increasing experimental evidence demonstrates that histone methylations play important roles in Arabidopsis plant growth and development, little information is available regarding <jats:italic>Brassica napus</jats:italic>. In this study, we characterized two genes encoding homologues of the Arabidopsis histone 3 lysine 36 (H3K36) methyltransferase <jats:styled-content style="fixed-case">SDG</jats:styled-content>8, namely, <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.A</jats:italic> and <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.C</jats:italic>. Although no duplication of <jats:styled-content style="fixed-case">SDG</jats:styled-content>8 homologous genes had been previously reported to occur during the evolution of any sequenced species, a domain‐duplication was uncovered in <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.C</jats:italic>. This duplication led to the identification of a previously unknown <jats:styled-content style="fixed-case">NNH</jats:styled-content> domain in the <jats:styled-content style="fixed-case">SDG</jats:styled-content>8 homologues, providing a useful reference for future studies and revealing the finer mechanism of <jats:styled-content style="fixed-case">SDG</jats:styled-content>8 function. One <jats:styled-content style="fixed-case">NNH</jats:styled-content> domain is present in Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.A, while two adjacent <jats:styled-content style="fixed-case">NNH</jats:styled-content> domains are present in Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.C. Reverse transcriptase‐quantitative polymerase chain reaction analysis revealed similar patterns but with varied levels of expression of <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.A/C</jats:italic> in different plant organs/tissues. To directly investigate their function, <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.A</jats:italic>/<jats:italic>C </jats:italic><jats:styled-content style="fixed-case">cDNA</jats:styled-content> was ectopically expressed to complement the Arabidopsis mutant. We observed that the expression of either <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.A</jats:italic> or <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.C</jats:italic> could rescue the Arabidopsis <jats:italic>sdg8</jats:italic> mutant to the wild‐type phenotype. Using <jats:styled-content style="fixed-case">RNA</jats:styled-content>i and <jats:styled-content style="fixed-case">CRISPR</jats:styled-content>/Cas9‐mediated gene editing, we obtained <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.A</jats:italic>/<jats:italic>C</jats:italic> knockdown and knockout mutants with the early flowering phenotype as compared with the control. Further analysis of two types of the mutants revealed that <jats:italic>Bna<jats:styled-content style="fixed-case">SDG</jats:styled-content>8.A/C</jats:italic> are required for H3K36m2/3 deposition and prevent the floral transition of <jats:italic>B.napus</jats:italic> by directly enhancing the H3K36m2/3 levels at the <jats:italic>Bna<jats:styled-content style="fixed-case">FLC</jats:styled-content></jats:italic> chromatin loci. This observation on the floral transition by epigenetic modification in <jats:italic>B.napus</jats:italic> provides useful information for breeding early‐flowering varieties.</jats:p>
摘要：
Ubiquitous CCCH nucleic acid-binding motif is found in a wide-variety of organisms. CCCH genes are involved in plant developmental processes and biotic and abiotic stress responses. Brassica rapa is a vital economic crop and classical model plant of polyploidy evolution, but the functions of CCCH genes in B. rapa are unclear. In this study, 103 CCCH genes in B. rapa were identified. A comparative analysis of the chromosomal position, gene structure, domain organization and duplication event between B. rapa and Arabidopsis thaliana were performed. Results showed that CCCH genes could be divided into 18 subfamilies, and segmental duplication might mainly contribute to this family expansion. C-X7/8-C-X5-C3-H was the most commonly found motif, but some novel CCCH motifs were also found, along with some loses of typical CCCH motifs widespread in other plant species. The multifarious gene structures and domain organizations implicated functional diversity of CCCH genes in B. rapa. Evidence also suggested functional redundancy in at least one subfamily due to high conservation between members. Finally, the expression profiles of subfamily-IX genes indicated that they are likely involved in various stress responses. This study provides the first genome-wide characterization of the CCCH genes in B. rapa. The results suggest that B. rapa CCCH genes are likely functionally divergent, but mostly involved in plant development and stress response. These results are expected to facilitate future functional characterization of this potential RNA-binding protein family in Brassica crops.
