关键词：
CaAFR1;CaMYB61;Khib;cellulose and hemicellulose;histone deacetylases;stem lodging
摘要：
Plant stems constitute the most abundant renewable resource on earth. The function of lysine (K)-2-hydroxyisobutyrylation (K(hib)), a novel post-translational modification (PTM), has not yet been elucidated in plant stem development. Here, by assessing typical pepper genotypes with straight stem (SS) and prostrate stem (PS), we report the first large-scale proteomics analysis for protein K(hib) to date. K(hib)-modifications influenced central metabolic processes involved in stem development, such as glycolysis/gluconeogenesis and protein translation. The high K(hib) level regulated gene expression and protein accumulation associated with cell wall formation in the pepper stem. Specially, we found that CaMYB61 knockdown lines that exhibited prostrate stem phenotypes had high K(hib) levels. Most histone deacetylases (HDACs, e.g., switch-independent 3 associated polypeptide function related 1, AFR1) potentially function as the "erasing enzymes" involved in reversing K(hib) level. CaMYB61 positively regulated CaAFR1 expression to erase K(hib) and promote cellulose and hemicellulose accumulation in the stem. Therefore, we propose a bidirectional regulation hypothesis of "K(hib) modifications" and "K(hib) erasing" in stem development, and reveal a novel epigenetic regulatory network in which the CaMYB61-CaAFR1 molecular module participating in the regulation of K(hib) levels and biosynthesis of cellulose and hemicellulose for the first time.
摘要：
<jats:p>Potato common scab, caused mainly by <jats:italic>Streptomyces scabies</jats:italic>, causes surface necrosis and reduces the economic value of potato tubers, but effective chemical control is still lacking. In this study, an attempt was made to control potato common scab by inoculating potatoes with <jats:italic>Bacillus velezensis</jats:italic> (<jats:italic>B. velezensis</jats:italic>) and to further investigate the mechanism of biological control. The results showed that <jats:italic>B. velezensis</jats:italic> Y6 could reduce the disease severity of potato common scab from 49.92 ± 25.74% [inoculated with <jats:italic>Streptomyces scabies</jats:italic> (<jats:italic>S. scabies</jats:italic>) only] to 5.56 ± 1.89% (inoculated with <jats:italic>S. scabies</jats:italic> and Y6 on the same day) and increase the potato yield by 37.32% compared with the control under pot experiment in this study. Moreover, in the field trial, it was found that Y6 could also significantly reduce disease severity from 13.20 ± 1.00% to 4.00 ± 0.70% and increase the potato yield from 2.07 ± 0.10 ton/mu to 2.87 ± 0.28 ton/mu (<jats:italic>p</jats:italic> &lt; 0.01; Tukey’s test). Furthermore, RNA-seq analysis indicated that 256 potato genes were upregulated and 183 potato genes were downregulated in response to <jats:italic>B. velezensis</jats:italic> Y6 inoculation. In addition, strain Y6 was found to induce the expression of plant growth-related genes in potato, including cell wall organization, biogenesis, brassinosteroid biosynthesis, and plant hormone transduction genes, by 1.01–4.29 times. As well as up-regulate hydroquinone metabolism-related genes and several transcription factors (bHLH, MYB, and NAC) by 1.13–4.21 times. In summary, our study will help to understand the molecular mechanism of biological control of potato common scab and improve potato yield.</jats:p>
摘要：
Tubers are vegetative reproduction organs formed from underground extensions of the plant stem. Potato tubers are harvested and stored for months. Storage under cold temperatures of 2-4 degrees C is advantageous for supressing sprouting and diseases. However, development of reducing sugars can occur with cold storage through a process called cold-induced sweetening (CIS). CIS is undesirable as it leads to darkened color with fry processing. The purpose of the current study was to find differences in biological responses in eight cultivars with variation in CIS resistance. Transcriptome sequencing was done on tubers before and after cold storage and three approaches were taken for gene expression analysis: 1. Gene expression correlated with end-point glucose after cold storage, 2. Gene expression correlated with increased glucose after cold storage (after-before), and 3. Differential gene expression before and after cold storage. Cultivars with high CIS resistance (low glucose after cold) were found to increase expression of an invertase inhibitor gene and genes involved in DNA replication and repair after cold storage. The cultivars with low CIS resistance (high glucose after cold) showed increased expression of genes involved in abiotic stress response, gene expression, protein turnover and the mitochondria. There was a small number of genes with similar expression patterns for all cultivars including genes involved in cell wall strengthening and phospholipases. It is proposed that the pattern of gene expression is related to chilling-induced DNA damage repair and cold acclimation and that genetic variation in these processes are related to CIS.
摘要：
Potato (Solanum tuberosum L.) is an important staple food worldwide. However, its growth has been heavily suppressed by salt stress. The molecular mechanisms of salt tolerance in potato remain unclear. It has been shown that the tetraploid potato Longshu No. 5 is a salt-tolerant genotype. Therefore, in this study we conducted research to identify salt stress response genes in Longshu No. 5 using a NaCl treatment and time-course RNA sequencing. The total number of differentially expressed genes (DEGs) in response to salt stress was 5508. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, it was found that DEGs were significantly enriched in the categories of nucleic acid binding, transporter activity, ion or molecule transport, ion binding, kinase activity and oxidative phosphorylation. Particularly, the significant differential expression of encoding ion transport signaling genes suggests that this signaling pathway plays a vital role in salt stress response in potato. Finally, the DEGs in the salt response pathway were verified by Quantitative real-time PCR (qRT-PCR). These results provide valuable information on the salt tolerance of molecular mechanisms in potatoes, and establish a basis for breeding salt-tolerant cultivars.
关键词：
Cd distribution;Cd-safe tubers;Phytoremediation;Potato (Solanum tuberosum L.)
摘要：
Cadmium (Cd) is a toxic element that can accumulate in plants and poses a threat to human health through biomagnification. There are differences in Cd levels among different plants tissues. Hence, an optimal crop that possesses low Cd levels in the edible parts but high levels in the inedible parts is urgently needed to simultaneously lower soil-Cd levels in contaminated fields and to produce Cd-safe crops. In this study, we investigated the Cd levels in tubers and other tissues of potato (Solanum tuberosum L.) using different experimental approaches, and identified variations in Cd accumulation in different potato cultivars and characterized the Cd-distribution pattern in potato. Our results showed that Cd accumulation in tubers of the tested cultivars varied greatly, and that tuber-Cd levels were much lower than in the stems or leaves. Two-way ANOVA revealed that the tuber-Cd levels in potato are determined by both genotypic differences and the soil-Cd levels of the farmlands. Among the cultivars tested, one cultivar, 'Eshu10', was found to have the lowest tuber-Cd levels but had much higher Cd levels in leaf and stem tissues. Our study shows that the Cd-distribution pattern within potato plants makes it an ideal candidate for the safe production of a staple food that also has the potential to contribute to the remediation of contaminated soils. (C) 2019 Elsevier B.V. All rights reserved.
摘要：
Fumarylacetoacetate hydrolase (FAH) catalyses the final step of the tyrosine degradation pathway, which is essential to animals but was of unknown importance in plants until we found that mutation of Short-day Sensitive Cell Death1 (SSCD1), encoding Arabidopsis FAH, results in cell death under short-day conditions. The sscd1 mutant accumulates succinylacetone (SUAC), an abnormal metabolite caused by loss of FAH. Succinylacetone is an inhibitor of delta-aminolevulinic acid (ALA) dehydratase (ALAD), which is involved in chlorophyll (Chl) biosynthesis. In this study, we investigated whether sscd1 cell death is mediated by Chl biosynthesis and found that ALAD activity is repressed in sscd1 and that protochlorophyllide (Pchlide), an intermediate of Chl biosynthesis, accumulates at lower levels in etiolated sscd1 seedlings. However, it was interesting that Pchlide in sscd1 might increase after transfer from light to dark and that HEMA1 and CHLH are upregulated in the light-dark transition before Pchlide levels increased. Upon re-illumination after Pchlide levels had increased, reactive oxygen species marker genes, including singlet oxygen-induced genes, are upregulated, and the sscd1 cell death phenotype appears. In addition, Arabidopsis WT seedlings treated with SUAC mimic sscd1 in decline of ALAD activity and accumulation of Pchlide as well as cell death. These results demonstrate that increase in Pchlide causes cell death in sscd1 upon re-illumination and suggest that a decline in the Pchlide pool due to inhibition of ALAD activity by SUAC impairs the repression of ALA synthesis from the light-dark transition by feedback control, resulting in activation of the Chl biosynthesis pathway and accumulation of Pchlide in the dark.
摘要：
WRKY是一类广泛参与高等植物各种抗逆调控活动的转录因子,可以通过激活下游相关信号转导途径调节自身的应激反应,进而增强植物抗逆性。本研究通过RNA-Seq从马铃薯(Solanum tuberosum)中筛选出一个晚疫病菌诱导WRKY转录因子基因StWRKY。采用RT-PCR技术获得该基因CDS全长,并对其进行序列分析及结构功能预测。根据StWRKY蛋白序列进行同源性搜索,得到与其蛋白序列相似度较高的其他物种的蛋白序列,使用MEGA7软件对StWRKY蛋白序列及其同源序列进行多序列比对分析并构建了系统进化树。利用在线工具ProtParam对StWRKY进行氨基酸理化性质分析;利用SMART在线工具进行蛋白序列分析;利用SWISS-MODEL在线工具和PredictProtein在线平台分别对StWRKY蛋白二级结构和三级结构进行分析。结果表明,StWRKY核苷酸序列CDS全长为957 bp,编码含318个氨基酸的蛋白质,预测蛋白分子量为36.17 kD,等电点为6.49。既不是分泌蛋白也不是膜蛋白,未发现跨膜区、信号肽和复合螺旋区。 StWRKY三维空间结构主要由无规卷曲以及β-折叠组成。通过XcmⅠ酶切、连接将StWRKY装载到pCXSN载体上,构建了该基因的超表达载体pCXSN-StWRKY。StWRKY基因的克隆,为进一步从分子水平上验证其抗晚疫病的生物学功能以及揭示马铃薯生物胁迫抗逆机制奠定基础,并为马铃薯抗病育种提供新的基因资源。 <&wdkj&>WRKY is a kind of transcriptional factor that widely participates in the regulation of various stress resistant activities of higher plants, which can regulate its own stress response by activating downstream related signal transduction pathway to enhance plant stress resistance. In this study, a WRKY transcription factor gene StWRKY induced by Phytophthora infestans was screened from Solanum tuberosum by RNA-seq. The full-length CDS of the gene was obtained by RT-PCR, and the sequence analysis and structural function prediction were carried out. Homology search was performed according to StWRKY protein sequence, and protein sequences of other species with high similarity to its protein sequences were obtained. A multiple sequence alignment was analyzed and phylogenetic tree was constructed on StWRKY protein sequence and its homologous sequences by MEGA7. The physical and chemical properties of StWRKY were analyzed by online tool ProtParam. StWRKY protein sequence was analyzed by SMART online tools. The secondary structure and tertiary structure of StWRKY protein were analyzed by SWISS-MODEL online tool and PreidictProtein online platform, respectively. The results showed that the full-length CDS of StWRKY nucleotide sequence was 957 bp, encoding 318 amino acids, with the predicted molecular mass of 36.17 kD and the isoelectric point of 6.49. Neither a secreted protein nor a membrane protein, and no transmembrane region, signal peptide and complex helix region were found. The StWRKY three-dimensional space structure was mainly composed of random coils and β-sheets. The overexpression vector pCXSN-StWRKY was constructed by loading StWRKY on plasmid pCXSN through XcmⅠenzyme digestion and linkage. The cloning of StWRKY gene could provide a basis for further identification of the biological function of anti-late blight on the molecular level, to reveal the resistance mechanism of potato biotic stress and offer new genetic resources for the resistance breeding of potato.
