摘要：
Boehmeria nivea L. Gaud (Ramie) produces one of the longest natural fibers in nature. The bark of ramie mainly comprises of the phloem tissue of stem and is the raw material for fiber. Therefore, identifying the molecular regulation of phloem development is important for understanding of bast fiber biosynthesis and improvement of fiber quality in ramie. In this study, we collected top bud (TB), bark from internode elongating region (ER) and bark from internode fully elongated region (FER) from the ramie variety Zhongzhu No. 1. Histological study indicated that these samples contain phloem tissues at different developmental and maturation stages, with a higher degree of maturation of phloem tissue in FER. RNA sequencing (RNA-seq) was performed and de novo transcriptome was assembled. Unigenes and differentially expressed genes (DEGs) in these three samples were identified. The analysis of DEGs by using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed clear differences in gene expression between ER and FER. Some unigenes involved in secondary cell wall biosynthesis were up-regulated in both ER and FER, while unigenes for some cell wall components or cell wall modifications showed differential expression between ER and FER. In addition, the ethylene respond factors (ERFs) in the ethylene signaling pathway were up-regulated in FER, and ent-kaurenoic acid oxidase (KAO) and GA 20-oxidase (GA20ox) for gibberellins biosynthesis were up-regulated while GA 2-oxidase (GA2ox) for gibberellin inactivation was down-regulated in FER. Both morphological study and gene expression analysis supported a burst of phloem and vascular developmental processes during the fiber maturation in the ramie stem, and ethylene and gibberellin are likely to be involved in this process. Our findings provide novel insights into the phloem development and fiber maturation in ramie, which could be useful for fiber improvement in ramie and other fiber crops.
关键词：
captation du plomb;croissance racinaire;endophytes;lead uptake;root growth
摘要：
Endophytic bacteria are generally helpful for plant growth and protection. We isolated from tobacco seeds three Pseudomonas strains (K03, Y04, and N05) that could produce siderophores, indole-3-acetic acid, and 1-aminocyclopropane-1-carboxylate deaminase, fix nitrogen, dissolve phosphorus and potassium, and tolerate heavy metals. In pot experiments, the three isolated strains significantly promoted root growth and increased the root enzyme activity in Nicotiana tobacum K326. Furthermore, bacterial inoculations increased the proportion of residual lead (Pb) by 8.36%-51.63% and decreased the total Pb content by 3.28%-6.38% in the contaminated soil during tobacco planting, compared with uninoculated soils. An effective decrease in Pb content was also found in tobacco leaves with bacterial inoculations. K03 inoculation decreased the Pb content in the upper leaves by 49.80%, and Y04 inoculation had the best effect, decreasing the Pb content in the middle leaves by 70.12%. Additionally, soil pH and root activity had significant effects on transformation and translocation of Pb. The study suggested that in response to Pb pollution in soil, a reasonable application of endophytes (e.g., Pseudomonas) might be a promising approach in promoting tobacco growth and reducing Pb content in tobacco, while simultaneously enhancing Pb stabilization in soils.
通讯机构：
Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Maize Research Center, Beijing Academy of Agriculture & Forestry Sciences, Beijing, China
关键词：
ZmMs7;genetic male sterility;hybrid seed production;maize;nontransgenic progeny;transgenic maintainer line
关键词：
Crop morbidity;Biological control agents;Bacterial interactions;Bacterial diversity;Bacterial community structure
摘要：
Bacterial wilt, caused by Ralstonia solanacearum, occurs occasionally during tobacco planting and potentially brings huge economic losses in affected areas. Soil microbes in different management stages play important roles in influencing bacterial wilt incidence. Studies have focused on the impacts of species diversity and composition during cropping periods on disease morbidity; however, the effects of the soil bacterial biomass, species diversity, species succession, and population interactions on morbidity remain unclear during non-cropping periods. In this study, we explored the soil bacterial communities in the non-cropping winter fallow (WF) and cropping late growing (LG) periods under consecutive monoculture systems using 16S ribosomal RNA gene sequencing and qPCR and further analyzed their effects on tobacco bacterial wilt incidence. We found that the bacterial communities in the WF period were significantly different from those in the LG period based on detrended correspondence analysis and dissimilarity tests. Crop morbidity was significantly related to bacterial community structure and to the presence of some genera during WF and LG periods. These genera, such as Arthrobacter, Pseudomonas, Acidobacteria GP6, and Pasteuria, may be potential biological control agents for bacterial wilt. Further analysis indicated that low soil bacterial diversity during the WF period, decrease of bacterial interactions from the WF to LG periods, and low soil biomass during the LG period all have the potential to increase morbidity. In conclusion, an increase of soil bacterial diversity and control of some bacterial abundances in the WF period might be an effective approach in controlling bacterial wilt incidence.
关键词：
auxins;cytokinins;gibberellins;Gossypium hirsutum;iTRAQ;near-isogenic line
摘要：
Identifying important regulative elements and pathways related to dwarfism in cotton is a major challenge in cotton breeding. An isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics of the stem terminal buds from the upland cotton (Gossypium hirsutum L.) dwarf line LA-1 and high near-isogenic line LH-1 was performed. Moreover, the transcriptional expression of differentially-expressed proteins (DEPs) belonging to the phytohormone signal transduction, hormone biosynthesis, and ubiquitin system were analysed using the quantitative real-time polymerase chain reaction.. A total of 4 849 proteins were identified from LA-1 and LH-1, 697 of which showed differential accumulations. Most of the DEPs have catalytic, binding, and transporter activity and are involved in metabolism- and protein processing-related pathways. In particular, seven DEPs, including two gibberellin (GA) receptors, three cytokinin (CK) receptors, CK oxidase and CK-N-glucosyltransferase were up-regulated in LA-1, and gibberellin 20-oxidase was down-regulated in LA-1. Our results suggest that the DELLA-independent GA signalling pathway is the primary cause of dwarfism in LA-1 and indicate that cytokinin response element CRE1-2, gibberellininsensitive dwarf, cytokinin oxidase,and gibberellin 3-β-dioxygenase are potential indicators of dwarf cotton. The profiling of DEPs may offer a valuable resource for cotton breeding.
摘要：
Miscanthus is a leading bioenergy candidate for biofuels, and it thus becomes essential to characterize the desire natural Miscanthus germplasm accessions with high biomass saccharification. In this study, total 171 natural Miscanthus accessions were geographically mapped using public database. According to the equation [P(H/L| East) = P(H/L∩East)/P(East)], the probability (P) parameters were calculated on relationships between geographical distributions of Miscanthus accessions in the East of China, and related factors with high(H) or low(L) values including biomass saccahrification under 1% NaOH and 1% H2SO4 pretreatments, lignocellulose features and climate conditions. Based on the maximum P value, a golden cutting line was generated from 42°25’ N, 108°22’ E to 22°58’ N, 116°28’ E on the original locations of Miscanthus accessions with high P(H|East) values (0.800–0.813), indicating that more than 90% Miscanthus accessions were originally located in the East with high biomass saccharification. Furthermore, the averaged insolation showed high P (H|East) and P(East|H) values at 0.782 and 0.754, whereas other climate factors had low P(East|H) values, suggesting that the averaged insolation is unique factor on Miscanthus distributions for biomass saccharification. In terms of cell wall compositions and wall polymer features, both hemicelluloses level and cellulose crystallinity (CrI) of Miscanthus accessions exhibited relative high P values, suggesting that they should be the major factors accounting for geographic distributions of Miscanthus accessions with high biomass digestibility.
关键词：
Bacterial blight resistance;Brown planthopper resistance;Gene pyramiding;Hybrid rice;Restorer line
摘要：
Development of resistant varieties is one of the most economical and effective strategies to prevent rice from bacterial blight disease (BB) and brown planthopper (BPH), the two main pests jeopardizing rice production. The hybrid rice Tianyouhuazhan (TianfengA/Huazhan) has been widely used in rice production in China, but this hybrid is susceptible to BB and BPH. In this study, one BB resistance gene (Xa23) and two BPH resistance genes (Bph14 and Bph15) were simultaneously introgressed into the restorer line Huazhan to improve the BB and BPH resistance of Tianyouhuazhan using marker -assisted backcrossing (MABC) strategy coupled with phenotypic selection. The results of identification of BB and BPH resistance revealed that almost all of the improved restorer lines and their derived hybrids showed high resistance (HR) or resistance (R) to BB and BPH. Almost all of the agronomic traits of improved restorer lines and their hybrids were similar to those of their respective original versions in field trial, except the 1000 -grain weight of improved hybrids showed an extremely significant increase than that of Tianyouhuazhan. Plot yields test in 2013 and 2014 suggested that two improved hybrid combinations named as TianfengA/R43-06 and TianfengA/R43-07 had higher grain yields per plot than Tianyouhuazhan and other improved hybrids. These results clearly indicate that pyramiding of Xa23, Bph14 and Bph15 genes is a useful approach for improving BB and BPH resistance, two hybrid combinations TianfengA/R43-06 and TianfengA/R43-07 could replace Tianyouhuazhan for extension in BB and/or BPH epidemic area in China. (C) 2015 Elsevier B.V. All rights reserved.
摘要：
The identification of quantitative trait loci (QTLs) that are stable and consistent across multiple environments and populations plays an essential role in marker-assisted selection (MAS). In the present study, we used 28,861 simple sequence repeat (SSR) markers, which included 12,560 Gossypium raimondii (D genome) sequence-based SSR markers to identify polymorphism between two upland cotton strains 0–153 and sGK9708. A total of 851 polymorphic primers were finally selected and used to genotype 196 recombinant inbred lines (RIL) derived from a cross between 0 and 153 and sGK9708 and used to construct a linkage map. The RIL population was evaluated for fiber quality traits in six locations in China for five years. Stable QTLs identified in this intraspecific cross could be used in future cotton breeding program and with fewer obstacles. The map covered a distance of 4,110 cM, which represents about 93.2 % of the upland cotton genome, and with an average distance of 5.2 cM between adjacent markers. We identified 165 QTLs for fiber quality traits, of which 47 QTLs were determined to be stable across multiple environments. Most of these QTLs aggregated into clusters with two or more traits. A total of 30 QTL clusters were identified which consisted of 103 QTLs. Sixteen clusters in the At sub-genome comprised 44 QTLs, whereas 14 clusters in the Dt sub-genome that included 59 QTLs for fiber quality were identified. Four chromosomes, including chromosome 4 (c4), c7, c14, and c25 were rich in clusters harboring 5, 4, 5, and 6 clusters respectively. A meta-analysis was performed using Biomercator V4.2 to integrate QTLs from 11 environmental datasets on the RIL populations of the above mentioned parents and previous QTL reports. Among the 165 identified QTLs, 90 were identified as common QTLs, whereas the remaining 75 QTLs were determined to be novel QTLs. The broad sense heritability estimates of fiber quality traits were high for fiber length (0.93), fiber strength (0.92), fiber micronaire (0.85), and fiber uniformity (0.80), but low for fiber elongation (0.27). Meta-clusters on c4, c7, c14 and c25 were identified as stable QTL clusters and were considered more valuable in MAS for the improvement of fiber quality of upland cotton. Multiple environmental evaluations of an intraspecific RIL population were conducted to identify stable QTLs. Meta-QTL analyses identified a common chromosomal region that plays an important role in fiber development. Therefore, QTLs identified in the present study are an ideal candidate for MAS in cotton breeding programs to improve fiber quality.
关键词：
Cotton;Verticillium wilt (VW);Quantitative trait loci (QTL);Interspecific backcross population
摘要：
Verticillium wilt (VW) caused by Verticillium dahliae (Kleb) is one of the most destructive diseases of cotton. The identification of highly resistant QTLs or genes in the whole cotton genome is quite important for developing a VW-resistant variety and for further molecular design breeding. In the present study, BC1F1, BC1S1, and BC2F1 populations derived from an interspecific backcross between the highly resistant line Hai1 (Gossypium barbadense L.) and the susceptible variety CCRI36 (G. hirsutum L.) as the recurrent parent were constructed. Quantitative trait loci (QTL) related to VW resistance were detected in the whole cotton genome using a high-density simple sequence repeat (SSR) genetic linkage map from the BC1F1 population, with 2292 loci covering 5115.16 centiMorgan (cM) of the cotton (AD) genome, and the data concerning VW resistance that were obtained from four dates of BC2F1 in the artificial disease nursery and one date of BC1S1 and BC2F1 in the field. A total of 48 QTLs for VW resistance were identified, and 37 of these QTLs had positive additive effects, which indicated that the G. barbadense alleles increased resistance to VW and decreased the disease index (DI) by about 2.2–10.7. These QTLs were located on 19 chromosomes, in which 33 in the A subgenome and 15 QTLs in the D subgenome. The 6 QTLs were found to be stable. The 6 QTLs were consistent with those identified previously, and another 42 were new, unreported QTLs, of which 31 QTLs were from G. barbadense. By meta-analysis, 17 QTL hotspot regions were identified and 10 of them were new, unreported hotspot regions. 29 QTLs in this paper were in 12 hotspot regions and were all from G. barbadense. These stable or consensus QTL regions warrant further investigation to better understand the genetics and molecular mechanisms underlying VW resistance. This study provides useful information for further comparative analysis and marker-assisted selection in the breeding of disease-resistant cotton. It may also lay an important foundation for gene cloning and further molecular design breeding for the entire cotton genome.
摘要：
<jats:title>Abstract</jats:title><jats:sec><jats:label /><jats:p>To introgress the good fiber quality and yield from <jats:italic>Gossypium barbadense</jats:italic> into a commercial Upland cotton variety, a high‐density simple sequence repeat (SSR) genetic linkage map was developed from a BC<jats:sub>1</jats:sub>F<jats:sub>1</jats:sub> population of <jats:italic>Gossypium hirsutum</jats:italic> × <jats:italic>Gossypium barbadense</jats:italic>. The map comprised 2,292 loci and covered 5115.16 centiMorgan (cM) of the cotton AD genome, with an average marker interval of 2.23 cM. Of the marker order for 1,577 common loci on this new map, 90.36% agrees well with the marker order on the D genome sequence genetic map. Compared with five published high‐density SSR genetic maps, 53.14% of marker loci were newly discovered in this map. Twenty‐six quantitative trait loci (QTLs) for lint percentage (LP) were identified on nine chromosomes. Nine stable or common QTLs could be used for marker‐assisted selection. Fifty percent of the QTLs were from <jats:italic>G</jats:italic>. <jats:italic>barbadense</jats:italic> and increased LP by 1.07%–2.41%. These results indicated that the map could be used for screening chromosome substitution segments from <jats:italic>G</jats:italic>. <jats:italic>barbadense</jats:italic> in the Upland cotton background, identifying QTLs or genes from <jats:italic>G</jats:italic>. <jats:italic>barbadense</jats:italic>, and further developing the gene pyramiding effect for improving fiber yield and quality.</jats:p></jats:sec>
摘要：
Ustilaginoidea virens (Cooke) Takah is an ascomycetous fungus that causes rice false smut, a devastating emerging disease worldwide. Here we report a 39.4 Mb draft genome sequence of U. virens that encodes 8,426 predicted genes. The genome has ~25% repetitive sequences that have been affected by repeat-induced point mutations. Evolutionarily, U. virens is close to the entomopathogenic Metarhizium spp., suggesting potential host jumping across kingdoms. U. virens possesses reduced gene inventories for polysaccharide degradation, nutrient uptake and secondary metabolism, which may result from adaptations to the specific floret infection and biotrophic lifestyles. Consistent with their potential roles in pathogenicity, genes for secreted proteins and secondary metabolism and the pathogen–host interaction database genes are highly enriched in the transcriptome during early infection. We further show that 18 candidate effectors can suppress plant hypersensitive responses. Together, our analyses offer new insights into molecular mechanisms of evolution, biotrophy and pathogenesis of U. virens. Rice false smut, caused by the pathogenic ascomycete fungus Ustilaginoidea virens (Cooke) Takah, has a significant economic impact on crop production. Here, Zhang et al. report the draft genome sequence of U. virensand provide insight into the evolution of genes involved in pathogenicity and adaptation to a biotrophic and floret-infecting lifestyle.
摘要：
Termites are an extremely successful group of wood-degrading organisms and are therefore important both for their roles in carbon turnover in the environment and as potential sources of biochemical catalysts for efforts aimed at converting wood into biofuels. To contribute to the evolutional study of termite digestive symbiosis, a bacterial 16S rRNA gene clone library from the gut microbial community of the fungus-growing termite Macrotermes barneyi was constructed. After screening by restriction fragment length polymorphism (RFLP) analysis, 25 out of 105 clones with unique RFLP patters were sequenced and phylogenetically analyzed. Many of the clones (95%) were derived from three phyla within the domain bacteria: Bacteroidetes, Firmicutes and Proteobacteria. In addition, a few clones derived from Deferribacteres, Actinobacteria and Planctomycetes were also found. No one clone affiliated with the phylum Spirochaetes was identified, in contrast to the case of wood-feeding termites. The phylogenetic analysis revealed that nearly half of the representative clones (11 phylotypes) formed monophyletic clusters with clones obtained from other termite species, especially with the sequences retrieved from fungus-growing termites. These results indicate that the presence of termite-specific bacterial lineages implies a coevolutional relationship of gut microbes and host termites. The remaining 14 clones formed a cluster, and there was very low sequence similarity (30 to 40%) to known 16S rRNA sequences. The 16S rRNA gene sequence data showed that the majority of the intestinal microflora of M. barneyi consisted of new, uncultured species previously unknown to microbiologists.
摘要：
Plants must effectively defend against biotic and abiotic stresses to survive in nature. However, this defense is costly and is often accompanied by significant growth inhibition. How plants coordinate the fluctuating growth-defense dynamics is not well understood and remains a fundamental question. Jasmonate (JA) and gibberellic acid (GA) are important plant hormones that mediate defense and growth, respectively. Binding of bioactive JA or GA ligands to cognate receptors leads to proteasome-dependent degradation of specific transcriptional repressors (the JAZ or DELLA family of proteins), which, at the resting state, represses cognate transcription factors involved in defense (e.g., MYCs) or growth [e.g. phytochrome interacting factors (PIFs)]. In this study, we found that the coi1 JA receptor mutants of rice (a domesticated monocot crop) and Arabidopsis (a model dicot plant) both exhibit hallmark phenotypes of GA-hypersensitive mutants. JA delays GA-mediated DELLA protein degradation, and the della mutant is less sensitive to JA for growth inhibition. Overexpression of a selected group of JAZ repressors in Arabidopsis plants partially phenocopies GA-associated phenotypes of the coi1 mutant, and JAZ9 inhibits RGA (a DELLA protein) interaction with transcription factor PIF3. Importantly, the pif quadruple (pifq) mutant no longer responds to JA-induced growth inhibition, and overexpression of PIF3 could partially overcome JA-induced growth inhibition. Thus, a molecular cascade involving the COI1-JAZ-DELLA-PIF signaling module, by which angiosperm plants prioritize JA-mediated defense over growth, has been elucidated.
