低温处理对牡丹春节催花及营养类物质变化的影响

连续观察、测定了牡丹春节催花进程中不同低温天数处理对温室外自然低温解除休眠及温室内培养过程中形态及某些生理生化变化的影响,结果显示：低温处理34d后的11月28日温室外牡丹花芽形态及可溶性糖、淀粉、可溶性蛋白、游离氨基酸含量变化显著,11月28日左右是低温处理期间牡丹花芽代谢变化剧烈的时期;处理41d后的12月5口及以后移入温室的植株能够正常开花。以上结果从形态与营养物质变化的角度说明了11月28日左右牡丹花芽开始逐步解除休眠,12月5日花芽已彻底解除休眠,不同低温对牡丹春节催花过程中花芽的发育有着质的作用。     

Transcript Profiling of Paoenia ostii during Artificial Chilling Induced Dormancy Release Identifies Activation of GA Pathway and Carbohydrate Metabolism

Endo-dormant flower buds must pass through a period of chilling to reinitiate growth and subsequent flowering, which is a major obstacle to the forcing culture of tree peony in winter. Customized cDNA microarray (8×15 K element) was used to investigate gene expression profiling in tree peony ‘Feng Dan Bai’ buds during 24 d chilling treatment at 0–4°C. According to the morphological changes after the whole plants were transferred to green house, endo-dormancy was released after 18 d chilling treatment, and prolonged chilling treatment increased bud break rate. Pearson correlation hierarchical clustering of sample groups was highly consistent with the dormancy transitions revealed by morphological changes. Totally 3,174 significantly differentially-expressed genes (P<0.05) were observed through endo-dormancy release process, of which the number of up-regulated (1,611) and that of down-regulated (1,563) was almost the same. Functional annotation of differentially-expressed genes revealed that cellular process, metabolic process, response to stimulus, regulation of biological process and development process were well-represented. Hierarchical clustering indicated that activation of genes involved in carbohydrate metabolism (Glycolysis, Citrate cycle and Pentose phosphate pathway), energy metabolism and cell growth. Based on the results of GO analysis, totally 51 probes presented in the microarray were associated with GA response and GA signaling pathway, and 22 of them were differently expressed. The expression profiles also revealed that the genes of GA biosynthesis, signaling and response involved in endo-dormancy release. We hypothesized that activation of GA pathway played a central role in the regulation of dormancy release in tree peony.     

Cloning and functional annotation of rare mRNA species from drought-stressed hot pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis>)

To better understand gene expression at very low levels, we have designed a method to eliminate cDNA clones representing abundant mRNAs. A cDNA library for drought-stressed hot pepper (Capsicum annuum) (Choi et al., 2002) underwent double-negative screening, once with probes made from a drought-stressed plant, the second time, with probes from a non-stressed plant. The cDNA clones that showed very weak or negative signals were isolated for further analysis, which resulted in 1399 cDNA clones from about 20,000 screened clones. When nucleotide sequences were determined, we obtained 1142 tentative unique genes, with a redundancy rate of 20.41%. An homology database search for the deduced amino acid sequences revealed that about 79% of the cDNA clones could not be matched for functioning with previously characterized sequences. However, when these uncategorized clones were subjected to classification based on functional domains, most could be cited. Notably, clones with possible functions in RNA transport, protein synthesis, and regulation of protein activity showed a dramatic increase in appearance while those coding for transposable elements, viral proteins, and plasmid proteins occupied a much smaller portion compared with those in theArabidopsis thaliana genome. In addition, those coding for proteins targeted to the endoplasmic reticulum were dramatically more abundant in our clones compared with theArabidopsis database.     

Expressed Sequence Tag Analysis of Kidney and Gill Tissues from Rainbow Trout (Oncorhynchus mykiss) Infected with Infectious Hematopoietic Necrosis Virus

Expressed sequence tags (ESTs) were obtained from the kidney and gill tissues of rainbow trout, Oncorhynchus mykiss, infected with infectious hematopoietic necrosis virus (IHNV). The results of single-pass sequencing of ESTs from 198 clones (AU081027–AU081192) from kidney complementary DNA and 45 clones (AU081193–AU081236) from gill cDNA are reported herein. Sequences of the cDNA clones were compared with sequences in the GenBank database. Fourteen clones (20%) appeared to be completely unknown and may represent newly described genes, whereas 158 clones (80%) were identified on the basis of matches to sequences in the database. Three of the unidentified sequences were isolated from both the kidney and the gill cDNA libraries. However, no sequences were identical between kidney and gill clones. Received December 7, 1999; accepted April 28, 2000.     

Phylogenetic Diversity of Bacteria Associated with the Marine Sponge <Emphasis Type="Italic">Gelliodes carnosa</Emphasis> Collected from the Hainan Island Coastal Waters of the South China Sea

Several molecular techniques were employed to document the bacterial diversity associated with the marine sponge Gelliodes carnosa. Cultivation-dependent and cultivation-independent methods were used to obtain the 16S rRNA gene sequences of the bacteria. Phylogenetic analysis based on the 16S rRNA gene sequences showed that the bacterial community structure was highly diverse with representatives of the high G + C Gram-positive bacteria, cyanobacteria, low G + C Gram-positive bacteria, and proteobacteria (α-, β-, and γ-), most of which were also found in other marine environments, including in association with other sponges. Overall, 300 bacterial isolates were cultivated, and a total of 62 operational taxonomic units (OTUs) were identified from these isolates by restriction fragment length polymorphism (RFLP) analysis and DNA sequencing of the 16S rRNA genes. Approximately 1,000 16S rRNA gene clones were obtained by the cultivation-independent method. A total of 310 clones were randomly selected for RFLP analysis, from which 33 OTUs were acquired by further DNA sequencing and chimera checking. A total of 12 cultured OTUs (19.4% of the total cultured OTUs) and 13 uncultured OTUs (39.4% of the total uncultured OTUs) had low sequence identity (≤97%) with their closest matches in GenBank and were probably new species. Our data provide strong evidence for the presence of a diverse variety of unidentified bacteria in the marine sponge G. carnosa. A relatively high proportion of the isolates exhibited antimicrobial activity, and the deferred antagonism assay showed that over half of the active isolates exhibited a much stronger bioactivity when grown on medium containing seawater. In addition to demonstrating that the sponge-associated bacteria could be a rich source of new biologically active natural products, the results may have ecological implications. This study expands our knowledge of the diversity of sponge-associated bacteria and contributes to the growing database of the bacterial communities within sponges.     

The Cold Awakening of <Emphasis Type="Italic">Doritaenopsis</Emphasis> ‘Tinny Tender’ Orchid Flowers: The Role of Leaves in Cold-induced Bud Dormancy Release

Massive flowering of tropical Phalaenopsis orchids is coordinated by the cold-induced release of reproductive bud dormancy. Light and temperature are the two key factors integrated by the dormancy mechanism to both stop and reactivate the meristem development of many other angiosperm species, including fruit trees and ornamental plants. It is well established that leaves and roots play a major role in inducing flower development; however, currently, knowledge of molecular events associated with reproductive bud dormancy release in organs other than the bud is limited. Using differential gene expression, we have shown that the leaves of a hybrid of Phalaenopsis species, Doritaenopsis ‘Tinny Tender’, undergo major metabolic modifications. These changes result in the production of sucrose and amino acids, both of which can sustain bud outgrowth, and auxin and ethylene, which may play important roles in awaking the dormant buds. Intake of abscisic acid and synthesis of the hormone jasmonate may also explain the inhibition of vegetative growth that coincides with bud growth. Interestingly, many genes that were upregulated by cold treatment are homologous for genes involved in flower induction and vernalization in Arabidopsis, indicating that processes regulating flowering induction and those regulating reproductive bud dormancy release may use similar pathways and effector molecules.     

赤霉素解除木本植物季节性休眠机制的研究进展

赤霉素是一种高效能的广谱植物生长调节剂,能够促进植物的生长发育,具有重要的生物学功能。该文主要对国内外近年来有关赤霉素在木本植物季节性休眠解除中的应用、赤霉素解除木本植物季节性休眠的生理机制、赤霉素代谢相关基因在木本植物季节性休眠中的作用以及赤霉素解除木本植物季节性休眠的分子机制等方面的研究进展进行综述,同时对下一步的研究方向进行了展望,以期能够更好地阐述赤霉素解除木本植物季节性休眠的分子机制,为赤霉素在木本植物季节性休眠解除中的应用提供理论依据。     

Relative developmental, environmental, and tree-to-tree variability in buds from field-grown apple trees

High-throughput genomic technologies are becoming more accessible to nonmodel plant species, and therefore, tissue collected outside controlled environments is being increasingly used for microarray analyses. In this study, we present a 15,720-feature apple microarray analysis of the variability of gene expression in buds from field-grown apple trees. Tree-to-tree and day-to-day variances were assessed during two different seasons: summer, when the meristems in the buds were undergoing the first stages of floral development, and autumn, when the buds were undergoing transition to winter dormancy. We found that apple trees with the same scion and rootstock cultivars, grown in a standard orchard environment, had small tree-to-tree variation. Gene expression differences caused by season was the dominant cause of variance while using false discovery rate control with a threshold of α* = 0.01 to select significantly different expression between genes. At this threshold, the environmental and location effects accounted for less than 10% of the genes selected. Consequently, we have shown that field microarray experiments are a viable approach for measuring seasonal changes in gene expression during apple bud development. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Factors regulating the expression of cell cycle genes in individual buds ofPopulus

The early and differential responses of the individual buds along a shoot have remained largely unknown due to the difficulties of analyzing early indicators that allow the monitoring of the effects of subtle changes in the environment on the growth activity of the individual bud. To overcome this problem, we transformed poplar [Populus tremula (L.) xP. alba (L.)] with two chimeric genes,Pcdc2a-gus andPcycl At-gus, the expression of which is closely linked to cell division inArabidopsis thaliana (L.) Heynh. We analyzed the expression levels of both chimeric genes in individual buds of the same tree, and under different conditions known to promote or retard growth in the buds. The expression levels of both chimeric genes were found to reflect closely the growth activity of the buds. After decapitation of the shoot, the expression ofPcdc2a-gus andPcycl At-gus revealed rapid and selective changes in the cell cycle, even when no morphological changes were observed. Furthermore, on the basis of the expression of the chimeric cell cycle genes, different degrees of growth activity and dormancy could be discriminated in the axillary buds. In addition, the expression ofPcycl At-gus was found to be closely associated with the day length, which is critical for dormancy induction in poplar.Abbreviations GUS -glucuronidase - MU methylumbelliferone     

Generation of 919 expressed sequence tags from immature flower buds and gene expression analysis using expressed sequence tags in the model plant Lotus japonicus

Lotus japonicus has received increased attention as a potential model legume plant. In order to study gene expression in reproductive organs and to identify genes that play a crucial function in sexual reproduction, we constructed a cDNA library from immature flower buds containing anthers at the stage of developing tapetum cells in L. japonicus, and characterized 919 expressed sequence tags (ESTs) randomly selected from a cDNA library of the immature flower buds. The 919 ESTs analyzed were clustered into 821 non-redundant EST groups. As a result of a database search, 436 groups (53%) out of the 821 groups showed sequence similarity to genes registered in the public database. Out of these 436 groups, 109 groups showed similarity to genes encoding hypothetical proteins whose function had not yet been estimated. Three hundred eighty five groups (47%) showed no significant homology to known sequences and were classified as novel sequences. A comparison of 821 non-redundant EST sequences and EST sequences derived from the whole plant L. japonicus revealed that 474 EST sequences derived from immature flower buds were not found in the EST sequences of the whole plant. In order to confirm the expression pattern of potential reproductive-organ specific EST clones, nine clones, which were not matched to ESTs derived from the whole plant, were selected, and RT-PCR analysis was performed on these clones. As a result of RT-PCR, we found two novel anther specific clones. One clone was homologous to a gene encoding human cleft lip and palate associated transmembrane protein (CLPTM1) like protein, and the other clone did not show a significant similarity to any genes deposited in the public database. These results indicate that ESTs analyzed here represent a valuable resource for finding reproductive-organ specific genes in Lotus japonicus.     

Development of thirty new polymorphic microsatellite primers for <Emphasis Type="Italic">Paeonia suffruticosa</Emphasis>

Four new microsatellite primer pairs were developed in tree peony (Paeonia suffruticosa) based on the database mining and other twenty-six primer pairs by fast isolation by AFLP of sequences containing repeats (FIASCO) method. The polymorphism of each locus was further evaluated in 40 individuals of one population plus 5 tree peony related species. The number of alleles per locus ranged from 3 to 7 and the expected (H_e) and observed (H_o) heterozygosity at each locus ranged from 0.42 to 0.78 and 0.28 to 0.59, respectively. These microsatellite markers will be useful for investigating genetic diversity and studies of population genetic structure of tree peony.