Berry texture QTL and candidate gene analysis in grape (Vitis vinifera L.).

Berry texture is a noteworthy economic trait for grape; however, the genetic bases and the complex gene expression and regulatory mechanism for the diverse changes in berry texture are still poorly understood. In this study, the results suggest that it is difficult to obtain high-mesocarp firmness (MesF) and high-pericarp puncture hardness (PPH) grape cultivars with high pericarp brittleness (PerB). The high-density linkage map was constructed using whole-genome resequencing based on 151 F1 individuals originating from intraspecific hybridization between the firm-flesh cultivar 'Red Globe' and soft-flesh cultivar 'Muscat Hamburg'. The total length of the consensus map was 1613.17 cM, with a mean genetic distance between adjacent bin markers of 0.59 cM. Twenty-seven quantitative trait loci (QTLs) for berry MesF, PPH, and PerB were identified in linkage groups (LGs) 1, 3, 4, 6, 8, 9, 10, 11, 14, 16, and 17, including twelve QTLs that were firstly detected in LGs 6, 11, and 14. Fourteen promising candidate genes were identified from the stable QTL regions in LGs 10, 11, 14, and 17. In particular, VvWARK2 and VvWARK8 refer to chromosome 17 and are two promising candidate genes for MesF and PPH, as the VvWARK8 gene may increase pectin residue binding with WARK for high berry firmness maintenance and the allele for VvWARK2 carrying the 'CC' and 'GA' genotypes at Chr17:1836764 and Chr17:1836770 may be associated with non-hard texture grape cultivars. In addition, real-time quantitative polymerase chain reaction (RT-qPCR) verification revealed that the promising candidate transcription factor genes VvMYB4-like, VvERF113, VvWRKY31, VvWRKY1, and VvNAC83 may regulate cell wall metabolism candidate gene expression for grape berry texture changes.

Autotoxin affects the rhizosphere microbial community structure by influencing the secretory characteristics of grapevine roots.

Autotoxins secreted by roots into the soil can trigger rhizosphere microecological imbalances and affect root secretory properties resulting in conditions such as replanting disease. However, information on the effect of autotoxins on root secretion characteristics and regulation of the composition of rhizosphere microorganisms by altered root exudates is limited. In this study, autotoxin ρ-hydroxybenzoic acid (4-HBA) was added to the soil of potted grapevine seedlings, CO2 pulse-labeling, and DNA stable isotope probing were used to track the rhizosphere microbiome that assimilates root exudates. Bacterial and fungal microbiomes that assimilated plant-derived carbon were identified by high-throughput sequencing. Results showed that 4-HBA treatment altered bacterial and fungal communities in 13C-labeled organisms, with a lower abundance of beneficial bacteria (e.g., Gemmatimonas, Streptomyces, and Bacillus) and a higher abundance of potential pathogen fungi (e.g., Fusarium, Neocosmospora, Gibberella, and Fusicolla) by changing the composition of root exudates. The exogenous addition of upregulated compound mixtures of root exudates reduced the abundance of beneficial bacterial Bacillus and increased the abundance of potential pathogen fungi Gibberella. These results suggest that 4-HBA can alter root secretion properties and altered root exudates may enrich certain potential pathogens and reduce certain beneficial bacteria, thereby unbalancing the structure of the rhizosphere microbial community.

Responses of soil bacterial and fungal communities to the long-term monoculture of grapevine.

Soil microorganisms are essential for the long-term sustainability of agricultural ecosystems. However, continuous grapevine replanting can disrupt the stability of soil microbial communities. We investigated the bacterial and fungal abundance, diversity, and community composition in rhizosphere soils with continuous grapevine replanting for 5, 6, 7 (Y5, Y6, and Y7; short-term), and 20 (Y20; long-term) years with high-throughput sequencing. Results showed that diversities and abundances of bacterial and fungal communities in Y20 were significantly lower than in other samples. The bacterial and fungal community compositions were markedly affected by the replanting time and planting year. After short-term grapevine replanting, relative abundances of potential beneficial bacteria and harmful fungi in rhizosphere soils were higher compared to long-term planting. Bacterial and fungal communities were significantly correlated with available nitrogen (AN), available phosphorus, available potassium (AK), and pH. AK and AN were the primary soil factors related to the shift of bacterial and fungal communities. Bacterial and fungal co-occurrence patterns were remarkably affected by replanting time, showing that fallow land harbored co-occurrence networks more complex than those in other groups, with the Y20 group showing the lowest complexity. Then, we isolated the dominant fungi in grapevine rhizosphere soil after continuous replanting and verified the harmful effects of three candidate strains through pot experiments. The results showed that 12 days post-treating the soil with fungal spore suspensions significantly inhibited grapevine seedlings' growth, whereas Fusarium solani inhibited plant growth. Overall, we showed that F. solani might be a potentially harmful fungus related to grapevine replant diseases. KEY POINTS: • Continuous grapevine planting reduced soil microbe diversities/abundances. • Beneficial bacteria and harmful fungi increased after short-term replanting. • F. solani may be a harmful fungus related to grapevine replant diseases.

High-Density Genetic Linkage Map Construction and White Rot Resistance Quantitative Trait Loci Mapping for Genus Vitis Based on Restriction Site-Associated DNA Sequencing.

Grape white rot (Coniothyrium diplodiella) is a major fungal disease affecting grape yield and quality. Quantitative trait locus (QTL) analysis is an important method for studying important horticultural traits of grapevine. This study was conducted to construct a high-density map and conduct QTL mapping for grapevine white rot resistance. A mapping population with 177 genotypes was developed from interspecific hybridization of a white rot-resistant cultivar (Vitis vinifera × V. labrusca 'Zhuosexiang') and white rot-susceptible cultivar (V. vinifera 'Victoria'). Single-nucleotide polymorphism (SNP) markers were developed by restriction site-associated DNA sequencing. The female, male, and integrated maps contained 2,501, 4,110, and 6,249 SNP markers with average genetic distances of adjacent markers of 1.25, 0.77, and 0.50 cM, respectively. QTL mapping was conducted based on white rot resistance identification of 177 individuals in July and August of 2017 and 2018. Notably, one stable QTL related to white rot resistance was detected and located on linkage group LG14. The phenotypic variance ranged from 12.93 to 13.43%. An SNP marker (chr14_3929380), which cosegregated with white rot resistance, was discovered and shows potential for use in marker-assisted selection to generate new grapevine cultivars with resistance to white rot.

VaAPRT3 Gene is Associated With Sex Determination in Vitis amurensis.

In the past decade, progress has been made in sex determination mechanism in Vitis. However, genes responsible for sexual differentiation and its mechanism in V. amurensis remain unknown. Here, we identify a sex determination candidate gene coding adenine phosphoribosyl transferase 3 (VaAPRT3) in V. amurensis. Cloning and sequencing of the VaAPRT3 gene allowed us to develop a molecular marker able to discriminate female individuals from males or hermaphrodites based on a 22-bp InDel. Gene expression and endogenous cytokinin content analysis revealed that the VaAPRT3 gene is involved in sex determination or, to be precise, in female organ differentiation, through regulating cytokinin metabolism in V. amurensis. This study enlarged the understanding of sex determination mechanism in the genus Vitis, and the sex marker could be used as a helpful tool for sexual identification in breeding programs as well as in investigation and collection of V. amurensis germplasms.

Bioabsorbable high-purity magnesium interbody cage: degradation, interbody fusion, and biocompatibility from a goat cervical spine model.

BACKGROUND: Bioabsorbable Mg-based implants have been a focus of orthopedic researches due to their intrinsic advantages in orthopedics surgeries. This study aimed to investigate the performance of bioabsorbable high-purity magnesium (HP Mg, 99.98 wt.%) interbody cages in anterior cervical discectomy and fusion (ACDF) and to evaluate the degradation of HP Mg cages under an interbody microenvironment. METHODS: ACDF was performed at C2-3 and C4-5, and a HP Mg cage or autologous iliac bone was randomly implanted. At 3, 6, 12 and 24 weeks after surgery, the cervical specimens were harvested to evaluate the fusion status, degradation and biocompatibility by CT, micro-CT, histological examinations and blood tests. RESULTS: There was no significant difference in the CT fusion score between cage group and autogenous ilium group at 3 and 6 weeks. At 12 and 24 weeks, the mean CT fusion score in the cage group was markedly lower than in the autogenous ilium group. CT and histological examinations showed bony junctions formed through the middle hole of the cage between upper and lower vertebral bodies in the cage group, but the total fusion area was less than 30%. The degradation rate of cages was relatively rapid within the first 3 weeks and thereafter became stable and slow gradually. The HP Mg cage had good biosecurity and biomechanical characteristics. CONCLUSIONS: Implantation of Mg-based interbody cage achieves successful histological fusion, while the total fusion area needs to be improved. More studies are needed to improve the bone-cage interface.

Transcriptome analysis of table grapes (Vitis vinifera L.) identified a gene network module associated with berry firmness.

Berry firmness is one of the main selection criteria for table grape breeding. However, the underlying genetic determinants and mechanisms involved in gene expression during berry development are still poorly understood. In this study, eighteen libraries sampled from Vitis vinifera L. cv. 'Red Globe' and 'Muscat Hamburg' at three developmental stages (preveraison, veraison and maturation) were analyzed by RNA sequencing (RNA-Seq). The firmness of 'Red Globe' was significantly higher than that of 'Muscat Hamburg' at the three developmental stages. In total, a set of 4,559 differentially expressed genes (DEGs) was identified between 'Red Globe' and 'Muscat Hamburg' in the preveraison (2,259), veraison (2030) and maturation stages (2682), including 302 transcription factors (TFs). Weighted gene coexpression network analysis (WGCNA) showed that 23 TFs were predicted to be highly correlated with fruit firmness and propectin content. In addition, the differential expression of the PE, PL, PG, ß-GAL, GATL, WAK, XTH and EXP genes might be the reason for the differences in firmness between 'Red Globe' and 'Muscat Hamburg'. The results will provide new information for analysis of grape berry firmness and softening.

High-density genetic linkage map construction and cane cold hardiness QTL mapping for Vitis based on restriction site-associated DNA sequencing.

BACKGROUND: Cold hardiness is an important agronomic trait and can significantly affect grape production and quality. Until now, there are no reports focusing on cold hardiness quantitative trait loci (QTL) mapping. In this study, grapevine interspecific hybridisation was carried out with the maternal parent 'Cabernet sauvignon' and paternal parent 'Zuoyouhong'. A total of 181 hybrid offspring and their parents were used as samples for restriction-site associated DNA sequencing (RAD). Grapevine cane phloem and xylem cold hardiness of the experimental material was detected using the low-temperature exotherm method in 2016, 2017 and 2018. QTL mapping was then conducted based on the integrated map. RESULTS: We constructed a high-density genetic linkage map with 16,076, 11,643, and 25,917 single-nucleotide polymorphism (SNP) markers anchored in the maternal, paternal, and integrated maps, respectively. The average genetic distances of adjacent markers in the maps were 0.65 cM, 0.77 cM, and 0.41 cM, respectively. Colinearity analysis was conducted by comparison with the grape reference genome and showed good performance. Six QTLs were identified based on the phenotypic data of 3 years and they were mapped on linkage group (LG) 2, LG3, and LG15. Based on QTL results, candidate genes which may be involved in grapevine cold hardiness were selected. CONCLUSIONS: High-density linkage maps can facilitate grapevine fine QTL mapping, genome comparison, and sequence assembly. The cold hardiness QTL mapping and candidate gene discovery performed in this study provide an important reference for molecular-assisted selection in grapevine cold hardiness breeding.

Candidate genes for grape white rot resistance based on SMRT and Illumina sequencing.

BACKGROUND: White rot is one of the most dangerous fungal diseases and can considerably affect grape berry production and quality. However, few studies have focused on this disease, and thus, finding candidate white rot resistance genes is of great importance for breeding resistant grapevine cultivars. Based on field observations and indoor experiments, the cultivars "Victoria" and "Zhuosexiang" showed significant differences in white rot resistance. For understanding the molecular mechanisms behind it, different phenotypes of grapevine leaves were used for RNA sequencing via Illumina and single-molecule real-time (SMRT) sequencing technology. RESULTS: A transcript library containing 53,906 reads, including known and novel transcripts, was constructed following the full-length transcriptome sequencing of the two grapevine cultivars. Genes involved in salicylic acid (SA) and jasmonic acid (JA) synthesis pathways showed different expression levels. Furthermore, four key transcription factors (TFs), NPR1, TGA4, Pti6, and MYC2, all involved in the SA and JA signal pathways were identified, and the expression profile revealed the different regulation of the pathogenesis related protein1 (PR1) resistance gene, as mediated by the four TFs. CONCLUSIONS: Full-length transcript sequencing can substantially improve the accuracy and integrity of gene prediction and gene function research in grapevine. Our results contribute to identify candidate resistance genes and improve our understanding of the genes and regulatory mechanisms involved in grapevine resistance to white rot.

Genetic Diversity in FUB Genes of Fusarium oxysporum f. sp. cubense Suggests Horizontal Gene Transfer.

Fusaric acid (FA) is an important secondary metabolite of many Fusarium species and involved in the wilt symptoms caused in banana by Fusarium oxysporum f. sp. cubense (Foc). To investigate the evolution characteristics of the 12 Foc FA biosynthetic genes (FUB), coding sequences of the 12 FUB genes and three housekeeping genes, EF-1α/RPB1/RPB2 (translation elongation factor-1α/RNA polymerase II subunit I/RNA polymerase II subunit II), were subjected to genetic diversity analysis, phylogenetic analysis, recombination detection, and selective pressure analysis. The results of selective pressure analysis showed that the 15 genes were mainly subjected to negative selection. However, a significantly higher number of silent mutations, which could not be simply explained by selective pressure difference, were observed in the 12 FUB genes in Foc than in the three housekeeping genes. Infraspecies phylogeny and recombination detection analysis showed that significantly more horizontal gene transfer (HGT) events (normalized) had occurred in the FUB genes than in the three housekeeping genes. In addition, many of these events involved outgroup isolates and significantly increased the genetic diversity of FUB genes in Foc. The infraspecies phylogenetic analysis suggested that the polyphyletic phylogeny proposed for Foc requires further discussion, and the divergence of race 1, race 4, and the common ancestor of several F. oxysporum (Fo) isolates pathogenic to nonbanana plants should have diverged over a short period. Finally, our results suggest that the FUB genes in Fo should have benefited from HGT to gain a relatively high genetic diversity to respond to different host plants and environments despite mainly being subject to negative selection.

A Cerato-Platanin Family Protein FocCP1 Is Essential for the Penetration and Virulence of Fusarium oxysporum f. sp. cubense Tropical Race 4.

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is well-known as the causal agent of Fusarium wilt of banana and is one of the most destructive phytopathogens for banana plants. The molecular mechanisms underlying Foc TR4 virulence remain elusive. Here, we demonstrate that a cerato-platanin (CP) protein, FocCP1, functions as a virulence factor that is required by Foc TR4 for penetration and full virulence. The FocCP1 gene was expressed in every condition studied, showing a high transcript level in planta at the early stage of infection. Infiltration of the recombinant FocCP1 protein induced significant cell death and upregulated defence-related gene expression. FocCP1 knock-out strains showed a significant decrease in aerial growth rather than aqueous growth, which is reminiscent of hydrophobins. Furthermore, deletion of FocCP1 significantly reduced virulence and dramatically reduced infective growth in banana roots, likely resulting from a defective penetration ability. Taken together, the results of this study provide novel insight into the function of the recently identified FocCP1 as a virulence factor in Foc TR4.

Construction of a highly saturated Genetic Map for Vitis by Next-generation Restriction Site-associated DNA Sequencing.

BACKGROUND: High-saturate molecular linkage maps are an important tool in studies on plant molecular biology and assisted breeding. Development of a large set of single nucleotide polymorphisms (SNPs) via next-generation sequencing (NGS)-based methods, restriction-site associated DNA sequencing (RAD-seq), and the generation of a highly saturated genetic map help improve fine mapping of quantitative trait loci (QTL). RESULTS: We generated a highly saturated genetic map to identify significant traits in two elite grape cultivars and 176 F1 plants. In total, 1,426,967 high-quality restriction site-associated DNA tags were detected; 51,365, 23,683, and 70,061 markers were assessed in 19 linkage groups (LGs) for the maternal, paternal, and integrated maps, respectively. Our map was highly saturated in terms of marker density and average "Gap ≤ 5 cM" percentage. CONCLUSIONS: In this study, RAD-seq of 176 F1 plants and their parents yielded 8,481,484 SNPs and 1,646,131 InDel markers, of which 65,229 and 4832, respectively, were used to construct a highly saturated genetic map for grapevine. This map is expected to facilitate genetic studies on grapevine, including an evaluation of grapevine and deciphering the genetic basis of economically and agronomically important traits. Our findings provide basic essential genetic data the grapevine genetic research community, which will lead to improvements in grapevine breeding.

Construction of a high-density genetic map for grape using specific length amplified fragment (SLAF) sequencing.

Genetic maps are important tools in plant genomics and breeding. We report a large-scale discovery of single nucleotide polymorphisms (SNPs) using the specific length amplified fragment sequencing (SLAF-seq) technique for the construction of high-density genetic maps for two elite wine grape cultivars, 'Chardonnay' and 'Beibinghong', and their 130 F1 plants. A total of 372.53 M paired-end reads were obtained after preprocessing. The average sequencing depth was 33.81 for 'Chardonnay' (the female parent), 48.20 for 'Beibinghong' (the male parent), and 12.66 for the F1 offspring. We detected 202,349 high-quality SLAFs of which 144,972 were polymorphic; 10,042 SNPs were used to construct a genetic map that spanned 1,969.95 cM, with an average genetic distance of 0.23 cM between adjacent markers. This genetic map contains the largest molecular marker number of the grape maps so far reported. We thus demonstrate that SLAF-seq is a promising strategy for the construction of high-density genetic maps; the map that we report here is a good potential resource for QTL mapping of genes linked to major economic and agronomic traits, map-based cloning, and marker-assisted selection of grape.

[Treatment of coronal shear fracture of the distal end of the humerus by the olecranon osteotomy approach].

OBJECTIVE: To explore the effectiveness of olecranon osteotomy approach for the treatment of coronal shear fracture of the distal end of the humerus. METHODS: A retrospective analysis was made on the clinical data of 34 patients with the coronal shear fracture of the distal end of the humerus treated by the olecranon osteotomy approach from January 2005 to January 2013. Of 34 cases, there were 15 boys and 19 girls, aged from 17 years to 84 years (mean, 54.9±10.2 years); 18 patients had fractures on the left and 16 patients had fractures on the right. Fractures were classified according to the Bryan and Morrey classification united Mckee classification: type Iinjuries occurred in 10 cases, type IIinjuries in 5 cases, type III injuries in 10 cases and type IV injuries in 9 cases. The Mayo elbow functional scores were evaluated for analysis. RESULTS: All the patients were followed up, and the duration ranged from 15 to 96 months, with a mean of (35.1±7.2) months. Average arc of motion was (132.1±11.2)° in flexion and (4.6±1.9)° in extension. The average Mayo score was 85.9±6.3(73 to 94 scores). Thirteen patients got an excellent result, 15 good and 6 poor. The average Mayo score was 88.6±3.7 in type Iinjuries, 85.8±4.6 in type IIinjuries, 81.8±5.8 in type III injuries and 87.5±9.1 in type IV injuries. There were no significant differences in outcomes. CONCLUSIONS: The treatment for the coronal shear fracture of the distal end of the humerus by the olecranon osteotomy approach can achieve the satisfactory curative effect, maintain the reduction and improve the elbow function.

[Comparison of clinical effect on locking plate for proximal humeral fracture with or without application of inferomedial screws].

OBJECTIVE: To compare clinical outcomes of locking plate for proximal humeral fracture whether application of inferomedial screws. METHODS: From January 2012 to July 2013, 46 patients with proximal humeral fracture underwent locking plates were retrospectively analyzed. There were 25 males and 21 females aged from 29 to 80 years old with an average of 55.1 years old. Among them, 25 patients were treated with inferomedial screws (support group), including 13 males and 12 females aged from 38 to 80 years old with an average of (55.8 ± 11.8) years old; 8 cases were part two fracture,10 cases were part three fracture and 7 cases were part four fracture according to Neer classification. Twenty-one patients were treated without inferomedial screws (non-support group), including 12 males and 9 females aged from 29 to 79 years old with an average of (54.2 ± 14.8)years old; 6 cases were part two fracture, 9 cases were part three fracture and 6 cases were part four fracture according to Neer classification. Operative time, fracture healing time and complications were observed and compared, Neer scoring of shoulder joint were used to evaluate clinical effect. RESULTS: All patients were followed up from 12 to 41 months with an average of 15.6 months. Operative time and fracture healing time in support group was (1.6 ± 0.4) h and (3.0 ± 0.6) months, and (1.5 ± 0.4) h and (3.1 ± 0.6) months in non-support group, while there was no statistical difference in operative time and fracture healing time between two groups. There was significant differences in Neer score between support group (89.7± 4.9) and non-support group (83.1 ± 7.1). No complication occurred in support group,while 4 cases occurred complications in non-support group. CONCLUSION: Locking plate with inferomedial screws for proximal humeral fracture has advantages of stable fixation, less complications, quick recovery of function and satisfied clinical effect.

Using specific length amplified fragment sequencing to construct the high-density genetic map for Vitis (Vitis vinifera L. × Vitis amurensis Rupr.).

In this study, 149 F1 plants from the interspecific cross between 'Red Globe' (Vitis vinifera L.) and 'Shuangyou' (Vitis amurensis Rupr.) and the parent were used to construct a molecular genetic linkage map by using the specific length amplified fragment sequencing technique. DNA sequencing generated 41.282 Gb data consisting of 206,411,693 paired-end reads. The average sequencing depths were 68.35 for 'Red Globe,' 63.65 for 'Shuangyou,' and 8.01 for each progeny. In all, 115,629 high-quality specific length amplified fragments were detected, of which 42,279 were polymorphic. The genetic map was constructed using 7,199 of these polymorphic markers. These polymorphic markers were assigned to 19 linkage groups; the total length of the map was 1929.13 cm, with an average distance of 0.28 cm between each maker. To our knowledge, the genetic maps constructed in this study contain the largest number of molecular markers. These high-density genetic maps might form the basis for the fine quantitative trait loci mapping and molecular-assisted breeding of grape.

SSR and SRAP marker-based linkage map of Vitis vinifera L.

An F1 population was created by the cross '87-1' × '9-22'. The female parent '87-1' was an extremely early maturing cultivar with strong flavour. The male parent was an excellent breeding line producing large berries maturing late. The mapping population included 149 randomly chosen individuals. Molecular genetic map for each parent and the consensus map were constructed using simple sequence repeat and sequence-related amplified polymorphism markers by software JoinMap 3.0. The '87-1' map covers a total length of 1272.9 cM distributed in 21 linkage groups and consists of 163 molecular markers with an average distance between adjacent markers of 8.9 cM. The '9-22' map covers a total length of 1267.4 cM distributed in 20 linkage groups and consists of 158 molecular markers with an average distance between adjacent markers of 9.1 cM. The consensus map covers a total length of 1537.1 cM distributed in 21 linkage groups and one doublet and consists of 217 molecular markers with an average distance of 7.8 cM between adjacent markers. The length of the linkage groups is 69.8 cM on average. The map covers the 19 chromosomes of the Vitis genome and can lay a solid foundation for further studies such as quantative trait loci (QTL) mapping of correlated traits and marker-assisted selection.

An improve method for somatic embryogenesis of Schisandra chinensis (Turcz.) Baillon.

A somatic embryogenesis protocol for plant regeneration of Schisandra chinensis (Turcz.) Baillon was established. Increased callus induction was obtained from mature zygotic embryos on Murashige and Skoog (MS) medium supplemented with 1.0 mg L(-1) N-phenyl-1,2,3-thidiazol-5-yl-urea (TDZ) or 2.0 mg L(-1) 2,4-dichlorophenoxyacetic acid (2,4-D). Addition of Zeatin (Zt) promoted the formation of embryogenic calli. To induce somatic embryogenesis, 2,4-D, TDZ and Zt were incorporated in the medium alone or in combination. Development of the maximum number of somatic embryos (81 globular, 37 heart, 52 torpedo and 37 cotyledon-stage) and germination of the highest number of embryos (50%) was observed on 1/2 MS medium supplemented with 1.0 mg L(-1) TDZ and 0.2 mg L(-1) Zt. Further development of somatic embryos into plantlets was completed in 1/2 MS medium free of plant growth regulators.

[Allelopathy of grape root aqueous extracts].

Taking the tissue-cultured seedlings of grape cultivar Red Globe as test objects, this paper examined the effects of their root aqueous extracts on seedling's growth, with the allelochemicals identified by LC-MS. The results showed that 0.02 g x ml(-1) (air-dried root mass in aqueous extracts volume; the same below), 0.1 g x ml(-1), and 0.2 g x ml(-1) of the aqueous extracts inhibited the growth of the seedlings significantly, and the inhibition effect increased with increasing concentration of the extracts. The identified allelochemicals of the extracts included p-hydroxybenzoic acid, salicylic acid, phenylpropionic acid, and coumaric acid. Pot experiment showed that different concentration (0.1, 1, and 10 mmol x L(-1)) salicylic acid and phenylpropionic acid inhibited the seedling' s growth remarkably. With the increasing concentration of the two acids, the plant height, stem diameter, shoot- and root fresh mass, leaf net photosynthetic rate and starch content, and root activity of the seedlings decreased, while the leaf soluble sugar and MDA contents increased. No obvious change pattern was observed in leaf protein content.

[Effects of grape-replanting on soil bacterial and fungal populations].

Rhizosphere and non-rhizosphere soil samples were collected from the vineyards having been planted for 3 and 30 years, and PCR-DGGE technique was adopted to study the effects of grape-replanting on the population structure and diversity of soil bacteria and fungi. The bacterial and fungal diversities were higher in 30-year-planted vineyard than in 3-year-planted vineyard, and higher in rhizosphere soil than in non-rhizosphere soil. After 30 years replanting, the population structure of bacteria and fungi approached the same in rhizosphere soil and non-rhizosphere soil but differed from that in fallow soil; while in the 3-year-planted vineyard, the population structure in rhizosphere soil was different from that in non-rhizosphere soil and fallow soil. Comparing with that in 3-year-planted vineyard, the rhizosphere soil microbial population in 30-year-planted vineyard had a greater change. In bacterial population, Flavobacterium sp. (DQ339585) and Bacillus sp. (AY039821) decreased while Pedobacter sp. (AJ871084) increased; in fungal population, Omphalina farinolens (EF413029) appeared, Pestalotiopsis sp. (DQ657877, DQ657875, DQ657871), Phacidium lacerum (DQ470976), and Lecythophora decumbens (AF353597) decreased, while Pilidium acerinum voucher (AY48709) increased. Bacillus sp., Flavobacterium sp. , and Pestalotiopsis sp. had antagonism to pathogen, and their decrease reduced the resistance of grape against pathogen. The increase of Pilidium acerinum voucher might relate to the severe disease after grape-replanting.