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The prior knowledge plays an important role in increasing the performance of the support vector machines (SVMs). Traditional SVMs do not consider any prior knowledge of the training set. In this paper, the neighbors' distribution knowledge is incorporated into SVMs. The neighbors' distribution can be measured by the sum of the cosine value of the angle, which is between the difference between the sample and its corresponding neighbor, and the difference between the sample and the mean of corresponding neighbors. The neighbors' distribution knowledge reflects the sample's importance in the training processing. It can be explained as the relative margin or instance weight. In this paper, the neighbors' distribution knowledge is regarded as the relative margin and incorporated into the framework of density-induced margin support vector machines whose relative margin is measured by relative density degree. The results of the experiments, performed on both artificial synthetic datasets and real-world benchmark datasets, demonstrate that SVMs performs better after incorporating neighbors' distribution. Furthermore, experimental results also show that neighbors' distribution are more suitable than relative density degree to represent the relative margin. [ABSTRACT FROM AUTHOR]

The complete nucleotide sequences of the mitochondrial (mt) genome of an extremophile species Thellungiella parvula (T. parvula) have been determined with the lengths of 255,773 bp. T. parvula mt genome is a circular sequence and contains 32 protein-coding genes, 19 tRNA genes, and three ribosomal RNA genes with a 11.5% coding sequence. The base composition of 27.5% A, 27.5% T, 22.7% C, and 22.3% G in descending order shows a slight bias of 55% AT. Fifty-three repeats were identified in the mitochondrial genome of T. parvula, including 24 direct repeats, 28 tandem repeats (TRs), and one palindromic repeat. Furthermore, a total of 199 perfect microsatellites have been mined with a high A/T content (83.1%) through simple sequence repeat (SSR) analysis and they were distributed unevenly within this mitochondrial genome. We also analyzed other plant mitochondrial genomes’ evolution in general, providing clues for the understanding of the evolution of organelles genomes in plants. Comparing with other Brassicaceae species, T. parvula is related to Arabidopsis thaliana whose characters of low temperature resistance have been well documented. This study will provide important genetic tools for other Brassicaceae species research and improve yields of economically important plants. [ABSTRACT FROM AUTHOR]

In plants, many small interfering RNAs (siRNAs) direct de novo methylation by DNA methyltransferase. DNA methylation typically occurs by RNA-directed DNA methylation (RdDM), which directs transcriptional gene silencing of transposons and endogenous transgenes. RdDM is driven by non-coding RNAs (ncRNAs) produced by DNA-dependent RNA polymerases IV and V (PolIV and PolV). The production of siRNAs is initiated by PolIV and ncRNAs produced by PolIV are precursors of 24-nucleotide siRNAs. In contrast, ncRNAs produced by PolV are involved in scaffolding RNAs. In this review, we summarize recent studies of RdDM. In particular, we focus on the mechanisms involved in chromatin remodeling by PolIV and PolV. [ABSTRACT FROM AUTHOR]

Abiotic stresses such as drought and high salinity inhibit plant growth and productivity. NAC transcription factors play a variety of important roles in plant development and abiotic stress responses. To date, the transformation of NAC genes into poplar plants has not been reported. In this study, we introduced the CarNAC3 and CarNAC6 salinity and drought tolerant genes from Cicer arietinum (chickpea) into Populus deltoides × Populus euramericana 'Nanlin895' (poplar) plants using Agrobacterium tumefaciens-mediated transformation . We verified the integration of the two genes into the poplar genome using polymerase chain reaction (PCR) and their stable expression was confirmed at the transcript level using real-time (RT)-PCR. The growth rates of roots and shoots and the clawed root rate increased in transformed plants grown in agar medium or in soil and increased in response to drought and salt stress conditions. Proline and photoprotectant pigment accumulation and antioxidant enzyme activities increased in response to abiotic stress, but the accumulation of photosynthetic pigments and malondialdehyde (MDA) decreased in transgenic lines relative to wild-type control plants. The CarNAC3 transgene was expressed at higher levels than the CarNAC6 transgene. Our results showed that the CarNAC3 and CarNAC6 genes enhanced the capacity for osmotic adjustment and increased antioxidant enzyme activity and suggest that these genes could play a significant role in improving drought and salt tolerance when expressed in poplar plants. [ABSTRACT FROM AUTHOR]

The paper optimizes the design for the needle head by mechanical analysis, the experiments of the needle head, structural improvements. The purpose is to design the best structure of the needle head, reduce the trunk fibre squeezed by the outer surface of the needle head. Extrusion capacity just is the thickness of the needle head's wall, which decreases splitting of wood fibres, thus ensuring the sealing effect and improving the injection efficiency of the trunk injector. According to the theory and experiments, it is obtained the range of the needle head's best size: the outer diameter is 6-8 mm, the thickness of the wall is 0.5-1mm. There are some relationships between the resistance and sizes of the needle heads. If the head needle's outer diameter is same, the larger the needle head's aperture is, the smaller the resistance of the needle head entering the trunk is. If the thickness of the wall is the same, the larger the needle head's outer diameter is, the larger the needle head's aperture is, the larger the resistance of the needle head entering the trunk is. Comparing the new needle head with the old needle head, the resistance of the needle head has been reduced. It can enhance strength and avoid fracture. It makes the wood core exist in the grooves of both sides without squeezing trunks and has good sealing effect. [ABSTRACT FROM AUTHOR]

The uredinial stage in the life cycle of Melampsora larici- populina on poplar leaves is the most important pathogenic phase. We captured partial phases of uredinial infection in the wild, aiming to reconstruct the process of uredinial ontogeny by using scanning and transmission electron microscope. At the initial infection stage, germ tubes germinated from the echinulate urediniospores. Germ tubes were frequently seen to merge with the leaf surface and cuticle breakage was observed, indicating direct hyphal penetration. Stomata penetration occurred commonly, sometimes with more than one germ tube penetrating the same stoma. Melampsora larici- populina did not form appressoria in the infection process, implying that infectious behavior of this pathogen may differ from the other rust pathogens. In general, germ tubes branched randomly, and no distinct evidence indicated that stoma could induce or orient germ tube branches. However, oriented germ tube growth has been occasionally observed in other studies. The urediniospores collapsed and finally wizened when they became nutrient stressed. At the last stage of infection, the uredinia erupted from the leaf epidermis and appeared as orange pustules on the leaf surface. [ABSTRACT FROM AUTHOR]

CarNAC3 contains 285 amino acids and a conserved NAC domain. NAC genes, including NAM, ATAF1, ATAF2, and CUC2, are members of one of the largest transcription factor families in plants. CarNAC3, a member of the NAP group, plays an important role in plant development and responses to abiotic stresses. In this study, CarNAC3 was transformed into hybrid poplar plants ( Populus deltoides × P. euramericana 'Nanlin895') using Agrobacterium tumefaciens. PCR analysis confirmed integration of the introduced T-DNA into the target genome. Reverse transcription PCR confirmed the transformation, and Southern and northern blotting verified the transgene copy number and gene expression, respectively. Fourteen lines of positive transformants were transplanted into a greenhouse to verify their drought and salt tolerances. Under normal conditions, transgenic poplar plants were shorter than the wild-type, but under drought and salt stresses, they maintained their normal rooting and stem growth rates, while those of the wild-type plants were suppressed. Under stress conditions, CarNAC3 expression caused increases in proline and photosynthetic pigment levels and in antioxidant enzyme activities. Furthermore, the expression of CarNAC3 lowered malondialdehyde concentrations compared with the wild-type control. Overall, our results indicated that the CarNAC3 transgene enhanced drought and salt tolerance in transgenic poplar plants. [ABSTRACT FROM AUTHOR]