根结线虫病是农业生产上的毁灭性病害，每年造成巨大的经济损失。南方根结线虫是一种寄生范围广、危害严重、防治困难的根结线虫，其防治主要依赖化学农药，不仅污染环境、危害人类健康，而且大大增加线虫的抗药性。解析根结线虫的致害分子机制，对于制定环保、经济、高效的防治策略具有重要研究价值。研究发现，根结线虫在寄生过程由食道腺表达、通过口针分泌出许多效应子，在线虫侵染和寄生阶段发挥重要作用。不同种类效应子与寄主植物之间产生错综复杂的相互作用，功能机制有待深入解析。在本研究中，我们鉴定了一种新的南方根结线虫效应子Minc03329，对氨基酸序列分析发现，其包含用于分泌的信号肽序列和一个C型凝集素结构域。酵母信号序列捕获实验表明Minc03329的信号肽是有功能的，具有分泌功能；原位杂交实验结果表明Minc03329在南方根结线虫亚腹食道腺中特异表达；实时荧光定量PCR结果证实 Minc03329 在线虫寄生初期表达量显著升高；病毒介导的基因沉默干扰线虫 Minc03329 表达，显著降低了南方根结线虫的致病性；相反，Minc03329转基因拟南芥接种南方根结线虫后根结数和卵块数显著增加，表明效应子Minc03329在植物细胞中表达，可以显著增加植物对南方根结线虫的敏感性；Minc03329 在本氏烟草叶片细胞中瞬时表达能抑制由小鼠促凋亡蛋白BAX引发的细胞程序性死亡；通过对Minc03329转基因拟南芥和野生型拟南芥进行转录组数据比较分析，发现Minc03329转基因拟南芥中许多防御相关基因表达显着下调；此外，一些差异表达基因可能参与了南方根结线虫摄食位点的形成，但是其分子机制有待深入解析。本研究是在揭示凝集素效应子MiCTL1功能机制后，解析的第二个南方根结线虫凝集素类效应子的功能。验证了凝集素类效应子在线虫与植物互作过程通过抑制植物免疫反应，帮助线虫寄生的分子机制。研究结果为揭示根结线虫致病分子机理，以及根结线虫防治分子靶标利用提供了重要理论依据。

The expression of mitogen-activated protein kinase (mapk) double-stranded RNA in cucumber is effective in controlling infestations of the root-knot nematode Meloidogyne incognita.  However, little is known about the ecological effects of transgenic plants.  Here, we analyzed the diversity of 16S rDNA genes derived from the rhizosphere archaea of transgenic cucumber plants as an indicator of ecological change.  A total of 17 and 18 operational taxonomic units were detected in the rhizospheres of non-transgenic cucumber and mapk dsRNA-expressing plants, respectively.  No significant difference was observed between the two groups according to Shannon and Simpson indices.  In soil samples of the two rhizospheres, the dominant group was Crenarchaeota at the phylum level, with Staphylothermus, Methanococcus, Pyrodictium and Sulfolobus the abundant taxa at the genus level.  These results suggest that expressing mapk double-stranded (ds) RNA in cucumber has no apparent effect on the diversity of rhizosphere archaea, and provide powerful evidence for the ecological safety of transgenic cucumber expressing mapk dsRNA.   

   Virus-tolerant plant, which allows the accumulation of virus and then generates virus-derived small RNAs (vsRNAs), is a valuable material to reveal the antiviral efficiency of vsRNAs. Here, a comparison of vsRNAs in Tomato yellow leaf curl virus tolerant and in susceptible tomato varieties showed the consistent trend of vsRNAs’ distribution on virus genome, which is presented as an obvious characteristic. However, the expression level of vsRNA in tolerant variety is less than that in susceptible variety. Slicing targets of vsRNA-mediated viral transcripts were investigated using parallel analysis of RNA ends, and geminivirus DNA methylation was determined by bisulfite sequencing, which uncovered that not all vsRNAs participated in viral mRNA degradation and DNA methylation. Additionally, by comparing with the expression pattern of vsRNAs, viral DNA and mRNA, we proposed the quantity of vsRNAs is corresponding to the expression level of viral mRNA, while the virus-suppression of vsRNAs is not high-efficient.

Fusarium oxysporum f. sp. conglutinans (Foc) is the causal agent of Fusarium wilt disease of Brassica oleracea. A rapid, accurate, and reliable method to detect and identify plant pathogens is vitally important to integrated disease management. In this study, using a comparative genome analysis among Fusarium oxysporum (Fo), we developed a Foc-specific primer set (Focs-1/Focs-2) and established a multiplex-PCR assay. In the assay, the Focs-1/Focs-2 and universal primers for Fusarium species (W106R/F106S) could be used to detect Foc isolates in a single PCR reaction. With the optimized PCR parameters, the multiplex-PCR assay showed a high specificity for detecting Foc and was very sensitive to detect as little as 100 pg of pure Foc genomic DNA or 1 000 spores in 1 g of twice-autoclaved soil. We also demonstrated that Foc isolates were easily detected from infected plant tissues, as well as from natural field soils, using the multiplex-PCR assay. To our knowledge, this is a first report on detection Fo by comparative genomic method.

Telomeres form the ends of eukaryotic chromosomes and serve as protective caps that keep chromosomes structure independency and completeness. The first plant telomere DNA was isolated from Arabidopsis thaliana and was shown to have tandemly repeated sequence 5´-TTTAGGG-3´. The Arabidopsis-type telomere has been found in many plants, but several reports indicate that this sequence is absent in some plants. Up to now, no research has been conducted on the telomere of cotton. In this paper, the Arabidopsis-type telomere sequence was amplified and cloned using the primers designed based on the fragment containing telomere sequence in an Arabidopsis bacterial artificial chromosome (BAC). Fluorescence in situ hybridization (FISH) with cotton metaphase chromosomes using the Arabidopsis-type telomere sequence as probes indicated that the signals were located at all chromosome ends of seven diploid and two tetraploid cotton species with different signal intensities among chromosome complements of different cotton species, even between long and short arms of the same chromosome. To identify the signals of FISH, the genome DNA of Xinhai 7, a cultivar of Gossypium barbadense, digested by BAL-31 nuclease was introduced in this study. The result of BAL-31 digestion indicated that the hybridization signals of FISH represent the outermost DNA sequence of each cotton chromosomes. So we first proved that the telomeric repeats of cotton cross-hybridize with that of Arabidopsis. The results of terminal restriction fragment (TRF) showed significant variation in telomere length among cotton species. The telomere length of cultivated cotton was close to 20 kb and was larger than those of wild cotton species whose telomere length ranged from 6 to 20 kb.