Fusarium oxysporum f. sp. cubense (Foc), the causal agent of Fusarium wilt (Panama disease), is one of the most devastating diseases of banana (Musa spp.). The Foc tropical race 4 (TR4) is currently known as a major concern in global banana production. No effective resistance is known in Musa to Foc, and no effective measures for controlling Foc once banana plants have been infected in place. Early and accurate detection of Foc TR4 is essential to protect banana industry and guide banana planting. A real-time fluorescence loop-mediated isothermal amplification assay (RealAmp) was developed for the rapid and quantitative detection of Foc TR4 in soil. The detection limit of the RealAmp assay was approximately 0.4 pg/µl plasmid DNA when mixed with extracted soil DNA or 103 spores/g of artificial infested soil, and no cross-reaction with other relative pathogens were observed. The RealAmp assay for quantifying genomic DNA of TR4 was confirmed by testing both artificially and naturally infested samples. Quantification of the soil-borne pathogen DNA of Foc TR4 in naturally infested samples was no significant difference compared to classic real-time PCR (P>0.05). Additionally, RealAmp assay was visual with an improved closed-tube visual detection system by adding SYBR Green I fluorescent dye to the inside of the lid prior to amplification, which avoided the inhibitory effects of the stain on DNA amplification and makes the assay more convenient in the field and could thus become a simple, rapid and effective technique that has potential as an alternative tool for the detection and monitoring of Foc TR4 in field, which would be a routine DNA-based testing service for the soil-borne pathogen in South China.

DCPTA (2-diethylaminoethyl-3, 4-dichlorophenylether) and CCC (2-chloroethyltrimethyl- ammonium chloride) have a great effect on maize growth, but applying DCPTA individually can promote the increase of plant height, resulting in the rise of lodging percent. Plant height and lodging percent decrease in CCC-treated plants, but the accumulation of biomass reduce, resulting in yield decrease. Based on the former experiments, the performance of a mixture which contained 40 mg DCPTA and 20 mg CCC as active ingredients per liter of solution, called PCH was tested with applying 40mg/L DCPTA and 20mg/L CCC individually. Grain yield, yield components, internode characters, leaf area per plant, plant height and lodging percent as well as chlorophyll content, chlorophyll fluorescence, enzymatic antioxidants, membranous peroxide and organic osmolyte were analyzed in two years (2011 and 2012), using maize hybrid, Zhengdan 958 (ZD 958) at density of 6.75 plants m-2. CCC, DCPTA and PCH were sprayed on the whole plant leaves at 7 expanded leaves stage and water was used as control. Compared to control, PCH significantly increased grain yield (by 9.53% and 6.68%) from 2011 to 2012. CCC significantly decreased kernel number per ear (by 6.78% and 5.69%) and thousand kernel weight (TKW) (by 8.57% and 6.55%) from 2011 to 2012. Kernel number per ear and TKW increased in DCPTA-treated and PCH-treated plants, but showed no significant difference between them. In CCC-treated and PCH-treated plants, internode length and plant height decreased, internode diameter increased, resulting in the significant decline of lodging percent. With DCPTA application, internode diameter increased, but internode length and plant height increased at the same time, resulting in the augment of lodging percent. Bending strength and puncture strength were increased by applying different plant growth regulators (PGRs). In PCH-treated plants, bending strength and puncture strength were greater than other treatments. Compared to control, the bending strength of 3rd internode was increased by 14.47% in PCH-treated plants in 2011, increased by 18.40% in 2012, and the difference was significant. Puncture strength of 1st, 3rd and 5th internode was increased by 37.25%, 29.17% and 26.09% in 2011 and 34.04%, 25% and 23.68% in 2012, compared to control. Leaf area and dry weight per plant reduced significantly in CCC-treated plants, increased in DCPTA-treated and PCH-treated plants from 2011 to 2012. Chlorophyll content and chlorophyll fluorescence improved with CCC and DCPTA application. Due to the additive effect of DCPTA and CCC, PCH showed the significant effect on chlorophyll content and chlorophyll fluorescence. Compared to control, total enzyme activity (SOD, POD, CAT, APX and GR) and soluble protein content increased, malonaldehyde (MDA) and hydrogen peroxide (H2O2) content reduced in PCH-treated plants. The transportation of soluble sugar from leaf to kernel improved significantly at the late silking stage. The research provided the way for the further use of DCPT...

Twenty-two isolates of Corynespora cassiicola obtained from cucumber, papaya, eggplant, tomato, bean, Vigna, sesame and Hevea rubber (Hevea brasiliensis) were analysed by morphological features, the differences of the ribosomal DNA internal transcribed spacer (rDNA-ITS) region sequence and the inter simple sequence repeat (ISSR) technique. Variability of morphological features was observed among the isolates. Pathogenicity tests showed that isolates from different hosts attacked Hevea rubber. Sequences of two outgroup taxa, C. proliferata and C. citricola, were downloaded from GenBank. The phylogenetic trees were constructed by using the rDNA-ITS region sequences from 24 Corynespora spp. isolates. In this analysis, the 24 sequences grouped into two clusters (A and B). Cluster A consists of sequences from all isolates of C. cassiicola; whereas cluster B consists of the two outgroup taxa, C. proliferata and C. citricola. However, the ITS region is conservative, and is not fit for studying differences among isolates. A total of 114 DNA fragments was amplified with 16 ISSR primers, among which 102 were polymorphic (89.5%). A dendrogram was created by the unweighted pair-group method with arithmetic averaging (UPGMA) analysis, and 22 isolates grouped into three clusters (C, D and E). Cluster C is composed of all of the Hevea rubber isolates, whereas cluster D is composed of nine isolates: four from papaya, five from cucumber, eggplant, bean, vigna and sesame. Cluster E is composed of two isolates from cucumber and tomato. These analyses showed that the genetic diversity was very rich among the tested isolates. There are no correlations between the morphological characteristics or rDNA-ITS region sequences of the 22 isolates and their host or geographical origin, but there is a link between ISSR clusters and their host origins. ISSR markers appear to be useful for intra-species population study in C. cassiicola.

HetR plays a key role in regulation of heterocyst differentiation and patterning in It directly regulates genes involved in heterocyst differentiation (such as and ), genes involved in pattern formation (), and many others. In this study, we investigated the functional relationship of and and their role in HetR-dependent cell differentiation. Coexpression of and from the promoter of , which encodes the global nitrogen regulator, enabled a mutant to form heterocysts with low aerobic nitrogenase activity. Overexpression of restored heterocyst differentiation in a mutant and vice versa. Overexpression of restored heterocyst formation in either a or a mutant but not in a double mutant. The functional overlap of and was further confirmed by reverse transcription-quantitative PCR (RT-qPCR) and transcriptomic analyses of their effects on gene expression. In addition, yeast two-hybrid and pulldown assays showed the interaction of HetZ with HetR. HetP and HetZ are proposed as the two major factors that control heterocyst formation in response to upregulation of Heterocyst-forming cyanobacteria contribute significantly to N fixation in marine, freshwater, and terrestrial ecosystems. Formation of heterocysts enables this group of cyanobacteria to fix N efficiently under aerobic conditions. HetR, HetP, and HetZ are among the most important factors involved in heterocyst differentiation. We present evidence for the functional overlap of and and for the key role of the HetR-HetP/HetZ circuit in regulation of heterocyst differentiation. The regulatory mechanism based on HetR, HetP, and HetZ is probably conserved in all heterocyst-forming cyanobacteria.

RNA capping and decapping tightly coordinate with transcription, translation, and RNA decay to regulate gene expression. Proteins in the DXO/Rai1 family have been implicated in mRNA decapping and decay, and mammalian DXO was recently found to also function as a decapping enzyme for NAD+‐capped RNAs (NAD‐RNA). The Arabidopsis genome contains a single gene encoding a DXO/Rai1 protein, AtDXO1. Here we show that AtDXO1 possesses both NAD‐RNA decapping activity and 5ʹ‐3ʹ exonuclease activity but does not hydrolyze the m7G cap. The atdxo1 mutation increased the stability of NAD‐RNAs and led to pleiotropic phenotypes, including severe growth retardation, pale color, and multiple developmental defects. Transcriptome profiling analysis showed that the atdxo1 mutation resulted in upregulation of defense‐related genes but downregulation of photosynthesis‐related genes. The autoimmunity phenotype of the mutant could be suppressed by either eds1 or npr1 mutation. However, the various phenotypes associated with the atdxo1 mutant could be complemented by an enzymatically inactive AtDXO1. The atdxo1 mutation apparently enhances post‐transcriptional gene silencing by elevating levels of siRNAs. Our study indicates that AtDXO1 regulates gene expression in various biological and physiological processes through its pleiotropic molecular functions in mediating RNA processing and decay.

No abstract

The Songnen Plain, whose climatic conditions are perfectly suited to sugar beet growth, is located in northeastern China. Unfortunately, this region has a lot of saline-alkaline land, which is the most important factor limiting sugar beet production. This study was undertaken to determine whether biochar-based organic fertilizer could alleviate the negative effect of saline-alkaline soil on sugar beet yield and whether such an effect correlated with changes in nitrogen assimilation, antioxidant system, root activity, and photosynthesis. Three treatments were established: Chemical fertilizers were applied to neutral soil (CK), chemical fertilizers were applied to saline-alkaline soil (SA), and biochar-based organic fertilizer was applied to saline-alkaline soil (SA + B). Our results showed that saline-alkaline stress significantly inhibited the nitrogen assimilation and antioxidant enzymes activities in root, root activity, and photosynthesis, thus significantly reducing the yield and sugar content of sugar beet. Under saline-alkaline conditions, the application of biochar-based organic fertilizer improved the activities of nitrogen assimilation enzymes in the root; at the same time, the antioxidant enzymes activities of the root were significantly increased for improving root activity in this treatment. Moreover, the application of biochar-based organic fertilizer could improve the synthesis of photosynthetic pigments, PSII (Photosystem II) activity, stomatal opening, and photosynthesis of sugar beet under saline-alkaline conditions. Hence, the growth and yield of sugar beet were improved by applying biochar-based organic fertilizer to saline-alkaline soil. These results proved the significance of biochar-based organic fertilizer in alleviating the negative effect of saline-alkaline stress on sugar beet. The results obtained in the pot experiment may not be viable in field conditions. Therefore, in the future, we will verify whether biochar-based organic fertilizer could alleviate the adverse effects of saline-alkaline stress on sugar beets yield under field conditions.

No abstract