Additions to Neopestalotiopsis (Amphisphaeriales, Sporocadaceae) fungi: two new species and one new host record from China.

Background: In this study, three Neopestalotiopsis taxa were identified, associated with leaves of Zingiberofficinale, Elaeagnuspungens and Salaccazalacca. New information: Based on morphology and multi-gene analyses of the internal transcribed spacer (ITS), beta-tubulin (TUB2) and translation elongation factor 1-alpha (TEF1), the five strains of Neopestalotiopsis represent two novel and one known species. They are introduced with descriptions, illustrations and notes herein.

Two new species of Neopestalotiopsis from southern China.

BACKGROUND: Pestalotiopsis-like fungi are widely distributed in many plants and include endophytes, pathogens and saprobes. Five strains of Neopestalotiopsis were isolated from diseased leaves of Rhapisexcelsa (Principes, Palmae), Rhododendronsimsii and Rho.championiae (Ericales, Ericaceae) and Erythropalumscandens (Santalales, Olacaceae) in southern China. NEW INFORMATION: Based on morphology and multi-gene (ITS, tub2, tef1) phylogeny, our five strains of Neopestalotiopsis represent two new species and one extant species. Descriptions, illustrations and notes are also provided for the new species.

[Epigenetics of plant vernalization regulated by non-coding RNAs].

Many higher plants must experience a period of winter cold to accomplish the transition from vegetative to reproductive growth. This biological process is called vernalization. Some crops such as wheat (Triticum aestivum L.) and oilseed rape (Brassica napus L.) produce seeds as edible organs, and therefore special measures of rotation and cultivation are necessary for plants to go through an early vernalization for flower differentiation and development, whereas the other crops such as Chinese cabbage (B rapa ssp. pekinenesis) and cabbage (Brassica napus L.) produce leafy heads as edible organs, and additional practice should be taken to avoid vernalization for a prolonged and fully vegetative growth. Before vernalization, flowering is repressed by the action of a gene called Flowering Locus C (FLC). This paper reviewed the function of non-coding RNAs and some proteins including VRN1, VRN2, and VIN3 in epigenetic regulation of FLC during vernalization.

A novel class of heat-responsive small RNAs derived from the chloroplast genome of Chinese cabbage (Brassica rapa).

BACKGROUND: Non-coding small RNAs play critical roles in various cellular processes in a wide spectrum of eukaryotic organisms. Their responses to abiotic stress have become a popular topic of economic and scientific importance in biological research. Several studies in recent years have reported a small number of non-coding small RNAs that map to chloroplast genomes. However, it remains uncertain whether small RNAs are generated from chloroplast genome and how they respond to environmental stress, such as high temperature. Chinese cabbage is an important vegetable crop, and heat stress usually causes great losses in yields and quality. Under heat stress, the leaves become etiolated due to the disruption and disassembly of chloroplasts. In an attempt to determine the heat-responsive small RNAs in chloroplast genome of Chinese cabbage, we carried out deep sequencing, using heat-treated samples, and analysed the proportion of small RNAs that were matched to chloroplast genome. RESULTS: Deep sequencing provided evidence that a novel subset of small RNAs were derived from the chloroplast genome of Chinese cabbage. The chloroplast small RNAs (csRNAs) include those derived from mRNA, rRNA, tRNA and intergenic RNA. The rRNA-derived csRNAs were preferentially located at the 3'-ends of the rRNAs, while the tRNA-derived csRNAs were mainly located at 5'-termini of the tRNAs. After heat treatment, the abundance of csRNAs decreased in seedlings, except those of 24 nt in length. The novel heat-responsive csRNAs and their locations in the chloroplast were verified by Northern blotting. The regulation of some csRNAs to the putative target genes were identified by real-time PCR. Our results reveal that high temperature suppresses the production of some csRNAs, which have potential roles in transcriptional or post-transcriptional regulation. CONCLUSIONS: In addition to nucleus, the chloroplast is another important organelle that generates a number of small RNAs. Many members of csRNA families are highly sensitive to heat stress. Some csRNAs respond to heat stress by silencing target genes. We suggest that proper temperature is important for production of chloroplast small RNAs, which are associated with plant resistance to abiotic stress.

Evidence that high activity of vacuolar invertase is required for cotton fiber and Arabidopsis root elongation through osmotic dependent and independent pathways, respectively.

Vacuolar invertase (VIN) has long been considered as a major player in cell expansion. However, direct evidence for this view is lacking due, in part, to the complexity of multicellular plant tissues. Here, we used cotton (Gossypium spp.) fibers, fast-growing single-celled seed trichomes, to address this issue. VIN activity in elongating fibers was approximately 4-6-fold higher than that in leaves, stems, and roots. It was undetectable in fiberless cotton seed epidermis but became evident in initiating fibers and remained high during their fast elongation and dropped when elongation slowed. Furthermore, a genotype with faster fiber elongation had significantly higher fiber VIN activity and hexose levels than a slow-elongating genotype. By contrast, cell wall or cytoplasmic invertase activities did not show correlation with fiber elongation. To unravel the molecular basis of VIN-mediated fiber elongation, we cloned GhVIN1, which displayed VIN sequence features and localized to the vacuole. Once introduced to Arabidopsis (Arabidopsis thaliana), GhVIN1 complemented the short-root phenotype of a VIN T-DNA mutant and enhanced the elongation of root cells in the wild type. This demonstrates that GhVIN1 functions as VIN in vivo. In cotton fiber, GhVIN1 expression level matched closely with VIN activity and fiber elongation rate. Indeed, transformation of cotton fiber with GhVIN1 RNA interference or overexpression constructs reduced or enhanced fiber elongation, respectively. Together, these analyses provide evidence on the role of VIN in cotton fiber elongation mediated by GhVIN1. Based on the relative contributions of sugars to sap osmolality in cotton fiber and Arabidopsis root, we conclude that VIN regulates their elongation in an osmotic dependent and independent manner, respectively.

A novel method for constructing pathogen-regulated small RNA cDNA library.

Pathogen-responsive endogenous small non-coding RNAs regulate gene expression in relation to plant immune responses by serving as RNA silencing machinery. Decay caused by the bacterium, Erwinia carotovora subsp. carotovora (Ecc), often leads to soft rot disease in the plant Brassica campestris L. ssp. pekinensis (Bcp). To discover endogenous small RNA species in Bcp in response to Ecc infection, we developed a highly efficient approach for cloning pathogen-regulated small RNAs. A group of degenerate stem-loop reverse primers was designed to synthesize first single-stranded cDNA (sscDNA) and the sscDNA was then tailed with a poly(C) at its 3' end to create a forward priming site. A novel cDNA/RNA subtractive hybridization was performed to capture Ecc-regulated small RNAs and this subsequently allowed construction of small RNA cDNA libraries for sequencing.

[Analysis of shoot apical anatomic changes during the development of Brassica plants].

In this study, we analyzed shoot apical anatomic changes during the development of Brassica plants including cauliflower (Brasscia oleracea L.var. botrytis), broccoli (B. oleracea L.var italica), Chinese cabbage (Brasscia compestris spp. pekinensis) and cabbage (Brasscia oleracea.L.). It has been showed that all of their apical meristems changed from the original tunica-corpus structure to the intergrade subarea, to typical 5-subarea structure and to 4-subarea structure when they went into reproductive development. The shoot apical meristem (SAM) cells were undergoing in different developmental way among these plants after they began reproductive development. The bilateral cells of sub-tunica of Chinese cabbage and cabbage divided into apical leafy primordial, in which lateral inflorescence meristem arised. While the bilateral cells of sub-tunica of cauliflower and broccoli divided into inflorescence meristem, which proliferated into curd or head. The results presented here provide the base for further investigation of anatomic identity of inflorescence phenotype formation and molecular events associated with meristem fate.

[Uptake, transformation and degradation of organic pollutants in transgenic plants].

Organic pollutants are major contaminants of soil, water and air whereas phytoremediation is an efficient way to clean up the polluted environment. In recent years, a number of exogenous genes encoding the proteins with remediation activities have been introduced into plants, and transgenic plants with enhanced ability of bioremediation obtained. In this paper, recent achievements in the research on phytoremediation of environments polluted by organic pollutants, especially the persistent organic pollutants (POPs), is briefly described, and recent achievements and potential uses of transgenic plants in pollution remediation are discussed.

[Organic mercury tolerance, absorption and transformation in Spartina plants].

Critical concentration of methylmercuric chloride (MeHgCl) in the nutrient solution to which Spartina plants are tolerant is 15 micromol/L, three times higher than that of tobacco plants. After being treated with methylmercuric chloride, total quantity of organic mercury within plants increased and that of nutrient solution decreased greatly so that total quantity of inorganic mercury rose. It is inferred that Spartina plants absorb organic mercury and partially transform organic into inorganic mercury, and then more inorganic mercury is accumulated in underground parts of plants. In addition, inorganic mercury derived from organic mercury moved to solution by diffusion and permeation. In this way, the features Spartina plants exhibit in mercury accumulation and transformation from organic to inorganic mercury are valuable for phytoremediation of environment pollution.

[Regulation to curd morphogenesis and genetics of exogenous BoCAL gene in cauliflower].

Cauliflower (Brassica oleracea var. botrytis L.) and cabbage (B. oleracea var capitata L.) are two varieties of species B. oleracea. Cauliflower BobCAL gene losses the original function due to its terminated mutation while cabbage BoCAL gene has the complete function. We obtained cauliflower plants transgenic for BoCAL gene using Arobacterium-mediated transformation. Genetic analysis of T2 generation indicated that all cauliflower plants transgenic for BoCAL failed to form curd and produced the green, loosed inflorescences composed of flower buds instead, demonstrating that cauliflower BobCAL was complemented by cabbage BoCAL, and thus transgenic cauliflower lost the ability to form curd. Selfing of these transgenic plants gave rise to the similar inflorescence phenotype of T3 plants except 15 days delay of inflorescence appearance compared with the plants of T1 generation. When transgenic cauliflower was crossed with wild-type cauliflower, the progenies formed the curd with a few of flower buds, and they delayed inflorescence onset till 135 days after sowing.