Response of plant growth and development to different light conditions in three model plant systems

Shade avoidance response to the reduced ratio of red:far-red (R:FR) light was studied in a white aspen Populus alba clone \u27Bolleana\u27 using two filter systems: a clear plastic filter system that allows a R:FR ratio less than 1.0 to pass from adjacent border plant reflection; and a special commercial plastic that blocks FR light and creates a R:FR ratio above 3.0. The response to low R:FR The reduced R:FR signals enhanced the stem elongation in response to competition at the expense of relative stem diameter growth. Trees grown inside clear chambers were 27% taller and 22% heavier in stem dry weight than trees grown inside the FR-blocking filter chambers. Stem taper of clear chamber trees was 16% less than the FR-blocking filter trees. Low R:FR also induced 13% greater petiole length per leaf compared to the FR-blocking filter trees.;The immutans (im) variegation mutant of Arabidopsis has green and white leaf sectors due to the action of a nuclear recessive gene. IM is a chloroplast homolog of the mitochondrial alternative oxidase. The ghost (gh) variegation mutant of tomato bears phenotypic similarities to im. We show that the im and gh phenotypes arise from mutations in orthologous genes. Structural analyses reveal that AOX, IM and GH are RNR R2 di-iron carboxylate proteins with perfectly conserved Fe-coordinating ligands that define a quinol-binding catalytic site. IM has a global impact on plant growth and development and that it is required for the differentiation of multiple plastid types. IM transcript levels do not necessarily correlate with carotenoid pool sizes, raising the possibility that IM function is not limited to carotenogenesis. Leaf anatomy is radically altered in the green and white sectors of im. The green im sectors have significantly higher than normal rates of O2 evolution and significantly elevated chlorophyl a/b ratios, typical of those found in sun leaves. We conclude that IM and GH are plastid quinol oxidases that act downstream from a quinone pool to dissipate electrons in plastids. In addition, im interrupts plastid-to-nucleus signaling pathways that control Arabidopsis leaf developmental programming

RFLP analysis of genetic variation in the laminated-root-rot fungal pathogen of conifers, Phellinus weirii

DNA markers that detect polymorphisms within and between two biological species of the coniferous laminated-root-rot fungus Phellinus weirii were developed and used to measure the amount and distribution of genetic variation. In a preliminary survey, total cellular DNA from 3 Douglas-fir-type isolates and 3 cedar-type isolates was digested with 12 restriction enzymes, gel-blotted, and probed with 16 random genomic clones derived from total cellular DNA of Phellinus weirii; one cloned nuclear ribosomal gene from Coprinus cinereus; and three cloned mitochondrial genes from Suillus sinuspaulianus. Our results were consistent with previous studies in that the two biological species were different in most characteristics (91% of probe-enzyme combinations differed between the two biological species). Polymorphisms within biological species were also detected with several probe-enzyme combinations (11.5% for the cedar type, and 14.4% for the Douglas-fir type). While ribosomal DNA of the fungus was polymorphic within and between biological species, mitochondrial DNA was monomorphic within, though polymorphic between biological species. One random genomic clone, pPW13, revealed a multiple-banded "DNA fingerprinting" type of fragment phenotype in the Douglas-fir type. Twenty-seven isolates representing 6 infection centers, 3 regions and 2 host species were analyzed with sixty-five probe-enzyme combinations (13 probes x 5 enzymes) that detected variation within the Douglas-fir-type isolates in the preliminary survey. Ribosomal DNA was very polymorphic among infection centers, but mitochondrial DNA was monomorphic. Eight of the 13 probes detected polymorphism within or among infection centers; three random genomic probes detected variation within the same infection centers. Apart from these rare polymorphisms- -which appear to result from somatic mutation- -infection centers had unitary genotypes that differed from other infection centers with respect to a number of probe-enzyme combinations. This suggests that infection centers are established from single basidiospore infections, and that genetic migration among centers either by vegetative spread or secondary basidiospore establishment is infrequent. Isolates from the two hosts sampled, Douglas-fir (Pseudotsuga menziesii) and mountain hemlock (Tsuga mertensiana), shared a number of polymorphic fragment phenotypes, indicating that the Douglas-fir type lacks strong, qualitative differentiation among these hosts

Identification of New Metabolites of Bacterial Transformation of Indole by Gas Chromatography-Mass Spectrometry and High Performance Liquid Chromatography

Arthrobacter sp. SPG transformed indole completely in the presence of an additional carbon source. High performance liquid chromatography and gas chromatography-mass spectrometry detected indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde as biotransformation products. This is the first report of the formation of indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde from indole by any bacterium

Fungal endophytes inhabiting mountain-cultivated ginseng (Panax ginseng Meyer) : diversity and biocontrol activity against ginseng pathogens

Fungal endophytes isolated from mountain-cultivated ginseng (MCG, Panax ginseng Meyer) were explored for their diversity and biocontrol activity against ginseng pathogens (Alternaria panax, Botrytis cinerea, Cylindrocarpon destructans, Pythium sp. and Rhizoctonia solani). A total of 1,300 isolates were isolated from three tissues (root, stem and leaf) from MCGs grown in 24 different geographic locations in Korea. In total, 129 different fungal isolates were authenticated by molecular identification based on internal transcribed spacer (ITS) sequences. The fungal endophytes belonged to Ascomycota (81.7%), Basidiomycota (7.08%), Zygomycota (10%) and Unknown (1.15%), with 59 genera. Analysis of diversity indices across sampling sites suggested species abundance as a function of geographical and environmental factors of the locations. Shannon diversity index and richness in the different tissues revealed that root tissues are colonized more than stem and leaf tissues, and also certain fungal endophytes are tissue specific. Assessment of the ethyl acetate extracts from 129 fungal isolates for their biocontrol activity against 5 ginseng pathogens revealed that Trichoderma polysporum produces the antimcriobial metabolite against all the pathogens. This result indicates the promise of its potential usage as a biocontrol agent

Drought-induced susceptibility for Cenangium ferruginosum leads to progression of Cenangium-dieback disease in Pinus koraiensis

Recently, the occurrence of "Cenangium-dieback" has been frequent and devastating. Cenangium-dieback is caused by an endophytic fungus Cenangium ferruginosum in stressed pine trees. Progression of the disease in terms of molecular interaction between host and pathogen is not well studied and there is a need to develop preventive strategies. Thus, we simulated disease conditions and studied the associated transcriptomics, metabolomics, and hormonal changes. Pinus koraiensis seedlings inoculated with C. ferruginosum were analyzed both under drought and well-watered conditions. Transcriptomic analysis suggested decreased expression of defense-related genes in C. ferruginosum-infected seedlings experiencing water-deficit. Further, metabolomic analysis indicated a decrease in the key antimicrobial terpenoids, flavonoids, and phenolic acids. Hormonal analysis revealed a drought-induced accumulation of abscisic acid and a corresponding decline in the defense-associated jasmonic acid levels. Pathogen-associated changes were also studied by treating C. ferruginosum with metabolic extracts from pine seedlings (with and without drought) and polyethylene glycol to simulate the effects of direct drought. From RNA sequencing and metabolomic analysis it was determined that drought did not directly induce pathogenicity of C. ferruginosum. Collectively, we propose that drought weakens pine immunity, which facilitates increased C. ferruginosum growth and results in conversion of the endophyte into the phytopathogen causing dieback

Characterization of Developmental- and Stress-Mediated Expression of Cinnamoyl-CoA Reductase in Kenaf ( Hibiscus cannabinus

Cinnamoyl-CoA reductase (CCR) is an important enzyme for lignin biosynthesis as it catalyzes the first specific committed step in monolignol biosynthesis. We have cloned a full length coding sequence of CCR from kenaf (Hibiscus cannabinus L.), which contains a 1,020-bp open reading frame (ORF), encoding 339 amino acids of 37.37 kDa, with an isoelectric point (pI) of 6.27 (JX524276, HcCCR2). BLAST result found that it has high homology with other plant CCR orthologs. Multiple alignment with other plant CCR sequences showed that it contains two highly conserved motifs: NAD(P) binding domain (VTGAGGFIASWMVKLLLEKGY) at N-terminal and probable catalytic domain (NWYCYGK). According to phylogenetic analysis, it was closely related to CCR sequences of Gossypium hirsutum (ACQ59094) and Populus trichocarpa (CAC07424). HcCCR2 showed ubiquitous expression in various kenaf tissues and the highest expression was detected in mature flower. HcCCR2 was expressed differentially in response to various stresses, and the highest expression was observed by drought and NaCl treatments

Exposure to sound vibrations lead to transcriptomic, proteomic and hormonal changes in Arabidopsis

Sound vibration (SV) is considered as an external mechanical force that modulates plant growth and development like other mechanical stimuli (e.g., wind, rain, touch and vibration). A number of previous and recent studies reported developmental responses in plants tailored against SV of varied frequencies. This strongly suggests the existence of sophisticated molecular mechanisms for SV perception and signal transduction. Despite this there exists a huge gap in our understanding regarding the SV-mediated molecular alterations, which is a prerequisite to gain insight into SV-mediated plant development. Herein, we investigated the global gene expression changes in Arabidopsis thaliana upon treatment with five different single frequencies of SV at constant amplitude for 1 h. As a next step, we also studied the SV-mediated proteomic changes in Arabidopsis. Data suggested that like other stimuli, SV also activated signature cellular events, for example, scavenging of reactive oxygen species (ROS), alteration of primary metabolism, and hormonal signaling. Phytohormonal analysis indicated that SV-mediated responses were, in part, modulated by specific alterations in phytohormone levels; especially salicylic acid (SA). Notably, several touch regulated genes were also up-regulated by SV treatment suggesting a possible molecular crosstalk among the two mechanical stimuli, sound and touch. Overall, these results provide a molecular basis to SV triggered global transcriptomic, proteomic and hormonal changes in plant

Expression analysis of sound vibration-regulated genes by touch treatment in Arabidopsis

Sound vibration (SV) is considered to be a mechanical stimulus which gives rise to various physiological and molecular changes in plants. Previously, we identified 17 SV-regulated genes (SRGs) which were up-regulated by SV treatments in Arabidopsis. Here, we analyzed the expression pattern of similar genes after an exposure of 500 Hertz at 80 decibels, for various time periods. Simultaneously, we confirmed the SV-mediated expression of these genes under lighted condition as many of them were reported to be dark-induced. For this, we designed an improved SV treatment chamber. Additionally, we checked the electrolyte leakage (EL), photosynthetic performance and expression of mechanosensitive (MS) ion channel genes after 5 days of SV treatment in the illuminated chamber. EL was higher, and the photosynthetic performance index was lower in the SV-treated plants compared to control. Seven out of the 13 MS ion channel genes were differentially expressed after the SV treatment. Simultaneously, we checked the touch mediated expression pattern of 17 SRGs and 13 MS ion channel genes. The distinct expression pattern of 6 SRGs and 1 MS ion channel gene generate an idea that SV as a stimulus is different from touch. Developmental stage-specific expression profiling suggested that the majority of the SRGs were expressed spatiotemporally in different developmental stages of Arabidopsis, especially in imbibed seed, seedlings and leaves

Actin Cytoskeleton and Golgi Involvement in Barley stripe mosaic virus Movement and Cell Wall Localization of Triple Gene Block Proteins.

Barley stripe mosaic virus (BSMV) induces massive actin filament thickening at the infection front of infected Nicotiana benthamiana leaves. To determine the mechanisms leading to actin remodeling, fluorescent protein fusions of the BSMV triple gene block (TGB) proteins were coexpressed in cells with the actin marker DsRed: Talin. TGB ectopic expression experiments revealed that TGB3 is a major elicitor of filament thickening, that TGB2 resulted in formation of intermediate DsRed:Talin filaments, and that TGB1 alone had no obvious effects on actin filament structure. Latrunculin B (LatB) treatments retarded BSMV cell-to-cell movement, disrupted actin filament organization, and dramatically decreased the proportion of paired TGB3 foci appearing at the cell wall (CW). BSMV infection of transgenic plants tagged with GFP-KDEL exhibited membrane proliferation and vesicle formation that were especially evident around the nucleus. Similar membrane proliferation occurred in plants expressing TGB2 and/or TGB3, and DsRed: Talin fluorescence in these plants colocalized with the ER vesicles. TGB3 also associated with the Golgi apparatus and overlapped with cortical vesicles appearing at the cell periphery. Brefeldin A treatments disrupted Golgi and also altered vesicles at the CW, but failed to interfere with TGB CW localization. Our results indicate that actin cytoskeleton interactions are important in BSMV cell-to-cell movement and for CW localization of TGB3