Identification and Characterization of the PEBP Family Genes in Moso Bamboo (Phyllostachys heterocycla).

Moso bamboo is one of the economically most important plants in China. Moso bamboo is a monocarpic perennial that exhibits poor and slow germination. Thus, the flowering often causes destruction of moso bamboo forestry. However, how control of flowering and seed germination are regulated in moso bamboo is largely unclear. In this study, we identified 5 members (PhFT1-5) of the phosphatidyl ethanolamine-binding proteins (PEBP) family from moso bamboo genome that regulate flowering, flower architecture and germination, and characterized the function of these PEBP family genes further in Arabidopsis. Phylogenetic analysis revealed that 3 (PhFT1, PhFT2 and PhFT3), 1 (PhFT4) and 1 (PhFT5) members belong to the TFL1-like clade, FT-like clade, and MFT-like clade, respectively. These PEBP family genes possess all structure necessary for PEBP gene function. The ectopic overexpression of PhFT4 and PhFT5 promotes flowering time in Arabidopsis, and that of PhFT1, PhFT2 and PhFT3 suppresses it. In addition, the overexpression of PhFT5 promotes seed germination rate. Interestingly, the overexpression of PhFT1 suppressed seed germination rate in Arabidopsis. The expression of PhFT1 and PhFT5 is significantly higher in seed than in tissues including leaf and shoot apical meristem, implying their function in seed germination. Taken together, our results suggested that the PEBP family genes play important roles as regulators of flowering and seed germination in moso bamboo and thereby are necessary for the sustainability of moso bamboo forest

A CRY-BIC negative-feedback circuitry regulating blue light sensitivity of Arabidopsis.

Cryptochromes are blue light receptors that regulate various light responses in plants. Arabidopsis cryptochrome 1 (CRY1) and cryptochrome 2 (CRY2) mediate blue light inhibition of hypocotyl elongation and long-day (LD) promotion of floral initiation. It has been reported recently that two negative regulators of Arabidopsis cryptochromes, Blue light Inhibitors of Cryptochromes 1 and 2 (BIC1 and BIC2), inhibit cryptochrome function by blocking blue light-dependent cryptochrome dimerization. However, it remained unclear how cryptochromes regulate the BIC gene activity. Here we show that cryptochromes mediate light activation of transcription of the BIC genes, by suppressing the activity of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), resulting in activation of the transcription activator ELONGATED HYPOCOTYL 5 (HY5) that is associated with chromatins of the BIC promoters. These results demonstrate a CRY-BIC negative-feedback circuitry that regulates the activity of each other. Surprisingly, phytochromes also mediate light activation of BIC transcription, suggesting a novel photoreceptor co-action mechanism to sustain blue light sensitivity of plants under the broad spectra of solar radiation in nature

Morphology, molecular phylogeny and okadaic acid production of epibenthic Prorocentrum (Dinophyceae) species from the northern South China Sea

Around 30 epibenthic Prorocentrum species have been described, but information about their biogeography is limited. Some species are able to produce okadaic acid (OA) and its derivatives, which are responsible for diarrheic shellfish poisoning (DSP). In the present study, we examined the diversity of epibenthic Prorocentrum in the northern South China Sea by isolating single cells from sand, coral, and macroalgal samples collected from 2012 to 2015. Their morphology was examined using light microscopy and scanning electron microscopy. Among 47 Prorocentrum strains, seven morphospecies were identified as P. lima, P. rhathymum, P. concavum, P. cf. emarginatum, P. fukuyoi, P. cf. maculosum and P. panamense. The latter five species have not been previously reported in Chinese waters, and this is the first record of P. panamense outside its type locality. Partial large subunit (LSU) ribosomal DNA and internal transcribed spacer region sequences were obtained and molecular phylogenetic analysis was carried out using maximum likelihood and Bayesian inference. Chinese P. cf. maculosum strains share 99.5% similarity of LSU sequences with the strain from Cuba (close to the type locality), but Chinese P. lima strains share only 96.7% similarity of LSU sequences with the strain from the type locality. P. cf. emarginatum differs from P. fukuyoi mainly in the presence/absence of marginal pores and they form a well-resolved clade together with P. sculptile. OA was detected in all Chinese strains of P. lima and P. cf. maculosum based on liquid chromatography-mass spectrometry analysis, but dinophysistoxin was produced only by two P. lima strains. Chinese strains of P. concavum, P. rhathymum, and P. panamense do not produce detectable level of OA. Our results support the wide distribution of epibenthic Prorocentrum species and highlight the potential risk of DSP in the northern South China Sea

Cryptochromes Orchestrate Transcription Regulation of Diverse Blue Light Responses in Plants.

Blue light affects many aspects of plant growth and development throughout the plant lifecycle. Plant cryptochromes (CRYs) are UV-A/blue light photoreceptors that play pivotal roles in regulating blue light-mediated physiological responses via the regulated expression of more than one thousand genes. Photoactivated CRYs regulate transcription via two distinct mechanisms: indirect promotion of the activity of transcription factors by inactivation of the COP1/SPA E3 ligase complex or direct activation or inactivation of at least two sets of basic helix-loop-helix transcription factor families by physical interaction. Hence, CRYs govern intricate mechanisms that modulate activities of transcription factors to regulate multiple aspects of blue light-responsive photomorphogenesis. Here, we review recent progress in dissecting the pathways of CRY signaling and discuss accumulating evidence that shows how CRYs regulate broad physiological responses to blue light

Coordination of Cryptochrome and Phytochrome Signals in the Regulation of Plant Light Responses

In nature, plants integrate a wide range of light signals from solar radiation to adapt to the surrounding light environment, and these light signals also regulate a variety of important agronomic traits. Blue light-sensing cryptochrome (cry) and red/far-red light-sensing phytochrome (phy) play critical roles in regulating light-mediated physiological responses via the regulated transcriptional network. Accumulating evidence in the model plant Arabidopsis has revealed that crys and phys share two mechanistically distinct pathways to coordinately regulate transcriptional changes in response to light. First, crys and phys promote the accumulation of transcription factors that regulate photomorphogenesis, such as HY5 and HFR1, via the inactivation of the CONSTITUTIVE PHOTOMORPHOGENIC1/SUPPRESSOR OF PHYA-105 E3 ligase complex by light-dependent binding. Second, photoactive crys and phys directly interact with PHYTOCHROME INTERACTING FACTOR transcription factor family proteins to regulate transcriptional activity. The coordinated regulation of these two pathways (and others) by crys and phys allow plants to respond with plasticity to fluctuating light environments in nature