ABSTRACT
Phytochrome B (phyB) is an essential red light receptor that predominantly mediates seedling de-etiolation, shade-avoidance response, and flowering time. In this study, we isolate a full-length cDNA of PHYB, designated BrPHYB, from Chinese cabbage (Brassica rapa L. ssp. pekinensis), and we find that BrphyB protein has high amino acid sequence similarity and the closest evolutionary relationship to Arabidopsis thaliana phyB (i.e., AtphyB). Quantitative reverse transcription (RT)-PCR results indicate that the BrPHYB gene is ubiquitously expressed in different tissues under all light conditions. Constitutive expression of the BrPHYB gene in A. thaliana significantly enhances seedling de-etiolation under red- and white-light conditions, and causes dwarf stature in mature plants. Unexpectedly, overexpression of BrPHYB in transgenic A. thaliana resulted in reduced expression of gibberellins biosynthesis genes and delayed flowering under short-day conditions, whereas AtPHYB overexpression caused enhanced expression of FLOWERING LOCUS T and earlier flowering. Our results suggest that BrphyB might play an important role in regulating the development of Chinese cabbage. BrphyB and AtphyB have conserved functions during de-etiolation and vegetative plant growth and divergent functions in the regulation of flowering time.
Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis/genetics , Brassica rapa/genetics , Etiolation/genetics , Gene Expression Regulation, Developmental , Phytochrome B/genetics , Arabidopsis/growth & development , Arabidopsis/radiation effects , Arabidopsis Proteins/metabolism , Base Sequence , Flowers/genetics , Flowers/growth & development , Flowers/radiation effects , Gene Expression , Gene Expression Regulation, Plant , Gibberellins/metabolism , Light , Molecular Sequence Data , Organ Specificity , Phylogeny , Phytochrome B/metabolism , Plant Growth Regulators/metabolism , Plant Leaves/genetics , Plant Leaves/growth & development , Plant Leaves/radiation effects , Plant Proteins/genetics , Plant Proteins/metabolism , Plants, Genetically Modified , Seedlings/genetics , Seedlings/growth & development , Seedlings/radiation effects , Sequence Analysis, DNA , Time FactorsABSTRACT
OBJECTIVE: To study the rule of mutation of Streptomyces fradiae during spaceflight, and to select efficient tylosin producing strains for industrial production. METHOD: Streptomyces fradiae 9940S(+)-86 were carried on-board spaceship "Shenzhou" I, "Shenzhou" III and "Shenzhou" IV sequentially to achieve spaceflight mutation breeding experiment. RESULT: After space experiments and the screening tests in the lab, 48 strains were obtained which promoted production by +20% or more at shaker level. And the highest production of a strain was 14950 micrograms/ml, which means an increase of 91.5%. CONCLUSION: Comparing the results of three tests, it is found that the outer space environment can lead to a cumulative mutation. After the medium scale tests and production experiments, strain T1-156-84-23 was finally selected to be used for sample production. And its output was increased by 18%.
