Psc-AFP from Psoralea corylifolia L. overexpressed in Pichia pastoris increases antimicrobial activity and enhances disease resistance of transgenic tobacco.

Psc-AFP, isolated from the seeds of Psoralea corylifolia L., is an antimicrobial protein with trypsin inhibitor activity. Its encoding gene was cloned by 3'- rapid amplification of cDNA ends (RACE) combined with Y-shaped adaptor-dependent extension (YADE) method. The gene Psc-AFP encodes a protein of 203 amino acids with a deduced signal peptide of 24 residues. The growth inhibition effect exerted by the heterologously expressed Psc-AFP in Pichia pastoris revealed that the recombinant Psc-AFP inhibited mycelium growth of Aspergillus niger, Rhizoctonia solani, and Alternaria brassicae and conidial germination of Alternaria alternata. The recombinant Psc-AFP also showed protease inhibitor activity manifested by the inhibition of trypsin. The transgenic tobacco bioassays confirmed that overexpressing Psc-AFP significantly enhanced the disease resistance of tobacco and that some of the transgenic lines were almost fully tolerant to Ralstonia solanacearum and A. alternata, whereas no apparent alteration in plant growth and development was observed. Collectively, these results indicate that the recombinant Psc-AFP is an active antimicrobial protein, with protease inhibitor activity that can be successfully produced in the yeast and tobacco and, therefore, maybe a potential antimicrobial candidate for practical use.

Ontogenetic changes in foliar features and psoralen content of Psoralea corylifolia Linn. exposed to SO2 stress.

Field-grown Psoralea corylifolia plants were exposed to 0.5 ppm and 1.0 ppm concentrations of sulphur dioxide gas and sampled for observation at the pre-flowering, flowering and post-flowering stages of plant ontogeny. One ppm SO2 concentration caused a significant decline in leaf number and leaf area per plant, total leaf dry weight, and the size and amount of midrib vasculature. The density and size of stomata decreased and many stomata were damaged. Interestingly new epidermis developed oversome of the damaged leaf stomata, thus showing a unique defence strategy against SO2 stress through dedifferentiation of the epidermal cells. Decline in the concentrations of leafchlorophylls and carotenoids in treated plants were up to 20% and 29% respectively. Stomatal conductance, intercellular CO2 content and net photosynthetic rate lowered byover 52%, 20% and 35%, respectively under the SO2 stress. Concentration of psoralen, a basic linear furanocoumarin known for its use in the treatment of dermal diseases, was highest (5.32%) in seeds and lowest (0.28%) in roots. It was heavily reduced in SO2 treated plants, the maximum decline occurring in seeds (86.70%) and leaves (56.27%). In the roots and shoots of the treated plants, it was low in pre-flowering stage, compared with the control, but showed a recovery during the post-flowering phase of plant growth.

[Study on seedling quality of Psoralea corylifolia and influence factors].

OBJECTIVE: To study the effects of different fertilization, measure of breeding seedling, breeding and sowing density on seedlings of Psoralea corylifolia. METHOD: The combination of field sowing and indoor test was applied. RESULT: All agricultural measures showed positive effect on the growth and development of seedling of P. corylifolia. CONCLUSION: The suitable sewing time should be the first and second ten days in March. The suitable sowing density is 150 kg x hm(-2). The combined of application of organic manure and chemical fertilizer is better than using one of them alone.