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The photosynthesis and fluorescence characteristics of five magnolia ornamental species naturally distributed in various subtropical areas were studied in Nanjing City in winter and spring. The results showed that the diurnal changes of net photosynthetic rate (P(n)) and water use efficiency (WUE) of test species in winter were different from those in spring. The diurnal integral values of P(n), apparent quantum yield (AQY) and carboxylation efficiency (CE) were lower in winter than in spring, and the F(o) was higher, while the F(v)/F(m) F(v)/F(o) phi PS II, F(v)'/F(m)', ETR, qP and NPQ were lower in winter than in spring. The differences among the five species were remarkable, among which, Parakmeria lotungensis and Michelia platypetala mainly distributed in middle-subtropical area had higher diurnal integral values of P(n), AQY, CE and LSP, but lower value of LCP than other species in winter and spring. Their F(v)/F(m), F(v)/F(o),phi PS II, F(v)'/F(m)', ETR, qP and NPQ were also higher, indicating that they had higher photosynthetic capacity and wider ecological ranges of light adaptability. Manglietia insignis and Michelia wilsonii mainly distributed in southern subtropical area had lower photosynthetic capacity, and their fluorescence parameters were also lower in winter. Grey correlation analysis showed the main factors affecting the P(n) of test magnolia species in winter were T(a) and PAR.

It was reported recently that changing the TIR (translational initiation region) of lambda N gene resulted in the increasing expression of lambda N gene and it was regulated at translational level. According to the alignment, the leader sequence of lambda N gene had three parts: a code region for ORF lambda N, the upstream sequence of ORF lambda N and 17 bp of spacer between ORF lambda N and downstream of lambda N gene. ORF lambda N is an open reading frame located at upstream of lambda N gene coding a peptide of 19 amino acids. To study the mechanism of regulation of lambda N gene expression, three serials of plasmids with mutant leader region of lambda N gene were constructed. (1) pMC1403-XT, in which the start codon or the partial code of ORF lambda N was connected with lacZ to obtain the ORF lambda N-lacZ fusion gene and in which the ORF lambda N-lacZ expression was under the control of a strong trp/lac promoter; (2) The ORF lambda N mutants in which the termination codon TAA was introduced into ORF lambda N at different positions by site-directed mutagenesis to preterminate the ORF lambda N on plasmid pMC1403N; (3) Mutants in which a deletion was located at upstream ORF lambda N in the ORF lambda N mutants above. The results obtained from determination of the beta-galactosidase activity in the transformants harboring the different plasmids showed that the ORF lambda N-lacZ expression was suppressed by the ORF lambda N code region and the lambda N expression was increased in both the second and third serials of mutants. At the same time the results from RNA-DNA dot hybridization showed that the lambda N gene expression was regulated at translational level. Therefore it was predicted that the reason of relatively low expression for lambda N gene in pMC1403N was due to the low efficiency of ORF lambda N translation. There are two ways to increase the expression of lambda N gene. One is to preterminate the translation of ORF lambda N at a suitable position to decrease the ORF lambda N effects on downstream lambda N gene translation; the other is to change the upstream sequence of ORF lambda N to improve its translation efficiency.

The reaction conditions for rice AFLP assay were optimized. The relative efficiencies for polymorphism detection of RFLP, RAPD and AFLP were compared through the analysis between a pair of PGMS allelic mutant lines(NK58S and NK58F). Results indicated that the efficiency for polymorphism detection in rice is in the order of AFLP > RAPD > RFLP, and also indicated that AFLP is a powerful DNA molecular marker technique for polymorphism detection, especially in the cases of extremely low polymorphism, such as isogeneic lines and allelic mutant lines. The advantages and disadvantages of these three molecular marker systems were discussed. Using AFLP in conjunction with bulked segregating analysis, 5106 AFLP loci were screened and 9 of them showed polymorphism between NK58S and NK58F, 4 of the polymorphic AFLP products were cloned, Southern bloting analysis showed that two of them were single copy sequences while the other two were low copy sequences in rice genome.