A full-length cDNA consisting of 1444 bp for NAD dependent sorbitol dehydrogenase (NAD-SDH) was cloned from fruit of plum (Prunus salicina var. cordata cv. Younai) by means of RT-PCR and RACE. The cDNA containing an open reading frame (ORF) of 1101 bp encoded a polypeptide of 367 amino acid residues. The maltose binding protein fusion SDH (MBP-SDH) was expressed and partially purified from Escherichia coli cells, and biochemical properties of MBP-SDH and SDH cleaved from the fusion protein by factor Xa were characterized. The MBP-SDH had the specific affinity for NAD and was able to oxidize sorbitol, xylitol, l-ribitol and mannitol but not ethyl alcohol, arabitol and other polyols. The optimum pH for the oxidation of sorbitol and the reduction of fructose was 9.0 and 7.0, respectively; the maximum reaction rate occurred when temperature increased up to 50 °C in the presence of sorbitol. The MBP-SDH with a subunit of 80 kDa appears to be a hexamer. Its molecular weight was 478.6 kDa estimated by gel filtration and 493.2 kDa estimated using native linear gradient PAGE. The K(m) values for sorbitol, NAD, fructose and NADH were 95.86 mM, 0.31 mM, 1.04 M and 0.038 mM, respectively. However, when MBP was cleaved from the fusion enzyme, the SDH exists as a homotetramer with the native molecular weight of 164.8 kDa estimated by gel filtration. The K(m) values were 111.8 mM, 0.35 mM, 1.25 M and 0.048 mM for sorbitol, NAD, fructose and NADH, respectively. The MBP-SDH and the SDH were similar with respect to their kinetic characteristics despite their difference in quaternary structures.

Using Citrus grandis 'Tuyou' as the control,pollen germination and pollen tube growth status of Citrus grandis 'Guanximiyou' and 'Duweimiyou' in water-soluble extracts from different pistil parts from the same and different varieties were observed by fluorescent microscopy.The results showed that pollen tube growth was retarded and bent seriously by the water-soluble extracts of 'Guanximiyou' and 'Duweimiyou' ovaries,and were also affected by stigma extracts with moderate bent.The pollen tube grew normally in their-own styles extracts,showing only a slight bend.However,there were no such suppression effects on pollen tube growth in the water-soluble extracts of stigmas,styles,and ovaries for the pollens of different varieties and self-compatible variety 'Tuyou'.

,中心柱实心,少有裂果和裂瓣发生,但食用品质受到影响.

On the basis of one cDNA-AFLP expressed sequence tag(EST) from longan(Dimocarpus longan Lour.) cotyledon embryos which is 84%homologous to Antirrhinum majus,the full length cDNA of glyceraldehyde-3-phosphate dehydrogenase(GAPDH) gene was cloned by rapid-amplification of cDNA ends(RACE).The gene consisted of 1395 bp encoding a protein of 336 amino acids,with 71 bp and 316 bp at 5′-UTR and 3′-UTR,respectively.The amino acid sequence comparison with the GAPDH gene of Oryza sativa,Vitis vinifera,Musa acuminata,Arabidopsis thaliana,and Ginkgo biloba showed that identity was all higher than 85%.The sequence was accepted and released by GenBank(accession number: FJ694011).

The entire chromosome 1 was microdissected by using a fine glass needle under the inverted microscope, and then transferred into a collection chamber. Procedure for chromosome preparation was the squash method, in which the root-tip cells of watermelon cultivar " Zhongyuyihao" were separated and spread. The microdissected chromosome adhered to the needles was digested with proteinase K, and its DNA was extracted and digested with Sau3A. DNA ligation to a linker/primer set and PCR was carried out, in which the sequence of the linker was 5'-GATCCTGAGCTCGAATTCGACCC -3' and 5'- GGGTCGAATTCGAATTCG AGCTCAG -3'. After two rounds of PCR amplification, a smear of DNA fragments ranging from 0.4 to 2.0 kb were generated. Southern hybridization result showed that the PCR products from the single watermelon chromosome was homogeneous with the watermelon genomic DNA, indicating that DNAs from the chromosome have been successfully amplified. The second-round PCR products from chromosome of watermelon were microcloned to construct the plasmid library, including 20 000 recombinant clones. It is first reported that a simple procedure for preparation and microdissection of small chromosomes in watermelon has been successfully established. In addition, this study demonstrates that chromosome microdissection and cloning can be applied in genomic study of melon crops.

The pistils of Citrus grandis (L.) Osbeck ‘ Guanximiyou’ and ‘ Duweimiyou’ were cut into 3 tissue parts, stigma, style and ovary, which were then transferred onto culture medium and pollinated with pollens from both the same cultivars and different cultivars to detect the reaction of different pistil parts on the cross compatibility by fluorescence microscopy. The results showed that pollens either from the same cultivars or different cultivars were able to germinate normally on all the 3 tissue parts, but strong incompatible reaction occurred on ovary tissue part from the same cultivars, and that strong fluorescence due to accumulation of callose was detected from the embryo sacs of ‘ Guanximiyou’. Therefore, it was supposed that ovary was the main inhibitory part for self-incompatible reaction of the 2 cultivars, and that embryo sac was also the primary inhibitory part for self incompatible reaction of ‘Guanximiyou’.

The finger map of longan (Dimdcarpus longan Lour. 'Honghezi') cotyledon embryo RNA was established by cDNA-AFLP,which extracted from thirty-five-day (early) and fifty-day (late) cotyledon embryos after anthesis,respectively. There were 41 differential fragments cloned and sequence analysed,in which 21 differential expression fragments had high homology with some known genes,the function mainly involved in the abaxial polarity of lateral organ,glycolysis,energy metabolism,ion transport,cell wall elongation,cell cycle regulation,RNA transcription,RNA translation and regulation,protein phosphorylation regulation and protein degradation,signal transduction and so on. While the others had low or no homology with known genes.

Anther abortion during litchi female flower development were studied by applying scanning electric microscope,transmission electron microscope and DAPI fluorochrome methods.The results are as follows: the epidermic cells in the abortive anthers begin to deteriorate before meiosis,after meiosis programmed cell death(PCD) takes place in the anther wall which leads to weakened competition ability for nutriment.In the apoptosis cells,nuclear chromatin condenses and the electron density is higher than normal cells.Nucleolus disappear,the chromatin trends to the verge of nuclear membrane and double nuclear membrane degrades.Some nucleus deform and dish,the nuclear membrane breaks and apoptotic body made of nuclear substance can be seen around the place where nuclear membrane cracks.Many mitochondria can be observed around the nucleus in most of apoptosis cells.Some mitochondria deform and prolong,cristae swell,some constrict and its membrane degrade and become vague,others have ruptured already.The above showed that mitochondria may relate to cell apoptosis directly.

Fluorescent in situ hybridization(FISH) technique, 45S rDNA as probe, was established in narcissus in the study.It showed that the modified procedures could be further used to identify narcissus phylogenetic process and relationship.Flame-drying protocol after enzyme digestion of cell wall was a good method for getting clear and well dispersed narcissus chromosome preparation.With probe DNA labeled by nick translation, and co-denaturation of chromosome DNA and probe for 5 min at 90℃, the rDNA was successfully localizated by FISH method.

With fluorescence in situ hybridization(FISH),the sites of the 45SrDNA and 5S rDNA on the mitotic metaphase chromosomes of Chinese Narcissus (Narcissus tazeta var. White Flower) were located and analyzed. The results indicated that there were two pairs of signals detected for 45S rDNA. According to the characteristics of the chromosome, the chromosome with bigger signal was No.7 and the other pair was chromosome No.6. The signal of 5S rDNA was relatively weak, and it was located on 2L. These results provide some molecular cytogenetics information for further study of changes of chromosomes in Narcissus evolution.

In this experiment the ramification from tea adult stem nodes was used as materials for the preliminary study on subculturing multiplication and rooting formation in Camellia sinensis cv Tieguanyin. The obtained results showed that the best medium for subculturing multiplication of tea adult stem nodes was 1/2MS+1.0 mg/L6-BA+0.2mg/LIAA+0.2mg/LGA3 supplemented with 8g/L agarose and 30g/L sucrose, pH5.6. The average multiplication rate was 7.57 and the highest could come up to 13. The optimal medium for rooting formation of aseptic lines from adult stem nodes was 1/2MS+3mg/LIBA+30g/L sucrose+7g/L agarose; further more the rooting rate improved with prolonging subculturing time, while the days of rooting formation shortened.

The procedure for cryopreservation by vitrification and plant regeneration from embryogenic calli were preliminarily developed in litchi.After subculturing for 15 d,the calli were precultured on the MS medium supplemented with 50 mL·L~(-1) DMSO,1 mg·L~(-1)2,4-D,20 g·L~(-1) sucrose and 6 g·L~(-1) agar at 5 ℃,and then the excised calli were loaded with 60% PVS_2 for 20 min at room temperature,and next they were exposed to PVS_2 for 40 min;after changing the solution with fresh PVS_2,the calli were put into liquid nitrogen.One week later,the calli were thawed rapidly in a 40 ℃ water bath;then they were washed with the MS medium with 1.2 mol·L~(-1) sucrose for 3 times and were further transferred to the fresh medium(MS with 1 mg·L~(-1) 2,4-D,20 g·L~(-1)sucrose and 6 g·L~(-1) agar) for growth.Plantlets regenerated normally via somatic embryogenesis from these cryopreservated calli.

Some aspects on the initial fruit set in Younai(Prunus salicina Lindl var.cordata J Y Zhang et al) were studied.The results showed that,large amount of flower/fruitlet drop occurred within 2 weeks after full blossom;low content of GA1+3 was closely correlated to the peak of fruit drop,however,the contents of endogenous zeatin ribosides(ZRs),dihydrozeatin ribosides(ZRs) and abscisic acid(ABA) were significantly positive correlated to the growth of fruitlet(ovary);during the initial fruit set of Younai,quite a few of female gametophytes degenerated or aborted,and,the developmental process was slow after anthesis,which therefore,blocked fertilization and resulted in flower/fruitlet abscission.The mechanism of initial fruit set in Younai was discussed in this paper.

Some aspects related to fruit growth and development of "Younai" (Prunus salicina Lindl var. cordata J Y Zhang et al) were studied, and the results showed as follows. The accumulations of soluble carbohydrates (including fructose, glucose, sorbitol and sucrose) in flesh showed their characteristic patterns in different special phase of fruit growth. In the initial rapid growth stage, the concentrations of soluble carbohydrates increased rapidly and paralleled the peak of growth rate, then decreased relatively during retarded growth phase. At the later stage of retarded growth, the soluble carbohydrates were accumulated markedly and then decreased with the increasing of the growth rate. When fruit, its growth rate increased at a second time and then went into maturation, the concentrations of soluble carbohydrates, especially of fructose and glucose, increased rapidly. The fluctuations of different endogenerous hormone showed their own special features, during the growth and development of fruit. Endogenerous ZRs and ABA were positively correlated to the first peak of growth rate and accumulation of soluble carbohydrates, but [diH]ZRs held a low level at this stage. The concentrations of CTKs (mainly [diH]ZRs) increased markedly and the peaks paralleled the soluble carbohydrates at the later stage of retarded growth, which suggested that cytokinins probably triggered the subsequent rapid growth of pericarp. ABA was correlated to the subsequent rapid growth and the accumulation of soluble carbohydrates (especially fructose glucose). Mechanism of fruit growth and development in Nai and its correlation to CTKs and ABA were discussed in this paper

Comparison was conducted by making observations on microscopic shructure and submicroscopic shucture of the embryonic development of "lühebao" litchi,a typical embro-abortive type litchi,and "Wuye",a normal type litchi.The results showed that there some embryos of "Lühebao" growing out of the embryo sac and the inner integument of "Lühebao" had aborted from the early time of its embryonic development while every part of the embryo of "Wuye" developed normally in the whole course of development.

Investigations on Narcissus tazetta var.chinensis Roem showed that there were 9 different types of N.tazetta var.chinensis in Fujian,which distributed in the coastal regions of Zhangzhou,Putian and Ningde.There were three colours of the flower,namely white,yellow or both white and yellow.The duration of blooming could last from November of present year through February of subsequent year.Genomes were two types of x=10 and x=11,and ploidy of the chromosomes included diploid,autotriploid and allotriploid.

A efficient regeneration system of plantlets was established with cotyledon as explants in melon (Cucumis melo L. cv. Mihe). The results showed that the adventitious buds were induced with the explants of cotyledons grew for 5 d on the medium MS added 2.0 mg·L-1 6-BA, 0.5 mg·L-1 IBA, 3.5% sucrose and 0.7% agar, whose value of pH was 5.8, the differentiation rate of bud was maximum reaching 100%. The optical concentrations of plant growth regulators were 0.5 mg·L-1 6-BA and 0.1 mg·L-1 IAA during the stage of bud stretching, hygromycin was optical antibiotic in selection of transformated plants.

Young leaves and mature leaves of litchi(Litchi chinensis Sonn.) were used as materials.Focusing time of the first dimensional IEF was optimized using mini vertical slab gel(gel size: 82 mm×82 mm,gel thickness: 1.0 mm),and a rapid system of analytical two dimensional electrophoresis(2-DE) of protein was established.More than 200 protein spots visualized when stained with Coomassie Brilliant Blue R-250.Application of this mini system was discussed as well.

Narcissus monosomes with middle centromeres were isolated with glass needles with the help of micromanipulator and then put into 0.2 mL Eppendorf tubes;next,the monosomes were deproteinised and digested with Sau3A;afterwards,the DNA fragments of the monosomes were ligated with Sau3A linkers at their two ends and PCR amplified in two rounds;after the amplification,DNA fragments of 300～(3 000 bp) was obtained.With genomic DNA maker as the probe,the southern blotting of the amplification products was conducted,which proved that monosome DNA were indeed successfully amplified.The products of the second round amplification were micro-cloned to construct the plasmid library and the analysis of 90 randomly chosen clones found that the inserted fragment ranged between 600~2 500 bp.