Abstract:From 389 species included in the China Rare and Endangered Plant List, Volume one, 59 species having their distribution in Guangdong Province (except Hainan Province formerly included in Guangdong) are presented, of which 1 pteridophyte, 10 gymnosperms,and 48 angiosperrns. Among them 9 are endangered, 34 vulnerable and 16 rare species. A list of these plants with their distribution in Guangdong is given.

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Abstract:An ultrastructural study on the development of the central cell was carried out on rice (Oryza sativa L.). The results showed that following the formation of the eight nuclei in the embryo sac, cellularization took place resulting in the formation of seven cells. One of the cells situated in the centre of the embryo sac was the central cell. The central cell contained a large vacuole, two polar nuclei (located in micropylar part and chalzal end, respectively) and a large number of cytoplasmic organella. Further development of the central cell mainly involved changes in the orientation of the polar nuclei and the distribution of the cytoplasm. Changes in the orientation of the polar nuclei involved the following stages of developments a. The two polar nuclei increased in size and became elliptical in shape. On both sides of the polar nuclei the cytoplasm showed an asymmetrical pattern of distribution. b. The two polar nuclei moved to the central region of embryo sac. At this stage the two polar nuclei were close to each other and they were lying ("one on top of the other") in parallel to the long axis of the embryo sac. When the polar nuclei moved to the central region of the embryo sac, a thick strand of cytoplasm (forming a cytoplasmic "bridge" ) became associated with the polar nuclei. The cytoplasm "bridge" ran from one end of the embryo sac to the other. c. The two polar nuclei began to move towards the egg cell and finally "sat" themselves on the top of the egg cell. The two polar nuclei had by now changed from a parallel (one on top of the other) to perpendicular (side by side) orientation (with respect to the long axis of the embryo sac). The side of the nuclear envelope of the two polar nuclei facing each other produced a lot of protrusions and fusion bridges throughout the different stages of development and reorientation of the polar nuclei. The cytoplasm surrounding the polar nuclei also went through some changes e. g. starch grains disappeared and smooth ER increased. UP till stage c the size of the embryo sac did not change much. But immediately after the completion of stage c the embryo sac greatly increased in size. The embryo sac then reached full maturity and apparently did not undergo any further changes.

Abstract:The study of caloric values of different aboveground organs of some dominant and common species in south subtropical evergreen broad-leaved forest in Heishiding Nature Reserve, Guangdong Province, showed that the dry weight caloric values were affected obviously by the ash contents of plant species and of different organs of plant,and the ash-free caloric values varied with different species and organs. Mean ash-free caloric values for different organs of the same species among 8 species in the tree layer ranged from 19.261 to 20.672 kJ g-1, the ranking of Which in species being Ormosia glaberrima > Neolitsea phanerophlebia > Quercus chungii > Machilus breviflora > Cryptocarya concinna >Artocarpus styracifolius>Lithocarpus lohangwa >Ixonathes chinensis. Mean ash-free caloric values of the same organ for 8 species in the tree layer were 21.417 kJ g-1 for leaves, 19.929 kJ g-1 for twigs, 19.961 kJ g-1 for trunk barks, and 18.664 kJ g-1 for trunks.Ash-free caloric values of the same organ in different abovearound lavers tended to be in the following sequence; tree layer>shrub layer>herbaceous layer, which was shown markedly in ash-free caloric values in leaves.

Abstract:Four-leaf seedlings of tobacco were used to study the resistance to anthracnose disease caused by Colletotrichum desructivum O' Gara infection. After or before treatment in seedlings sprayed with 1 mg ml-1 methyl jasmonate (MJ) one time a day for 3 days, fungous spores (108 ml-1) were inoculated to the leaves by spraying 2 times at an interval of 12 hours. The numbers of lesion of leaves were recorded and pathogenesis-related proteins (PRP) were determined after treatment for 7 to 15 days. When tobacco seedlings were inoculated with spores, the resistibility was quite different among three varieties. Brazil variety showed stronger resistance to this disease than K326 and Guanghuang55. Treating with MJ before spore inoculation, the infection symptom in seedlings was reduced, indicating that MJ can induce the resistance of tobacco to fungous infection. The PRP contents of seedlings increased after treating with MJ or inoculating with spores. The correlation coefficient between PRP of Brazil variety and infection degree was -0.9958. It is suggested that PRP is significantly related to fungus resistance in tobacco seedlings of this variety.

Abstract:Rice seedlings treated with methyl jasmonate (MJ) showed that the activity of RuBP oxygenase in leaves was apparently increased since the second day after 2.5 x 10-4 mol/L MJ treatment, and the activity of glycolate oxidase markedly increased on the fourth day. Meanwhile the accumulation of glycolate in leaves of rice seedlings was also enhanced, and the content of glycolate was increased more markedly when the leaves were pretreated with a-HPMS. These results indicated that the treatment with 2.5 x 10-4 mol/L MJ could hasten the photorespiration of rice seedlings. But the accumulation of glycolate and the activities of some enzymes related to photorespiratory process were not affected by the treatment with 2.5 x 10-7 mol/L MJ.

Abstract:The generation of active oxygen and the activities of active oxygen scavenging enzymes as well as the effect of light on active oxygen metabolism were studied in soybean during germination. The O2 uptake, the rate of O2 production, and the level of H2O2 in imbibed seeds all increased at the beginning of germination, but all decreased after 4 days of imbibition. Gradual increases in activities of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) were observed at the early stage of germination, then the activities of SOD, POD, and APX tended to be in a certain level with little alteration. A new band of SOD isoenzyme presented respectively on the 2nd and 3rd day of seed imbibition. There was about a 50-fold increase in catalase (CAT) activity at the early stage of germination, and then turned stable. Among the three H2O2-scavenging enzymes (CAT, POD and APX), the capacity of CAT for scavenging H2O2 was much higher than those of POD and APX. So it seems that CAT is the most important H2O2 scavenging enzyme during germination. Although the O2 uptake of seeds germinating under light was lower than that in the dark, the rate of O2 production and the H2O2 level under light were higher than those in the dark. The ratio of O2- production to total O2 uptake was 1.1 - 2.7% in seeds germinated under light, while this ratio was 0.9 - 1.3% in the dark. The activities of SOD and APX under light were higher than those in the dark, but the activities of POD and CAT had no distinct difference under light and dark.

Abstract:The vigour of wampee seeds decreased rapidly as moisture content was reduced to about 40% after desiccation, or after continued storage for one year or more. Direct PEG priming could not improve but decrease the vigour of deteriorated wampee seeds,even made their germinability lost. The experiments showed that the solute leakage of wampee seeds or excised embryos increased greatly after priming. The pretreatments with ABA, Ca2+ or tea polyphenol before desiccation obviously reduced the desiccation sensitivity of seeds, and those in combination with PEG priming after desiccation could markedly increase the vigour of the seeds. In comparison with control, the short-term and high-temperature priming with Ca2+ before storage improved the vigour of seeds preserved after one year. The results showed that the pretreatments before desiccation were necessary for increasing the viability of wampee seeds.

Abstract:The soluble protein content in spikelet of Zhenshan 97A of cytoplasmic male sterile rice decreased rapidly after the formation stage of pollen mother cell (PMC). It was 56%, 34.6% and 30.3% at uninucleate, binucleate and trinucleate stages of pollen, respectively, as compared with that at the formation stage of PMC. The content of soluble protein in maintainer line Zhenshan 97B also decreased, but again increased at pollen binucleate stage which showed a pattern with saddle curve The activity of azocasein protease increased in Zhenshan 97A after the PMC formation stage, whereas less change in activity of this enzyme was found in the maintainer line. The activity of endopeptidase in Zhenshan 97A at the stage of first panicle branch differentiation was higher than that in Zhenshan 97B, and it decreased at the stage of pistil and stamen formation in both the sterile and the maintainer lines. The activity of endopeptidase in sterile line was higher than that in maintainer line by 15% to 55.5% at all developmental stages. At the stage of first panicle branch differelltiation, tile activity of aminopeptidase for tile sterile line was higher than that for the maintainer one. After the stage of PMC formation, the activity of aminopeptidase increased rapidly and reached to the maximum level at pollen trinucleate stage for the sterile line. It may implay that more protein in sterile plants was proteolysised at this stage. The results of protease inhibitor test indicated that aminopeptidase in sterile and maintainer lines after the formation stage of pistil and stamen was of cysteine type with 10% of metalloprotease. However, aminopeptidase in maintainer line at trinucleate pollen stage belonged mainly to the cysteine type. Endopeptidase, BAPA, from sterile line at trinucleate stage showed cysteine- and serine types, and also part of type with metalloprotease, but it was the serine type only in maintainer line. The changes in peptidase types may reflect the derepression of the gene coding of peptidase in cytoplasmic male sterile rice.

Abstract:The activities of respiratory enzymes in cytoplasmic male sterile (CMS) rice Zhenshan 97A and its maintainer Zhenshan 97B were studied. The results showed that the activities of malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH), glucose-6phosphate dehydrogenase (G6PDH), 6-phospho-gluconate dehydrogenase (6PGDH) and 5-Phosphoribose isomerase (RSPI) in sterile anthers were all lower than those in fertile ones.But in panicles only the activities of G6PDH, 6PGDH and RSPI in sterile line were lower than those in fertile line. The results indicated that the cytoplasmic sterility of rice was associated with the obvious decrease of tricarboxylic acid cycle(TCA) and pentose phosphate pathway (PPP) activities, and the change in PPP operation was shown to be earlier than that in TCA.

Abstract:Comparative study of agronomic characters in 18 combinations of two-line hybrid rice indicated that the heterosis was shown to be in the order: Indica/Japonica>Indica/ Javanica>Indica/Indica>there-line hybrid rice" Weiyu 64". The same two-line hybrids showed different heterosis performance between early and late season rices. Low seed setting and low grain-straw ratio were the main problems for utilization of indica-Japonica hybrid.

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