December 1999, Volume 41 Issue 12


          Research Articles
Genetic Study on the Herbicide (Liberty) Resistibility and Its Application on Utilizing Heterosis in Rice
Author: LI Yuan-Qing, LIU Gang, YAN Wen-Gui and XU Qiu-Sheng
Journal of Integrative Plant Biology 1999 41(12)
    Three restoring lines (Minghni 63, Ce 64 and Teqing) as female parents were crossed with herbicide-resistant transgenic cultivars (Bengal-Hul0 and Gulfmont) as male parents. Genetic analysis on generations of F1, F2 and BC1 indicated that the resistance to the herbicide (Liberty) was controlled by a single deminant nuclear gene. The resistance to the herbicide will work as a marker for the true hybrid from crossing with the male parent, but not for all other plants from either selfing, or intracrossing in female parent population. After the application of the herbicide, all plants except the true hybrid were eliminated. With the aid of this technology, the strict requirement of complete sterility for male sterile hne in crops can be reduced. It will be beneficial not only for breeding new excellent male sterile lines, but also for commercializing chemically induced male sterile system in crops.
Abstract (Browse 1741)  |  Full Text PDF       
Protein Electrophoretic Analysis of Amyloplast and Cytoplasm Ribosomes from Lotus Cotyledon
Author: SUN De-Lan, WANG Hong and DONG Yun-Zhou
Journal of Integrative Plant Biology 1999 41(12)
    Amyloplasts and cytoplasmic ribosomes in cotyledon cells of lotus (Nelvmbo nucifeva Gaertn. ) have been observed on the basis of morphology. Isolation of these ribosomes by centrifugation through 30% to 55% (W/V) sucrose density gradient resulted in three bands of amyloplasts ribosomes and four bands of cytoplasmic ribosomes. The authors used these ribosomes bands for SDS-PAGE electrophoresis to analyse ribosomes of proteins. The patterns of SDS-PAGE between cytoplasmic ribosomes of proteins and amyloplasts ribosomes of proteins were different. The amyloplasts ribosomes of proteins showed 26 kD and 23 kD bands, and the cytoplasmic ribosomes of proteins showed 65 kD band. The analysis of electrophoretic patterns of the cytoplasmic ribosomes of proteins showed that there was a newly synthesized ribosomes protein with 19 kD molecular weight in 18 to 20 days after fertilization.
Abstract (Browse 1789)  |  Full Text PDF       
Effects of High Kª¬+ and Alkaline pH on Ultrastructure of Dunaliella salina Chloroplasts
Author: MA Shu-Ying, HUANG Yang-Cheng, YANG Xiao-He and WU Wei-Hua
Journal of Integrative Plant Biology 1999 41(12)
    It was reported that the growth of Dunaliella salina Teod. cultured in medium containing 1 mol/L NaC1 was almost completely inhibited by the addition of 100 mmol/L KC1. The high K+ (100 mmol/L KC1) treatment also significantly inhibited the photosynthetic rate of D. salina and decreased chlorophyll contents in algae. This study focuses on possible effects of high K+ or alkaline pH on the ultrastructural change of chloroplasts in D. salina. After D. salina was cultured in a medium containing 100 n,anol/L KC1 or in a medium with alkaline pH for 8 to 10 days, dramatic ultrastructural changes occurred in the chloroplasts including thylakoid swelling, volume increase of chloroplast, and significant accumulation of starch grains in chloroplasts. The results are consistent with our previous report indicating that the ultrastmctuml changes in chloroplast under high K + or alkaline pH may lead to an inhibitory effects on photosynthesis and overall growth of D. salina.
Abstract (Browse 1768)  |  Full Text PDF       
Detection and Fluorescence in Situ Hybridization of Homologous Sequences for Mammalian Gene rb Related to Apoptosis in Maize
Author: YANG Zheng, CAI Chen-Leng, LIU Li-Hua and SONG Yun-Chun
Journal of Integrative Plant Biology 1999 41(12)
    Human gene rb related to apoptosis was used as the probe for the Southern blot hybridization of the genomic DNA in both maize ( Zea mays L. ) and rice ( Oryza sativa L. ). The results indicated that the homologous sequences of rb were presented in the two species. The physical location of the rb homologous sequences was also carried out in maize chromosomes by fluorescence in sim hybridization (FISH). The gene rb was hybridized onto the long arms of the chromosomes 5 and 6, and the short ann of the chromosome 8. The detection rates of FISH were 7.58%, 16.16% and 10.10%, and percent distances from centromere to the detection sites were 86.17 + 3.22, 94.10 + 2.59 and 92.47 + 2.33 respectively. These results provided important clues to further research of plant apoptosis genes.
Abstract (Browse 1713)  |  Full Text PDF       
Multiª²scale Distribution Pattern of Natural Ramet Population in the Rhizomatous Herb, Thermopsis lanceolata
Author: YU Fei-Hai and DONG Ming
Journal of Integrative Plant Biology 1999 41(12)
    The distribution pattern of natural ramet population in the rhizomatous herb, Thermopsis lanceolata R.Br., at 5 scales (0.2 m, 0.4 m, 0.6 m, 0.8 m and 1.0 m) was investigated using grid samphng and spatial auto-correlation analysis (Moran' s I) in Maowusu sandland of Inner Mongolia of China. The result showed that the ramet population had non-random distribution pattern at four scales (0.2 m, 0.4 m, 0.6 m and 1.0 m). The most frequently observed pattern was contagious at the scale of 0.2 m. The genet had sympodial growth and nearly phalanx architecture. The branching angle of the rhizomes was from 10˚ to 30˚.The density of the ramet population was from 35 to 131 ramets¡¤m£­2. The mean height of ramets was between 11.0 cm and 25.9 cm. The biomass of the ramet population was 263.63 g¡¤m£­2 and 306.19 g¡¤m£­2 in the two plots, respectively. 33.71% and 44.97% of the biomass allocation to rhizomes were observed and the biomass allocation to roots was 29.91% and 29.95% and that to leaves was 25.12% and 36.35% in the two plots, respectively. The ratio of root to shoot was 0.44 in both plots while the ratio of below- to above- ground biomass was 2.12 and 3.59, respectively.
Abstract (Browse 1846)  |  Full Text PDF       
Change in the Concentration and Tissueª²localization of Endogenous IAA During the Regeneration of Vascular Tissues After Xylem Removal in Broussonetia papyrifera
Author: WANG Xiang-Bin, WANG Zhen, DUAN Jun-Hua and CUI Ke-Ming
Journal of Integrative Plant Biology 1999 41(12)
    Change in the concentration of endogenous IAA was monitored with enzyme-linked immunesorbent assay (ELISA), and IAA localization in the tissues was demonstrated by means of immunogold-silver microscopy, with authors' modification, during the regeneration after removal of xylem in Broussonetia popyrifera (L.) Vent. The stimulation exerted from xylem removal produced a rapid increase of about 70% of the endogenous IAA concentration. However, the concentration decreased during differentiation of the vascular tissues. Although removal of the tree crown inhibited the regeneration of vascular tissues, the change tendency in the concentration of endogenous IAA during the regeneration remained the same as if the tree crown was intact. This suggested that rapid increase of endogenous IAA induced by wounding could be a result from a release of the combined form into free IAA. Tissue-localization showed that there were more silver-grains labelled in the rays, callus and the regenerated differentiating vascular tissue cells than in other tissues. It could suggest that the high concentration of endogenous IAA triggered the dedifferentiation of the vascular tissues after removal of xylem, and the less concentrated IAA flow could promote the initiation and activity of the regenerated cambium.
Abstract (Browse 1673)  |  Full Text PDF       
Ultrastructural Studies on Megaspore Formation in Ginkgo biloba
Author: JI Cheng-Jun, YANG Xiong and LI Zheng-Li (Lee C L)
Journal of Integrative Plant Biology 1999 41(12)
    The megaspore mother cell of G/nkgo biloba L. became elliptical before the initiation of meiosis with its nucleus migrating towards the micropylar end and surrounded with starch-bearing plastids. Mitochondria were distributed at the chalazal end. Large amount of the rough endoplasmic reticulum (RER) accumulated at the micropylar end but mitochondria and plastids were hardly visualized there. At the prophase I of meiosis, vacuole enlarged, endoplasmic reticulum (ER) at the micropylar end decreased and mitochondria and plastids became indistinctive. The dyad, formed after the first division of meiosis, demonstrated more substantial polar differentiation, in which the cell towards the micropylar end was relatively smaller and contained looped ER and sparsely arranged mitochondria but almost no plastids. In contrast, the cell towards the chalazal end became enlarged with enriched organelles. During the second division of meiosis, the cell towards the chalazal end (B) divided ahead of the cell towards the micropylar end (A). After the formation of the linear tetrad, the cell towards the cbalazal end (B2) which was the largest of all, became the functional megaspore. The other three cells (Al, A2 and B1 ) began to degenerate at quite different time. A1 and Aa cells degenerated first. Later, a thick wall formed between B1 and B2. Owing to the change of polarity during meiosis, aside from the conventional formation of linear tetrads, T-shaped tetrads (Al ,A2 horizontally lain and B1, B2 cells vertically lain) or linear triads (Al, A2 and an undivided B cell which later became the functional megaspore) were infrequently observed.
Abstract (Browse 1908)  |  Full Text PDF       
A New Genus (Protosciadopityoxylon gen. nov.) of Early Cretaceous Fossil Wood from Liaoning, China
Author: ZHANG Wu, ZHENG Shao-Lin and DING Qiu-Hong
Journal of Integrative Plant Biology 1999 41(12)
    A new genus ( Protosciadopityoxylon gen nov. ) of Early Cretaceous fossil wood reported in the present paper was discovered from Liaoning Province, China, and is named as a new species:Protosciadopityoxylon liaoningense gen. et sp. nov. It is described here and this generic name, adopted by the authors, is employed for fossil wood that is believed to be nearly related to the recent genus Sciadopitys and the fossil genus Sciadopityoxylon. The new genus bears some similarities to Protophyllocladoxylon,Protocircoporoxylon and Xenoxylon in different geological ages, but it differs from them in the types of cross-field pitting.
Abstract (Browse 1921)  |  Full Text PDF       
Light-induced Damage of Photosystem ¢ò Primary Electron Donor P680: a High Performance Liquid Chromatographic Analysis of Pigment Content in D1/D2/Cytochrome b559 Complex Under Photoinhibitory Conditions
Author: PENG De-Chuan, HOU Jian-Min, KUANG Ting-Yun, TANG Chong-Qin and TANG Pei-Song
Journal of Integrative Plant Biology 1999 41(12)
    By HPLC analytical method, the change of PS ¢ò RC' s pigment content in the process of photodamage under strong illumination from spinach ( Spinacia oleracea Mill. ) was comparatively studied. The experimental results show that: (1) In authors' analytical conditions, (of which, [Chl] = 150 µg/mL, and the illumination strength was put at 2.3 ¡Á10 6 mJ¡¤m£­2¡¤s£­1 ), 45 rain of illumination could cause almost the whole loss of A680 in the fourth derivative absorption spectra, while A670 decreased to about one half of its original intensity; the absorption maximum in red, concurrently, was shifted from 676 nm to 671 nm, representing the loss of more than 90% of the photochemical activities of the PS Il RC. (2) During the period of continuous illumination, the Chl concentration decreased in a 3-period style, which meant that the first [Chl] decreased to the 2/3 of its original amount from 20 min to 40 rain after illumination had started, then became stabilized up to about 60 min of illumination, there after a second decrease of [ Chl ] in another about 20 min until it reached about 30 % of the original level and remained unchanged from about 80 min on. The original pigment components of D1/D2/Cyt b559 was approximately as 6 Chl a:2 Pheo:2¦Â-Car which are in support of authors' previous proposal about the minimum Chl/Pheo ratio of 4: 2 in PS ¢ò RC¡¯s pigment contents. (3) After about 40 min of illumination, a newly appeared elution peak was found between the Pheo and¦Â-Car peaks in HPLC profile, at the retention time of 7.2 min, a little later than that (6.9 rain) of Pheo molecules, the newly appeared elution peak was supposed to be a kind of accumulated and stable product of the PS II RC's photodamage process and very much possible the Pheo-like molecules.
Abstract (Browse 1775)  |  Full Text PDF       
Abnormality in Male Organ Development and Fertility of Photoperiodª²sensitive Genic Male Sterile Rice Plants Under Short Day Condition
Author: ZHANG Rui, XUE Guang-Xing, SONG Jia-Xiang and JIANG Xi-Wen
Journal of Integrative Plant Biology 1999 41(12)
    Ten photoperiod-sensitive genic male sterile rice (PGMSR) lines were studied to observe the development of male organs of their short day (SD) plants. The results were shown as follows: 1 ) The self seed-setting rate and the percentage of fertile pollen of these PGMSR lines were much lower than those of the controls. 2) All the male sterile line plants had variant barriers in anther dehiscing and pollen scattering. In addition, some of their stigmas were devoid of pollen, and some self pollen grains on their stignas germinated weakly. 3) Female fertility of those plants was believed to be normal through observation in their embryo sac development and cross seed-setting rate. The authors deduced that the male sterile gene expression becomes the major factor for low rate of self seed-setting of PGMSR plants under SD condition.
Abstract (Browse 1770)  |  Full Text PDF       
Identification of Myosin on the Surface of Wheat Mitochondria
Author: ZHAO He-Ping, LIU Ai-Xiao, REN Dong-Tao, LIU Guo-Qin and YAN Long-Fei (YEN Lung Fei)
Journal of Integrative Plant Biology 1999 41(12)
    It was demonstrated that myosin was associated with the surface of mitochondria in wheat ( Triticum aestivum L. ). Assays of polyacrylamide gel electrophoresis and Western blotting have shown that a polypeptide with molecular weight of 210 kD could be recognized by a polyclonal antibody against hmnan muscle myosin. It was found that the ATPase activity of mitochondrial suspension could be stimulated by F-actin isolated from chicken muscle, which indicated that there was myosin on the surface of wheat mitochondria. This result was confirmed by electron microscopic observation: mitochondria treated with N-ethylmaleimide (NEM) could be wrapped by the F-actin.
Abstract (Browse 1742)  |  Full Text PDF       
Fe Accumulation and Mobilization in Root Apoplast of Soybean Seedlings Under Feª²deficiency Condition
Author: SONG Ya-Na, WANG He, LI Chun-Jian and ZHANG Fu-Suo
Journal of Integrative Plant Biology 1999 41(12)
    Fe accumulation and mobilization in root apoplast of soybean ( Clycine max (L.) Merr. ) seedlings grown under Fe supplement of 10-6 mol/L FeEDTA, or Fe-deficient condition were studied. Under Fe sufficient condition, the content of the root apoplastic Fe pools of soybean seedlings changed in a rhythmic fashion of alternative accumulation and mobilization in every three-day cycling, together with orchestrated rhythmic changes of root Fe ( ¢ó )-reduction capacity and peroxidase activity. In Fe deficient condition, Fe content in the root apoplastic pools deceased steadily almost to nil, and the root Ye( ¢ó )-reduction capacity and peroxidase activity, ahhrough under went rhythmic changes but only in 2-day cycling. The results showed an important relation among root apoplastic Ye pools, Fe( ¢ó )-reduction capacity and peroxidase activity.
Abstract (Browse 1760)  |  Full Text PDF       
Tissue Variance of Salicylic Acid-sensitive Catalase and Enhancement of Disease Resistance with Exogenous ª©Salicylic Acid in Maize
Author: YU Di-Qiu, CEN Chuan, YANG Ming-Lan and LI Bao-Jian
Journal of Integrative Plant Biology 1999 41(12)
    The response to pathogen mediated by salicylic acid (SA) in plant required not only a high level of SA but also an effective SA signal perception and transduction mechanism. The maize ( Zea mays L. ) leaves contained extremely low level of free SA. Catalases from different maize tissues also exhibited different sensitivity to SA. Catalases from leaves were sensitive to SA, but roots contained SA-insensitive eatalases, indicating the presence of different tissue specific catalase isozymes. It seems that there is such an effective mechanism signal sensitization and signal conductance in maize leaves just the same as in tabacco and Arabidopsis. The ability of resistance to Helminthosporium turcicum Pass. in maize leaves can be enhanced by SA.
Abstract (Browse 1766)  |  Full Text PDF       
Effects of Salinity on the Contents of Osmotica of Monocotyledenous Halophytes and Their Contribution to Osmotic Adjustment
Author: ZHAO Ke-Fu and LI Jun
Journal of Integrative Plant Biology 1999 41(12)
    Three monocotyledenous halophyte seedlings (Puccinellia tenuifiora (Griseb.) Scribn. Merr., Aneurolepidium chinese (Trim.) Kitag. and Aeluropus sinensis (Debeaux) Tzvel. ) were treated with different concentration, of NaC1 for two weeks. Their growth status, the contents of main organic solutes and inorganic ions, the osmotic potential and osmotic adjustment ability were then determined. The results are as follows: Of all the inorganic osmotica, the contents of Na + and C1£­ increase with salinity, while K + decreases. The other ions such as Mg7 + , Ca2 + and NO3£­either increase or decrease with salinity. Overall, the contribution of ions to osmotic adjustment decreases with salinity, and Na+ and Cl£­ play the most important role. As for the organic osmofica, however, they all increase with salinity except for organic acid, and the most increased is soluble sugar, of which sucrose is important, which is 1/2 of the soluble sugar. Further more, the Na+/K+ ratio of the 3 plants is about 1 except for A. sinensis, whose Na+/K+ ratio is bigger under high salinity. On the other hand, the measured osmotic potential (MOP) is bigger than computational osmotic potential (COP), which implies that there still exists other osmotic in the plants except for the 11 substances determined in the experiment. The paper explains the reasons for all the above results.
Abstract (Browse 1839)  |  Full Text PDF       
Identification of Rice Signal Factor Inhibiting the Growth and Transfer of Agrobacterium tumefaciens
Author: XU Dong-Hui, XU Shi-Bo, LI Bao-Jian, LIU Yu, HUANG Zhi-Shu and GU Lian-Quan
Journal of Integrative Plant Biology 1999 41(12)
    A rice signal factors which could inhibit the growth of Agrobacterium tumefaciens (Smith et Townsend) Conn and absorption on the surface of rice cells was for the first time isolated from rice ( Oryza sativa L. cv. IR72) roots. This is a new natural thiourea compound, i.e. ethyl-4-(O-nitrophenyl)-3-thioallophanate. Most of the thiourea compounds are synthesis. One of the reasons which rice is not sensitive to A. tumefaciens gene transfer is that rice contains the signal factor which can inhibit the growth of A. tumefaciens as well as its gene transfer to the surface of rice cells.
Abstract (Browse 1761)  |  Full Text PDF       
Transformation of Populus tomentosa with Insecticidal Cowpea Proteinase Inhibitor Gene
Author: HAO Gui-Xia, ZHU Zhen and ZHU Zhi-Ti
Journal of Integrative Plant Biology 1999 41(12)
    Cowpea trypsin inhibitor (CpTI) gene, an insecticidal gene, was introduced into poplar ( Populus tomentosa Carr. ) by gene transformation mediated by Agrobacterium tumefac/ens (Smith et Townsend) Conn. The influences on regeneration and transformation frequency of poplar by the concentration and addition of kanamycin were compared. Kanamycin resistant (Kmr) plantlets were obtained by 3 -4 cycles screening in selective condition. The ability of leaf regeneration and shoot subculture and rooting from the transformed and non-transformed plants in the presence of 50 mg/L kanamycin was examined. The presence of CpTI gene in the transgenic plants were confirmed by PCR and PCR-Southern blot. Assay on proteinase inhibition activity demonstrated that leaf protein extracts of the transgenic poplar showed higher inhibition activity against trypsin than that of control plants.
Abstract (Browse 1729)  |  Full Text PDF       
Construction and Characterization of the Microclone Library from Chromosome 1R in Rye
Author: ZHOU Yi-Hua, DANG Ben-Yuan, WANG Huai, HU Zan-Min, WANG Lan-Lan and CHEN Zheng-Hua
Journal of Integrative Plant Biology 1999 41(12)
    Two and five 1R chromosomes were microdissected from the metaphase spreads of rye ( Secale cereale L. ) root-rip cells with the aids of glass needles. The dissected chromosomes were amplified in vitro by the Sau3A linker adaptor mediated PCR technique, by which 0.3 to 2.5 kb smear DNA fragments were obtained. After hybridized with DIG labeled probes, it was confirmed that the PCR products of the microdissected chromosomes were homologous with the rye genomic DNA, and derived from the 1R chromosome as well. Then, the second round PCR products from five chromosomes of 1R were microcloned to construct the plasmid library, including 220 000 clones. 172 randomly selected clones were evaluated ranged in size from 300 to 1 800 bp. Furthermore, the genomic dot hybridization results indicated that the library contained nearly 42% medium/high repetitive sequences and 58% low/single copy sequences, and its redundancy was very low. In this research, many aspects of the 1R chromosome microclone library exceeded or approached those of the previous reports in the literatures. Those are potential for construction of a high density genetic map of chromosome IR, from which some important genes can be tagged and isolated.
Abstract (Browse 1787)  |  Full Text PDF       
Identification of Zea diploperennis Chromosome Fragments Introgressed to Maize via Genomic in Situ ª©Hybridization
Author: WANG Ling, SONG Yun-Chun, NING Shun-Bin, LIU Li-Hua, GU Ming-Guang and GUO Le-Qun
Journal of Integrative Plant Biology 1999 41(12)
    Zea diploperennis Doebley (DP) chromosome fragments introgressed to maize ( Zea mays L. ) were identified by genomie in situ hybridization in the stable alloplasmic pure line 540 and its hybrid Fl, Yidan 6 was obtained by crossing with maize inbred line. Diaminobenzidine tetrahydrochloride (DAB) and fluorescence staining systems were utilized for detection of the hybridization signals respectively, and both of them gave almost the same results. The hybridization signals of DP elm)matin were showed on the long arms of two members for each of chromosomes 1, 2, 5, and 8 in pure line 540 and on those of only one member for each of chromosomes 1, 2, and 8 in Yidan 6. Not only located DP chromatin on the same chromosome arms but also their percentage distances from the centromeres to the hybridization sites were close to each other for chromosomes I and 2 between pure line 540 and Yidan 6. The percentage distance of the signal on the long ann of chromosome 8 was notably shorter in Yidan 6 than in 540. The differences of the signal distribution between pure line 540 and Yidan 6 were discussed.
Abstract (Browse 1881)  |  Full Text PDF       
Ultrastructural Alteration of Host Plants Infected with Tomato Mosaic Virus
Author: HONG Jian, XUE Chao-Yang, XU Ying, ZHOU Xue-Ping and LI De-Bao
Journal of Integrative Plant Biology 1999 41(12)
    The ultrastructural aheration of two host plants infected with tomato mosaic virus (ToMV) were studies with transmission electron microscopy. A large number of virus particles were found being accumulated in different cells such as epidermis, parenchyma cells and vascular bundle cells of Lycopersicon esculentum Mill. grown at 25¡æ Crystalline inclusions and paracrystal inclusions composed of ToMV particles were observed in the cytoplasm or vacuoles. Some muhivesicular bodies and myeloid bodies protming into the vacuole and vires-specific vesicles associated with the tonoplast were also observed. The ultrastructuml alteration of Nicotiana tabacum L. tv. Xanthinn was similar to that in tomato infected by ToMV grown at 25 cE. In addition to the aggregate inclusions described above, some cytoplasmic angularly-layered aggregates and abnormal chloroplasts with small peripheral vesicles were observed in the parenchyma cells. The densely stained amorphous material was seen in the cytoplasm of N. tabacum L. cv. Xanthiun grown at 35¡æ. No X- body was observed in the cytoplasm of the ToMV infected tomato and tobacco grown at 25¡æ or 35¡æ. The authors' results suggest a significant difference between the cytopathological effects of ToMV and tobacco mosaic virus (TMV). These characteristic difference may be useful in the virus diagnosis and identification virus infections in plants.
Abstract (Browse 1905)  |  Full Text PDF       
Ontogeny of Staminate and Carpellate Flowers of Schisandra sphenanthera(Schisandraceae)
Author: LIU Zhong and LU An-Ming
Journal of Integrative Plant Biology 1999 41(12)
    The ontogenetic process of the staminate and carpellate flowers of Schisandra sphenanthera Rehd. et Wils., an endemic species to China, was observed for the first time under the scanning electron microscope (SEM). In the staminate flowers, the perianth units and stamens were initiated acropetally in a continuous fasion with 2/5 spiral phyllotaxis, while no female structures were formed. Anthers were differentiated prior to the filaments formation. Throughout all the stages were the stamens arranged spirally on a columniform receptacle. In the carpellate flowers, the initiation sequence of the perianth units and carpels were similar to that of the staminate flowers. In contrast, no male structures were formed. Shortly after initiation, the carpel primordia began their marginal growth besides the apical growth and then appresses were formed on the adaxial surfaces of the primordia. However the lower margins of these appresses were inconspicuous, resulting in conduplicate carpels. Two ovules were developed on the inner surface near either lateral margins of the carpel, shaping laminar placentae. Compared with S. glabra (Brickell) Rehd., a related American species, the evolutionary trend of phyllotaxis of androecia is considered that stamens may change from spiral to approximately whorled arrangement, accompanying with the change of receptacle from a column to a flattened shield. It was also suggested that the stamens being numerous and uncertain in number become certain and decrease in number to 5 (4£­7). Sterile stamens are observed and the unisexual nature of the flowers is discussed. Two types of carpel primordia are categorized, corresponding to two types of carpels, namely, ascidiate and conduplicate carpels, respectively.
Abstract (Browse 2138)  |  Full Text PDF       
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