Stomata Area Research Articles

Ultrastructure and Estrogen Regulation of the Lymphatic Stomata of Ovarian Bursa in Mice

The ovarian bursa is a key player in maintaining adaptive ovarian microenvironment for ovulation. The lymphatic stomata are believed to be a major contributor to execute the function of the ovarian bursa, whereas little is known about their ultrastructure and regulation. Here, we examined the ultrastructure of lymphatic stomata in mouse ovarian bursa by scanning electron microscopy and transmission electron microscopy and investigated its regulation by estrogen. We found that the mesothelium on the visceral layer of mouse ovarian bursa was composed of the cuboidal and flattened cells. The lymphatic stomata with round and oval shapes were mainly among the cuboidal cells. The particles, cells, and fluid passed through the stomata and entered into the lymphatic drainage unit composed of connective tissue and lymphatic endothelial cells beneath the stomata. We also used trypan blue as a tracer and found that the absorption of trypan blue through the lymphatic stomata was increased by estrogen that enlarged the average opening area of lymphatic stomata. Furthermore, we detected that there existed estrogen receptors in the nuclei of the mesothelial cells on the visceral ovarian bursa by using immunoelectron microscopy. Taken together, these data suggest that both the absorption and opening area of the lymphatic stomata in mouse ovarian bursa may be influenced by estrogen.

Evaluation and selection of elite clonal genotypes of the sweet crop licorice (Glycyrrhiza glabra) in a new environment

The adaptability and vigour of exotic licorice,Glycyrrhiza glabra, as a source of sugar substitute in the subtropics of Papua New Guinea (PNG) was monitored from seed germination to 3-month in the greenhouse and to 12-month in the field. The germination potential of sulphuric acid-scarified seeds was significantly (p>0.01) higher than un-scarified. A total of 120 early-germinated seeds were selected and maintained in greenhouse for 3-month. In a stepwise manner, 65 plants with Biomass Fresh Weight (BFW) = average were initially selected, out of which 36 with Root Fresh Weight (RFW) = average were further selected, from which 12 plants with and Root Bulk Density (RBD) = average + SD were finally selected; namely P2, P5, P14, P23, P33, P37, P49, P58, P83, P94, P112 and P118. Clonal stock lines of the 12 selected genotypes (L2 to L118) were established by shoot culture. The agronomical vigour of the clonal genotypes was tested at four time points over 12-month under open field conditions and rainfall averaged 275 mm/month and frequent dry spills. Means of parameters measured increased over the growth period, where rootstock grew steadly, and then growth was directed to shoot recovery until reached a balance. Based on a novel value named Principle Selection Index, (PSI=RFW x RBD), three genotypes including L58 followed by L112 and subsequently L 33 were selected and multiplied to a clonal stockin vitro. No common direct relation was found between the vigour and physiological attributes to drought tolerance. However, the low stomata area of L33 and L58 may have played a role in their vigour, especially L58, which showed extremely low peroxidase activity, a characteristic of higher level of drought tolerance, compared to that of L33 and L112. The three genotypes were the lowest in chlorophyll “a” and “b” content showing no special evidence of better photosynthetic apparatus compared to the other genotypes. The agro-physiological advantages of the selected lines, especially L58 suggest their potential as a new crop, at least in the low land of PNG for its economically important rootstock as a source of sugar-substitute in dietary food.

Patchy stomatal behavior in broad-leaved trees grown in different habitats

Effects of heterogeneity in stomatal behavior on gas-exchange characteristics of leaves from four tree species growing in different climates, including temperate, tropical monsoon and tropical rain forest, were investigated by combining gas-exchange measurements and the pressure-infiltration method. Field observations indicated linear relationships between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area (open stomata area) in Dipterocarpus sublamellatus Foxw. and Neobalanocarpus heimii (King) Ashton in a tropical rain forest in Peninsular Malaysia, whereas the ratio of infiltrated to non-infiltrated area rapidly increased up to the whole-leaf conductance at which the entire leaf was infiltrated in Cinnamomum camphora Sieb. in a temperate evergreen forest in Japan and in Azadirachta indica Juss. in a tropical monsoon area in Thailand. These results strongly suggest small ranges in bell-shaped stomatal conductance distributions in C. camphora and A. indica and bimodal stomatal conductance distributions in D. sublamellatus and N. heimii. The values of normalized maximum carboxylation rate at 25 degrees C (V(cmax25)) derived from gas-exchange measurements were not constant, but decreased with decreasing whole-leaf conductance in D. sublamellatus and N. heimii. A gas-exchange model analysis revealed a linear relationship between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area for bimodal stomatal conductance distributions, whereas for bell-shaped distributions, the relationships were nonlinear. Midday depression of apparent V(cmax25) in these species was mainly caused by bimodal stomatal closure. The bimodal stomatal distribution model could also explain diurnal changes in photosynthetic assimilation and transpiration rates in these species.

Sensitivity of Response to Abscisic Acid Affects the Power of self-thinning in Arabidopsis thaliana

本文以兩個擬南芥脫落酸突變體（abil-1，脫落酸不敏感型；eral-2，對脫落酸超敏感型）為試驗材料，研究了脫落酸敏感性對擬南芥群體的自疏指數的效應。結果顯示，abil-1的自疏指數小於野生型且eral-2的自疏指數大於野生型。資源利用的兩個參數（l根距中部葉片的平均高度；α全部葉片面積）也表明，在密度脅迫條件下eral-2對資源利用優於abil-1。葉片光資源利用的參數（光合速率，光合指數PSI），水分損失（如蒸騰速率，氣孔導度）及水分利用率的結果與上述兩個參數（1和α）相一致，這表明脫落酸敏感性通過資源利用（光和水）影響擬南芥群體的自疏指數。

DIURNAL CHANGES OF PHOTOSYNTHETIC CHARACTERISTICS AND CHLOROPHYLL FLUORESCENCE IN CANOPY LEAVES OF FOUR DIPTOCARP SPECIES UNDER EX_SITU CONSERVATION

Dipterocarps dominate the canopy of tropical rainforest of Southeast Asia. They are not only the world's main source of hardwood timber, but their canopy leaves are main organs for global carbon sequestration. Due to anthropogenic activities, many species of dipterocarps are threatened. Because of this situation, ex-situ conservation efforts were employed to conserve the genetic resources of several dipterocarps. In this study, four dipterocarp species, Dipterocarpus retusus, Hopea hainanensis, Parashorea chinensis (emergent tree species in the rainforest) and Vatica xishuangbannaensis, were selected as study species that had been transplanted in 1981 to an ex-situ dipterocarp conservation forest in Xishuangbanna Tropical Botanical Garden. We measured the diurnal changes in photosynthetic rates, parameters of chlorophyll fluorescence, and morphological traits of their canopy leaves at 15-21 m height during the rainy season of 2004. The results indicated that the maximum photosynthetic rates (Pmax) per unit leaf area (7.5 to 18.1 μmol·m~-2·s~-1) and mass (89.08 to 150.82 nmol·g~-1 DW·s~-1), dark respiration rates (Rd), light saturation point (LSP), light compensation point (LCP) and leaf morphological traits differed significantly among species. Photosynthesis in the four species was depressed at midday. The results revealed that stomatal closure induced by high leaf-to-air vapor pressure deficit (LAVPD) led to photosynthetic depression at midday. Quantum yields of photosystem II (ΦPSⅡ) in four dipterocarp species decreased significantly at midday, indicating that photoinhibition occurred. However, their PSⅡ values recovered to the early morning value by sunset, indicating that photoinhibition was reversible. The nonphotochemical quenching rate (NPQ) increased significantly in D. retusus, H. hainanensis and V. xishuangbannaensis, indicating that NPQ was used mainly to dissipate excess light energy absorbed by PSⅡ. At midday, the electron transport rate (ETR) in P. chinensis was maintained at high levels, while its photosynthetic rate decreased, suggesting that a large proportion of electrons were allocated to photorespiration. Thus photorespiration was the main mechanism protecting the photosynthetic apparatuses of P. chinensis during the midday photosynthesis depression. Other parameters, such as leaf area, size and density of stomata, and total chlorophyll content, also were measured at the same time. There was a general ranking of Pmax in the following order from highest to lowest: D. retusus, P. chinensis, H. hainanensi, V. xishuangbannaensis. Based on the diurnal changes in chlorophyll fluorescence, both leaf stomatal limitations and non-stomatal effects played an important role to prevent photodamage during the midday depression of photosynthesis brought by the high irradiances, high air temperature, low humidity, and so on. The high midday leaf water potential of the four species showed that water limitations had no influence on photosynthetic rates.

Study of chinese herbal medicine in treating ascites and its mechanism in regulating lymphatic stomata

To study the therapeutic effect of Chinese herbal medicines (CHM) in treating ascites to elucidate its mechanism in regulating the lymphatic stomata and promoting the absorption of ascites from the peritoneal cavity. Using scanning electron microscope (SEM) and computerized image processing and quantitative analysis assays, the CHM extract consisting of Atractylodes macrocephala, Salvia miltiorrhiza, Codonopsis pilosula, Alismatis orientale and Leonurus heterophyllus were studied. Intraperitoneal injection of nitric oxide (NO) supplier or CHM administration could cause the average area of lymphatic stomata obviously enlarged (P < 0.05), and the open numbers significantly increased (P < 0.01) in normal healthy mice. When L-notroarginine, a NO synthetase suppressor, was injected after CHM administration, it was found that the regulating effect of CHM on lymphatic stomata was inverted obviously, i.e. the average area and the density of lymphatic stomata were markedly reduced (P < 0.01). CHM might treat ascites through increasing the endogenous NO concentration to open the lymphatic stomata and in turn to conduct the peritoneal water through lymphatic path.

Carbon Production of Sunflower Cultivars in Field and Controlled Environment. II. Leaf Growth

In field studies of several cultivars of sunflower grown on stored soil moisture or with irrigation, yield was positively related to leaf area at anthesis. The regression which described this relationship stated that 1370 kg seed ha-1 were associated with a unit increment in leaf area index. Cultivars differed in final leaf number, rate of leaf appearance, and in the vertical distribution of leaf area in the profiles. Final leaf number of plants grown on stored moisture remained the same as in irrigated plants, but the period for which each leaf grew was reduced from 19 to 16 days while the average growth rate was reduced from 13 to 6 cm2 day-1. These changes reduced the final leaf area from 5700 to 1900 cm2 per plant. As water stress increased, the period when leaves grew fastest became progressively earlier, from approximately 35% Amax to when leaves were less than 5 cm2. Water stress increased stomatal frequencies but reduced the area of individual stomata so that the area of the stomatal apparatus per unit leaf area was unchanged. This may partially explain the constancy of peak gas exchange per unit leaf area of sunflower grown under different water regimes. There was evidence that leaves could recommence growth when the stress was alleviated.

Observações citológicas em citrus: V. poliploidia em relação à densidade e ao tamanho dos estomas em Citrus e outros gêneros das Aurantioideae.

No presente trabalho dois aspectos diversos são analisados referentes às relações entre poliploidia e os caracteres dos estomas em Citrus e outros gêneros próximos. Na primeira parte analisam-se os dados apresentados por Hirano (5) sôbre a densidade dos estomas em numerosos representantes da sub-família das Aurantioidex à luz da sua constituição citológica. Esperava-se poder explicar a grande variabilidade desta densidade, pela possível existência de formas poliplóides. A contagem dos cromosômios de muitas plantas por êle utilizadas na Estação Experimental de Riverside, Califórnia, e uma extensa pesquisa bibliográfica, visando esclarecer a constituição cromosômica daquelas variedades, espécies e gêneros que não puderam ser analisados, revelaram, porém, que, provàvelmente, apenas no grupo de Citrus aurantifolia Swingle, existem duas variedades triplóides, sendo tôdas as demais diplóides. Sòmente naquele caso é que a variabilidade na densidade dos estornas pôde ser explicada pela diferença no número de cromosômios. No restante do material estudado por Hirano, as diferenças no número de estornas por unidade de área devem ser atribuídas, de preferência, a grande variabilidade da constituição genética. Na segunda parte apresentam-se os resultados de uma detalhada análise sôbre a área dos estomas e a sua variabilidade em formas cítricas di- tri- e tetraplóides, numa tentativa de separar êstes poliplóides sem recorrer à contagem dos cromosômios. Um total de 36 indivíduos pertencendo a 5 espécies diferentes foram estudados. Agrupando-se cs valores obtidos em ordem decrescente de área dos estornas, verifica-se uma série contínua, associando-se, entretanto, os di- tri- e tetraplóides em três grupos separados. Notaram-se diferenças estatisticamente significantes tanto entre as médias dos três grupos, como entre os limites extremos de grupos consecutivos e também dentro dêles. A variabilidade dêste caráter também se manifesta dentro de cada uma da maioria das espécies e grupos di- e tetraplóides. A-pesar disso, entretanto, chegou-se à conclusão de que a determinação da área dos estornas poderá ser útil mesmo no caso em que se queira separar triplóides de tetraplóides, da mesma progênie, conhecendo-se a área dos estornas das respectivas formas diplóides em idênticas condições de meio.