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1.
《Plant Production Science》2013,16(5):567-577
AbstractThe changes in chloroplast ultrastructure and the contents of chlorophyll, Na and K in response to salinity stress were investigated in leaves of maize, an NADP-malic enzyme-type C4 plant species possessing dimorphic chloroplasts. The seedlings were treated with 0, 1, 2 or 3% NaCl for three or five days under a light or dark condition. In both light and dark conditions, the dry weight of salt-treated plants decreased as NaCl concentration increased. Chlorophyll and K contents of the second leaf blade decreased as NaCl concentration increased under the light condition but not under the dark condition. Na content of the second leaf blade was significantly higher at high NaCl concentrations under both light and dark conditions. However, Na content was much lower under the dark condition than light condition. Higher concentrations (2 and 3%) of NaCl significantly increased the size of plastoglobules, decreased the number and size of starch granules and altered the chloroplast ultrastructure. Under the light condition, mesophyll cell (MC) chloroplasts appeared more sensitive to the damaging effect of salinity than the bundle sheath cell (BSC) chloroplasts. MC chloroplasts became more globular in shape and showed swollen and disorganized thylakoids and reduced thickness of grana by salinity. BSC chloroplasts were less affected by salinity than MC chloroplasts. Although chloroplast size and number and size of starch granules were reduced, there was no structural distortion in the thylakoids of BSC chloroplasts. However, the thickness of grana was increased by salinity. Under the dark condition, the chloroplast structure was less affected by salinity. Though the envelope of BSC chloroplasts was occasionally damaged, the thylakoids in both MC and BSC chloroplasts were preserved under salinity stress. The present study suggests that the chloroplast damage caused by salinity is light-dependent and MC chloroplasts are more sensitive to salinity than BSC chloroplasts. 相似文献
2.
《Plant Production Science》2013,16(1):139-145
AbstractThe seedlings of Oryza sativa L. cv. Nipponbare grown by hydroponic culture for 3 wks were treated with 75, 100, 150 and 200 mM NaCl for 14, 14, 6 and 3 days, respectively, and examined for chloroplast ultrastructure in the region where chlorophyll fluorescence had been recorded. NaCl treatment decreased the ratio of variable to maximum chlorophyll fluorescence yield (Fv/Fm) and caused swelling of thylakoids. The swelling of thylakoids was quantified by the percentage of the length of swollen thylakoids to the total length of thylakoids. This value was increased with increasing NaCl concentration. Although Fv/Fm decreased at all concentrations of NaCl, the minimal fluorescence yield F0 was not increased by the treatment with 75 or 100 mM NaCl. The percentage of the length of swelling was low at 75 and 100 mM NaCl. On the other hand, F0 increased and the swelling of thylakoids was prominent with 150 and 200 mM NaCl treatment. These results suggest that the decrease in Fv/Fm due to the increase in F0 under salt stress correlates with the ultrastructural damage. The decrease in Fv/Fm due to the increase in F0 is expected to be useful as an indicator to evaluate the damage in chloroplasts, especially in thylakoid membranes, under salinity. 相似文献
3.
Yutaro Makino 《Plant Production Science》2018,21(1):39-50
Nitrogen (N) is one of the major nutrients influencing photosynthesis and productivity of C4 plants as well as C3 plants. C4 photosynthesis operates through close coordination between mesophyll (M) and bundle sheath (BS) cells. However, how the development of structural and physiological traits in leaves of C4 plants is regulated under N limitation remains uncertain. We investigated structural and physiological responses of leaves of the NADP-ME-type C4 grass Sorghum bicolor to N limitation. Plants were grown under four levels of N supply (.05 to .6 g N per 5-L pot). Decreasing N supply resulted in decreases in net photosynthetic rate, stomatal conductance, leaf N and chlorophyll contents, and the activity ratio of phosphoenolpyruvate carboxylase to ribulose 1,5-bisphosphate carboxylase/oxygenase and increases in δ13C values and photosynthetic N use efficiency. Low-N leaves were thinner and had smaller photosynthetic cells, especially in M, resulting in lower M/BS tissue area ratio, and contained smaller and fewer chloroplasts. The BS chloroplasts in the low-N leaves accumulated abundant starch grains. The number of thylakoids per granal stack was reduced in M chloroplasts but not in BS chloroplasts. The low-N leaves had thicker cell walls, especially in the BS cells, which might be associated with less negative δ13C values, and fewer plasmodesmata in the BS cells. These data reveal structural and physiological responses of C4 plants to N limitation, most of which would be related to cellular N allocation, light use, CO2 diffusion and leakiness, and metabolite transport under N limitation. 相似文献
4.
《Plant Production Science》2013,16(1):67-74
SummaryThis paper describes the ultrastructure of the electric field-induced fusion products of C3 and C4 species of Amaranthaceae at the early developmental stage. Protoplasts of C3 species were isolated from a Ceiosia cristata L. cell suspension and, those of C4 species were isolated from an Amaranthus tricolor L. cotyledon. Incompatibility occurred in the C3/C4 hybrid. The incompatibility reactions were detected in the newly formed hybrid cells accompanied with significant changes in the nucleolus (segregation of nucleolar components) and plastids (cup-like shape or amoeboid plastid enclosing cytoplasmic materials) of C3 species parent. The structural changes in the organelles of the C4 partner were less marked. After 5 days of culture, most organelles showed high cellular activity, and a normal dedifferentiation process of mesophyll chloroplasts was observed. At this stage nucleolar segregation was not detected and the C3 species plastids were difficult to distinguish from the proplastids formed from mesophyll chloroplasts. In addition, some mitochondria showed bursting-like structure. However, under the culture condition used these somatic incompatibility did not seem to impair further growth of fusion products since they were still proliferating well resulting in callus formation. 相似文献
5.
以玉米进行C4光合的全展第5位叶片为材料,分析从叶基部到顶部的解剖结构和叶绿素含量变化,研究玉米C4光合叶片"花环"结构随叶片发育的变化规律。结果表明,玉米第5位叶从基部到顶部都具有完整的典型"花环"结构,维管束鞘细胞(BSC)和叶肉细胞(MC)的体积在叶片发育过程中具有渐变性,从叶基部到顶部BSC和MC均呈先增大后变小的趋势,而且叶绿素a、b和a+b含量呈相同的变化趋势,说明BSC和MC细胞体积与叶绿素含量的变化具有相关性。叶绿素a/b总体呈上升趋势,说明玉米第5叶基部到顶部的光合途径存在C3向C4转变的过程。玉米第5叶不同部位C4光合途径发育的渐变性比前3叶更为明显。 相似文献
6.
《Plant Production Science》2013,16(1):70-79
AbstractWe are maintaining five Moricandia arvensis monosomic addition lines of Raphanus sativus carrying R. sativus cytoplasm (autoplasmic MALs) and twelve M. arvensis MALs of R. sativus carrying M. arvensis cytoplasm (alloplasmic MALs) from BC6 to BC8 generation, and newly produced five M. arvensis disomic addition lines of R. sativus (autoplasmic DALs) and seven M. arvensis DALs of R. sativus carrying M. arvensis cytoplasm (alloplasmic DALs) from selfing and sib-crossing of the MALs and DALs in S3BC5 and S2BC6 generations. The structural, biochemical and physiological characteristics related to photorespiration of these MALs and DALs were compared to study the genetic mechanisms of the C3-C4 intermediate photosynthesis in the individual chromosomes of M. arvensis. The CO2 compensation point of the autoplasmic and alloplasmic DALs (RMa-b and MaR-b DALs) with one pair of M. arvensis ‘b’ chromosome were 29.4 and 30.1 μmol mol-1, respectively, which were significantly lower than that of other DALs and MALs as well as R. sativus (34.5 𰂼mol mol-1). An immunogold electron microscopic study of the P-protein of glycine decarboxylase (GDC) in photosynthetic cells of the RMa-b DAL revealed that the bundle sheath cell (BSC) mitochondria were more intensively labeled for the protein than the mesophyll cell (MC) mitochondria. The ratio of the labeling density of the BSC mitochondria to that of the MC mitochondria was 1.13, which lies between values in M. arvensis (2.66) and R. sativus (0.76). These data suggest that the ‘b’ chromosome of M. arvensis genome controls the expression of C3-C4 intermediate characteristics. 相似文献
7.
Among various physiological responses to salt stress, the synthesis of a lectin-related protein of 14.5 kDa was observed in rice plants (Oryza sativa L.) under the treatment of 170 mmol/L NaCl. In order to better understand the role of the SALT protein in the physiological processes involving salinity, it was immunolocalized in mesophilic cells of leaf sheath and blade of a rice variety IAC-4440 following monoclonal antibodies produced by hybridome culture technique. This variety turned out to be an excellent model for that purpose, since it accumulates SALT protein even in absence of salt treatment and it has been classified as moderately sensitive to salinity and a superior grain producer. This feature was relevant for this work since it allowed the use of plants without the deleterious effects caused by salinity. Immunocytochemistry assays revealed that the SALT protein is located in the stroma of chloroplasts under non-stressing condition. Since the chloroplast is the main target affected by salinity and considering that the SALT protein does not present any apparent signal peptide for organelle localization, its lectin-like activity seems to play an important role in the establishment of stable complexes, either to other proteins or to oligosaccharides that are translocated to the chloroplast. 相似文献
8.
ABSTRACTThe successful introduction of the C4 pathway into C3 crops would increase photosynthetic rates and crop productivity. However, our poor understanding of how Kranz leaf anatomy develops poses a great obstacle. In particular, the origin, development, and genetics of bundle sheath (BS) cells in C4 plants are key points to elucidate. Here we report that Elymus tsukushiensis, a common C3 grass of the subfamily Pooideae, contains chloroplasts in the mestome sheath (MS) cells of the leaf, unlike most MS cells of C3 grasses. The chloroplasts are smaller than those of mesophyll cells. Immunogold localization showed that the chloroplasts and mitochondria of MS cells, respectively, accumulate ribulose 1,5-bisphosphate carboxylase/oxygenase and a photorespiratory enzyme, glycine decarboxylase, as in mesophyll cells. Thus, we suggest that the MS cells have weak photosynthetic and photorespiratory functions. This finding provides an insight into the development and evolution of C4-type BS cells in leaves of C3 grasses. 相似文献
9.
《Plant Production Science》2013,16(2):136-144
SummaryUnlike the parent line, the hybrid calli between C3 and C4 species of Amaranthaceae have poor division capability. Therefore, in this study the fine structures of hybrid callus derived from protoplasts of Celosia cristata L. cv. Pink Charm (C3 species) cell suspension and Amaranthus tricolor L. cv. Perfecta (C4 species) cotyledon callus were investigated by light and electron microscopy, and compared with the parental. All callus lines were composed of parenchymatous cells possessing a voluminous vacuole. Parental callus lines contained organelles with a relatively normal structure. The peculiar feature characterizing the C3/C4 hybrid callus was the presence of highly lobed nucleus with multinucleoli and numerous small vacuoles having autophagic activity scattered in the cytoplasm. The autophagic activity is apparently related to the existence of several inclusions such as cytoplasmic organelles in the central vacuole. It might also be related to the pronounced expansion of central vacuole and the reduced cytoplasm. The failure to sustain proliferation related to some atypical features of the organelles is discussed. 相似文献
10.
11.
《Plant Production Science》2013,16(3):319-326
AbstractWe investigated the mechanisms of increased sensitivity to Na+ in the apical and basal regions of the rice leaf under salinity. Three-week-old plants were treated with 200 mM NaCl in hydroponic culture for 3 d. Segments 6 cm in length were obtained from the apical and basal regions of the fully expanded uppermost leaves (6th leaf blades) as old and young tissues, respectively. In the plants exposed to 200 mM NaCl, Nitro blue tetrazolium (NBT) reducing activity, and H2O2 and Malondialdehyde (MDA) contents significantly increased, accompanied by the swelling of thylakoids and destruction of thylakoid membranes in the apical regions. However, no indication of oxidative damages was observed in the basal region, even though the Na+ content in the basal region was comparable to that in the apical region. In the apical region, the capacity to scavenge H2O2 was lower than that in the basal region due to decrease in the constitutive levels of ascorbate peroxidase and guaiacol peroxidase. In addition, the activities of antioxidant enzymes except superoxide dismutase and guaiacol peroxidase decreased drastically after 48 hr of exposure to NaCl. By contrast, the activities of catalase and glutathione reductase in the basal region increased compared with those in the control, and other antioxidant enzymes did not decrease under salinity during the experimental period. These results suggest that the capacity to scavenge reactive oxygen species decreased with age, and thus the apical region of the leaf blade suffered severer damage by Na+ than the basal region. 相似文献
12.
《Plant Production Science》2013,16(3):215-218
AbstractDistribution of Na+ along the root axis under salinity stress was analyzed in two rice (Oryza sativa L.) cultivars with different salt resistance (salt-sensitive IR 24 and salt-resistant Pokkali). Rice plants were grown hydroponically and NaCl was applied with nutrient solution at concentrations of 0, 25 and 50 mM for 7 d after germination. The distribution of Na+ in roots under salinity was analyzed by the cryo time-of-flight secondary ion mass spectrometry (cryo TOF-SIMS). The Na+ content in the root was higher in salt-sensitive IR 24 than in salt-resistant Pokkali under NaCl stress. The content was highest at the root tip and was decreased basipetally along the root axis. The difference in Na+ content between the cultivars was apparent in all regions from the root tip. 相似文献
13.
Zusammenfassung Ver?nderungen in der Blattfeinstruktur als Folge von in verschiedenen Entwicklungsstadien einsetzender Versalzung wurden bei
den Kartoffelsorten Hansa und Clivia mehrmals im Vegetationsablauf untersucht. Die Chloroplasten reagierten am deutlichsten
auf den Salzstre\: ein Abbau der Granastapel, Schwellungen der Thylakoide, mehr und gr?\ere Plastoglobuli sowie St?rkeakkumulation
wurden beobachtet.
‘Hansa’ schien zu Beginn der Vegetationsperiode salzempfindlicher zu sein, da sich hier st?rkere strukturelle Ver?nderungen
zeigten als bei der Sorte Clivia, deren Chloroplasten erst gegen Ende der Vegetationsperiode Beeintr?chtigungen aufwiesen.
Summary The leaves of the potato cultivars Hansa and Clivia were examined by light and electron microscopy after salt treatment. Salt was applied once: a week after emergence, at the beginning of tuber formation, or during tuber development. The salt solution (conductivity 12 mS/cm) contained NaCl and Na2SO4, and was administered to the water capacity of the pots. Leaf samples were taken at three different stages of vegetative development (Figure 1). In leaf sections examined by light microscopy, salt stress resulted in a rounding off of cells, smaller intercellular spaces and a reduction in chloroplast number. With the electron microscope salt-induced changes were more marked in the chloroplasts than other organelles. Salt reduced the numbers and depth of the granastacks and caused a swelling of the thylakoid. Changes in ultrastructure were already apparent before the occurrence of other symptoms in the leaf. The observed changes in the chloroplasts of plants treated with salt were alwas greater in the palisade parenchyma than in the spongy parenchyma (Figure 3a, 3b). The cultivars Hansa and Clivia reacted differently to salt. At the start of the vegetative period ‘Hansa’ (Figure 2b, d) appeared more sensitive than ‘Clivia’ (Figure 2c) with greater ultrastructural changes. By the last sampling date ‘Clivia’ was showing the greatest effects (Figure 4). Large starch grains in the chloroplasts indicated disturbed transport of assimilates. Often there were no grana, but severely swollen thylakoids, usually with disintegrating membranes. Changes in the chloroplasts, especially in the thylakoids, as established by microscopy, presumably affected photosynthetic and assimilative performance.相似文献
14.
《Plant Production Science》2013,16(1):33-44
AbstractThe effects of exogenously applied glycinebetaine on the salt-stress-induced inhibition of growth and ultrastructural damages in rice seedlings were investigated. Glycinebetaine was not effective in alleviating the NaCl-induced inhibition of root growth and rather enhanced the NaCl-induced inhibition. However, it was found to alleviate the inhibition of shoot growth induced by NaCl stress. Concentrations of Na were higher in salt-stressed plants than in unstressed plants. Stressed plants receiving glycinebetaine had a significantly lower Na and higher K concentrations in the shoots than the plants grown without application of glycinebetaine. Salinity induced ultrastructural damages in leaf such as swelling of thylakoids, disintegration of grana stacking and intergranal lamellae and destruction of mitochondria (deficiency of cristae, swelling and vacuolation). Such damages were largely prevented by pretreatment with glycinebetaine resulting in greening of the plants. In roots, the epidermis, cortex and root cap were more sensitive to salt stress than the meristem and stele. The most frequently observed ultrastructural alteration due to NaCl salinity was the formation of many large vacuoles in the root tip and root cap cells. The number of mitochondria was increased and they were aggregated in the cytoplasm of the root tip and root cap cells by treatment with NaCl or NaCl plus glycinebetaine. Glycinebetaine could not prevent the NaCl-induced ultrastructural damages in root cells. The effects of glycinebetaine to mitigate the ultrastructural damages in the chloroplast and mitochondria induced by NaCl might be due to the production of many vacuoles in root cells which may act to store Na and decrease its accumulation in the shoot. 相似文献
15.
Summary Increased potassium (K) fertilization of saline soils has been implicated in alleviating salt stress in plants. We examined
whether varying K concentrations in Murashige & Skoog (MS: 1962) basal medium could affect salt (NaCl) stress in micropropagated
potatoes. Plantlets of cvs Sierra and Russet Burbank were evaluated after 1 month of growth in a medium containing 0. 40,
or 80 mM NaCl and 6,20, or 30 mMK. The medium K was adjusted using KNO3 while total nitrogen was kept constant using NH4NO3. Growth parameters were less affected in Sierra than Russet Burbank, and roots were less affected than shoots, as the medium
salinity increased. Tissue Na levels were greater when the medium K was 6 mM compared with 20 mM MS control. The medium K
concentration 50% greater than MS control did not promote growth and did not limit tissue Na levels. While this should be
confirmed by field assessment, our results suggest that while K deficiency promotes salt damage, its addition beyond the usual
fertilizer recommendations is not beneficial in alleviating salinity stress. 相似文献
16.
Leymus chinensis is a dominant and most promising grass species in the Songnen Grassland of Northern China. Experiments were conducted to determine the effect of temperature, salinity, alkalinity and their interactions on seed germination. Seeds were germinated at four alternating temperatures (10–20, 15–25, 20–30 and 25–35°C), with saline stress (9:1 molar ratio of NaCl:Na2SO4) and alkaline stress (9:1 molar ratio of Na2CO3:NaHCO3). Germination percentage and rate were inhibited by either an increase or decrease in temperature from the optimal temperature range of 20–30°C, and were also inhibited by an increase in salinity and alkalinity at all temperatures. The inhibitory effects of high salinity on germination were greater at 25–35°C, but seeds were subjected to more stress even though the alkalinity was low under this temperature. Recovery percentage was highest at 400 mm salinity at 20–30°C, but only at 100 mm alkalinity, and 25–35°C also resulted in lower recovery percentage under both stresses. Results suggest that saline stress and alkaline stress have different impacts on seed germination and that saline‐alkaline tolerance of L. chinensis seeds is affected by the interactions of temperature and salinity‐alkalinity. Early July sowing in the field is recommended when temperature is optimal and salinity‐alkalinity concentrations are reduced by the high rainfall. 相似文献
17.
《Plant Production Science》2013,16(4):351-359
Abstract: Halophytes can be used as a crop on salinized agricultural land. Suaeda japonica Makino is an annual highly salt-tolerant plant, that inhabits salt marshes in the Ariake Sea, Japan. Accompanying growth, leaves of S. japonica change from green to red with accumulation of a red pigment, betacyanin. To elucidate the physiological roles of betacyanin in S. japonica, we tested the antioxidant capacity of purified betacyanin and leaf extracts containing different levels of betacyanin under oxidative-stress conditions. The assay with 1,1-diphenyl-2-picrylhydrazyl (DPPH) showed that the purified betacyanin had antioxidant activity. H2O2-induced protein oxidation of the leaf extracts was prevented by the addition of betacyanin. The antioxidant enzyme activity decreased in the red leaves, but the content of malondialdehyde (MDA), an oxidative stress marker in the red leaves was nearly the same as that in the green leaves. Betacyanin synthesis was induced under photoinhibition-inducible conditions of low temperature and high-intensity light. These results indicate that betacyanin serves as an antioxidant in S. japonica and that the leaf reddening of this species is a key adaptive strategy for coping with the harsh environmental conditions in salt marshes of the Ariake Sea. 相似文献
18.
Germination responses of the halophyte Chloris virgata to temperature and reduced water potential caused by salinity,alkalinity and drought stress 
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下载免费PDF全文 Chloris virgata is considered a useful grass species for grassland restoration in northern China. However, little information exists concerning the germination responses of this species to temperature and water potential caused by stress conditions. Experiments were conducted in growth chambers to assess the effect of temperature, salinity, alkalinity, drought and the interactions of temperature and stress on seed germination. Seeds were germinated at three diurnal temperature regimes, with four water potentials in NaCl, NaHCO3 and PEG solutions. Results showed that optimal germination under stress occurred at 15–25 °C, and germination percentages and rates were inhibited by either an increase or decrease in temperature from the optimal temperature. The inhibitory effects of the low water potential caused by salinity and drought on germination were greater at 25–35 °C, but seeds were subjected to more stress despite the relatively higher water potential because of the alkalinity at this temperature. The recovery percentage under salinity was highest at ?1·2 MPa at 15–25 °C, and more than 80% of seeds also germinated at this water potential after they were transferred from drought stress. However, seeds lost their viability in higher alkalinities under all temperatures, and at 25–35 °C, there was lower recovery percentage under stress. Results suggest that salinity, alkalinity and drought stress have different impacts on seed germination, and the tolerance to stress of C. virgata seeds is affected by the interactions of temperature and water potential caused by salinity, alkalinity and drought. Chloris virgata shows potential utility as a promising grass species in salinity–alkalinity and drought‐stressed environments. 相似文献
19.
Hiroshi Fukayama Takashi Kobara Keita Shiomi Ryutaro Morita Daisuke Sasayama Tomoko Hatanaka 《Plant Production Science》2013,16(2):296-300
ABSTRACT
Overexpression of Rubisco small subunit (RbcS) of C4 plant, sorghum (sorghum bicolor) was shown to enhance the catalytic turnover rate (k cat) of Rubisco in rice (Oryza sativa). In this study, the effects of other Rubisco small subunits of C4 plants, Napier grass (Pennisetum purpureum) and guinea grass (Megathyrsus maximus) on kinetic properties of Rubisco in rice were studied. The expression levels of Napier grass RbcS (NgRbcS) and guinea grass RbcS (GgRbcS) proteins accounted for 41% and 45% of total RbcS, respectively in homozygous overexpression lines. The k cat and K m for CO2 (Kc) of Rubisco were increased in all transgenic lines. Interestingly, the k cat was markedly higher in NgRbcS homozygous line, whereas K c was notably higher in GgRbcS homozygous line. Although its effects depend on species, these results suggest that the introduction of C4 RbcS are effective approaches to alter the catalytic properties of Rubisco in rice. 相似文献
20.
Yuto Hatakeyama 《Plant Production Science》2016,19(4):540-551
In C3 plants, photosynthetic efficiency is reduced by photorespiration. A part of CO2 fixed during photosynthesis in chloroplasts is lost from mitochondria during photorespiration by decarboxylation of glycine by glycine decarboxylase (GDC). Thus, the intracellular position of mitochondria in photosynthetic cells is critical to the rate of photorespiratory CO2 loss. We investigated the intracellular position of mitochondria in parenchyma sheath (PS) and mesophyll cells of 10 C3 grasses from 3 subfamilies (Ehrhartoideae, Panicoideae, and Pooideae) by immunostaining for GDC and light and electron microscopic observation. Immunostaining suggested that many mitochondria were located in the inner half of PS cells and on the vacuole side of chloroplasts in mesophyll cells. Organelle quantification showed that 62–75% of PS mitochondria were located in the inner half of cells, and 62–78% of PS chloroplasts were in the outer half. In mesophyll cells, 61–92% of mitochondria were positioned on the vacuole side of chloroplasts and stromules. In PS cells, such location would reduce the loss of photorespiratory CO2 by lengthening the path of CO2 diffusion and allow more efficient fixation of CO2 from intercellular spaces. In mesophyll cells, it would facilitate scavenging by chloroplasts of photorespiratory CO2 released from mitochondria. Our data suggest that the PS cells of C3 grasses have already acquired an initial structure leading to proto-Kranz and further C3–C4 intermediate anatomy. We also found that in the Pooideae, organelle positioning in PS cells on the phloem side resembles that in mesophyll cells. 相似文献