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971.
The K+/H+ antiporter LeNHX2 increases salt tolerance by improving K+ homeostasis in transgenic tomato 总被引:1,自引:0,他引:1
RAÚL HUERTAS LOURDES RUBIO OLIVIER CAGNAC MARÍA JESÚS GARCÍA‐SÁNCHEZ JUAN DE DIOS ALCHÉ KEES VENEMA JOSÉ ANTONIO FERNÁNDEZ MARÍA PILAR RODRÍGUEZ‐ROSALES 《Plant, cell & environment》2013,36(12):2135-2149
The endosomal LeNHX2 ion transporter exchanges H+ with K+ and, to lesser extent, Na+. Here, we investigated the response to NaCl supply and K+ deprivation in transgenic tomato (Solanum lycopersicum L.) overexpressing LeNHX2 and show that transformed tomato plants grew better in saline conditions than untransformed controls, whereas in the absence of K+ the opposite was found. Analysis of mineral composition showed a higher K+ content in roots, shoots and xylem sap of transgenic plants and no differences in Na+ content between transgenic and untransformed plants grown either in the presence or the absence of 120 mm NaCl. Transgenic plants showed higher Na+/H+ and, above all, K+/H+ transport activity in root intracellular membrane vesicles. Under K+ limiting conditions, transgenic plants enhanced root expression of the high‐affinity K+ uptake system HAK5 compared to untransformed controls. Furthermore, tomato overexpressing LeNHX2 showed twofold higher K+ depletion rates and half cytosolic K+ activity than untransformed controls. Under NaCl stress, transgenic plants showed higher uptake velocity for K+ and lower cytosolic K+ activity than untransformed plants. These results indicate the fundamental role of K+ homeostasis in the better performance of LeNHX2 overexpressing tomato under NaCl stress. 相似文献
972.
Pierre L. van den Berghe Walker Connor A. H. M. Kirk‐Greene Robert Mahuta Robert Miles John Beattie 《Ethnic and racial studies》2013,36(4):484-498
Milton M. Gordon, HUMAN NATURE, CLASS AND ETHNICITY. London and New York, Oxford University Press, 1978, 302 pp., £6.50, $11.95 ($3.50 paper). June Teufel Dreyer, CHINA'S FORTY MILLIONS: MINORITY NATIONALITIES AND NATIONAL INTEGRATION IN THE PEOPLE'S REPUBLIC OF CHINA. Cambridge (Mass.) and London, Harvard University Press, 1976, 333 pp., £9.55. W. Stanford Reid (ed), THE SCOTTISH TRADITION IN CANADA. Toronto, McClelland & Stewart, 1976, xi + 324 pp., $12.55. I. H. Kawharu, MAORI LAND TENURE: STUDIES OF A CHANGING INSTITUTION. Oxford, Clarendon Press, 1977, 362 pp., £13.50. David T. Wellman, PORTRAITS OF WHITE RACISM. London, Cambridge University Press, 1977, 254 pp., £9.50 (£4.00 paper). Lucy Mair, AFRICAN KINGDOMS. Oxford, Clarendon Press, 1977, 151 pp., £3.95, (£1.95 paper). Roger Scott, NORTHERN IRELAND: THE POLITICS OF VIOLENCE. Canberra Series in Administrative Studies 2., Canberra College of Advanced Education, 1977, 84 pp., n.p. James A. Geschwender, CLASS, RACE AND WORKER INSURGENCY: THE LEAGUE OF BLACK REVOLUTIONARY WORKERS. London, Cambridge University Press, 1977, 249 pp., £8.50 (£3.50 paper). Crawford Young, THE POLITICS OF CULTURAL PLURALISM. Madison, University of Wisconsin Press, 1976. 560 pp., £13.60. D. C. R. A. Goonetilleke, DEVELOPING COUNTRIES IN BRITISH FICTION. London, Macmillan, 1977, 282 pp., £8.95. M. M. Mahood, THE COLONIAL ENCOUNTER. London, Rex Collings, 1977, 210 pp., £4.75. Brian V. Street, THE SAVAGE IN LITERATURE. London, Routledge & Kegan Paul, 1975, 207 pp., £5.75. 相似文献
973.
Rubia austrozhejiangensis Z. P. Lei, Y. Y. Zhou & R. W. Wang, a new species of Rubiaceae from China, is described and illustrated. The new species is similar to R. ovatifolia Z. Ying Zhang and R. argyi (H. Lév. & Vaniot) H. Hara ex Lauener, but differs from the former in having stems and branches cylindrical, not quadrate‐angled, long‐ovate to ovate‐lanceolate leaf blades, many‐flowered inflorescence, and smaller mericarps, 3–4 mm in diameter. In R. ovatifolia, stems and branches are quadrate‐angled, leaf blades ovate, ovate‐cordate to rounded cordate, and the inflorescences are sparsely flowered. Compared to R. argyi, the new species has cylindrical, not quadrate‐angled stems and branches, leaf blades that are long‐ovate to ovate‐lanceolate, 3–5‐veined, and slightly reflexed corolla lobes. In R. argyi, stems and branches are quadrate‐angled or winged, the corolla lobes are spreading, and the mericarps are 5–7 mm in diameter. 相似文献
974.
A new species is added to the monotypic African genus Djinga. Djinga cheekii Ghogue, Huber & Rutish. (Podostemaceae) is described as a new species from Cameroon (Littoral Province) and its morphological affinities and conservation status are assessed. The main distinguishing characters are: stamens 2 (not 1 as in D. felicis), flower buds inside spathella strongly inclined (not only slightly inclined as in D. felicis), and stems lacking or only up to 6 mm long (not up to > 6 cm as in D. felicis). A molecular analysis revealed that D. cheekii is sister to D. felicis, and both together are sister to Ledermanniella linearifolia and L. pusilla which show completely inverted flower buds inside the spathella, as typical for the large and still artificial genus Ledermanniella. 相似文献
975.
AGATHE COURTEILLE GILLES INNOCENTI FRANÇOISE EYMERY DOMINIQUE RUMEAU EMMANUELLE ISSAKIDIS‐BOURGUET PASCAL REY 《Plant, cell & environment》2013,36(3):670-682
Methionine (Met) in proteins can be oxidized to two diastereoisomers of methionine sulfoxide, Met‐S‐O and Met‐R‐O, which are reduced back to Met by two types of methionine sulfoxide reductases (MSRs), A and B, respectively. MSRs are generally supplied with reducing power by thioredoxins. Plants are characterized by a large number of thioredoxin isoforms, but those providing electrons to MSRs in vivo are not known. Three MSR isoforms, MSRA4, MSRB1 and MSRB2, are present in Arabidopsis thaliana chloroplasts. Under conditions of high light and long photoperiod, plants knockdown for each plastidial MSR type or for both display reduced growth. In contrast, overexpression of plastidial MSRBs is not associated with beneficial effects in terms of growth under high light. To identify the physiological reductants for plastidial MSRs, we analyzed a series of mutants deficient for thioredoxins f, m, x or y. We show that mutant lines lacking both thioredoxins y1 and y2 or only thioredoxin y2 specifically display a significantly reduced leaf MSR capacity (–25%) and growth characteristics under high light, related to those of plants lacking plastidial MSRs. We propose that thioredoxin y2 plays a physiological function in protein repair mechanisms as an electron donor to plastidial MSRs in photosynthetic organs. 相似文献
976.
977.
JUAN LI YONG‐BO DUAN HAO LI YA‐CHUN YANG RUI‐YING QIN LI LI PENG‐CHENG WEI JIAN‐BO YANG 《Plant, cell & environment》2013,36(4):775-788
Mitochondrial retrograde regulation (MRR) is the transduction of mitochondrial signals to mediate nuclear gene expression. It is not clear whether MRR is a common regulation mechanism in plant abiotic stress response. In this study, we analysed the early abiotic stress response of the rice OsAOX1 genes, and the induction of OsAOX1a and OsAOX1b (OsAOX1a/b) was selected as a working model for the stress‐induced MRR studies. We found that the induction mediated by the superoxide ion (O2·‐)‐generating chemical methyl viologen was stronger than that of hydrogen peroxide (H2O2). The addition of reactive oxygen species (ROS) scavengers demonstrated that the stress induction was reduced by eliminating O2·‐. Furthermore, the stress induction did not rely on chloroplast‐ or cytosol‐derived O2·‐. Next, we generated transgenic plants overexpressing the superoxide dismutase (SOD) gene at different subcellular locations. The results suggest that only the mitochondrial SOD, OsMSD, attenuated the stress induction of OsAOX1a/b specifically. Therefore, our findings demonstrate that abiotic stress initiates the MRR on OsAOX1a/b and that mitochondrial O2·– is involved in the process. 相似文献
978.
YAN‐SHIH LIN AIMEE BOURNE BELINDA E. MEDLYN DAVID S. ELLSWORTH 《Plant, cell & environment》2013,36(2):262-274
Models of stomatal conductance (gs) are based on coupling between gs and CO2 assimilation (Anet), and it is often assumed that the slope of this relationship (‘g1’) is constant across species. However, if different plant species have adapted to different access costs of water, then there will be differences in g1 among species. We hypothesized that g1 should vary among species adapted to different climates, and tested the theory and its linkage to plant hydraulics using four Eucalyptus species from different climatic origins in a common garden. Optimal stomatal theory predicts that species from sub‐humid zones have a lower marginal water cost of C gain, hence lower g1 than humid‐zone species. In agreement with the theory that g1 is related to tissue carbon costs for water supply, we found a relationship between wood density and g1 across Eucalyptus species of contrasting climatic origins. There were significant reductions in the parameter g1 during drought in humid but not sub‐humid species, with the latter group maintaining g1 in drought. There are strong differences in stomatal behaviour among related tree species in agreement with optimal stomatal theory, and these differences are consistent with the economics involved in water uptake and transport for carbon gain. 相似文献
979.
Arabidopsis thaliana acyl‐CoA‐binding protein 2 (ACBP2) is a stress‐responsive protein that is also important in embryogenesis. Here, we assign a role for ACBP2 in abscisic acid (ABA) signalling during seed germination, seedling development and the drought response. ACBP2 was induced by ABA and drought, and transgenic Arabidopsis overexpressing ACBP2 (ACBP2‐OXs) showed increased sensitivity to ABA treatment during germination and seedling development. ACBP2‐OXs also displayed improved drought tolerance and ABA‐mediated reactive oxygen species (ROS) production in guard cells, thereby promoting stomatal closure, reducing water loss and enhancing drought tolerance. In contrast, acbp2 mutant plants showed decreased sensitivity to ABA in root development and were more sensitive to drought stress. RNA analyses revealed that ACBP2 overexpression up‐regulated the expression of Respiratory Burst Oxidase Homolog D (AtrbohD) and AtrbohF, two NAD(P)H oxidases essential for ABA‐mediated ROS production, whereas the expression of Hypersensitive to ABA1 (HAB1), an important negative regulator in ABA signalling, was down‐regulated. In addition, transgenic plants expressing ACBP2pro:GUS showed beta‐glucuronidase (GUS) staining in guard cells, confirming a role for ACBP2 at the stomata. These observations support a positive role for ACBP2 in promoting ABA signalling in germination, seedling development and the drought response. 相似文献
980.
YONG‐JIANG ZHANG FREDERICK C. MEINZER JIN‐HUA QI GUILLERMO GOLDSTEIN KUN‐FANG CAO 《Plant, cell & environment》2013,36(1):149-158
Midday depressions in stomatal conductance (gs) and photosynthesis are common in plants. The aim of this study was to understand the hydraulic determinants of midday gs, the coordination between leaf and stem hydraulics and whether regulation of midday gs differed between deciduous and evergreen broadleaf tree species in a subtropical cloud forest of Southwest (SW) China. We investigated leaf and stem hydraulics, midday leaf and stem water potentials, as well as midday gs of co‐occurring deciduous and evergreen tree species. Midday gs was correlated positively with midday stem water potential across both groups of species, but not with midday leaf water potential. Species with higher stem hydraulic conductivity and greater daily reliance on stem hydraulic capacitance were able to maintain higher stem water potential and higher gs at midday. Deciduous species exhibited significantly higher stem hydraulic conductivity, greater reliance on stem capacitance, higher stem water potential and gs at midday than evergreen species. Our results suggest that midday gs is more associated with midday stem than with leaf water status, and that the functional significance of stomatal regulation in these broadleaf tree species is probably for preventing stem xylem dysfunction. 相似文献