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Plant, Cell & Environment

Cover image for Vol. 35 Issue 5

May 2012

Volume 35, Issue 5

Pages 839–1012

  1. Original Articles

    1. Top of page
    2. Original Articles
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      Developmental changes in mesophyll diffusion conductance and photosynthetic capacity under different light and water availabilities in Populus tremula: how structure constrains function (pages 839–856)

      TIINA TOSENS, ÜLO NIINEMETS, VIVIAN VISLAP, HILLAR EICHELMANN and PILAR CASTRO DÍEZ

      Article first published online: 4 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02457.x

      Finite mesophyll diffusion conductance (gm) significantly constrains net assimilation rate (An), but gm variations and variation sources in response to environmental stresses during leaf development are imperfectly known. These results emphasize the importance of gm and its components in determining An variations during leaf development and in response to stress.

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      Combined impacts of irradiance and dehydration on leaf hydraulic conductance: insights into vulnerability and stomatal control (pages 857–871)

      GAËLLE GUYOT, CHRISTINE SCOFFONI and LAWREN SACK

      Article first published online: 14 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02458.x

      The leaf is a hydraulic bottleneck, accounting for a large part of plant resistance. Consequently, the leaf hydraulic conductance (Kleaf) is of key importance in determining stomatal conductance (gs) and rates of gas exchange, and previous studies showed that Kleaf is dynamic with leaf water status and irradiance. For four species, we determined responses of Kleaf and gs to declining leaf water potential under low and high irradiance. For all four species, the Kleaf light response declined from full hydration to turgor loss point. Kleaf and gs differed strongly in their light- and dehydration responses, supporting optimization of hydraulic transport across irradiances, and semi-independent, flexible regulation of liquid and vapour phase water transport with leaf water status.

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      Degradation of seed mucilage by soil microflora promotes early seedling growth of a desert sand dune plant (pages 872–883)

      XUEJUN YANG, CAROL C. BASKIN, JERRY M. BASKIN, WENHAO ZHANG and ZHENYING HUANG

      Article first published online: 13 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02459.x

      Each plant species has evolved its own complex of adaptive life history strategies for survival. Seed coat mucilage is thought to play an ecologically important role in seed dispersal of desert plants. Here, we report that the seed mucilage of Artemisia sphaerocephala, a dominant pioneer species inhabiting moving desert sand dunes functions by aiding early seedling growth of this species in barren sandy soils through uptake of derivatives resulting from mucilage biodegradation by the soil microbial community. Our study defines a role of mucilage in the plant life cycle that heretofore has been overlooked.

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      Vertical gradient in soil temperature stimulates development and increases biomass accumulation in barley (pages 884–892)

      K. FÜLLNER, V. M. TEMPERTON, U. RASCHER, S. JAHNKE, R. RIST, U. SCHURR and A. J. KUHN

      Article first published online: 13 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02460.x

      In nearly all experiments with living plants the temperature of root system and shoot are identically or spatially uniform. But this is not the case outside under field conditions, where temperature in the soil is heterogeneous. Under controlled conditions we found that this abiotic parameter has a strong effect on root distribution and dynamic of biomass production of barley.

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      An ATP signalling pathway in plant cells: extracellular ATP triggers programmed cell death in Populus euphratica (pages 893–916)

      JIAN SUN, CHUN-LAN ZHANG, SHU-RONG DENG, CUN-FU LU, XIN SHEN, XIAO-YANG ZHOU, XIAO-JIANG ZHENG, ZAN-MIN HU and SHAO-LIANG CHEN

      Article first published online: 6 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02461.x

      Extracellular ATP (eATP) acts as a signalling agent in plant growth and defence, but its role in programmed cell death (PCD) is less known. Using a wide range of fluorescence microscopic imaging techniques and non-invasively Ca2+-selective microelectrodes, we elucidated the eATP signalling cascade active in PCD of Populus euphratica cultures. The eATP-induced PCD was mediated by a series of signaling events, such as purinergic receptor activation, intracellular Ca2+ mobilizations (including Ca2+ influx, Ca2+ elevation in the cytosol, Ca2+ release from the vacuole and mitochondrial Ca2+ uptake), mitochondrial hyperpolarization, H2O2 bursts in the mitochondria, cytochrome c release and stimulation of caspase-like proteases. NO is implicated as a downstream component of the cytosolic Ca2+ concentration but plays a negligible role in eATP-stimulated cell death.

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      Integrating fluctuating nitrate uptake and assimilation to robust homeostasis (pages 917–928)

      YONGSHUN HUANG, TORMOD DRENGSTIG and PETER RUOFF

      Article first published online: 6 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02462.x

      Nitrate is an important nitrogen source used by plants. Despite of considerable variations in the amount of soil nitrate plants keep cytosolic nitrate at a homeostatic controlled level. Here we describe a set of homeostatic controller motifs and their interaction that can maintain robust cytosolic nitrate homeostasis at changing environmental nitrate concentrations and nitrate assimilation levels.

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      Complex genetics controls natural variation among seed quality phenotypes in a recombinant inbred population of an interspecific cross between Solanum lycopersicum × Solanum pimpinellifolium (pages 929–951)

      RASHID H. KAZMI, NOORULLAH KHAN, LEO A. J. WILLEMS, ADRIAAN W. VAN HEUSDEN, WILCO LIGTERINK and HENK W. M. HILHORST

      Article first published online: 8 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02463.x

      Seed quality is a complex trait which comprises a large number of physiological principles related to important plant developmental processes. We used a RIL population of Solanum lycopersicum (cv. Money maker) × Solanum pimpinellifolium to determine the genetic factors influencing the different aspects of seed quality in tomato. In total 42 seed quality traits were analyzed and one or more QTLs were identified for each trait with some of these QTLs co-locating. However, several QTLs also dissected seed quality in its separate components, suggesting different physiological mechanisms and signaling pathways for different seed quality attributes.

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      SKP1 is involved in abscisic acid signalling to regulate seed germination, stomatal opening and root growth in Arabidopsis thaliana (pages 952–965)

      CHIJUN LI, ZUOJUN LIU, QIRUI ZHANG, RUOZHONG WANG, LANGTAO XIAO, HONG MA, KANG CHONG and YUNYUAN XU

      Article first published online: 8 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02464.x

      SCF complex regulates several phytohormonal signalling pathways via a ubiquitination-mediated protein degradation. Here we report that transgenic Arabidopsis plant overexpressing Triticum aestivum SKP1-like 1 (TSK1) exhibited an ABA hypersensitive phenotype; whereas ask1/ask1 ASK2/ask2 mutant plants showed an opposite ABA response. These results suggest that SKP1-like genes may positively regulate ABA signalling through an SCF-mediated protein degradation process. The functional conservation and divergence of SKP1 genes are discussed.

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      Light inhibition of leaf respiration in field-grown Eucalyptus saligna in whole-tree chambers under elevated atmospheric CO2 and summer drought (pages 966–981)

      KRISTINE Y. CROUS, JOANA ZARAGOZA-CASTELLS, DAVID S. ELLSWORTH, REMKO A. DUURSMA, MARKUS LÖW, DAVID T. TISSUE and OWEN K. ATKIN

      Article first published online: 14 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02465.x

      We investigated whether rates of leaf respiration in the light (Rlight) and darkness (Rdark) differ among large Eucalyptus saligna grown in whole-tree chambers and exposed to present and future atmospheric [CO2] and summer drought. Although both processes were unaffected by [CO2], marked effects of drought were found, with light inhibition of leaf R (which decreased the proportion of light-saturated photosynthesis respired) being greatest in drought-stressed trees.

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      The influence of light quality on C4 photosynthesis under steady-state conditions in Zea mays and Miscanthus × giganteus: changes in rates of photosynthesis but not the efficiency of the CO2 concentrating mechanism (pages 982–993)

      WEI SUN, NEREA UBIERNA, JIAN-YING MA and ASAPH B. COUSINS

      Article first published online: 13 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02466.x

      Differences in light quality penetration within a leaf and absorption by the photosystems alter rates of CO2 assimilation in C3 plants. It is also expected that light quality will have a profound impact on C4 photosynthesis due to disrupted coordination of the C4 and C3 cycles. To test this hypothesis, we measured leaf gas exchange, 13CO2 discrimination (Δ13C), photosynthetic metabolite pools and Rubisco activation state in Zea mays and Miscanthus × giganteus under steady-state red, green, blue and white light. Photosynthetic rates, quantum yield of CO2 assimilation, and maximum phosphoenolpyruvate carboxylase activity were significantly lower under blue light than white, red and green light in both species. However, similar leakiness under all light treatments suggests the C4 and C3 cycles were coordinated to maintain the photosynthetic efficiency. Measurements of photosynthetic metabolite pools also suggest coordination of C4 and C3 cycles across light treatments. The energy limitation under blue light affected both C4 and C3 cycles, as we observed a reduction in C4 pumping of CO2 into bundle-sheath cells and a limitation in the conversion of C3 metabolite phosphoglycerate to triose phosphate. Overall, light quality affects rate of CO2 assimilation rates, but not the efficiency of CO2 concentrating mechanism.

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      Tomato plants overexpressing cryptochrome 2 reveal altered expression of energy and stress-related gene products in response to diurnal cues (pages 994–1012)

      LOREDANA LOPEZ, FABRIZIO CARBONE, LINDA BIANCO, GIOVANNI GIULIANO, PAOLO FACELLA and GAETANO PERROTTA

      Article first published online: 14 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02467.x

      Plant cryptochromes (CRYs) are responsible for photomorphogenesis and play a role in circadian, developmental and adaptive growth regulation of plants. We applied, in tomato, large-scale molecular approaches to identify altered transcripts and proteins in WT vs a CRY2 overexpressing transgenic genotype, under a diurnal rhythm. We found tomato CRY2 profoundly affects both gene and protein expression in response to daily light cycle. One of the most interesting results is the coordinated upregulation, in the transgenic genotype, of a consistent number of transcripts and proteins involved in photorespiration and photosynthesis.

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