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51.
Martínez-Ballesta MC Diaz R Martínez V Carvajal M 《Journal of plant physiology》2003,160(12):1487-1492
In this study we have compared the short-term effects of both NaCl and HgCl2 on aquaporins of Capsicum annuum L. plants, in order to determine whether or not they are similar. Stomatal conductance, turgor, root hydraulic conductance and water status were measured after 0.5, 2, 4 and 6 h of NaCl (60 mmol/L) or HgCl2 (50 μmol/L) treatment. When 60 mmol/L NaCl was added to the nutrient solution, a large decrease in stomatal conductance was observed after 2 h. However, when HgCl2 (50 μmol/L) was added, the decrease occurred after 4 h. The number of open stomata closed was always lower in plants treated with HgCl2 than in plants treated with NaCl. The water content of the Hg2+-treated plants was decreased, compared with controls and NaCl-treated. The root hydraulic conductance decreased after HgCl2 and NaCl treatment plants. Turgor of leaf epidermal cells was greatly reduced in plants treated with HgCl2, but remained constant in the NaCl treatment, compared with control plants. The fact that the stomatal conductance was reduced more rapidly after NaCl addition, followed by the stomatal closure, and that both water content and turgor did not differ from the control suggests that in NaCl-treated plants there must be a signal moving from root to shoot. Therefore, the control of plant homeostasis through a combined regulation of root and stomatal exchanges may be dependent on aquaporin regulation. 相似文献
52.
The exotic temperate liana (woody vine) Celastrus orbiculatus has become a weed in Michigan, occurring in many of the same habitats as the native liana Vitis riparia. However, C. orbiculatus frequently develops into extensive monospecific infestations, while V. riparia does not. Freezing-induced embolism may be responsible for limiting liana distribution. Root pressure has been observed in numerous tropical lianas and temperate species of Vitis and has been implicated as vital to the recovery of xylem function in wide vessels following winter freezes. For both of these co-occurring lianas we investigated root pressure and water conductance as possible explanatory factors for their differential spread. According to our hypothesis, C. orbiculatus should have produced greater or more frequent root pressures than V. riparia. However, the reverse proved true, indicating that root pressure is not a prerequisite for weedy proliferation of C. orbiculatus. Additionally, the seasonal patterns of specific conductivity of stem xylem indicate that each species responds differently to environmental constraints. Vitis riparia establishes conductivity early in the growing season, before the leaves emerge, using root pressure to reverse embolism, but loses conductivity with the first freeze in early autumn. Celastrus orbiculatus is slow to establish conductivity, depending on new wood production, but leafs out sooner than V. riparia and maintains green leaves after the first freeze. Vulnerability curves of xylem to cavitation caused by water stress for the two species indicate that they respond similarly to dehydration. These results indicate that root pressures are not responsible for the invasive success of C. orbiculatus and suggest that other factors must be key to its prolific invasion. 相似文献
53.
The power to separate the variance of a quantitative trait locus (QTL) from the polygenic variance is determined by the variability
of genes identical by descent (IBD) at the QTL. This variability may increase with inbreeding. Selfing, the most extreme form
of inbreeding, increases the variability of the IBD value shared by siblings, and thus has a higher efficiency for QTL mapping
than random mating. In self-incompatible organisms, sib mating is the closest form of inbreeding. Similar to selfing, sib
mating may also increase the power of QTL detection relative to random mating. In this study, we develop an IBD-based method
under sib mating designs for QTL mapping. The efficiency of sib mating is then compared with random mating. Monte Carlo simulations
show that sib mating designs notably increase the power for QTL detection. When power is intermediate, the power to detect
a QTL using full-sib mating is, on average, 7% higher than under random mating. In addition, the IBD-based method proposed
in this paper can be used to combine data from multiple families. As a result, the estimated QTL parameters can be applied
to a wide statistical inference space relating to the entire reference population.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
54.
José M. Quintero José M. Fournier José Ramos Manuel Benlloch 《Physiologia plantarum》1998,102(2):279-284
Twenty‐day‐old sunflower plants ( Helianthus annuus L. cv. Sun‐Gro 380) grown in nutrient solutions with different KCl levels were used to study the effects of K+ status of the root and of abcisic acid (ABA) on the exudation rate (Jv ), the hydraulic conductivity of the root (Lp ), the fluxes of exuded K+ and Na+ (JK and JNa ), and the gradient of osmotic pressure between the xylem and the external medium. Jv and Lp increased in direct proportion to the K+ starvation of the root. Also addition of ABA (4 µ M ) at the onset of exudation in the external medium made Jv and Lp rise, and this effect also increased with the degree of K+ starvation. Similarly, K+ starvation and ABA promoted both the flux of exuded Na+ and the accumulation of Na+ in the root. We suggest that ABA acts as a regulating signal for the radial transport of water across the root, and that potassium may be an effector of this mechanism. 相似文献
55.
M. N. Inagaki G. Varughese S. Rajaram M. van Ginkel A. Mujeeb-Kazi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(4):550-556
Yield performance of each group of ten spring bread wheat lines selected by doubled haploid (DH), single-seed descent (SSD)
and pedigree selection (PS) methods from three F1 crosses was compared with the aim of evaluating the DH method in breeding programs. Populations of 65–97 DH lines and 110
SSD lines per cross were used for selection. PS lines were developed by repeated selections from 1500 F2 plants. Yield evaluation was performed at the F6 generation of SSD and PS lines along with DH lines in a 2-year field experiment. It took only 2 years from the planting of
wheat materials for DH production to the planting of selected DH lines for yield evaluation. There was no significant difference
in grain yield between DH lines and PS lines selected from an F1 cross whose parental varieties were closely related in their pedigrees. In two crosses with low coefficients of parentage
and a large variation in their progenies, grain yield of selected DH lines was significantly lower than those of selected
SSD and PS lines. These results confirm that the DH method can save time in obtaining recombinant inbred lines ready for yield
evaluation. However, a larger DH population is required to achieve the same level of genetic advance with the PS method in
crosses containing greater genetic variation.
Received: 23 December 1997 / Accepted: 12 March 1998 相似文献
56.
The response of an Eastern Amazonian rain forest to drought stress: results and modelling analyses from a throughfall exclusion experiment 总被引:2,自引:0,他引:2
R. A. FISHER M. WILLIAMS A. LOLA da COSTA † Y. MALHI‡ R. F. da COSTA § S. ALMEIDA¶ P. MEIR 《Global Change Biology》2007,13(11):2361-2378
Warmer and drier climates over Eastern Amazonia have been predicted as a component of climate change during the next 50–100 years. It remains unclear what effect such changes will have on forest–atmosphere exchange of carbon dioxide (CO2 ) and water, but the cumulative effect is anticipated to produce climatic feedback at both regional and global scales. To allow more detailed study of forest responses to soil drying, a simulated soil drought or 'throughfall exclusion' (TFE) experiment was established at a rain forest site in Eastern Amazonia, Brazil, for which time-series sap flow and soil moisture data were obtained. The experiment excluded 50% of the throughfall from the soil. Sap flow data from the forest plot experiencing normal rainfall showed no limitation of transpiration throughout the two monitored dry seasons. Conversely, data from the TFE showed large dry season declines in transpiration, with tree water use restricted to 20% of that in the control plot at the peak of both dry seasons. The results were examined to evaluate the paradigm that the restriction on transpiration in the dry season was caused by limitation of soil-to-root water transport, driven by low soil water potential and high soil-to-root hydraulic resistance. This paradigm, embedded in the soil–plant–atmosphere (SPA) model and driven using on-site measurements, provided a good explanation ( R 2 > 0.69) of the magnitude and timing of changes in sap flow and soil moisture. This model-data correspondence represents a substantial improvement compared with other ecosystem models of drought stress tested in Amazonia. Inclusion of deeper rooting should lead to lower sensitivity to drought than the majority of existing models. Modelled annual GPP declined by 13–14% in response to the treatment, compared with estimated declines in transpiration of 30–40%. 相似文献
57.
Roman Gebauer Daniel Volaík Josef Urban Isabella Brja Nina Elisabeth Nagy Toril Drabls Eldhuset Paal Krokene 《Ecology and evolution》2015,5(21):4989-4998
Predicted increases in the frequency and duration of drought are expected to negatively affect tree vitality, but we know little about how water shortage will influence needle anatomy and thereby the trees’ photosynthetic and hydraulic capacity. In this study, we evaluated anatomical changes in sun and shade needles of 20‐year‐old Norway spruce trees exposed to artificial drought stress. Canopy position was found to be important for needle structure, as sun needles had significantly higher values than shade needles for all anatomical traits (i.e., cross‐sectional needle area, number of tracheids in needle, needle hydraulic conductivity, and tracheid lumen area), except proportion of xylem area per cross‐sectional needle area. In sun needles, drought reduced all trait values by 10–40%, whereas in shade needles, only tracheid maximum diameter was reduced by drought. Due to the relatively weaker response of shade needles than sun needles in drought‐stressed trees, the difference between the two needle types was reduced by 25% in the drought‐stressed trees compared to the control trees. The observed changes in needle anatomy provide new understanding of how Norway spruce adapts to drought stress and may improve predictions of how forests will respond to global climate change. 相似文献
58.
59.
在四川西北部松潘县卡卡沟对青藏高原东缘高海拔地区3个不同放牧强度下的窄叶鲜卑花灌丛的空间结构进行了研究,结果表明:放牧干扰对卡卡沟东南坡的窄叶鲜卑花空间结构影响显著,植株的总生物量、总叶面积和茎的边材面积在重度放牧下显著低于轻度和中度放牧梯度样地。中度和重度放牧情况下叶片长度、宽度以及面积均比轻度放牧显著提高;植株高度随放牧强度增加出现先升后降的现象,而顶部枝叶生物量分配则出现与之相反的情况。虽然植物空间结构发生变化,但是单位边材面积上支持的叶面积并没有变化,中度放牧使植株枝叶生物量更加均匀分布。放牧干扰下植物空间结构的塑性变化依然受到Huber数的制约,使叶片蒸腾耗水与茎的供水能力上维持平衡。 相似文献
60.
Studying global change through investigation of the plastic responses of xylem anatomy in tree rings 总被引:1,自引:0,他引:1
Patrick Fonti Georg von Arx Ignacio García-González Britta Eilmann Ute Sass-Klaassen Holger Gärtner Dieter Eckstein 《The New phytologist》2010,185(1):42-53
Variability in xylem anatomy is of interest to plant scientists because of the role water transport plays in plant performance and survival. Insights into plant adjustments to changing environmental conditions have mainly been obtained through structural and functional comparative studies between taxa or within taxa on contrasting sites or along environmental gradients. Yet, a gap exists regarding the study of hydraulic adjustments in response to environmental changes over the lifetimes of plants. In trees, dated tree-ring series are often exploited to reconstruct dynamics in ecological conditions, and recent work in which wood-anatomical variables have been used in dendrochronology has produced promising results. Environmental signals identified in water-conducting cells carry novel information reflecting changes in regional conditions and are mostly related to short, sub-annual intervals. Although the idea of investigating environmental signals through wood anatomical time series goes back to the 1960s, it is only recently that low-cost computerized image-analysis systems have enabled increased scientific output in this field. We believe that the study of tree-ring anatomy is emerging as a promising approach in tree biology and climate change research, particularly if complemented by physiological and ecological studies. This contribution presents the rationale, the potential, and the methodological challenges of this innovative approach. 相似文献