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1.
Phosphate availability regulates root system architecture in Arabidopsis 总被引:31,自引:0,他引:31
Plant root systems are highly plastic in their development and can adapt their architecture in response to the prevailing environmental conditions. One important parameter is the availability of phosphate, which is highly immobile in soil such that the arrangement of roots within the soil will profoundly affect the ability of the plant to acquire this essential nutrient. Consistent with this, the availability of phosphate was found to have a marked effect on the root system architecture of Arabidopsis. Low phosphate availability favored lateral root growth over primary root growth, through increased lateral root density and length, and reduced primary root growth mediated by reduced cell elongation. The ability of the root system to respond to phosphate availability was found to be independent of sucrose supply and auxin signaling. In contrast, shoot phosphate status was found to influence the root system architecture response to phosphate availability. 相似文献
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Inhibition of maize root growth by high nitrate supply is correlated with reduced IAA levels in roots 总被引:8,自引:0,他引:8
The plant root system is highly sensitive to nutrient availability and distribution in the soil. For instance, root elongation is inhibited when grown in high nitrate concentrations. To decipher the mechanism underlying the nitrate-induced inhibition of root elongation, the involvement of the plant hormone auxin in nitrate-dependent root elongation of maize was investigated. Root growth, nitrogen and nitrate concentrations, and indole-3-acetic acid (IAA) concentrations in roots and in phloem exudates of maize grown under varying nitrate concentrations were analyzed. Total N and nitrate concentrations in shoots and roots increased and elongation of primary, seminal and crown roots were inhibited with increasing external nitrate from 0.05 to 5 mM. High nitrate-inhibited root growth resulted primarily from the reduced cell elongation and not from changes in meristem length. IAA concentrations in phloem exudates reduced with higher nitrate supply. Inhibition of root growth by high nitrate was closely related to the reduction of IAA levels in roots, especially in the sections close to root tips. Exogenous NAA and IAA restored primary root growth in high nitrate concentrations. It is concluded that the inhibitory effect of high nitrate concentrations on root growth may be partly attributed to the decrease in auxin concentrations of roots. 相似文献
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Response of root system architecture to nutrient availability in soils is an essential way for plants to adapt to soil environments.
Nitrate can affect root development either as a result of changes in the external concentration, or through changes in the
internal nutrient status of the plant. Nevertheless, less is known about the physiological mechanisms. In the present study,
two maize (Zea mays L.) inbred lines (478 and Wu312) were used to study a possible role of cytokinin in nitrate-mediated root growth in nutrient
solutions. Root elongation of 478 was more sensitive to high nitrate supply than that of Wu312. Medium high nitrate (5 mM) inhibited root elongation in 478, while, root elongation in Wu312 was only inhibited at high NO
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supply (20 mM). Under high nitrate supply, the root elongation zone in 478 became swollen and the site of lateral root elongation was close
towards the root tip. Both of the phenomena are typical of root growth induced by exogenous cytokinin treatments. Correspondingly,
zeatin and zeatin nucleotide (Z + ZR) concentrations were increased at higher nitrate supply in 478, whereas they were constant
in Wu312. Furthermore, exogenous cytokinin 6-benzylaminopurine (6-BA) completely reversed the stimulatory effect of low nitrate
on root elongation. Therefore, it is supposed that the inhibitory effect of high concentration of nitrate on root elongation
is, at least in part, mediated by increased cytokinin level in roots. High nitrate supply may have negative influences on
root apex activity by affecting cytokinin metabolism so that root apical dominance is weakened and, therefore, root elongation
is suppressed and lateral roots grow closer to the root apex. Nitrate suppressed lateral root elongation in Wu312 at concentration
higher than 5 mM. In 478, however, this phenomenon was not significant even at 20 mM nitrate. Although exogenous 6-BA (20 nM) could suppress lateral root elongation as well, the inhibitory effect of high NO
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concentration of nitrate on lateral root growth cannot be explained by changes in endogenous cytokinin alone. 相似文献
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《植物学报(英文版)》2005,47(3)
Plants have evolved some mechanisms to maximize the efficiency of phosphorus acquisition.Changes in root architecture are one such mechanism. When Fraxinus mandshurica Rupr. seedlings were grown under conditions of low phosphorus availability, the length of cells in the meristem zone of the lateral roots was longer, but the length of cells in the elongation and mature zones of the lateral roots was shorter,compared with seedlings grown under conditions of high phosphorus availability. The elongation rates of primary roots increased as phosphorus availability increased, but the elongation rates of the branched zones of the primary roots decreased. The number of lateral root primordia and the length of the lateral roots decreased as phosphorus availability increased. The topological index (altitude slope) decreased as phosphorus availability increased, suggesting that root architecture tended to be herringbone-like when seedlings were grown under conditions of low phosphate availability. Herringbone-like root systems exploit nutrients more efficiently, but they have higher construction costs than root systems with a branching pattern. 相似文献
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ChuWU XingWEI Hai-LongSUN Zheng-QuanWANG 《植物学报(英文版)》2005,47(3):292-301
Plants have evolved some mechanisms to maximize the efficiency of phosphorus acquisition. Changes in root architecture are one such mechanism. When Fraxinus mandshurica Rupr. seedlings were grown under conditions of low phosphorus availability, the length of cells in the meristem zone of the lateral roots was longer, but the length of cells in the elongation and mature zones of the lateral roots was shorter,compared with seedlings grown under conditions of high phosphorus availability. The elongation rates of primary roots increased as phosphorus availability increased, but the elongation rates of the branched zones of the primary roots decreased. The number of lateral root primordia and the length of the lateral roots decreased as phosphorus availability increased. The topological index (altitude slope) decreased as phosphorus availability increased, suggesting that root architecture tended to be herringbone-like when seedlings were grown under conditions of low phosphate availability. Herringbone-like root systems exploit nutrients more efficiently, but they have higher construction costs than root systems with a branching pattem. 相似文献
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《植物学报(英文版)》2016,(3)
Plant root development is strongly affected by nutrient availability. Despite the importance of structure and function of roots in nutrient acquisition,statistical modeling approaches to evaluate dynamic and temporal modulations of root system architecture in response to nutrient availability have remained as widely open and exploratory areas in root biology. In this study,we developed a statistical modeling approach to investigate modulations of root system architecture in response to nitrogen availability. Mathematical models were designed for quantitative assessment of root growth and root branching phenotypes and their dynamic relationships based on hierarchical con figuration of primary and lateral roots formulating the fishbone-shaped root system architecture in Arabidopsis thaliana. Time-series datasets reporting dynamic changes in root developmental traits on different nitrate or ammonium concentrations were generated for statistical analyses. Regression analyses unraveled key parameters associated with:(i) inhibition of primary root growth under nitrogen limitation or on ammonium;(ii) rapid progression of lateral root emergence in response to ammonium; and(iii) inhibition of lateral root elongation in the presence of excess nitrate or ammonium. This study provides a statistical framework for interpreting dynamic modulation of root system architecture,supported by metaanalysis of datasets displaying morphological responses of roots to diverse nitrogen supplies. 相似文献
8.
Comparing morphological plasticity of root orders in slow- and fast-growing citrus rootstocks supplied with different nitrate levels 总被引:1,自引:0,他引:1
BACKGROUND AND AIMS: Studies of the plasticity of functional root traits involved in resource acquisition have focused mainly on root length without considering such 'morphological components' as biomass allocation, specific root length, root fineness, and tissue density that affect root length. The plasticity of the above components in response to nitrate supply was studied in each root order of two co-generic citrus rootstocks, namely the fast-growing Citrus jambhiri 'Rough Lemon' (RL) and the slow-growing Citrus reshni 'Cleopatra Mandarin' (CM). METHODS: Morphological traits of individual root orders of CM and RL, grown at different nitrate levels (NO(3)-N at 0.1, 0.5, 1 and 10 mm) were examined by using an image-specific analysis system. KEY RESULTS: At high nitrate levels, the root length ratio, root mass ratio and, to a lesser degree, specific root length, root fineness and tissue density of tap and 1st-order laterals in both CM and RL were reduced. In 2nd-order laterals, however, the same treatment led to increased values of each morphological trait in CM but decreased values of the same traits in RL. At low nitrate supply, CM exhibited longer tap roots whereas RL developed longer 2nd-order laterals. These effects were due to root mass ratio and, to a lesser extent, specific root length. CONCLUSIONS: Biomass allocation was the main component of nitrate-induced changes in root length ratio. The 2nd-order laterals were more sensitive to nitrate availability than the tap root and 1st-order laterals. At low nitrate availability, RL displayed longer 2nd-order lateral roots and lower root plasticity than CM. This suggests a different root growth strategy among citrus rootstocks for adapting to nitrate availability: RL invests in 2nd-order laterals, the preferred zone for acquiring the nutrient, whereas CM responds with longer tap roots. 相似文献
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Approximately 35–55% of total nitrogen (N) in maize plants is taken up by the root at the reproductive stage. Little is known about how the root of an adult plant responds to heterogeneous nutrient supply. In this study, root morphological and physiological adaptations to nitrate‐rich and nitrate‐poor patches and corresponding gene expression of ZmNrt2.1 and ZmNrt2.2 of maize seedlings and adult plants were characterized. Local high nitrate (LoHN) supply increased both lateral root length (LRL) and density of the treated nodal roots of adult maize plants, but only increased LRL of the treated primary roots of seedlings. LoHN also increased plant total N acquisition but not N influx rate of the treated roots, when expressed as per unit of root length. Furthermore, LoHN markedly increased specific root length (m g?1) of the treated roots but significantly inhibited the growth of the lateral roots outside of the nitrate‐rich patches, suggesting a systemic carbon saving strategy within a whole root system. Surprisingly, local low nitrate (LoLN) supply stimulated nodal root growth of adult plants although LoLN inhibited growth of primary roots of seedlings. LoLN inhibited the N influx rate of the treated roots and did not change plant total N content. The gene expression of ZmNrt2.1 and ZmNrt2.2 of the treated roots of seedlings and adult plants was inhibited by LoHN but enhanced by LoLN. In conclusion, maize adult roots responded to nitrate‐rich and nitrate‐poor patches by adaptive morphological alterations and displayed carbon saving strategies in response to heterogeneous nitrate supply. 相似文献
10.
Water supply and not nitrate concentration determines primary root growth in Arabidopsis 总被引:1,自引:0,他引:1
Understanding how root system architecture (RSA) adapts to changing nitrogen and water availability is important for improving acquisition. A sand rhizotron system was developed to study RSA in a porous substrate under tightly regulated nutrient supply. The RSA of Arabidopsis seedlings under differing nitrate (NO3‐) and water supplies in agar and sand was described. The hydraulic conductivity of the root environment was manipulated by using altered sand particle size and matric potentials. Ion‐selective microelectrodes were used to quantify NO3‐ at the surface of growing primary roots in sands of different particle sizes. Differences in RSA were observed between seedlings grown on agar and sand, and the influence of NO3‐ (0.1–10.0 mm ) and water on RSA was determined. Primary root length (PRL) was a function of water flux and independent of NO3‐. The percentage of roots with laterals correlated with water flux, whereas NO3‐ supply was important for basal root (BR) growth. In agar and sand, the NO3‐ activities at the root surface were higher than those supplied in the nutrient solution. The sand rhizotron system is a useful tool for the study of RSA, providing a porous growth environment that can be used to simulate the effects of hydraulic conductivity on growth. 相似文献