Root traits as tools for creating phosphorus efficient crop varieties
Root traits as tools for creating phosphorus efficient crop varieties
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DOI：
10.1023/b:plso.0000030168.53340.bc
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发表时间：
2004-03-01
期刊：
影响因子：
4.9
通讯作者：
Nielsen, NE
中科院分区：
文献类型：
--
作者：
Gahoonia, TS;Nielsen, NE
本文简要介绍了不同作物品种及其基因型根际特性（包括根毛在内的根形态）、菌根共生、吸收动力学参数和根诱导变化（pH、有机酸和酸性磷酸酶）的遗传变异，并简要讨论了利用这些知识通过遗传手段提高未来作物基因型磷效率的机遇和挑战。根系形态、根毛长度和根毛密度的广泛基因型变异和遗传力以及由此获得的磷为选择和育种根系特征以增加磷的获得提供了机会。这一进展受到了较大根系的高碳成本问题以及缺乏在田间条件下确定大量基因型根长的成本有效方法的挑战。根毛的碳成本很低。此外，现在存在低成本的方法来比较田间生长的基因型的根毛形成。先进的方法的发展和应用，提高了我们的知识菌根共生在磷收购的作用，也对真菌和植物相互作用的分子基础。然而，广泛的研究，探讨基因型变异的菌根反应是罕见的，这使得它难以评估，如何菌根共生可以通过育种工作进行操纵。在少数研究中发现的作物基因型磷吸收动力学参数的有希望的变化表明，更多的基因型可以通过相对简单的营养液培养技术进行筛选。阳离子-阴离子吸收的总体差异，这是根际pH值变化的主要原因，遗传操作可能是困难的。对于根际pH值的操纵，农艺措施，如铵或硝酸盐肥料的应用可能比育种方法更有用。此外，似乎很难评估应该进行什么样的遗传分析来支持育种工作。pH值对磷素的活化作用取决于土壤磷素的组成，因此会因土壤类型而异。根际土壤有机酸释放量的增加和酸性磷酸酶活性的提高可能分别有助于增加无机磷库和有机磷库中磷的吸收。应考虑通过遗传手段改变这些性状。对于成功的育种计划，各种根性状的作用，需要有针对性的综合方式，然后需要开发的方法，研究其在自然土壤条件下的重要性，使基因型变异可以探索和他们的生态意义，在磷收购可以建立。
This paper provides a brief assessment of the genetic variation in root properties (root morphology, including root hairs), mycorrhizal symbiosis, uptake kinetics parameters and root-induced changes (pH, organic acids and acid phosphatase) in the rhizosphere of various crop species and their genotypes and then briefly discusses the opportunities and challenges of using such knowledge for enhancing P efficiency of future crop genotypes by genetic means. Wide genotypic variation and heritability of root morphology, root hair length and density and thereby P acquisition provide opportunities for selection and breeding for root characteristics for increasing P acquisition. The progress is challenged by the concerns of high carbon cost of larger root systems and by the lack of cost effective methods to determine root length of a large number of genotypes under field conditions. The carbon cost of root hairs is low. Furthermore, low cost methods now exist to compare root hair formation of field grown genotypes. The development and application of sophisticated methods has advanced our knowledge on the role of mycorrhizal symbiosis in P acquisition and also on the molecular basis of fungi and plant interactions. However, extensive studies to explore genotypic variation in mycorrhizal responsiveness are rare, which makes it difficult to assess, how mycorrhizal symbiosis can be manipulated through breeding efforts. The promising variation found in P uptake kinetics parameters of crop genotypes in few studies indicates that more genotypes may be screened by relatively simple nutrient solution culture techniques. The genetic manipulation of the overall differences in cationanion uptake, which is the main cause of rhizosphere pH change, may be difficult. For manipulation of rhizosphere pH, agronomic measures such as applications of ammonium or nitrate fertilisers may be more useful than breeding approaches. Also it seems difficult to assess what kind of genetic analysis should be performed to support the breeding efforts. Phosphorus mobilisation effect of pH depends on soil P compounds, therefore will differ with soil type. Both the enhanced release of organic acids and higher acid phosphatase activity in the rhizosphere may be useful for increasing P acquisition from inorganic and organic P pools, respectively. Modification of these traits by genetic means should be considered. For successful breeding programmes, the role of various root traits needs to be targeted in an integrated manner and then methods need to be developed for studying their importance under natural soil conditions, so that the genotypic variation can be explored and their ecological significance in P acquisition can be established.