Sulfur application enhances secretion of organic acids by soybean roots and solubilization of phosphorus in rhizosphere
Sulfur application enhances secretion of organic acids by soybean roots and solubilization of phosphorus in rhizosphere
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施硫增强大豆根系有机酸的分泌和根际磷的溶解
DOI：
10.1080/00380768.2021.1919011
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发表时间：
2021
影响因子：
2
通讯作者：
Naoko Ohkama‐Ohtsu
中科院分区：
文献类型：
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作者：
Hinako Sugiura;S. Sugihara;Takehiro Kamiya;M. D. Artigas Ramírez;Minori Miyatake;T. Fujiwara;Ohyama Takuji;T. Motobayashi;T. Yokoyama;S. Bellingrath‐Kimura;Naoko Ohkama‐Ohtsu
根瘤菌固氮在大豆氮素同化过程中起着重要作用。固氮酶是根瘤菌中负责固氮的酶，含有大量的硫（S）分子，需要三磷酸腺苷中的磷（P）。因此，S和P是植物生长和根瘤菌固氮所必需的。然而，土壤中的P与金属形成不溶性的PO 43-盐。植物根通过分泌有机酸溶解这些PO 43-盐并吸收溶解的PO 43-。研究了施硫对大豆根系溶磷和根瘤菌参与的影响。大豆植株接种重氮慢生根瘤菌USDA 110生长在蛭石中，并添加Ca 3（PO 4）2作为唯一的P源。施用补充有三种S浓度（0、20和1000 μM）的溶液培养溶液，并使植物生长5周。施硫显著增加了根鲜重、SPAD值、地上部和根系硫浓度，但对根瘤数和固氮酶活性影响不显著。施硫显著增加了根系有机酸的分泌，地上部磷的浓度和含量也显著增加。这些结果表明，施硫可通过增加根系分泌有机酸来促进磷的溶解，而至少在营养生长早期，增加氮的固定并不参与这种促进作用。
ABSTRACT Nitrogen (N) fixation by rhizobia plays an important role in N assimilation of soybean (Glycine max). Nitrogenase, the enzyme responsible for N fixation in rhizobia, contains a large amount of sulfur (S) molecules and requires phosphorus (P) in adenosine triphosphate. Thus, S and P are essential for plant growth and N fixation by rhizobia. However, P in soils forms insoluble PO4 3 – salts with metals. Plant roots solubilize these PO4 3- salts by secreting organic acids and absorb solubilized PO4 3-. In this study, the effects of S application on P solubilization by soybean roots and the involvement of rhizobia were evaluated. Soybean plants inoculated with Bradyrhizobium diazoefficiens USDA110 were grown in vermiculite, and Ca3(PO4)2 was added as the sole P source. A hydroponic solution supplemented with three S concentrations (0, 20, and 1000 µM) was applied, and plants were grown for 5 weeks. Root fresh weight, the soil-plant analysis development (SPAD) values, and shoot and root S concentrations increased significantly with S application, but root nodule numbers and nitrogenase activity were not significantly affected. Organic acid secretion by roots was drastically increased by S application, and shoot P concentration and content also increased significantly. These results indicated that S application can promote P solubilization by increasing the secretion of organic acids by roots and increase in N fixation is not involved in this promotion at least in early vegetative growth period.