Rhizosphere priming of barley with and without root hairs
Rhizosphere priming of barley with and without root hairs
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DOI：
10.1016/j.soilbio.2016.05.009
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发表时间：
2016-09
影响因子：
9.7
通讯作者：
J. Pausch;S. Loeppmann;Anna Kühnel;Kelsey Forbush;Y. Kuzyakov;W. Cheng
中科院分区：
文献类型：
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作者：
J. Pausch;S. Loeppmann;Anna Kühnel;Kelsey Forbush;Y. Kuzyakov;W. Cheng
植物根系及其根际活动对土壤有机质分解的影响，即根际启动效应，已成为全球碳氮循环的重要调控机制。然而，根形态在控制根际引发效应中的作用仍然很大程度上未知。调查根毛，整个根形态的关键部分，根际引发效应之间的联系，我们生长的大麦野生型和大麦突变体没有根毛在温室中，并不断标记它们与13 C-耗尽CO2。在植物生长的分蘖期和抽穗期测定土壤CO2通量。根据其δ 13 C特征，将CO2分为根源CO2和SOM源CO2，并计算了根际SOM的分解量。通过测定土壤微生物生物量C、N和6种胞外酶（β-纤维二糖水解酶、β-葡萄糖苷酶、酸性磷酸酶、β-木糖苷酶、亮氨酸氨肽酶和N-乙酰-β-氨基葡萄糖苷酶）的活性，研究了根毛对土壤微生物生物量C、N的影响。相反，根毛形成的高C成本可能会降低大麦野生型的生长。在此阶段，野生型与规则的根毛产生了积极的根际引发效应（69%的增加），但突变体没有根毛产生了负引发效应的SOM分解（28%的下降）。在抽穗期，当养分缺乏时，突变体的植物生物量生产减少，可能是由于在没有根毛的情况下养分吸收效率低下。在这个阶段，两种类型的大麦产生积极的根际引发效应（72%和209%的野生型和突变体，分别增加）和微生物生物量是较高的两种种植土壤相比，分蘖期。胞外酶负责分解稳定的SOM有较高的活动，在积极的启动效应的情况下。总体而言，根毛在调节根际引发中发挥了重要作用。
The influence of plant roots and the associated rhizosphere activities on decomposition of soil organic matter (SOM), the rhizosphere priming effect, has emerged as a crucial mechanism regulating global carbon (C) and nitrogen (N) cycles. However, the role of root morphology in controlling the rhizosphere priming effect remains largely unknown. To investigate the link between root hairs, a critical part of the entire root morphology, and the rhizosphere priming effect, we grew a barley wild type and a barley mutant without root hairs in a greenhouse and continuously labeled them with13C-depleted CO2. Soil CO2efflux was measured during tillering and head-emergence stages of plant growth. Based on its δ13C signature, total CO2was partitioned for root-derived and SOM-derived CO2,and the SOM decomposition primed in the rhizosphere was calculated. Soil microbial biomass C and N, and the activities of six extracellular enzymes (β-cellobiohydrolase, β-glucosidase, acid phosphatase, β-xylosidase, leucin-aminopeptidase, and N-acetyl-β-glucosaminidase) were measured to test the effects of root hairs.During the early stage of development (tillering), when plants were sufficiently supplied with nutrients, the barley mutant without root hairs produced more shoot biomass. In contrast, high C costs for root-hair formation likely reduced the growth of the barley wild type. At this stage, the wild type with regular root hairs produced a positive rhizosphere priming effect (69% increase), but the mutant without root hairs produced a negative priming effect on SOM decomposition (28% decline). At the head-emergence stage, when nutrients were scarce, plant biomass production of the mutant was reduced, probably due to inefficient nutrient uptake in the absence of root hairs. At this stage, both barley types produced positive rhizosphere priming effects (72% and 209% increase for the wild type and the mutant, respectively) and the microbial biomass was higher for both planted soils compared to the tillering stage. Extracellular enzymes responsible for the decomposition of stable SOM had higher activities in cases of positive priming effects. Overall, root hairs played an important role in regulating rhizosphere priming.