BACKGROUND AND AIMS An increase in the root hair length and density, as well as the development of arbuscular mycorrhiza symbiosis, are two alternative strategies of most plants to increase the root-soil surface area under phosphorus (P) deficiency. Across many plant species, root hair length and mycorrhization density are inversely correlated. Root architectures, rooting density and physiology also differ between species. This study aims to understand the relationship among root hairs, arbuscular mycorrhizal fungi (AMF) colonisation, plant growth, P acquisition, and mycorrhizal-specific Pi transporter gene expression of maize. METHODS Using nearly isogenic maize lines, the B73 wild type and the rth3 root hairless mutant, we quantified the effect of root hairs and AMF infection in a calcareous soil under P-deficiency through a combined analysis of morphological, physiological and molecular factors. KEY RESULTS Wild type root hairs extended the rhizosphere for acid phosphatase activity by 0.5 mm compared to the rth3 hairless mutant, as measured by in situ zymography. Total root length of the wild type was longer than rth3 under P-deficiency. Higher AMF colonisation and mycorrhiza-induced phosphate transporter gene expression were identified in the mutant under P-deficiency, but plant growth and P acquisition were similar between mutant and the wild type. Ultimately, the mycorrhizal dependency of maize was 33% higher than the root hair dependency. CONCLUSIONS The results identified a larger mycorrhizal dependency than root hair dependency under P-deficiency in maize. Root hairs and AMF inoculation are two alternative ways to increase Pi acquisition under P-deficiency, but these two strategies compete with each other.

中文翻译：

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在磷利用率低的情况下，丛枝菌根定植在玉米中胜过根毛


背景和目的 增加根毛长度和密度，以及发展丛枝菌根共生，是大多数植物在磷（P）缺乏的情况下增加根-土壤表面积的两种替代策略。在许多植物物种中，根毛长度和菌根密度呈负相关。根结构、根密度和生理学也因物种而异。本研究旨在了解玉米的根毛、丛枝菌根真菌 (AMF) 定植、植物生长、磷获取和菌根特异性 Pi 转运蛋白基因表达之间的关系。方法 使用近同基因玉米品系、B73 野生型和 rth3 根无毛突变体，通过形态、生理和分子因素的综合分析，我们量化了缺磷石灰质土壤中根毛和 AMF 感染的影响。关键结果 通过原位酶谱法测量，与 rth3 无毛突变体相比，野生型根毛将根际酸性磷酸酶活性延长了 0.5 毫米。缺磷条件下野生型的总根长比rth3长。在磷缺乏的情况下，突变体中发现较高的 AMF 定植和菌根诱导的磷酸盐转运蛋白基因表达，但突变体和野生型之间的植物生长和磷获取相似。最终，玉米的菌根依赖性比根毛依赖性高33%。结论 结果发现，在缺磷情况下，玉米对菌根的依赖性大于对根毛的依赖性。根毛和 AMF 接种是在 P 缺乏的情况下增加 Pi 获取的两种替代方法，但这两种策略相互竞争。