Aims Longer root hair length (RHL) increases root surface area, thereby contributing to increased phosphorous uptake. This study aimed to identify useful germplasms and quantitative trait loci (QTL) for RHL improvement in wheat. Methods The genetic variation in RHL was examined using hydroponic culture in 117 hexaploid wheat strains. Rhizosheath size and phosphorous uptake ability were also examined using high P-fixing soils with extremely low phosphorous availability (Andisols). QTL analysis was performed using backcross inbred lines from a cross between a Spanish spelt strain and a bread wheat variety. Results A wide range in genetic variation was found, especially in spelt wheat and landraces of bread wheat, whereas modern bread wheat varieties tended to show shorter RHL. Interestingly, remarkably longer RHL were observed in Spanish spelt strains than in strains from other countries. RHL exhibited a significant positive correlation with rhizosheath size and phosphorous uptake in soils. A QTL on chromosome 2A ( QRhl.obu-2A ) conferring longer RHL by the allele of a Spanish spelt strain was identified. It was co-located with TaRSL4-2AS , a key regulator of root hair elongation. Conclusions Spanish spelt wheat strains could be unique germplasms that provide a useful allele for increasing RHL to enhance phosphorous uptake ability.

中文翻译：

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西班牙拼写是一种独特的种质，用于改善六倍体小麦的根毛长度

目的 更长的根毛长度 (RHL) 会增加根表面积，从而有助于增加磷的吸收。本研究旨在鉴定可用于小麦 RHL 改良的有用种质和数量性状位点 (QTL)。方法采用水培法对117个六倍体小麦品系进行RHL遗传变异研究。还使用磷含量极低的高固磷土壤（Andisol）检查了根鞘大小和磷吸收能力。QTL 分析使用来自西班牙拼写品系和面包小麦品种之间的杂交的回交自交系进行。结果 发现了广泛的遗传变异，特别是在斯佩尔特小麦和面包小麦的地方品种中，而现代面包小麦品种往往表现出较短的 RHL。有趣的是，在西班牙拼写菌株中观察到的 RHL 明显长于其他国家的菌株。RHL与土壤中根鞘大小和磷吸收量呈显着正相关。鉴定了染色体 2A (QRhl.obu-2A) 上的 QTL，它通过西班牙拼写菌株的等位基因赋予更长的 RHL。它与 TaRSL4-2AS 共同定位，TaRSL4-2AS 是根毛伸长的关键调节剂。结论西班牙斯佩尔小麦菌株可能是独特的种质，为增加 RHL 以增强磷吸收能​​力提供有用的等位基因。根毛伸长的关键调节剂。结论西班牙斯佩尔小麦菌株可能是独特的种质，为增加 RHL 以增强磷吸收能​​力提供有用的等位基因。根毛伸长的关键调节剂。结论西班牙斯佩尔小麦菌株可能是独特的种质，为增加 RHL 以增强磷吸收能​​力提供有用的等位基因。