基生根轮数：菜豆（Phaseolus vulgaris）磷吸收的调节剂。
Basal root whorl number: a modulator of phosphorus acquisition in common bean (Phaseolus vulgaris).
机构信息
Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA.
出版信息
Ann Bot. 2013 Oct;112(6):973-82. doi: 10.1093/aob/mct164. Epub 2013 Aug 7.
BACKGROUND AND AIMS
Root architectural phenes enhancing topsoil foraging are important for phosphorus acquisition. In this study, the utility of a novel phene is described, basal root whorl number (BRWN), that has significant effects on topsoil foraging in common bean (Phaseolus vulgaris).
METHODS
Whorls are defined as distinct tiers of basal roots that emerge in a tetrarch fashion along the base of the hypocotyl. Wild and domesticated bean taxa as well as two recombinant inbred line (RIL) populations were screened for BRWN and basal root number (BRN). A set of six RILs contrasting for BRWN was evaluated for performance under low phosphorus availability in the greenhouse and in the field. In the greenhouse, plants were grown in a sand-soil media with low or high phosphorus availability. In the field, plants were grown in an Oxisol in Mozambique under low and moderate phosphorus availability.
KEY RESULTS
Wild bean accessions tended to have a BRWN of one or two, whereas cultivated accessions had BRWN reaching four and sometimes five. BRWN and BRN did not vary with phosphorus availability, i.e. BRWN was not a plastic trait in these genotypes. Greater BRWN was beneficial for phosphorus acquisition in low phosphorus soil. Genotypes with three whorls had almost twice the shoot biomass, greater root length and greater leaf area than related genotypes with two whorls. In low phosphorus soil, shoot phosphorus content was strongly correlated with BRWN (R(2) = 0.64 in the greenhouse and R(2) = 0.88 in the field). Genotypes with three whorls had shallower root systems with a greater range of basal root growth angles (from 10 to 45 ° from horizontal) than genotypes with two whorls (angles ranged from 60 to 85 ° from horizontal).
CONCLUSIONS
The results indicate that BRWN is associated with increased phosphorus acquisition and that this trait may have value for selection of genotypes with better performance in low phosphorus soils.
背景与目的
增强表土觅食能力的根系形态特征对于磷的获取很重要。本研究描述了一个新表型，即基生根轮数（BRWN），它对普通菜豆（Phaseolus vulgaris）的表土觅食有显著影响。
方法
轮是指在胚轴基部以四轮方式出现的明显的基生根层。对野生和驯化的豆科植物以及两个重组自交系（RIL）群体进行了 BRWN 和基生根数（BRN）的筛选。对一组 6 个 RIL 进行了对比，以评估它们在低磷供应条件下在温室和田间的表现。在温室中，植物在沙壤土中生长，沙壤土中磷的供应水平较低或较高。在田间，植物在莫桑比克的氧化土中生长，磷的供应水平较低和中等。
主要结果
野生豆科植物的 BRWN 倾向于为 1 或 2，而栽培品种的 BRWN 可达 4，有时可达 5。BRWN 和 BRN 不受磷供应的影响，即在这些基因型中，BRWN 不是一种可塑性状。更多的 BRWN 有利于在低磷土壤中获取磷。具有 3 个轮的基因型的地上生物量几乎是具有 2 个轮的相关基因型的两倍，根长和叶面积更大。在低磷土壤中，地上部磷含量与 BRWN 呈强相关（温室中 R²=0.64，田间中 R²=0.88）。具有 3 个轮的基因型的根系较浅，基生根生长角度（从水平方向 10 到 45°）范围更大，而具有 2 个轮的基因型的角度范围（从水平方向 60 到 85°）。
结论
结果表明，BRWN 与磷的获取增加有关，该性状可能对选择在低磷土壤中表现更好的基因型具有价值。
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