Complex Biosystems Ph.D. program, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
Plant Cell Environ. 2024 Feb;47(2):611-628. doi: 10.1111/pce.14755. Epub 2023 Nov 17.
Root hairs are considered important for rhizosphere formation, which affects root system functioning. Through interactions with soil microorganisms mediated by root exudation, root hairs may affect the phenotypes and growth of young plants. We tested this hypothesis by integrating results from two experiments: (1) a factorial greenhouse seedling experiment with Zea mays B73-wt and its root-hairless mutant, B73-rth3, grown in live and autoclaved soil, quantifying 15 phenotypic traits, seven growth rates, and soil microbiomes and (2) a semi-hydroponic system quantifying root exudation of maize genotypes. Possibly as compensation for lacking root hairs, B73-rth3 seedlings allocated more biomass to roots and grew slower than B73-wt seedlings in live soil, whereas B73-wt seedlings grew slowest in autoclaved soil, suggesting root hairs can be costly and their benefits were realized with more complete soil microbial assemblages. There were substantial differences in root exudation between genotypes and in rhizosphere versus non-rhizosphere microbiomes. The microbial taxa enriched in the presence of root hairs generally enhanced growth compared to taxa enriched in their absence. Our findings suggest the root hairs' adaptive value extends to plant-microbe interactions mediated by root exudates, affecting plant phenotypes, and ultimately, growth.
根毛被认为对影响根系功能的根际形成很重要。通过根分泌作用与土壤微生物的相互作用，根毛可能会影响幼苗的表型和生长。我们通过整合两个实验的结果来验证这一假设：（1）在温室中进行的玉米 B73-wt 及其无根毛突变体 B73-rth3 的因子幼苗实验，在活体和灭菌土壤中生长，量化了 15 个表型特征、7 个生长速率以及土壤微生物组；（2）在半水培系统中量化玉米基因型的根分泌作用。B73-rth3 幼苗在活体土壤中比 B73-wt 幼苗分配更多的生物量到根上，生长速度较慢，而 B73-wt 幼苗在灭菌土壤中生长最慢，这表明根毛可能是有代价的，并且它们的好处是在更完整的土壤微生物组合中实现的。基因型之间的根分泌作用以及根际和非根际微生物组之间存在很大差异。根毛存在时富集的微生物类群通常比不存在时富集的微生物类群更能促进生长。我们的研究结果表明，根毛的适应价值扩展到由根分泌物介导的植物-微生物相互作用，影响植物表型，最终影响生长。
