Lopez-Valdivia Ivan, Vallebueno-Estrada Miguel, Rangarajan Harini, Swarts Kelly, Benz Bruce F, Blake Michael, Sidhu Jagdeep Singh, Perez-Limon Sergio, Sawers Ruairidh J H, Schneider Hannah, Lynch Jonathan P
Department of Plant Science, The Pennsylvania State University, University Park, PA, 16802, USA.
Gregor Mendel Institute of Molecular Plant Biology GmbH: Vienna, Wien, 1030, Austria.
New Phytol. 2025 Oct;248(1):339-353. doi: 10.1111/nph.70245. Epub 2025 May 30.
Roots are essential for plant adaptation to changing environments, yet the role of roots in crop domestication remains unclear. This study examined the evolution of root phenotypes from teosinte to maize, a transition resulting in reduced nodal root number (NRN), multiseriate cortical sclerenchyma (MCS), and increased seminal root number (SRN). We reconstructed the root phenotypes of maize and teosinte, as well as the environments of the Tehuacán Valley over the last 18 000 yr using a combination of ancient DNA, paleobotany, and functional-structural modeling. Our models reveal that increasing Holocene atmospheric CO concentrations favored the appearance of reduced NRN and MCS between 12 000 and 8000 yr before present (yrBP), promoting deeper root systems. The advent of irrigation by 6000 yrBP switched nitrogen distribution from topsoil to subsoil domains, a change that increased the utility of reduced NRN and MCS. Comparison of allelic frequencies among ancient samples ranging from 5500 to 500 yrBP suggests that increased SRN may have appeared c. 3500 yrBP, coinciding with a period of increased human population, agricultural intensification, and soil degradation. Our results suggest that root phenotypes that enhance plant performance under nitrogen stress are important for maize adaptation to changing agricultural practices in the Tehuacán Valley.
根系对于植物适应不断变化的环境至关重要，然而根系在作物驯化中的作用仍不明确。本研究考察了从大刍草到玉米根系表型的演变，这一转变导致节根数量（NRN）减少、多层皮质厚壁组织（MCS）减少以及种子根数量（SRN）增加。我们结合古DNA、古植物学和功能结构建模，重建了玉米和大刍草的根系表型以及特瓦坎谷过去18000年的环境。我们的模型显示，全新世大气CO浓度增加有利于在距今12000年至8000年期间出现减少的NRN和MCS，促进根系更深。到距今6000年时灌溉的出现将氮的分布从表土转移到了底土区域，这一变化增加了减少的NRN和MCS的效用。对距今5500年至500年的古代样本中等位基因频率的比较表明，增加的SRN可能出现在约距今3500年，这与人口增加、农业集约化和土壤退化的时期相吻合。我们的结果表明，在氮胁迫下增强植物性能的根系表型对于玉米适应特瓦坎谷不断变化的农业实践很重要。
