Gradual domestication of root traits in the earliest maize from Tehuacán

25 de abril de 2022

Les invitamos a leer el artículo: "Gradual domestication of root traits in the earliest maize from Tehuacán", un trabajo realizado en la UGA-Langebio.

Autores: Ivan Lopez-Valdivia^1,2, Alden C. Perkins³, Hannah M. Schneider³, Miguel Vallebueno-Estrada^1,2, James D. Burridge³, Eduardo Gonzalez-Orozco¹,Aurora Montufar⁴, Rafael Montiel², Jonathan P. Lynch³, and Jean-Philippe Vielle-Calzada¹.

1. Grupo de Desarrollo Reproductivo y Apomixis, Unidad de GenomicaAvanzada, Laboratorio Nacional de Genomica para la Biodiversidad, Cinvestav, Irapuato36821 Guanajuato, Mexico.
2. Grupo de Interaccion Nucleo-Mitocondrial y Paleogenomica,Unidad de Genomica Avanzada, Laboratorio Nacional de Genomica para la Biodiversidad,Cinvestav,  Irapuato  36821  Guanajuato,  Mexico.
3. Department  of  Plant  Science, Pennsylvania State University, State College, PA 16802.
4. Subdireccion de Laboratorios y Apoyo Academico, Instituto Nacional de Antropologıa e Historia, CP6010 Ciudad de Mexico, Mexico.

Felicitamos al estudiantado y profesorado que contribuyeron en esta investigación por su arduo trabajo.

Abstract: Efforts to understand the phenotypic transition that gave rise to maize from teosintehave mainly focused on the analysis of aerial organs, with little insights into possibledomestication traits affecting the root system. Archeological excavations in San Marcoscave (Tehuacan, Mexico) yielded two well-preserved 5,300 to 4,970 calibrated y B.P.specimens (SM3 and SM11) corresponding to root stalks composed of at leastfivenodes with multiple nodal roots and, in case, a complete embryonic root system. Tocharacterize in detail their architecture and anatomy, we used laser ablation tomographyto reconstruct a three-dimensional segment of their nodal roots and a scutellar node,revealing exquisite preservation of the inner tissue and cell organization and providingreliable morphometric parameters for cellular characteristics of the stele and cortex.Whereas SM3 showed multiple cortical sclerenchyma typical of extant maize, the scutel-lar node of the SM11 embryonic root system completely lacked seminal roots, an attri-bute found in extant teosinte and in two specificmaizemutants:root with undetectablemeristem1(rum1)androotless concerning crown and seminal roots(rtcs). Ancient DNAsequences of SM10—a third San Marcos specimen of equivalent age to SM3 andSM11—revealed the presence of mutations in the transcribed sequence of both genes,offering the possibility for some of these mutations to be involved in the lack of seminalroots of the ancient specimens. Our results indicate that the root system of the earliestmaize from Tehuacan resembled teosinte in traits important for maize drought adaptation.

Keywords:maize, teosinte, domestication, root anatomy, laser ablation.