Differences in plant morphology between teosinte and maize are highlighted in A, while differences in ear morphology are shown in B. Teosinte plant has many branches with multiple ears on each branch and tassel at the tip of the branch; maize plant has few branches with a single ear on each branch and ear at the tip of the branch. Ressources. However, there is an exception: teosinte possesses less G×E than maize landrace for traits that relate to ear and grain size. We observed strongest selection intensities within the Reproductive group, followed by Environmental Response, and last, Vegetative/Flowering Time. Of all 18 traits, only four traits (PLHT, LFLN, LBNN, and EILN) showed a slight decrease in VD/VG from teosinte to maize landrace. Overall, we see that the teosinte and maize landrace G-matrices have very different structures and predicted evolutionary responses, and these differences cannot be explained by neutral drift alone. laboratory, and Panzea, especially Adam Mittermaier, Eric Rentmeester, and Jason Brewer, for their assistance in this project. Epub 2018 Jul 23. The dissimilarity of G-matrices of teosinte and maize landrace is primarily due to changes in the submatrix for Reproductive traits, while the submatrix for Vegetative/Flowering Time traits is conserved. Une évolution sous influence humaine: histoire de la domestication du maïs. Our results here suggest that if the ancient farmers were to domesticate teosinte by selecting for only a single trait, EL would be the ideal candidate as EL produced the maximum desired multivariate gains with the least genetic constraint. Au milieu du xviiie siècle, le naturaliste suédois Carl von Linné nomme le maïs Zea mays. These angles were θTi= 67.3°, 79.4°, 88.1°, 54.1°, and 81.0°, indicating moderate to strong constraint to the trajectory of domestication in the five most important directions of multivariate genetic variation. mays) and teosinte (ssp. 4). There are 55 trait pairs significantly correlated in teosinte but not in maize landrace, and 17 are significant in maize landrace but not teosinte. These three traits were probably either indirectly selected or weakly selected at most. Isotope ratios could offer a new way to closely track animal movements. Maize domestication and gene interaction. To compare individual trait contribution to genetic constraint, we calculated the angle θdroponei between Z and gmax for every ith trait that is dropped from Z and gmax. MAF was calculated from parent data. Chez le maïs, 2 gènes sont particulièrement intéressants en terme agronomique : What do the structures of the teosinte and landrace G-matrices and the differences between them tell us about early and subsequent evolutionary potential and constraint during domestication? Doc 2 : Comparaison de la téosinte et du maïs Plant non ramifié, croissance en hauteur. Trait evaluations of the two subspecies were conducted in adjacent field blocks of a daylength-neutral environment over 2 y. Genome-wide DNA markers were used to estimate the additive and dominance-realized genomic relationships among all pairs of individuals in each population. Although genetic correlations can influence evolution of multiple traits through indirect response to selection, it is the genetic variances and covariances that define the magnitude of the influence. Fig 2. The maize landrace population was chosen from individuals in a site less than 1 km away from the teosinte population (University of Guadalajara collection JSG-RMM-LCL-529; latitude, 18.6483°; longitude, −100.3542°; altitude, 983 m). Fig 3. The matrices of genetic variance–covariance among traits (G-matrices) within maize and teosinte are strongly differentiated, especially with respect to reproductive traits and this divergence was driven by selection. We found that the overall predicted evolutionary responses are not significantly more correlated than random (r = 0.19; P = 1.00), again suggesting that teosinte and maize landrace G-matrices are quite different. [ citation needed ] The genus is divided into two sections : Luxuriantes , with Z. diploperennis , Z. luxurians , Z. nicaraguensis , Z. perennis ; and Zea with Z. mays . The Environmental Response group is composed of traits that are highly affected by environmental factors. The covariances of genotype-by-environment effects were modeled to be proportional to the additive relationships of individuals tested in a common year and zero for pairs of individuals tested in different years. S2). If θdroponei is larger than θT, then the ith trait is said to assist evolution. Overall, teosinte shows more significant and stronger genetic correlations among traits than maize. The exact number of QTL in each group is shown above each bar. While the angle between the genetic lines of least resistance in teosinte (gmax) and the axis along which teosinte evolved into maize is large (67.3°), indicating substantial constraint, the similar angle in maize landrace is 74.3°, indicating higher constraint. 2). Before imputation, we used the CrossMap (80) software to convert the GBS SNP positions from maize B73 reference AGPv2 coordinates to AGPv4 coordinates. The overall genotyping process from raw sequencing reads to final, clean, and imputed GBS dataset is highlighted in a flowchart (SI Appendix, Fig. Descriptions and methods of measurement for each trait are summarized in Table 1 and SI Appendix, Table S12. To what extent was that genetic variation depleted by domestication? Regions of the genome that are strongly differentiated between teosinte and maize (high FST) explain less quantitative variation in maize than teosinte, suggesting that, in these regions, allelic variants were brought to (or near) fixation during domestication. An ultimate objective of QTL mapping is cloning genes responsible for quantitative traits. Each trait group is named after a common biological theme shared among the group members. La téosinte, plante sauvage, est l'ancêtre supposé du maïs moderne. 2011 Jul;188(3):673-81. doi: 10.1534/genetics.111.126508. While θZi measures the deviation between Ri and Z, |projZRi| measures the gain along Z for each Ri. tp12 : la domestication du maÏs ts – thème 2b Le maïs est cultivé aujourd’hui dans presque toutes les régions du monde, c’est la troisième céréale du monde, il est la base de l’alimentation d’une grande partie de la population mondiale. We asked whether the G-matrices are conserved between teosinte and maize landrace. First, there appears to have been substantial evolutionary constraint imposed by the structure of the G-matrix at the initial phase of domestication as measured by the angle of 67.3° between the genetic lines of least resistance in teosinte (gmax) and the axis along which teosinte evolved into maize. Genetics. In contrast, teosinte exhibits about 49% less VG×E/VP for Reproductive group compared with the maize landrace. Additional details on imputation and quality check are described in SI Appendix, Materials and Methods and Fig. origine et domestication du maÏs L’histoire du maïs commence il y a 9.000 ans, dans une haute vallée du Mexique, où s’écoule le fleuve Rio Balsas. Teosinte plants are taller and broader-leaved than most grasses .Their general growth form is similar to that of maize, although they have much longer lateral branches. There is not a consistent pattern for h2 within the Environmental Response trait group, since h2 for PROL and TILN were depleted in the maize landrace, while h2 for LBNN was increased in the maize landrace and h2 for LBLN and LBIL remained similar (Fig. The genetics of domestication has been extensively studied ever since the rediscovery of Mendel's law of inheritance and much has been learned about the genetic control of trait differences between crops and their ancestors. Or, en 1896, José Segura, un agronome … We imputed the GBS data for teosinte and maize landrace using the ParentPhasingPlugin and ImputeProgenyStatesPlugin as implemented in TASSEL5 (79). Phylogenetic analysis and archaeological data revealed that maize originated from a single domestication event in southern Mexico about 9,000 y ago (9, 10). Quel est l’ancêtre sauvage du maïs ? Mais la domestication de la plante aura permis d’observer quelque chose de singulier. The increase in VD/VG for those traits suggests that the additive genetic variance was depleted at a faster rate than the dominance genetic variance during domestication, congruent with the expected changes in VD/VG due to increase in frequency of recessive alleles (SI Appendix, Fig. La plante domestiquée, par Marine Morandeau - L’exemple de la téosinte et du maïs. We also checked for the similarity in genetic correlation matrices by comparing the angle between the first two leading eigenvectors of the matrices, as well as the three submatrices defined by the trait groups. This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. We observed lower VD/VG in teosinte (VD/VG=0.14±0.11, ranging from 0.04 to 0.36) than maize landrace (VD/VG=0.29±0.26, ranging from 0.00 to 0.86). To explore how evolutionary constraint changed during domestication, we also estimated θM, the angle between the domestication trajectory (Z) and the direction of maximum genetic variation in maize (gmax,M), as a comparison with θT. Genetic correlations for traits in teosinte are shown in the Bottom Left triangle of the matrix, and maize landrace is shown in the Top Right triangle of the matrix. Ce genre comprend le maïs et les téosintes, originaires du Mexique et souvent considérées comme les ancêtres du maïs cultivé. The archaeological record also shows slow and continuous change in ear traits over a 5,000-y period, suggesting a gradual rather than abrupt process by which maize became a productive food source (57, 58). Martin Bizzarro tells what zircon crystals reveal about the geological history of Mars. -, Gross BL, Olsen KM. Both phylogenetic and archaeological evidence revealed that maize was domesticated from Balsas teosinte (Z. mays ssp. Gage et al. The process of evolution under domestication has been studied using phylogenetics, population genetics–genomics, quantitative trait locus (QTL) mapping, gene expression assays, and archaeology. Given that selection likely brought beneficial alleles to fixation, it is not surprising to find an overall reduction in h2 in any domesticated relative of its wild progenitor. Teosinte adapts by varying the number of ears per plant while maintaining constant ear and grain size across environments. Within the submatrices for each trait group, both random skewers and Bayesian estimation reaffirmed that the submatrices for Vegetative/Flowering Time and Environmental Response are conserved while the submatrix for Reproductive is not.  |  Il est cultivé dans presque toute les régions du globe et présente de nombreuses variétés. Overall, our findings corroborate the hypothesis that the G-matrix is not conserved over long-term evolution (65), which limit us in making further predictions on the evolution of maize from teosinte. Data deposition: The data reported in this paper have been deposited in the figshare database (https://doi.org/10.6084/m9.figshare.7655588). Given the genetic architecture in teosinte, how strong would selection need to be to complete domestication within the known time frame? Considering that 9,000 y of selection may not have increased yield per plant, it is not too surprising to find that modern maize breeding has only been successful in increasing yield per area but not yield per plant (60). Le maïs a été domestiqué par l’Homme alors que la téosinte est considérée comme son ancêtre sauvage. As per GBS protocol, all DNA samples were digested using ApeKI restriction enzyme and sequenced in 96-plex on Illumina HiSeq 2000, SE 1 × 100 bp (Illumina).  |  In contrast, maize plants typically have one or two short branches, each with a single ear at its tip. Reviewers: L.H.R., University of British Columbia, Vancouver; and B.W., University of Arizona. θZ measures the deviation in direction from Z, while |projZRi| measures the amount of evolutionary gain along Z. On the other hand, eigenstructure comparison of the teosinte and maize landrace genetic correlation matrices yielded slightly different results. In this article, we report that the narrow-sense heritabilities (h2) for domestication traits are generally depleted in maize landrace compared with teosinte. Large effect QTL is defined as a QTL with a standardized additive effect greater than 1 phenotypic standard deviation as indicated by blue dotted lines. Second, the reduction in the magnitude of genetic correlations from teosinte to maize landrace is much stronger between trait groups than within them (Fig. A : plant de téosinte C : Pied de maïs normal E : Pied de maïs mutant (tb1) First, selection was clearly focused on ear architecture since most of the traits that define ear architecture suffered a loss of heritable variation and ear morphology changed dramatically. Evolution of crop species: genetics of domestication and diversification. Among the three predefined trait groups, Reproductive traits showed the strongest depletion in h2 from teosinte to maize landrace while h2 in the Vegetative/Flowering Time group showed little difference between teosinte and maize landrace (Fig. The lowest magnitude of i is found for DTA, DTS, and TGWP (|i| = 0.0002–0.0007). Generally, the traits with high magnitude of i fall within the Reproductive group (|i| = 0.0022–0.0040) except for TGWP. Change in the G-matrices of teosinte and maize landrace appears to be due to selection and not merely drift. The random skewers analysis indicated there would be highly correlated predicted evolutionary responses for Vegetative/Flowering Time traits (r = 0.89; P = 0.001), but uncorrelated responses for Reproductive traits (r = 0.09; P = 1.00). This site needs JavaScript to work properly. Maize has a more fixed growth form, producing one or two large ears over a wide range of environments, which represents an adaptation for easy harvest of the grain by its human cultivators. Teosinte versus mais moderne. Using the multivariate breeders’ equation of Gβ=R (37), we can estimate the multivariate response (R) based on teosinte G-matrix and hypothetical selection differentials (β). Please enable it to take advantage of the complete set of features! Amazing grass: developmental genetics of maize domestication. The first three subspecies are teosintes; the last is maize, or corn, the only domesticated taxon in the genus Zea. Il la baptise Euchlaena mexicana et la considère comme proche du riz. The Mantel’s test is performed using mantel.test function with 10,000 permutations implemented in the package “ape” (87) in R (88). In addition, PLHT, LFLN, and LFWD also displayed favorable genetic correlations with many Reproductive traits, which would have facilitated simultaneous selection for larger ears and plants, or in a broader sense, gigantism, a common feature of domestication (64). NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. Un demi-siècle plus tard, en 1832, le botaniste allemand Heinrich Schrader décrit une poacée (autrefois graminée) d'Amérique centrale, appelée téosinte. Am J Bot. In addition to the overall constraint seen between Z and gmax,T, there is variation in the degree to which different traits contribute to genetic constraint (Fig. The researchers, led by Anthony Ranere of Temple University and Dolores Piperno of the … If the genetic constraint decreases (θdroponei<θT) after dropping trait i, then it is said that trait i constrained evolution. However, there are differences in VG×E/VP between teosinte and the maize landrace among the trait groups. The molecular genetics of crop domestication. Le processus de domestication de la téosinte vers le maïs « moderne » s’est déroulé sur des centaines d’années et à fait l’objet d’étapes décisives dans la sélection de plants présentant des caractères d’intérêt. Previously, Ladizinsky (43) and Lester (44) argued that a major force in domestication is the fixation of recessive loss-of-function alleles. Moderate magnitude of i are observed for the Environmental Response group (|i| = 0.0018–0.0026). Strongest preservation of genetic correlations is observed within the Vegetative/Flowering Time group (r = 0.90; P < 0.05), followed by the Reproductive group (r = 0.79; P < 0.01) and the Environmental Response group (r = 0.77; P < 0.05). 10.1016/j.cell.2006.12.006 Our estimate of θT is 67.3°, which suggests that maize domestication proceeded despite strong constraint imposed by the G-matrix. Maize was domesticated from its wild grass ancestor more than 8,700 years ago, according to biological evidence uncovered by researchers in Mexico’s Central Balsas River Valley. … The covariances of additive and dominance effects of each individual were modeled to be proportional to the realized additive and dominance relationship matrices, respectively. The multivariate QST–FST test compares the proportionality of the between-population G-matrix (GB) to within-population G-matrix (GW). While additive genetic variation is reduced in maize landrace relative to teosinte, the proportion of the genetic variance attributable to dominance effects is generally increased, suggesting that dominance genetic variance depletes more slowly than additive genetic variance during domestication (Fig. Copyright © 2021 National Academy of Sciences. Fig 7. Given the recent origin of crops, they typically remain cross-compatible with their nearest wild relatives, allowing genetic analysis using crosses of domesticated by wild species. 19. wrote the paper; J.d.J.S.-G. provided seeds for maize landrace; and M.C.R., J.C.G., and Q.S. Genotype files are available in Figshare, and phenotype files are available in Datasets S1 and S2. Similarly, maize landrace has very low h2 for Reproductive traits, suggesting that many beneficial alleles for Reproductive traits were brought to fixation during domestication. To compare the VA between teosinte and the maize landrace, we used the narrow-sense heritabilities (h2=VA/VP), which is a VP-standardized measure of the VA. We observed higher h2 in teosinte (h2=0.39±0.19, ranging from 0.07 to 0.73) than in maize landrace (h2=0.19±0.11, ranging from 0.01 to 0.38) for 15 of 18 traits (Fig. Available at, Efficient methods to compute genomic predictions, Shrinkage estimation of the realized relationship matrix, TASSEL: Software for association mapping of complex traits in diverse samples, CrossMap: A versatile tool for coordinate conversion between genome assemblies, ASReml User Guide, Release 4.1, Structural Specification, The effect of selection on genetic variability, Predicting cumulated response to directional selection in finite panmictic populations, Effects of population size and linkage on optimal selection intensity, APE: Analyses of phylogenetics and evolution in R language, R: A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, Vienna), Version 3.5.1. Techniques d’amélioration des variétés de maïs GNIS pédagogie. Phenotypic plasticity is the ability of an individual genotype to express phenotypes differently as a response to environmental fluctuation (50, 51). This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). Examples of QTL under balancing selection. gmax,M explains 19.1% of the variance (SI Appendix, Fig. 1) (17, 18). Within each season, we planted the seeds in a randomized design and grid of 100 plants by 30 rows along with borders surrounding the experimental section. An in-depth examination on the genetic correlation matrices revealed strong differences between teosinte and the maize landrace including change in sign of the correlations for some Reproductive traits, suggesting domestication modified the genetic networks underlying Reproductive trait variation. Briefly, among the fixed effects in the model are year, inbreeding coefficient, shading (SI Appendix, Fig. Genetic correlations for 18 teosinte and maize landrace comparable traits. As a result, maize landraces serve as a rich source of genetic diversity for breeding modern maize (12). -, Burger JC, Chapman MA, Burke JM. It is not surprising to find θM>θT since the domestication process likely depleted variants that contributed beneficially to the structure of the G-matrix.

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