Phenotypic response of teosinte parviglumis and wild-type W22 maize grown under heavy metal stress.

(a) to (e), teosinte parviglumis; (f) to (j), W22 maize. (a) Teosinte parviglumis in absence of heavy metal stress at early flowering stage. (b) Teosinte parviglumis grown under heavy metal stress at early flowering stage. (c) Teosinte parviglumis in absence of heavy metal stress at late flowering stage. (d) Teosinte parviglumis grown under heavy metal stress at late flowering stage. (e) Teosinte parviglumis showing absence of lateral branching, and proliferation of female inflorescences arising from independent axillary meristems under heavy metal stress (detail of d). (f) W22 maize in absence of heavy metal stress at early flowering stage. (g) W22 maize grown under heavy metal stress at early flowering stage. (h) W22 maize in absence of heavy metal stress at late flowering stage. (i) W22 maize grown under heavy metal stress at late flowering stage. (j) W22 maize female inflorescences at late flowering stage (detail of i). Scale bars: 10 cm.

Estimation of phenotypic traits in wild-type and zmhma1 maize grown in absence and presence of heavy metal stress.

Estimation of phenotypic traits in teosinte parviglumis grown in absence and presence of heavy metal stress.

Genetic diversity of loci encompassing ZmHMA1, ZmHMA7, and ZmSKUs5.

The nucleotide variability index (π) was calculated for all HapMap3 accessions of teosinte parviglumis (blue line), maize (red line), and Tripsacum dactyloides (orange line), taking in consideration the coding sequence (arrow) and an upstream and downstream region of 15 Kb encompassing each gene. (a) Nucleotide variability in the ZmHMA1 locus. (b) Nucleotide variability in the ZmHMA7 locus. (c) Nucleotide variability in the ZmSKUs5 locus. (d) Nucleotide variability in the ZmGLB1 locus.

Structure and gene expression of ZmHMA1 and ZmHMA7 in teosinte parviglumis and W22 maize.

(a) Structural analysis of ZmHMA1, ZmHMA7, and ZMSKUs5. Blue triangles indicate the location of motifs predicted in the regulatory region of each gene. The insertion site of Mu line LANMu1029790 is indicated by a red triangle. (b) RT-PCR analysis of ZmHMA1 and ZMHMA7 expression throughout development of teosinte parviglumis and W22 maize in presence or absence of heavy metal stress; L=leaf; S=stem; PR=primary root; NR=nodal root; CR=crown root. V2: 15 days after transplant; V6: 30 days after transplant; R1: 50 days after transplant. Controls: (-) absence of DNA; (+) genomic DNA. (c) qPCR analysis of ZmHMA1 expression in 1-month old primary roots, in absence or presence of heavy metal stress. (d) qPCR analysis of ZmHMA7 expression in 1-month old primary roots, in absence or presence of heavy metal stress. Histograms in (c) and (d) show the relative fold-change (normalized to actin, based on technical and biological triplicates); standard deviations are shown by vertical lines and Student T-test P-values represented by asterisks. * P<0.01; ** P<0.001.

Tb1 and ZmHMA1 expression in the shoot apical meristem of plantlets grown under heavy metal stress.

(a) qPCR analysis of Tb1 expression in 1-month old teosinte parviglumis plantlets grown in absence or presence of heavy metal stress. (b) qPCR analysis of ZmHMA1 expression in 1-month old teosinte parviglumis and W22 maize plantlets in absence or presence of heavy metal stress. Histograms show the relative fold-change (normalized to actin, based on technical and biological triplicates); standard deviations are shown by vertical lines and Student T-test P-values represented by asterisks; * P<0.01.

Location and age of volcanic eruptions occurred during the Holocene in comparison to collection sites of teosinte parviglumis populations most closely related to maize.

(a) Black asterisks correspond to the location and accession numbers of collected teosinte parviglumis populations that are phylogenetically most closely allied with extant maize, following Matzuoka et al. 2002. The location of 21 volcanoes belonging to the Michoacan-Guanajuato Volcanic Field is indicated with yellow circles. The locations of the Nevado de Toluca and Popocatéptl craters are indicated with a red and brown circle, respectively. Orange squares indicate the location of paleoenvironmental studies covering from 14,000 cal yr BP to current era, as described in Lozano-García et al. 2013 (i), Piperno et al. 2007 (ii), and Ludlow-Wiechers et al., 2005 (iii). (b) Time versus age of volcanic eruptions occurred in the map area of the Transmexican Volcanic Belt during the Holocene; numbers correspond to volcanoes illustrated in (a). Adapted from Macías and Arce, 2019.

Cumulative plot of QTL detected in a region of chromosome five that includes ZmSKUs5 and ZmHMA1.

© 2014 Oxford University Press. This figure is modfied from from Figure 1 in Lemmon and Doebley, 2014 with permission from Oxford University Press. It is not covered by the CC-BY 4.0 licence and further reproduction of this figure would need permission from the copyright holder.

Comparison of chromosome 5 nucleotide variability between maize landraces and teosinte parviglumis.

Large scale transcriptional comparison of HM response genes across six maize experiments based on fold change >1 and false discovery rate (FDR) < 0.05.

Expression of ZmHMA1 in wild-type and homozygous zmhma1 maize individuals.

Distribution of soils of volcanic origin (andosols; pink) in geographic regions of teosinte parviglumis populations most closely related to extant maize.

Speculative model illustrating the influence of heavy metal stress on the evolutionary transition of teosinte parviglumis to maize.

Additional estimation of phenotypic traits in teosinte parviglumis grown in absence or presence of heavy metal stress.

Additional estimation of phenotypic traits in wild-type and zmhma1 maize grown in absence or presence of heavy metal stress.

Full comparison of phenotypic values for wild-type W22, zmhma1, and teosinte parviglumis individuals grown under absence or presence of heavy metal stress

Nucleotide variability across the ZmSKUS5, ZmHMA1 and ZmHMA7 locus; and their upstream and downstream neighboring genes in maize landraces, maize improved lines, and teosinte parviglumis accessions included in HapMap3.

Description of six transcriptomes reporting HM response genes under different growing conditions and developmental stages.

Collection of primers used in this study.

Maize landrace accessions used in the genetic diversity analysis chr.5.

Teosinte parviglumis accessions used in the genetic diversity analysis chr.5.