Seed Dormancy in Mexican Teosinte

Lopez, Adriana N. Avendano; González, José de Jesús Sánchez; Corral, José Ariel Ruíz; Larios, Lino De la Cruz; Santacruz-Ruvalcaba, Fernando; Sánchez-Hernández, Carla; Holland, James B.

doi:10.2135/cropsci2010.09.0538

Cited by 22 publications

(13 citation statements)

References 23 publications

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“…A number of other traits distinguish maize and teosinte, many of which can be explained by the premature cessation of growth in axillary branches, leaves and internodes (Doebley & Iltis, ). Other traits involved in domestication, and improvement of maize allowing its worldwide spread include a loss of seed dormancy (Avendaño López et al ., ), a loss of photoperiod sensitivity (Huang et al ., ), nutritional alterations (Hanson et al ., ; Whitt et al ., ), and other phenotypes less apparent than these morphological changes. Collectively, these phenotypes represent radical departures of maize from Z. mays subsp.…”

Section: The Genetic Basis Of Maize Domesticationmentioning

confidence: 99%

Maize domestication and gene interaction

Stitzer

Ross‐Ibarra

2018

New Phytologist

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Contents Summary 395 I. Introduction 395 II. The genetic basis of maize domestication 396 III. The tempo of maize domestication 401 IV. Genetic interactions and selection during maize domestication 401 V. Gene networks of maize domestication alleles 404 VI. Implications of gene interactions on evolution and selection404 VII. Conclusions 405 Acknowledgements 405 References 405 SUMMARY: Domestication is a tractable system for following evolutionary change. Under domestication, wild populations respond to shifting selective pressures, resulting in adaptation to the new ecological niche of cultivation. Owing to the important role of domesticated crops in human nutrition and agriculture, the ancestry and selection pressures transforming a wild plant into a domesticate have been extensively studied. In Zea mays, morphological, genetic and genomic studies have elucidated how a wild plant, the teosinte Z. mays subsp. parviglumis, was transformed into the domesticate Z. mays subsp. mays. Five major morphological differences distinguish these two subspecies, and careful genetic dissection has pinpointed the molecular changes responsible for several of these traits. But maize domestication was a consequence of more than just five genes, and regions throughout the genome contribute. The impacts of these additional regions are contingent on genetic background, both the interactions between alleles of a single gene and among alleles of the multiple genes that modulate phenotypes. Key genetic interactions include dominance relationships, epistatic interactions and pleiotropic constraint, including how these variants are connected in gene networks. Here, we review the role of gene interactions in generating the dramatic phenotypic evolution seen in the transition from teosinte to maize.

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Section: The Genetic Basis Of Maize Domesticationmentioning

confidence: 99%

Maize domestication and gene interaction

Stitzer

Ross‐Ibarra

2018

New Phytologist

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Section: Resultsmentioning

confidence: 99%

“…We should be able to detect such loci by testing for segregation distortion at each marker in the families we were able to genotype. We caution, however, that although we removed the seed coat, teosinte varies for seed dormancy, a trait adaptive in natural populations (Avendaño López et al 2011), and it is possible that some seeds that did not germinate may have been alive but dormant. We identified 3 significant segregation distortion regions (SDR) across three different chromosomes in 3 self-families in maize landraces and 16 significant SDR on seven different chromosomes in 11 self-families in teosinte (Figure 6; Table S13).…”

Section: Early Seedling Lethal Variants Inferred From Segregation Distortionmentioning

confidence: 99%

Domestication Reshaped the Genetic Basis of Inbreeding Depression in a Maize Landrace Compared to its Wild Relative, Teosinte

Holland

Samayoa

Olukolu

et al. 2021

Preprint

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Inbreeding depression is the reduction in fitness and vigor resulting from mating of close relatives observed in many plant and animal species. The extent to which the genetic load of mutations contributing to inbreeding depression is due to rare large-effect variation versus potentially more common variants with very small individual effects is unknown and may be affected by population history. We compared the effects of outcrossing and self-fertilization on 18 traits in a landrace population of maize, which underwent a population bottleneck during domestication, and a neighboring population of its wild relative teosinte. Inbreeding depression was greater in maize than teosinte for 15 of 18 traits, congruent with the greater segregating genetic load predicted from sequence data in the maize population. For many traits - and more commonly in maize - genetic variation among self-fertilized families was less than expected based on additive and dominance variance estimated in outcrossed families, suggesting that a negative covariance between additive and homozygous dominance effects limits the variation available to selection under partial inbreeding. We identified quantitative trait loci (QTL) representing large-effect rare variants carried by only a single parent, which were more important in teosinte than maize. Teosinte also carried more putative juvenile-acting lethal variants identified by segregation distortion. These results suggest a mixture of mostly polygenic, small-effect recessive variation underlying inbreeding depression, with an additional contribution from rare larger-effect variants that was more important in teosinte but depleted in maize following to the domestication bottleneck. Purging associated with the maize domestication bottleneck may have selected against large effect variants, but polygenic load is harder to purge and segregating mutational burden increased in maize compared to teosinte.

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“…Furthermore, mechanized harvesting in Northern Spain lends itself to positive selection of potential weed ancestors; in field conditions with both teosinte and maize, harvester machines carry a sieve that retains larger maize kernels, but shunts the smaller teosinte seed to a spreader that cast-seeds the teosinte in the field, effectively generating a seed-bank for the next years [5]. Teosinte seed can germinate immediately or remain dormant for years [61] exacerbating the problem of detection and early eradication of a potential weed ancestor.…”

Section: Origin Of a Noxious Weed With Increased Fitnessmentioning

confidence: 99%

Transgene behavior in genetically modified teosinte hybrid plants: transcriptome expression, insecticidal protein production and bioactivity against a target insect pest

et al. 2021

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Background In 2009, Spanish farmers reported a novel weed, now identified as a relative of maize’s ancestor, teosinte, in their maize fields. Introgression of the insect resistance transgene cry1Ab from genetically modified (GM) maize into populations of this weedy Spanish teosinte could endow it with additional defense mechanisms. The aims of this study were: (1) to test if hybridization between GM maize and weedy plants from Spain is possible; (2) to understand the relationship between transgene transcription activity, concentrations of the expected transgene product (Cry1Ab protein) and the bioactivity of the latter on target insect pests following transgene flow from GM maize into Spanish teosinte plants. Results We demonstrated that hybridization between GM maize and the weedy Spanish teosinte is possible, with no observable barrier to the formation of crop/weed hybrids when teosinte served as pollen donor. When GM maize plants were used as pollen donors, significant crossing incompatibility was observed: hybrid plants produced only few “normal” seeds. Nevertheless, viable F1 seeds from GM pollen crossed onto teosinte were indeed obtained. The cry1Ab transgene was stably expressed as mRNA in all crossings and backgrounds. Similarly, toxicity on neonate Ostrinia nubilalis, presumably due to Cry1Ab protein, was consistently expressed in teosinte hybrids, with mortality rates 95% or higher after only 4 days exposure, similar to rates on parental GM maize plants. Nevertheless, no strong correlations were observed between transgene transcription levels and Cry1Ab concentrations, nor between Cry1Ab concentrations and insect mortality rates across all of the different genetic backgrounds. Conclusions Our results establish fundamental parameters for environmental risk assessments in the European context: first, we show that crop/weed hybridization in fields where maize and teosinte exist sympatrically can lead to potentially catastrophic transfer of resistance traits into an already noxious weed; second, our results question the viability of using gene dosage to model and predict ecological performance in either the intended crop plant or the undesired teosinte weed. Significant questions remain that should be addressed in order to provide a scientific, sound approach to the management of this novel weed.

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Seed Dormancy in Mexican Teosinte

Cited by 22 publications

References 23 publications

Maize domestication and gene interaction

Maize domestication and gene interaction

Domestication Reshaped the Genetic Basis of Inbreeding Depression in a Maize Landrace Compared to its Wild Relative, Teosinte

Transgene behavior in genetically modified teosinte hybrid plants: transcriptome expression, insecticidal protein production and bioactivity against a target insect pest

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