Abstract
The objective of this work was to assess the genetic variability and structure of a new weed in Spanish maize fields, and investigate its geographical patterns using 17 microsatellites. Commercial maize varieties (C), maize-like weeds (MLW), putative hybrids with C (WCH), and teosintes (Tm: Zea mays ssp. mexicana and Tp: Z. mays ssp. parviglumis) were analyzed. The weed genetic diversity (MLW and WCH: 0.52) was the lowest (C: 0.59, Tm: 0.66, and Tp: 0.71). Weeds (0.21) and teosintes (Tm: 0.27, Tp: 0.34) showed positive values for the inbreeding coefficient (FIS), which agrees with their low values for the observed heterozygosity (HO), common in wild species; whereas C exhibited a negative FIS value (− 0.06, excess of heterozygous), common in domesticated species. Major clustering agreed with the different types of samples, even if some of the most hybridized weeds branched with the C cluster. Within the weeds, an evident tendency to group together depending on their geographical origin was perceived. Structure analyses confirmed the contribution of C to the genome of those weeds with the highest degree of hybridization. Consistently, the genetic variation (FST) was not negligible only when the teosintes were compared to the C group. Most of the molecular variance occurred within populations (51.83%) and not among populations (10.09%), with the highest value (32.33%) being found within the weed population. These new weeds seem to have a complex origin. Even if they are related to both, C and teosintes (Tm and Tp), they form an unidentified and genetically distinct group (FST: 0.13).
Highlights
It is widely accepted that the wild ancestor of maize (Zea mays L.) is a Mexican annual teosinte
The same ordering was observed for the proportion of shared alleles (PSA) (Tp: 33.01%, Tm 29.79%, maize-like weeds (MLW) and weed-commercial maize putative hybrid (WCH): 20.58%, C: 19.20%, Online Resource 3)
The high genetic similarity between three C samples from two varieties developed by the same seed breeding company (CR46 and CR50) and one accession of teosinte (Z. mays ssp. parviglumis), could suggest the use of this kind of exotic material in breeding programs, though it does not seem a common practice (Warburton et al 2017)
Summary
It is widely accepted that the wild ancestor of maize (Zea mays L.) is a Mexican annual teosinte. Spain is in 29th place in the world ranking of producer countries and 10th at European level (FAO 2017) These numbers are not negligible, especially if we take into account that, in terms of surface dedicated to the maize cultivation, Spain occupies the 59th and the 12th position in the world and in Europe, respectively. The focal points of this new weed are mainly located in the Northeast of Spain, in the region of Aragon and, to a lesser extent, in Catalonia, and on a smaller scale, in the North of the French region New Aquitaine (EFSA 2016) Those two Spanish regions are among the most productive in maize cultivation, reaching the second and fourth positions, respectively, in the national ranking (Mapama 2016). The Center for Plant Health and Certification of the Government of Aragon and the
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
