Eco-Geography of Feral Cotton: A Missing Piece in the Puzzle of Gene Flow Dynamics Among Members of Gossypium hirsutum Primary Gene Pool

Abstract

Mexico is the center of origin and genetic diversity of upland cotton (Gossypium hirsutum L.), the most important source of natural fiber in the world. Currently, wild and domesticated populations (including genetically modified [GM] varieties) occur in this country and gene flow among them has shaped the species’ genetic diversity and structure, setting a complex and challenging scenario for its conservation. Moreover, recent gene flow from GM cultivars to wild Mexican cotton populations has been reported since 2011. In situ conservation of G. hirsutum requires knowledge about the extent of its geographic distribution, both wild and domesticated, as well as the possible routes and mechanisms that contribute to gene flow between the members of the species wild-to-domesticated continuum (i.e., the primary gene pool). However, little is known about the distribution of feral populations that could facilitate gene flow by acting as bridges. In this study, we analyzed the potential distribution of feral cotton based on an ecological niche modeling approach and discussed its implications in the light of the distribution of wild and domesticated cotton. Then, we examined the processes that could be leading to the escape of seeds from the cultivated fields. Our results indicate that the climatic suitability of feral plants in the environmental and geographic space is broad and overlaps with areas of wild cotton habitat and crop fields, suggesting a region that could bridge cultivated cotton and its wild relatives by allowing gene flow between them. This study provides information for management efforts focused on the conservation of wild populations, native landraces, and non-GM domesticated cotton at its center of origin and genetic diversity.

Multiple domestication events explain the origin of Gossypium hirsutum landraces in Mexico

“…Based on the less variable regions, we reconstructed a phylogeny similar to the previously reported ones, in which G. herbaceum , G. arboreum , and G. thurberi are the closest taxa to the AD clade (Figure 7; Wu et al, 2018; Xu et al, 2012). In addition, the phylogenetic analysis supported the identity and occurrence of the wild populations described by Wegier et al (2011) and Alavez et al (2021).…”

“…Using only chloroplast limits the differentiation between introgression events that occurred in the past from recent events, therefore we consider that further research should include the chloroplast of the rest of metapopulation, more samples of landraces; and should incorporate nuclear genome markers. The aforementioned actions will allow detailing evolutionary history; recognizing the origin of the genetic material used in crops and research throughout the world; and providing information to describe the transgenes dispersion routes (Alavez et al, 2021). This information is key for sharing the benefits and avoiding harm to the local and indigenous communities, which are fundamental to the domestication processes and to the protection of genetic resources.…”

“…and providing information to describe the transgenes dispersion routes (Alavez et al, 2021). This information is key for sharing the…”

“…These events have often occurred in Mesoamerica, a region recognized as the main center of origin of crop domestication, mainly induced by the diffusion of seeds and vegetative propagules carried out by humans (Kraft et al, 2014; Moreno‐Letelier et al, 2020; Roullier et al, 2013; Zizumbo‐Villarreal & Colunga‐GarcíaMarín, 2010). The cultural and biological aspects related to the use and management of plants have caused the formation of wild‐to‐domesticated complexes, which are formed by wild populations; landraces; breeding lines (BL); feral individuals; transgene‐introgressed (TI) wild populations; TI‐landraces; and genetically modified BL (Alavez et al, 2021; Velázquez‐López et al, 2018; Figure 1). Wild‐to‐domesticated complexes have been documented in beans, maize, tomato, pumpkin, and avocado crops, in which genetic diversity is differently maintained and modified by humans while also being influenced by natural evolutionary processes (Castellanos‐Morales et al, 2019; Chen et al, 2009; Moreno‐Letelier et al, 2020; Motta‐Aldana et al, 2010; Razifard et al, 2020).…”

Residual Effects of Transgenic Cotton on the Intestinal Microbiota of Dysdercus concinnus

“…Mexico is the center of origin and diversity of American cotton, and despite warnings about gene flow [ 12 ] since 1996, genetically modified cotton has been planted in the north of the country. In other words, in Mexico wild populations of cotton coexist with transgenic crops.…”