Biology subjects

Iob, A.

Publications and source records attributed to Iob, A..

2 recordsLinked to original sources

bioRxiv2023

Wild emmer contribution in wheat domestication and adaptation to new environments

Wheat is a staple crop, and its production is heavily threatened by climate change and soil erosion. Breeding programmes commonly rely on the wild progenitor, wild emmer wheat, Triticum turgidum subsp. dicoccoides, to find markers associated with traits conferring higher resistance to biotic and abiotic stresses, albeit how its genetic diversity contributed into domestication and adaptation to agricultural systems has never been studied. We explore the population structure and the influence of wild emmer populations from both the Northern and Southern Levant during the domestication process. Additionally, we examine their potential contribution to facilitating the adaptation and dispersal of domestic landraces to new environments. We quantify the genomic proportion of wild Southern Levant ancestry in two different domestic germplasms, including landraces from Europe, Africa and Asia. We obtain direct evidence that as much as 26% of the genome has Southern Levant ancestry in the population from Europe, and up to 40% in the population from Africa and Asia. We also estimate the time since admixture of the two wild populations to produce the domestic forms, obtaining two dates, one matching the domestication in Southwest Asia (ca 9500 BP) and the other matching the dispersal towards Africa (ca 6500 BP). We also inquire about the possible adaptive role of wild emmer from the Southern Levant into domestication and dispersal and find an overrepresentation of genes associated with resistance to biotic stress and drought. Overall, our work provides more information on the origins of domestic wheat and highlights the potential of modern domestic landraces of emmer wheat in the study of the genetic basis of resilience. Modeling wheat genome evolution under different demographic scenarios is needed to confirm the observed signals of positive selection and facilitate the use of emmer landraces in future wheat breeding programmes.

genomics↗

bioRxiv2019

Ancient genomes reveal early Andean farmers selected common beans while preserving diversity

All crops are the product of a domestication process that started less than 12,000 years ago from one or more wild populations [1, 2]. Farmers selected desirable phenotypic traits, such as improved energy accumulation, palatability of seeds or reduced natural shattering [3], while leading domesticated populations through several more or less gradual demographic contractions [2, 4]. As a consequence, erosion of wild genetic variation [5] is typical of modern cultivars making them highly susceptible to pathogens, pests and environmental change [6,7]. The loss of genetic diversity hampers further crop improvement programs to increase food production in a changing world, posing serious threats to food security [8,9]. Using both ancient and modern seeds, we analyzed the temporal dynamic of genetic variation and selection during the domestication process of the common bean (Phaseolus vulgaris) that occurred in the Southern Andes. Here we show that most domestic traits were selected for prior to 2,500 years ago, with no or only minor loss of whole-genome variation. In fact, i) all ancient domestic genomes dated between 600 and 2,500 years ago are highly variable - at least as variable as a modern genome from the wild; the genetic erosion that we observe in modern cultivars is therefore a recent process that occurred in the last centuries; ii) the majority of changes at coding genes that differentiate wild and domestic genomes are already present in the ancient genomes analyzed here. Considering that most desirable phenotypic traits are likely controlled by multiple polymorphic genes [10], a likely explanation of this decoupling of selection and genomic erosion is that early farmers applied a relatively weak selection pressure [2] by using many phenotypically similar but genomically diverse individuals as breeders. Selection strategies during the last few centuries were probably less sustainable and produced further improvements focusing on few plants carrying the traits of interest, at the cost of marked genetic erosion.

genomics↗