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   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Evolution of wheat spikes since the Neolithic revolution    
      
     Date:   
         February 2, 2023   
     Source:   
         University of Barcelona   
     Summary:   
         Around 12,000 years ago, the Neolithic revolution radically changed   
         the economy, diet and structure of the first human societies   
         in the Fertile Crescent of the Near East. With the beginning of   
         the cultivation of cereals -- such as wheat and barley -- and the   
         domestication of animals, the first cities emerged in a new social   
         context marked by a productive economy. Now, a study analyses   
         the evolution of wheat spikes since its cultivation began by the   
         inhabitants of ancient Mesopotamia -- the cradle of agriculture --   
         between the Tigris and the Euphrates.   
      
      
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   FULL STORY   
   ==========================================================================   
   Around 12,000 years ago, the Neolithic revolution radically changed the   
   economy, diet and structure of the first human societies in the Fertile   
   Crescent of the Near East. With the beginning of the cultivation of   
   cereals - - such as wheat and barley -- and the domestication of animals,   
   the first cities emerged in a new social context marked by a productive   
   economy. Now, a study published in the journal Trends in Plant Science   
   and co-led by the University of Barcelona, the Agrotecnio centre and the   
   University of Lleida, analyses the evolution of wheat spikes since its   
   cultivation began by the inhabitants of ancient Mesopotamia -- the cradle   
   of agriculture in the world - - between the Tigris and the Euphrates.   
      
      
   ==========================================================================   
   The authors of the study are Rut Sa'nchez-Bragado and Josep Llui's Araus-   
   Ortega, from the UB Faculty of Biology and Agrotecnio-UdL; Gustavo   
   A. Slafer, ICREA researcher at the UdL School of Agrifood and Forestry   
   Science and Engineering, and Gemma Molero, from the International Maize   
   and Wheat Improvement Center in Mexico, currently a researcher at KWS   
   Seeds Inc.   
      
   A cereal that changed human history The cultivation of wheat -- a grass   
   that became basic food -- represented a turning point in the progress   
   of human civilisation. Today it is the world's most important crop in   
   terms of food security, but EU data warn that the impact of climate   
   change could significantly increase its price and modify its production   
   process in certain areas of the world.   
      
   Throughout the domestication process of wheat, the plant phenotype has   
   undergone both rapid (within a few hundred years) and slow (thousands   
   of years) changes, such as the weakening of the rachis, the increase in   
   seed size, and the reduction or disappearance of the awns. In particular,   
   awned and awnless wheat varieties are found all over the world, although   
   the latter tend to be abundant in regions with arid climates, especially   
   during the final stages of cultivation in late spring, a condition   
   typical of Mediterranean environments.   
      
   "It is important to conduct studies that show which wheat varieties are   
   best adapted to different environmental growing conditions, especially in   
   a context of climate change. Studying the past retrospectively can give   
   us an idea of the evolution of wheat cultivation over the millennia since   
   agriculture appeared in ancient Mesopotamia," says Rut Sa'nchez-Bragado,   
   first author of the study, who got a PhD at the UB.   
      
   "Awns are organs of the spike that have traditionally been associated   
   with the plant's adaptations to drought conditions," says Josep Llui's   
   Araus, professor at the Department of Evolutionary Biology, Ecology and   
   Environmental Sciences of the Faculty of Biology.   
      
   "However, archaeological and historical records show that the wheat spike   
   has existed predominantly with awns for more than ten millennia after   
   the domestication of wheat. It is not until the last millennium that   
   evidence shows in many cases the absence of awns, indicating a selection   
   by farmers - - probably in an undirected way -- against this organ,"   
   stresses Araus, one of the most cited authors in the world according to   
   Clarivate Analytics' Highly Cited Researchers (2022).   
      
   "The role of wheat awns in their performance remains controversial despite   
   decades of studies," says researcher Gustavo A. Slafer, corresponding   
   author of the study.   
      
   Spike awns: beneficial for the plant?  Is the presence of awns on the   
   spike beneficial for the plant and the crops?  Although there is no   
   scientific consensus, "everything suggests that in conditions where   
   the plant does not suffer from water stress, the extra photosynthetic   
   capacity of the awns does not compensate for other potential negative   
   effects (reduced susceptibility to fungal diseases, limitation in the   
   total number of large ones that an ear supports, etc.)," says Araus.   
      
   "However, in wetter climates the awns accumulate moisture and can promote   
   the spread of diseases," says Rut Sa'nchez-Bragado. "So, as the world's   
   population is continuously growing, it is necessary to investigate the   
   role of the awned spikes in the changing conditions of our climate in   
   order to meet the world's demand for a primary food commodity such   
   as wheat."  In arid conditions, the spikes -- including the awns --   
   "have better physiological characteristics than the leaves. In addition,   
   the awns allow the light captured by the crop to be more diffused,   
   which facilitates a better distribution of light energy and allows the   
   crop to photosynthesise more.   
      
   Therefore, in arid conditions, the awns can still be beneficial for the   
   crop, or at most, neutral," concludes Professor Josep Llui's Araus.   
      
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   ==========================================================================   
   Story Source: Materials provided by University_of_Barcelona. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Rut Sanchez-Bragado, Gemma Molero, Jose' L. Araus, Gustavo   
      A. Slafer.   
      
         Awned versus awnless wheat spikes: does it matter? Trends in Plant   
         Science, 2022; DOI: 10.1016/j.tplants.2022.10.010   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230202153525.htm   
      
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