Big differences found in male and female jojoba plant sex genes  
    
    Date:  
        October 14, 2021  
    Source:  
        University of Queensland  
    Summary:  
        Hot desert sex has resulted in major genetic differences between  
        male and female jojoba plants -- one of only 6 percent of plants  
        that require a male and female plant to reproduce. New research  
        suggests male and female jojoba plants have diverged so much, that  
        the jojoba plant has more novel sex genes than any other known  
        living organism. The discovery may help researchers develop a DNA  
        test to identify male and female jojoba plants, which cannot be  
        distinguished from each other as seedlings - and shed light on  
        how plants adapt to environmental stress.  
    
    
    
  FULL STORY  
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  The hot and dry desert environment has led to big genetic differences  
  between male and female jojoba plants, a discovery which could boost  
  jojoba production and shed light on how plants adapt to environmental  
  stress.  
    
    
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  A team of researchers in a collaboration between King Faisal University  
  and The University of Queensland have identified a wide divergence of  
  sex chromosomes in jojoba.  
    
  UQ's Queensland Alliance for Agriculture and Food Innovation research  
  leader Professor Robert Henry said that most plants were hermaphrodites  
  and contained both male and female parts.  
    
  "Just six percent are dioecious, like jojoba, requiring both a male  
  plant and female plant to reproduce.  
    
  "Jojoba plants reproduce through sexual reproduction, the way humans  
  do, but male and female genomes in humans are 99.9 per cent the same,  
  whereas in jojoba, there is something like a 15 per cent difference.  
    
  "People say men are from Mars and women from Venus when there is a 0.1  
  genetic difference between the sexes, but male and female jojoba plants  
  have diverged so much more genetically -- the harsh environments in which  
  they grow have resulted in the plant having more novel sex genes than  
  any other known living organism."  The discovery may help researchers  
  develop a DNA test to identify male and female jojoba plants, which  
  cannot be distinguished from each other as seedlings.  
    
    
    
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  Jojoba oil is derived from liquid wax from the seed of female Simmondsia  
  chinensis plants, a shrub native to the deserts of North America.  
    
  The plant is known for its high-temperature and high-salinity tolerance,  
  and its oil is used in skin care and pharmaceuticals, with applications  
  for medical and industrial-related products.  
    
  Only female plants carry seed.  
    
  "As mature plants, the male and female are very different," Professor  
  Henry said.  
    
  "The females are bigger, the males tend to be smaller plants and a  
  different shape.  
    
    
    
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  "The females have much deeper root systems."  Professor Henry said a  
  problem for jojoba famers was that although in the wild the male-female  
  jojoba plant growth ratio was similar, in cultivation systems, five  
  times more males were produced than females.  
    
  "Growers don't want to plant males -- they have to dig out the male  
  plants and replant," he said.  
    
  "It's not a good use of resources in a harsh growing environment."  
  Professor Henry said male and female jojoba plants may have evolved  
  in response to differing reproductive resource allocation requirements  
  under the stress of the desert environment.  
    
  "Male specific regions included many flowering-related and stress response  
  genes," he said.  
    
  Female plants devote resources to seed production, and greater root  
  growth allows the female plants to establish for the longer growth phase  
  required to support seed production.  
    
  The global jojoba oil market is growing at a rate of 8.4 per cent  
  per annum.  
    
  Key production regions for jojoba in Australia are the central western  
  plains of New South Wales and southern Queensland.  
    
  The United States of America accounted for 39 per cent of jojoba  
  production in 2019 -- Mexico, Israel, Chile and Argentina are other  
  major producers.  
    
  Jojoba is also being planted in Saudi Arabia at the campus of King Faisal  
  University with plans for large-scale plantings.  
    
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  Story Source: Materials provided by University_of_Queensland. Note:  
  Content may be edited for style and length.  
    
    
  ==========================================================================  
  Journal Reference:  
     1. Othman Al‐Dossary, Bader Alsubaie, Ardashir  
        Kharabian‐Masouleh, Ibrahim Al‐Mssallem, Agnelo Furtado,  
        Robert J. Henry. The jojoba genome reveals wide divergence of the  
        sex chromosomes in a dioecious plant. The Plant Journal, 2021;  
        DOI: 10.1111/ tpj.15509  
  ==========================================================================  
    
  Link to news story:  
  https://www.sciencedaily.com/releases/2021/10/211014142007.htm  
    
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