The research group at Nara Institute of Science and Technology discovered the world's first sex-determining gene that determines the sex of asparagus by a comprehensive analysis method for the entire genome (genetic information) and gene expression.This achievement is based on joint research with the Institute of Basic Biology, Tokushima University, Tohoku University, Kyushu University, and the University of Tokyo.

 Like mammals, asparagus has an XY-type sex chromosome and becomes a male strain in XY and a female strain in XX.There was almost no morphological difference between the male and female strains other than the flowers, and it was thought that the sex-determining gene was encoded on the Y chromosome, but the substance was unknown.

 This time, as a result of searching for a gene expressed only in the male strain using a high-speed sequencer (DNA analyzer), only the male strain has a gene encoding a transcription factor (named MSE1), and it is on the Y chromosome. It turned out to be in.It was also found that the MSE1 gene is expressed and functions only in the stamens in the early stage of flower development.As a result of examination using genome editing technology, it was shown that the MSE1 gene encoded by the Y chromosome is expressed in the stamens during flower development and develops normal stamens to form male flowers. rice field.

 In addition, whole genome analysis revealed the presence of the MSE1 gene on the X chromosome, but it lost its function as a gene.This indicates that the ancestor of asparagus was an amphoteric flower with both sexes, but the MSE1 gene required for stamen development became the X chromosome due to loss of function due to mutation.The chromosome with the normal MSE1 gene becomes the Y chromosome, and it is said that males and females were born.

 This study is the first to demonstrate Darwin's theory of evolution, which predicted that males and females of plants evolved from amphoteric flowers.In the future, it is expected to be useful for plant breeding, such as the development of technology for artificially converting amphoteric flowers and males and females.

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