Voir la page en français

Transposon-induced sex transition

Harbinger transposon insertion in ethylene signaling gene leads to emergence of new sexual forms in cucurbits

In a recent study published in the journal Nature Communications, the FloCad (IPS2) team explored how new sexual forms emerge in plants. Using melon as a model plant, they identified a spontaneous mutant exhibiting a sexual transition from andromonoecy (male and hermaphrodite flowers) to androecy (male flowers only). They discovered that the causal mutation was a Harbinger transposon altering the expression of the Ethylene Insensitive 2 (CmEIN2) gene. Genetic and transcriptomic analysis revealed that CmEIN2 plays a dual role in sex determination and fruit development. During the early stages of floral development, EIN2 controls the expression of the carpel inhibitor gene, CmWIP1. Subsequently, EIN2 is recruited to mediate stamen inhibition. After the sex determination phase, EIN2 promotes elongated fruit development. A genome-wide analysis showed that the mobilization of the causal transposon is triggered by heat stress and preferentially integrates into active chromatin, particularly in the promoter regions of genes. Characterization of a collection of genetic resources subsequently showed that the causal transposon is more active in wild melons. This study highlights the association between chromatin dynamics and the temporal aspects of mobile genetic element insertions, providing valuable insights into plant adaptation and crop genome evolution.

 

Insertion of the AndroPIF transposon in the CmEIN2 ethylene signaling gene leads to sex transition. ∆SNP index between andromonoecious and androecious bulks, calculated with a 1-Mb sliding window. Arrows indicate the causal mutation on chromosome 8. Below, structure of the CmEIN2 gene and position of the AndroPIF insertion. The ein2_SP1 and ein2_SP2 splicing mutants used for the genetic validation, are shown with arrowheads.
Insertion of the AndroPIF transposon in the CmEIN2 ethylene signaling gene leads to sex transition. ∆SNP index between andromonoecious and androecious bulks, calculated with a 1-Mb sliding window. Arrows indicate the causal mutation on chromosome 8. Below, structure of the CmEIN2 gene and position of the AndroPIF insertion. The ein2_SP1 and ein2_SP2 splicing mutants used for the genetic validation, are shown with arrowheads.

14/06/2024