Genome and Transcriptome Sequencing of Populus × sibirica Identified Sex-Associated Allele-Specific Expression of the CLC Gene.

Transcriptome sequencing of leaves, catkin axes, and flowers from male and female trees of Populus × sibirica and genome sequencing of the same plants were performed for the first time. The availability of both genome and transcriptome sequencing data enabled the identification of allele-specific expression. Such an analysis was performed for genes from the sex-determining region (SDR). P. × sibirica is an intersectional hybrid between species from sections Aigeiros ( Populus nigra ) and Tacamahaca ( Populus laurifolia , Populus suaveolens , or Populus × moskoviensis ); therefore, a significant number of heterozygous polymorphisms were identified in the SDR that allowed us to distinguish between alleles. In the SDR, both allelic variants of the TCP (T-complex protein 1 subunit gamma), CLC (Chloride channel protein CLC-c), and MET1 (DNA-methyltransferase 1) genes were expressed in females, while in males, two allelic variants were expressed for TCP and MET1 but only one allelic variant prevailed for CLC . Targeted sequencing of TCP , CLC , and MET1 regions on a representative set of trees confirmed the sex-associated allele-specific expression of the CLC gene in generative and vegetative tissues of P. × sibirica . Our study brings new knowledge on sex-associated differences in Populus species.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2021 Pushkova, Krasnov, Lakunina, Novakovskiy, Povkhova, Dvorianinova, Beniaminov, Fedorova, Snezhkina, Kudryavtseva, Dmitriev and Melnikova.)