The genus Populus is an effective model in tree genetics. This genus includes dioecious species and, recently, whole genome resequencing of P. trichocarpa and P. balsamifera enabled the identification of sex-linked regions and sex-associated single nucleotide polymorphisms (SNPs). These results created new opportunities to study sex determination in poplars. In the present work, we performed deep sequencing of genes encoding METHYLTRANSFERASE1 (MET1) and homolog of ARABIDOPSIS RESPONSE REGULATOR 17 (ARR17), which are localized in a sex-linked region of Populus genome and contain a number of sex-associated SNPs. Amplicon libraries for 38 samples of P. × sibirica (19 males and 19 females) were sequenced on MiSeq Illumina (300 nt paired-end reads) and approximately 4000× coverage was obtained for each sample. In total, from 80 to 179 SNPs were detected in poplar individuals for MET1, and from 16 to 49 SNPs were detected for ARR17. We identified 17 sex-specific SNPs (11 in MET1 and 6 in ARR17) - they were present in all males but absent in all females. For identified sex-specific SNP sites, females were homozygous, while males were heterozygous. Moreover, colocation of sex-specific SNPs confirming the XY sex-determination system of poplars was revealed: in one allelic variant, males had the same nucleotides as females, while in the other, sex-specific SNPs were present. Based on the data obtained, we developed and successfully applied a high-resolution melting-based approach for sex identification in poplars. The developed molecular markers are useful for distinguishing between male and female poplars in scientific research and can also be applied to select male-only genotypes for use in city landscaping and production of paper, pulp, and biofuel.

中文翻译：

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西伯利亚胡杨MET1和ARR17基因的性别特异性多态性。

杨属是树木遗传学的有效模型。该属包括雌雄异体的物种，近来，毛果单胞菌和苦瓜假单胞菌的全基因组重测序使得能够鉴定性别相关区域和性别相关的单核苷酸多态性（SNP）。这些结果为研究杨树的性别决定提供了新的机会。在目前的工作中，我们对编码甲基转移酶1（MET1）和ARABIDOPSIS RESVALSE REGULATOR 17（ARR17）的同源基因进行了深度测序，它们位于Populus基因组的性连接区域，并包含许多与性相关的SNP。在MiSeq Illumina（300 nt配对末端读数）上对38个西伯利亚毕赤酵母样品（男性19例，女性19例）的扩增子文库进行了测序，每个样品获得约4000倍的覆盖率。总共，在杨树个体中检测到80至179个SNPs用于MET1，检测到16至49个SNPs用于ARR17。我们鉴定出17种性别特异性SNP（MET1中为11种，ARR17中为6种）-它们存在于所有男性中，而在所有女性中均不存在。对于确定的性别特异性SNP位点，雌性为纯合子，而雄性为杂合子。此外，揭示了确认杨树的XY性别决定系统的性别特异性SNP的共置：在一个等位基因变体中，雄性与雌性具有相同的核苷酸，而在另一种中，存在性别特异性SNP。基于获得的数据，我们开发并成功应用了基于高分辨率融解的杨树性别鉴定方法。