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Article|01 Jun 2021|OPEN
Sex-biased genes and metabolites explain morphologically sexual dimorphism and reproductive costs in Salix paraplesia catkins
Zeyu Cai1,2, Jun Liao3, Congcong Yang4, Haifeng Song3 & Sheng Zhang3,
1University of Chinese Academy of Sciences, Beijing, China
2Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China
3College of Geography and Tourism, Chongqing Normal University, Chongqing, China
4Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China

Horticulture Research 8,
Article number: 125 (2021)
doi: 10.1038/hortres.2021.125
Views: 612

Received: 14 Jan 2021
Revised: 16 Mar 2021
Accepted: 22 Mar 2021
Published online: 01 Jun 2021


Dioecious species evolved from species with monomorphic sex systems in order to achieve overall fitness gains by separating male and female functions. As reproductive organs, unisexual flowers have different reproductive roles and exhibit conspicuous sexual dimorphism. To date, little is known about the temporal variations in and molecular mechanisms underlying the morphology and reproductive costs of dioecious flowers. We investigated male and female flowers of Salix paraplesia in three flowering stages before pollination (the early, blooming and late stages) via transcriptional sequencing as well as metabolite content and phenotypic analysis. We found that a large number of sex-biased genes, rather than sex-limited genes, were responsible for sexual dimorphism in S. paraplesia flowers and that the variation in gene expression in male flowers intensified this situation throughout flower development. The temporal dynamics of sex-biased genes derived from changes in reproductive function during the different flowering stages. Sexually differentiated metabolites related to respiration and flavonoid biosynthesis exhibited the same bias directions as the sex-biased genes. These sex-biased genes were involved mainly in signal transduction, photosynthesis, respiration, cell proliferation, phytochrome biosynthesis, and phenol metabolism; therefore, they resulted in more biomass accumulation and higher energy consumption in male catkins. Our results indicated that sex-biased gene expression in S. paraplesia flowers is associated with different reproductive investments in unisexual flowers; male flowers require a greater reproductive investment to meet their higher biomass accumulation and energy consumption needs.