Gene expression trajectories during male and female reproductive development in balsam poplar (Populus balsamifera L.)

Quentin Cronk,Katharina Bräutigam,Raju Soolanayakanahally

doi:10.1038/s41598-020-64938-w

Quentin Cronk, Katharina Bräutigam + Show 1 more

Open Access

https://doi.org/10.1038/s41598-020-64938-w

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Abstract

Plant reproductive development from the first appearance of reproductively committed axes through to floral maturation requires massive and rapid remarshalling of gene expression. In dioecious species such as poplar this is further complicated by divergent male and female developmental programs. We used seven time points in male and female balsam poplar (Populus balsamifera L.) buds and catkins representing the full annual flowering cycle, to elucidate the effects of time and sex on gene expression during reproductive development. Time (developmental stage) is dominant in patterning gene expression with the effect of sex nested within this. Here, we find (1) evidence for five successive waves of alterations to the chromatin landscape which may be important in setting the overall reproductive trajectory, regardless of sex. (2) Each individual developmental stage is further characterized by marked sex-differential gene expression. (3) Consistent sexually differentiated gene expression regardless of developmental stage reveal candidates for high-level regulators of sex and include the female-specific poplar ARR17 homologue. There is also consistent male-biased expression of the MADS-box genes PISTILLATA and APETALA3. Our work provides insights into expression trajectories shaping reproductive development, its potential underlying mechanisms, and sex-specific translation of the genome information into reproductive structures in balsam poplar.

Highlights

Reproductive development is a single process resulting from the unitary development of the organism
In vegetative buds, there follows the production of numerous preformed leaf primordia, which will not expand until the following spring
Chromatin structure is influenced by chemical modifications to DNA, post-translational modification to histone tails or by remodelers, and it can shape gene expression patterns at individual genetic loci as well as larger genomic regions

Summary

Introduction

Reproductive development is a single process resulting from the unitary development of the organism. Axillary meristems committed to reproduction, on the other hand, do not produce leaf primordia but they form a domed meristem (inflorescence primordium), which in turn produces floral primordia (and their subtending bract scales) on its flanks These immature inflorescences can be detected inside axillary buds in May or June (depending on seasonal timing). Sporogenesis occurs inside stamens and carpels and floral maturation, flowering and gametophyte production Each stage of this process requires a different developmental program. RNAseq has previously been employed to study gene expression in floral tissue of Chinese white poplar (Populus tomentosa Carrière) but on males only[11], and in P. balsamifera, but at a single time point[12]. A developmental series combined with RNAseq is of considerable potential value

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