Cytological and proteomic analyses of floral buds reveal an altered atlas of meiosis in autopolyploid Brassica rapa

Abstract

Background Polyploidy is considered as a basic event in plant speciation and evolution in nature, and the cytological and proteomic profilings of floral buds at meiosis (FAM) would definitely contribute to a better understanding of the polyploid-associated effects during plant reproduction cycle. Results Herein, the cytological investigations demonstrated that chromosome behaviors such as univalent and multivalent at prophase I, chaotic alignments at metaphase, aberrant segregation at telophase, were frequently observed during meiosis in autotetraploid Brassica rapa . The proteomic analysis showed a total of 562 differentially expressed proteins (DEPs) were identified in FAM between autotetraploid and diploid B. rapa . Notably, PARP2 and LIG1 related to base excision repair and BARD1 involved in recombination were significantly down-regulated in autotetraploid B. rapa , which indicated DNA repair pathway were more likely affected during meiosis in autotetraploid B. rapa . The functional analysis showed that DEPs assigned to “chromatin structure and dynamics”, “cell cycle control, cell division, chromosome partitioning” and “cytoskeleton” were preferentially up-regulated, which suggested a robust regulation of cell division in autotetraploid B. rapa . In combination with the floral RNA-seq data released, a number of DEPs were found positively correlated with their transcript abundance, but posttranslational modification of proteins might also play a role in regulating meiosis course after polyploidization. Conclusions In general, this study provides a detailed cytology and proteome landscape of FAM between diploid and autotetraploid B. rapa , which definitely affords us a better understanding of uniformity and discrepancy of meiosis at the plant reproductive stage before and after polyploidization. Electronic supplementary material The online version of this article (10.1186/s13578-019-0313-z) contains supplementary material, which is available to authorized users.

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“…Protein digestion and TMT labeling were performed according to Yang et al (2019). The samples were fractionated using a C18 chromatographic column (250 mm × 4.6 mm).…”

“…The samples were fractionated using a C18 chromatographic column (250 mm × 4.6 mm). The dry peptides were dissolved and separated using 0.1% formic acid and a reversed‐phase analytical column (Hajduch et al, 2006; Yang et al, 2019). The peptide fragment data gathered by elution liquid chromatography were collected using LC‐MS/MS and analyzed by Proteome Discoverer 2.2 (http://www.protein.iastate.edu/docs/ProteomeDiscovererInstructions.pdf) according to the oilseed proteomics server (http://oilseedproteomics.missouri.edu).…”

Comparative transcriptome analysis revealed differential gene expression in multiple signaling pathways at flowering in polyploid Brassica rapa

“…The samples were then stored in 70% ethanol at 4 °C until use. Anthers were removed from the floret using forceps and a dissecting needle under a stereo-microscope and incubated as previously outlined [ 44 ]. The chromosome spreads were prepared as previously described [ 45 ].…”

Integrated cytological and transcriptomic analysis reveals insights into pollen fertility in newly synthetic Brassica allohexaploids

“…For the detection of b-tubulin, procedures from a previous study were adopted, with few modifications (Yang et al, 2019). Fresh inflorescences were collected and fixed immediately in 4% (w/v) paraformaldehyde.…”