Cytological and transcriptome analyses reveal abrupt gene expression for meiosis and saccharide metabolisms that associated with pollen abortion in autotetraploid rice

Lin Chen,Zhixiong Chen,Muhammad Qasim Shahid,Xiangdong Liu,Jinwen Wu,Lan Wang

doi:10.1007/s00438-018-1471-0

Lin Chen, Zhixiong Chen + Show 4 more

Open Access

https://doi.org/10.1007/s00438-018-1471-0

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Abstract

Autotetraploid rice is a useful germplasm that has four chromosome sets and strong biological advantages; however, low fertility limits its commercial utilization. Little information is available about the DNA variation and differential gene expressions associated with low fertility in autotetraploid rice. In the present study, 81 SNPs and 182 InDels were identified in T449 (an autotetraploid rice line with low fertility) compared to E249 (diploid counterpart) by whole-genome re-sequencing. We detected only three non-synonymous SNPs and six large-effect InDels, which were associated with three and six genes, respectively. A total of 75 meiosis-related differentially expressed genes were detected during the meiosis stage by transcriptome analysis, including OsMTOPVIB, which is essential for meiotic DSB formation, and OsMOF, which takes part in homologous chromosome pairing and synapsis. Approximately 20.69% lagging chromosome at metaphase I and 4.65% abnormal tetrad were observed in T449. Moreover, transcriptome analysis revealed down-regulation of a sucrose transporter (OsSUT5) and two monosaccharide transporters (OsMST1 and OsMST8) in T449 at the single microspore stage, and their expression levels were verified by qRT-PCR. Cytological observation of saccharide distribution showed abnormal accumulation of saccharides in T449 and the contents of fructose and glucose were markedly higher in T449 than E249 at the single microspore stage. Our results suggested that polyploidy not only induces abrupt expression changes in the meiosis-related genes that lead to abnormal chromosome behavior, but also causes changes in the saccharide distribution and expression patterns of saccharide-related genes, which jointly causes sterility in the autotetraploid rice.

Highlights

Whole-genome duplication (WGD) or polyploidy has played an important role in plant evolution
We found that abrupt changes in the expression patterns of meiosis and saccharide-related genes cause low fertility in autotetraploid rice
Meiotic stages in T449 were consistent with E249, and could be divided into nine development stages, including prophase I (Fig. S1 A, B and Fig. 2a–e), metaphase I (Fig. S1C and Fig. 2f), anaphase I (Fig. S1D and Fig. 2g), telophase I (Fig. S1E and Fig. 2h), prophase II, metaphase II (Fig. S1F and Fig. 2i), anaphase II (Fig. S1G and Fig. 2j), telophase II (Fig. S1H and Fig. 2k), and tetrad (Fig. S1I and Fig. 2l)

Summary

Introduction

Whole-genome duplication (WGD) or polyploidy has played an important role in plant evolution. Allopolyploids originate through the duplication of chromosome sets of different species, a major pathway for plant evolution, which may have a survival advantage, because different chromosome sets are key determinants of adaptive success in the new environment (Soltis et al 2009; Paun et al 2011; Van de Peer et al 2017). Autopolyploids involve whole-genome duplication within-species, which is more prevalent than indicated by taxonomy alone and has become an important element of plant diversity (Soltis et al 2007; Van de Peer et al 2017). Autopolyploid species are widely found in plants and have higher economic and resistance importance than their progenitors (Gebhardt and Valkonen 2001; Barker et al 2016; Van de Peer et al 2017). To improve the fertility and yield of autotetraploid rice, it is of utmost importance to investigate pollen development and its molecular mechanism in this organism

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