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

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.Electronic supplementary materialThe online version of this article (10.1007/s00438-018-1471-0) contains supplementary material, which is available to authorized users.

Heterosis analysis and underlying molecular regulatory mechanism in a wide-compatible neo-tetraploid rice line with long panicles

“…Intersubspecific hybrids of autotetraploid rice have a powerful biological and yield potential, which may become a new way to breed rice in future [5][6][7]. However, low seed setting is the major hindrance in the use of autotetraploid rice at commercial level [8][9][10][11][12][13]. Polyploidy fortifies F 1 pollen sterility loci interactions, which causes meiosis abnormalities and produce high pollen sterility in autotetraploid rice hybrids that could be overcome by double pollen fertility neutral genes (Sa n and Sb n ) [14,15].…”

Comparative cytological and transcriptome analysis reveals high pollen fertility and upregulation of environmentally sensitive genic male sterility genes in neo-tetraploid rice

“…DNA library construction, massive re-sequencing, and validation analysis Genomic DNA of three materials, H1, T44-4x and T45-4x, were extracted from fresh leaves according to the procedure described by Chen et al (2018). Sequencing libraries were constructed from genomic DNA of neo-tetraploid rice and its two parents and sequenced on an Illumina HiSeqTM2500 according to the manufacturer's instructions.…”

“…Autotetraploid rice is a useful germplasm derived from diploid rice by chromosome doubling. In comparison with corresponding rice, stronger biological vigour and heterosis were found in autotetraploid rice (Shahid et al 2010;He et al 2011;Wu et al 2013;Chen et al 2019); however, low pollen fertility is the major hindrance of its utilization (Wu et al 2014;Chen et al 2018). Pollen abnormalities appear to be the major obstacles for a normal seed set (He et al 2011;Wu et al 2014).…”

“…After years of efforts, we successfully developed a new "autotetraploid rice lines" by selective breeding and crossing for successive generations (Guo et al 2017;Bei et al 2019; Ghaleb et al 2020). The new "autotetraploid rice" displayed high fertility (>80%) and high heterosis while crossed with other autotetraploid rice lines having low fertility (Guo et al 2017;Chen et al 2018;Bei et al 2019). Moreover, F 2 and F 3 populations also displayed high fertility and stable morphological traits like neo-Arabidopsis (Yu et al 2009;Guo et al 2017;Bei et al 2019).…”

“…Neo-tetraploid rice is a created new tetraploid rice lines with normal fertility and is a key step to overcome the sterility of F 1 hybrids in tetraploid rice. Our group has reported three neo-tetraploid rice materials that could overcome the sterility of autotetraploid rice and produce high heterosis (Guo et al 2017;Chen et al 2018;Bei et al 2019). However, little is known regarding the complex regulatory mechanisms of heterosis and fertility in neotetraploid rice.…”