Transcriptome profile analysis of young floral buds of fertile and sterile plants from the self-pollinated offspring of the hybrid between novel restorer line NR1 and Nsa CMS line in Brassica napus.

Xiaohong Yan,Qiong Hu,Chenghong Jiang,Wanghui Liu,Jingyin Yu,Wenhui Wei,Xiaoping Fang,Caihua Dong,Jia Liu

doi:10.1186/1471-2164-14-26

Xiaohong Yan, Qiong Hu + Show 7 more

Open Access

https://doi.org/10.1186/1471-2164-14-26

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Abstract

BackgroundThe fertile and sterile plants were derived from the self-pollinated offspring of the F1 hybrid between the novel restorer line NR1 and the Nsa CMS line in Brassica napus. To elucidate gene expression and regulation caused by the A and C subgenomes of B. napus, as well as the alien chromosome and cytoplasm from Sinapis arvensis during the development of young floral buds, we performed a genome-wide high-throughput transcriptomic sequencing for young floral buds of sterile and fertile plants.ResultsIn this study, equal amounts of total RNAs taken from young floral buds of sterile and fertile plants were sequenced using the Illumina/Solexa platform. After filtered out low quality data, a total of 2,760,574 and 2,714,441 clean tags were remained in the two libraries, from which 242,163 (Ste) and 253,507 (Fer) distinct tags were obtained. All distinct sequencing tags were annotated using all possible CATG+17-nt sequences of the genome and transcriptome of Brassica rapa and those of Brassica oleracea as the reference sequences, respectively. In total, 3231 genes of B. rapa and 3371 genes of B. oleracea were detected with significant differential expression levels. GO and pathway-based analyses were performed to determine and further to understand the biological functions of those differentially expressed genes (DEGs). In addition, there were 1089 specially expressed unknown tags in Fer, which were neither mapped to B. oleracea nor to B. rapa, and these unique tags were presumed to arise basically from the added alien chromosome of S. arvensis. Fifteen genes were randomly selected and their expression levels were confirmed by quantitative RT-PCR, and fourteen of them showed consistent expression patterns with the digital gene expression (DGE) data.ConclusionsA number of genes were differentially expressed between the young floral buds of sterile and fertile plants. Some of these genes may be candidates for future research on CMS in Nsa line, fertility restoration and improved agronomic traits in NR1 line. Further study of the unknown tags which were specifically expressed in Fer will help to explore desirable agronomic traits from wild species.

Highlights

The fertile and sterile plants were derived from the self-pollinated offspring of the F1 hybrid between the novel restorer line NR1 and the Nsa cytoplasmic male sterility (CMS) line in Brassica napus
Selection of fertile and sterile plants To obtain the plant materials with the closest genetic background, fertile and sterile plants were made from the self-pollinated offspring of the F1 hybrid between novel restorer line NR1 and Nsa CMS line
The cytoplasmic genetic background of fertile plants is the same as that of sterile plants, arising from Nsa CMS line. Both the fertile and sterile plants had the complete set of chromosomes from B. napus, there was one or two members of the added S. arvensis alien chromosome pair in the fertile plants

Summary

Introduction

The fertile and sterile plants were derived from the self-pollinated offspring of the F1 hybrid between the novel restorer line NR1 and the Nsa CMS line in Brassica napus. The novel allo-cytoplasmic male sterility (CMS) system, Nsa CMS line, and the corresponding restorer system, NR1 line, have been successfully developed from somatic hybrids between Brassica napus (oilseed rape) and its wild relative Sinapis arvensis (Yeyou 18, Xinjiang wild mustard from northwestern China) by fusing mesophyll protoplasts [1,2]. NR1, as a B. napus-S. arvensis disomic alien addition line, carries one pair of homologous chromosomes from S. arvensis and 19 chromosome pairs from B. napus, and displays important agricultural characters which arise from the alien chromosomes, such as fertility restoration ability to Nsa CMS line, low erucic acid and low glucosinolate contents, S. sclerotiorum resistance and pod shattering resistance [14]

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