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

Zhaoran Tian; Chengyan Ji; Zhengqing Xie; Xinjie Shi; Baoming Tian; Gangqiang Cao; Xiaochun Wei; Yan Yang; Fang Wei; Gongyao Shi

doi:10.3389/fpls.2022.1096804

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

Front Plant Sci. 2023 Jan 13:13:1096804. doi: 10.3389/fpls.2022.1096804. eCollection 2022.

Authors

Zhaoran Tian¹, Chengyan Ji^{1

2}, Zhengqing Xie¹, Xinjie Shi^{1

2}, Baoming Tian¹, Gangqiang Cao¹, Xiaochun Wei², Yan Yang¹, Fang Wei¹, Gongyao Shi¹

Affiliations

¹ Henan International Joint Laboratory of Crop Gene Resources and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China.
² Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China.

Abstract

Trigenomic Brassica allohexaploids (AABBCC, 2n = 6x = 54) have great potential in oilseed breeding and genetic diversity. However, Brassica allohexaploids do not exist naturally, and the underlying mechanism regulating pollen fertility in artificially synthesized Brassica allohexaploids is still unclear. In this study, synthetic Brassica allohexaploids were produced by crossing allotetraploid B. carinata (BBCC, 2n = 4x = 34) and diploid B. rapa (AA, 2n = 2x = 20), followed by chromosome doubling. The results showed that the pollen fertility was significantly reduced and the pollen structures were mostly distorted, but the nursing anther tapetum developed normally in the synthetic Brassica allohexaploids. Furthermore, the data showed that the meiotic events occurred irregularly with uneven chromosome segregation and microspore development appeared mostly abnormal. Transcription analysis showed that the upregulation of genes related to the negative regulation of flower development and the downregulation of genes related to chromosome segregation might play an essential role in reduction of pollen fertility in the Brassica allohexaploids. In conclusion, this study elucidated the related mechanisms affecting pollen fertility during male gametophytic development at the cytological and transcriptomic levels in the newly synthesized Brassica allohexaploids.

Keywords: Brassica allohexaploid; anther; chromosome segregation; meiosis; microspore development; mitosis; pollen fertility; tapetum.

Grants and funding

This work was financially supported by Henan Provincial Natural Science Foundation of China (No. 202300410366), and the Program for Science & Technology Innovation Talents in Universities of Henan Province (No. 19HASTIT014), and Youth Innovation Project of Key discipline of Zhengzhou University (No. XKZDQN202002), and the Fostering Project for Basic Research of Zhengzhou University (No. JC21310015).