AUTHOR=Li Mengdi , Wang Fan , Ma Jiayu , Liu Hengzhao , Ye Hang , Zhao Peng , Wang Jianbo 

TITLE=Comprehensive Evolutionary Analysis of CPP Genes in Brassica napus L. and Its Two Diploid Progenitors Revealing the Potential Molecular Basis of Allopolyploid Adaptive Advantage Under Salt Stress

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.873071

DOI=10.3389/fpls.2022.873071

ISSN=1664-462X

ABSTRACT=<p>Allopolyploids exist widely in nature and have strong environmental adaptability. The typical allopolyploid <italic>Brassica napus</italic> L. is a widely cultivated crop, but whether it is superior to its diploid progenitors in abiotic stress resistance and the key genes that may be involved are not fully understood. <italic>Cystein-rich polycomb-like protein</italic> (<italic>CPP</italic>) genes encode critical transcription factors involved in the response of abiotic stress, including salt stress. To explore the potential molecular basis of allopolyploid adaptation to salt stress, we comprehensively analyzed the characteristics and salt stress response of the <italic>CPP</italic> genes in <italic>B. napus</italic> and its two diploid progenitors in this study. We found some molecular basis that might be associated with the adaptability of <italic>B. napus</italic>, including the expansion of the CPP gene family, the acquisition of introns by some <italic>BnCPPs</italic>, and abundant <italic>cis</italic>-acting elements upstream of <italic>BnCPPs</italic>. We found two duplication modes (whole genome duplication and transposed duplication) might be the main reasons for the expansion of CPP gene family in <italic>B. napus</italic> during allopolyploidization. <italic>CPP</italic> gene expression levels and several physiological indexes were changed in <italic>B. napus</italic> and its diploid progenitors after salt stress, suggesting that <italic>CPP</italic> genes might play important roles in the response of salt stress. We found that some <italic>BnCPPs</italic> might undergo new functionalization or subfunctionalization, and some <italic>BnCPPs</italic> also show biased expression, which might contribute to the adaptation of <italic>B. napus</italic> under saline environment. Compared with diploid progenitors, <italic>B. napus</italic> showed stronger physiological responses, and <italic>BnCPP</italic> gene expression also showed higher changes after salt stress, indicating that the allopolyploid <italic>B. napus</italic> had an adaptive advantage under salt stress. This study could provide evidence for the adaptability of polyploid and provide important clues for the study of the molecular mechanism of salt stress resistance in <italic>B. napus</italic>.</p>