Ge Fei, Huang Xing, Hu Hongmei, Zhang Yanling, Li Zhaoling, Zou Chaoying, Peng Huanwei, Li Lujiang, Gao Shibin, Pan Guangtang, Shen Yaou
Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Maize Research Institute of Sichuan Agricultural University, Chengdu, Sichuan Province, China.
Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan Province, China.
PLoS One. 2017 Jul 3;12(7):e0180567. doi: 10.1371/journal.pone.0180567. eCollection 2017.
The induction efficiency of maize embryonic callus is highly dependent on the genotype, and only a few lines possess a high capacity for callus formation. Although certain genes and pathways have been reported to contribute to the regulation of callus induction, to the best of our knowledge, the functions of the small interfering RNAs (siRNAs) involved in this process remain unknown. In this study, we identified 861 differentially expressed siRNAs and 576 target genes in the callus induction process. These target genes were classified into 3 clusters, and their functions involve controlling metalloexopeptidase activity, catalase activity, transcription regulation, and O-methyltransferase activity. In addition, certain genes related to auxin transport and stem cell or meristem development (e.g., PLT5-like, ARF15, SAUR-like, FAS1-like, Fea3, SCL5, and Zmwox2A) were regulated by the differentially expressed siRNAs. Moreover, zma-siR004119-2 directly cleaves the 5' UTR of Homeobox-transcription factor 25, which further leads to the down-regulation of its expression. Twelve 24-nt-siRNAs led to the hyper-methylation of GRMZM2G013465, which further decreases its expression. These results suggest that differentially expressed siRNAs regulate callus formation by controlling the expression of their target genes.
玉米胚性愈伤组织的诱导效率高度依赖于基因型，只有少数品系具有高愈伤组织形成能力。尽管已有报道某些基因和途径参与愈伤组织诱导的调控，但据我们所知，参与此过程的小干扰RNA（siRNA）的功能仍不清楚。在本研究中，我们在愈伤组织诱导过程中鉴定出861个差异表达的siRNA和576个靶基因。这些靶基因被分为3个簇，其功能涉及控制金属外肽酶活性、过氧化氢酶活性、转录调控和O-甲基转移酶活性。此外，某些与生长素运输以及干细胞或分生组织发育相关的基因（例如，类PLT5、ARF15、类SAUR、类FAS1、Fea3、SCL5和Zmwox2A）受差异表达的siRNA调控。此外，zma-siR004119-2直接切割同源盒转录因子25的5'UTR，进而导致其表达下调。12个24-nt-siRNA导致GRMZM2G013465发生超甲基化，进而降低其表达。这些结果表明，差异表达的siRNA通过控制其靶基因的表达来调节愈伤组织的形成。
