Horticell, Department Plants and Crops, Faculty of Bioscience Engineering, Ghent University, 9000, Ghent, Belgium.
Institute of Food and Biotechnology, Can Tho University, 900000, Can Tho City, Vietnam.
New Phytol. 2023 Dec;240(5):1883-1899. doi: 10.1111/nph.19292. Epub 2023 Oct 3.
Upon exposure to light, etiolated Arabidopsis seedlings form adventitious roots (AR) along the hypocotyl. While processes underlying lateral root formation are studied intensively, comparatively little is known about the molecular processes involved in the initiation of hypocotyl AR. AR and LR formation were studied using a small molecule named Hypocotyl Specific Adventitious Root INducer (HYSPARIN) that strongly induces AR but not LR formation. HYSPARIN does not trigger rapid DR5-reporter activation, DII-Venus degradation or Ca signalling. Transcriptome analysis, auxin signalling reporter lines and mutants show that HYSPARIN AR induction involves nuclear TIR1/AFB and plasma membrane TMK auxin signalling, as well as multiple downstream LR development genes (SHY2/IAA3, PUCHI, MAKR4 and GATA23). Comparison of the AR and LR induction transcriptome identified SAURs, AGC kinases and OFP transcription factors as specifically upregulated by HYSPARIN. Members of the SAUR19 subfamily, OFP4 and AGC2 suppress HYS-induced AR formation. While SAUR19 and OFP subfamily members also mildly modulate LR formation, AGC2 regulates only AR induction. Analysis of HYSPARIN-induced AR formation uncovers an evolutionary conservation of auxin signalling controlling LR and AR induction in Arabidopsis seedlings and identifies SAUR19, OFP4 and AGC2 kinase as novel regulators of AR formation.
在光照下，黄化拟南芥幼苗沿下胚轴形成不定根（AR）。虽然侧根形成的过程被深入研究，但关于下胚轴 AR 起始涉及的分子过程知之甚少。使用一种名为 Hypocotyl Specific Adventitious Root INducer（HYSPARIN）的小分子研究了 AR 和 LR 的形成，该小分子强烈诱导 AR 但不诱导 LR 形成。HYSPARIN 不会触发快速的 DR5-报告基因激活、DII-Venus 降解或 Ca 信号转导。转录组分析、生长素信号报告基因系和突变体表明，HYSPARIN AR 诱导涉及核 TIR1/AFB 和质膜 TMK 生长素信号转导，以及多个下游 LR 发育基因（SHY2/IAA3、PUCHI、MAKR4 和 GATA23）。AR 和 LR 诱导转录组的比较确定了 SAURs、AGC 激酶和 OFP 转录因子是由 HYSPARIN 特异性上调的。SAUR19 亚家族成员、OFP4 和 AGC2 抑制 HYS 诱导的 AR 形成。虽然 SAUR19 和 OFP 亚家族成员也轻度调节 LR 形成，但 AGC2 仅调节 AR 诱导。HYSPARIN 诱导的 AR 形成分析揭示了生长素信号转导控制拟南芥幼苗中 LR 和 AR 诱导的进化保守性，并确定了 SAUR19、OFP4 和 AGC2 激酶作为 AR 形成的新调节剂。
