Gaddam Subhash Reddy, Sharma Ashish, Anyatama Anwesha, Trivedi Prabodh Kumar
CSIR-National Botanical Research Institute, Council of Scientific and Industrial Research (CSIR-NBRI), Rana Pratap Marg, Lucknow 226001, India.
Plant Biotechnology Division, CSIR-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP) P.O. CIMAP, Near Kukrail Picnic Spot, Lucknow 226015, India.
Plant Physiol. 2025 Aug 4;198(4). doi: 10.1093/plphys/kiaf329.
Plant development in Arabidopsis thaliana transitions through various stages influenced by environmental cues and internal processes. ELONGATED HYPOCOTYL 5 (HY5), a critical light-signaling transcription factor, plays a key role in plant development; however, its function in flowering and vegetative phase change (VPC) remains unclear. Our study reveals that HY5 directly regulates the expression of microRNA156d (miR156d) by binding to G-box-like motifs in the miR156d promoter. This interaction inversely modulates the expression of miR156d and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes between wild-type and hy5 mutant plants. Notably, the miR156d overexpression (miR156dOX/hy5) plants exhibited delayed flowering, extended vegetative phases, and increased longevity, primarily due to a delay in the maturation of the axillary meristem associated with elevated levels of AT-HOOK MOTIF NUCLEAR LOCALIZED 15 (AHL15), a target of SPL genes. To investigate the role of AHL15, we developed knockdown lines for AHL15 in a miR156dOX background. Interestingly, the AHL15 knockdown combined with miR156dOX in hy5 plants (AHL15CR/miR156dOX/hy5) displayed hypersensitivity, bolting substantially earlier than other genotypes. This finding highlights the regulatory balance between HY5, miR156d, and AHL15. Overall, this interplay is crucial for controlling the transition from the vegetative to reproductive stages and influencing plant lifespan, providing essential insights into the molecular regulation of plant life history.
拟南芥的植物发育会经历受环境线索和内部过程影响的各个阶段。ELONGATED HYPOCOTYL 5（HY5）是一种关键的光信号转录因子，在植物发育中起关键作用；然而，其在开花和营养阶段转变（VPC）中的功能仍不清楚。我们的研究表明，HY5通过与miR156d启动子中的G-box样基序结合，直接调控microRNA156d（miR156d）的表达。这种相互作用反向调节野生型和hy5突变体植株之间miR156d和SQUAMOSA启动子结合蛋白样（SPL）基因的表达。值得注意的是，miR156d过表达（miR156dOX/hy5）植株表现出开花延迟、营养阶段延长和寿命增加，这主要是由于与SPL基因的靶标AT-HOOK基序核定位15（AHL15）水平升高相关的腋生分生组织成熟延迟所致。为了研究AHL15的作用，我们在miR156dOX背景下构建了AHL15的敲低株系。有趣的是，hy5植株中AHL15敲低与miR156d过表达相结合（AHL15CR/miR156dOX/hy5）表现出超敏性，比其他基因型更早抽薹。这一发现突出了HY5、miR156d和AHL15之间的调控平衡。总体而言，这种相互作用对于控制从营养阶段到生殖阶段的转变以及影响植物寿命至关重要，为植物生活史的分子调控提供了重要见解。
