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Authors: Ruijuan Yang, Zhenying Wu, Ying Sun, Yuchen Liu, Yuqing Hang, Min Liu, Yajun Liu, Xiaoshan Wang, Wenwen Liu and Chunxiang Fu.
The Plant Journal (2024)
Significance Statement: It is well known that excessive grass tiller number negatively impacts culm development. Suppressing CYTOKININ OXIDASE/DEHYDROGENASE4 in miR156-overexpressing background switchgrass plants reduced the negative impacts of miR156 on culm development while leaving tiller number unaffected. Finally, the double transgenic plants yielded 110% more biomass than the wild type. Thus, the trade-off between tiller number and culm development widely observed in grasses can be successfully altered through precise manipulation of the miR156-SPL2-CKX4 module."
Abstract: "Culm development in grasses can be controlled by both miR156 and cytokinin. However, the crosstalk between the miR156-SPL module and the cytokinin metabolic pathway remains largely unknown. Here, we found CYTOKININ OXIDASE/DEHYDROGENASE4 (PvCKX4) plays a negative regulatory role in culm development of the bioenergy grass Panicum virgatum (switchgrass). Overexpression of PvCKX4 in switchgrass reduced the internode diameter and length without affecting tiller number. Interestingly, we also found that PvCKX4 was always upregulated in miR156 overexpressing (miR156OE) transgenic switchgrass lines. Additionally, upregulation of either miR156 or PvCKX4 in switchgrass reduced the content of isopentenyl adenine (iP) without affecting trans-zeatin (tZ) accumulation. It is consistent with the evidence that the recombinant PvCKX4 protein exhibited much higher catalytic activity against iP than tZ in vitro. Furthermore, our results showed that miR156-targeted SPL2 bound directly to the promoter of PvCKX4 to repress its expression. Thus, alleviating the SPL2-mediated transcriptional repression of PvCKX4 through miR156 overexpression resulted in a significant increase in cytokinin degradation and impaired culm development in switchgrass. On the contrary, suppressing PvCKX4 in miR156OE transgenic plants restored iP content, internode diameter, and length to wild-type levels. Most strikingly, the double transgenic lines retained the same increased tiller numbers as the miR156OE transgenic line, which yielded more biomass than the wild type. These findings indicate that the miR156-SPL module can control culm development through transcriptional repression of PvCKX4 in switchgrass, which provides a promising target for precise design of shoot architecture to yield more biomass from grasses."
Authors: Masato Shindo & Mikihisa Umehara
In book: "Plant Hormones and Climate Change" (2023)
Abstract: "Plants must adapt to climate changes because they are rooted in place. Climate changes greatly affect the soil environment, sometimes reducing the nutrient content. Plants require 17 essential elements for healthy growth and development. Among these, nitrogen, phosphorus, and sulfur are macroelements required for the biosynthesis of primary and secondary organic metabolites, such as proteins and nucleic acids, and for the maintenance of photosynthetic activity. Under nitrogen, phosphorus, or sulfur deficiency, plant growth is suppressed, resulting in poorer crop yield. Thus, to avoid the risk of climate changes to food production, it is important to understand how plants adapt to their environment in response to inorganic nutrient deficiency. Plant roots directly contact the soil environment, but the mechanism by which the amount of inorganic nutrients is recognized is complicated. Plants can accurately perceive the nutrient levels in soil and use this information to change their architecture and expression of nutrient transporters and to enhance plant–microbe interaction in the rhizosphere through shoot-to-root or root-to-shoot transportable signals such as plant hormones and microRNA. In this chapter, we summarize the roles of auxins, cytokinins, and strigolactones as long-distance signals in the pathways involved in nitrogen, phosphorus, and sulfur uptake and sensing and in signaling pathways."
Authors: Xingqiang Fan, Hui Li, Yushuang Guo, Qi Qi, Xiangning Jiang, Yi Wang, Xuefeng Xu, Changpeng Qiu, Wei Li and Zhenhai Han.
Authorea (2021)
Abstract: "Adventitious root (AR) formation is important for the vegetative propagation. The effects of strigolactones (SLs) on AR formation have been rarely reported, especially in woody plants. In this study, we first verified the inhibitory effects of SLs on AR formation in apple materials. Transcriptome analysis identified 12,051 differentially expressed genes over the course of AR formation, with functions related to organogenesis, cell wall biogenesis or plant senescence. WGCNA suggests SLs might inhibit AR formation through repressing the expression of two core hub genes, MdLAC3 and MdORE1. We further verified that enhanced cell wall formation and accelerated senescence were involved in the AR inhibition caused by SLs. Combining small RNA and degradome sequencing, as well as a dual-luciferase sensor system, we identified and validated three negatively correlated miRNA–mRNA pairs, including mdm-miR397–MdLAC3 involved in secondary cell wall formation, and mdm-miR164a/b–MdORE1 involved in senescence. Finally, we have experimentally demonstrated the role of mdm-miR164b–MdORE1 in SLs-mediated inhibition of AR formation. Overall, our findings not only propose a comprehensive regulatory network for the function of SLs on AR formation, but also provide novel candidate genes for the potential genetic improvement of AR formation in woody plants using transgenic or CRISPR technology."
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Authors: Sonia Balyan, Deepika Sharma, Shivani Kansal, Vaishali Panwar, Ringyao Jajo, Tonu Angaila Chithung and Saurabh Raghuvanshi.
bioRxiv (2023)
Abstract: "miRNAs are a critical component of regulatory mechanisms involved in plant growth, development, and stress response including phytohormone action. The role of miRNAs in regulating the strigolactone (SL) signaling in plants is still unexplored. Here we report that miR528 impacts the SL signaling via the post-transcriptional regulation of Dwarf 3 (OsD3). Comparative miRNome analysis under drought conditions in flag leaf, inflorescence, and roots uncovered the tissue-biased unique stress response of miR528 in drought-tolerant N22 (down in inflorescence and roots; up in flag leaf). Consequently, its target, OsD3 which encodes for the F-BOX/LRR-REPEAT MAX2 HOMOLOG and is a critical component of the rice SL signaling pathway exhibit opposite expression to miR528 in all three tissues. Interestingly, OsD3 is a rice-specific target of miR528. miR528 overexpression plants exhibited early heading, increment in the number of tillers, flag leaf length, and width, number of panicle branches, grain per panicle, effective grains per panicle, seed length, and photosynthesis rate. miR528 overexpression plants exhibited similar traits to Osd3 mutants including high tiller number, root architecture under low nitrogen conditions, and moderate insensitivity to GR24 and TIS1 levels in addition to shared transcriptional regulation. Furthermore, SL (GR24) negatively impacts the miR528 transcription. The impact of the miR528:D3 module is also reflected in the D53-mediated downstream signaling involving IPA1 regulon."
Authors: Juan Zhao, Xing Liu, Mei Wang, Lingjuan Xie, Zhengxin Wu, Jiuming Yu, Yuchen Wang, Zhiqiao Zhang, Yufang Jia and Qingpo Liu
Rice (2022)
Abstract: "Plant height, as one of the important agronomic traits of rice, is closely related to yield. In recent years, plant height-related genes have been characterized and identified, among which the DWARF3 (D3) gene is one of the target genes of miR528, and regulates rice plant height and tillering mainly by affecting strigolactone (SL) signal transduction. However, it remains unknown whether the miR528 and D3 interaction functions in controlling plant height, and the underlying regulatory mechanism in rice. In this study, we found that the plant height, internode length, and cell length of internodes of d3 mutants and miR528-overexpressing (OE-miR528) lines were greatly shorter than WT, D3-overexpressing (OE-D3), and miR528 target mimicry (OE-MIM528) transgenic plants. Knockout of D3 gene (d3 mutants) or miR528-overexpressing (OE-miR528) triggers a substantial reduction of gibberellin (GA) content, but a significant increase of abscisic acid (ABA) accumulation than in WT. The d3 and OE-miR528 transgenic plants were much more sensitive to GA, but less sensitive to ABA than WT. Moreover, the expression level of GA biosynthesis-related key genes, including OsCPS1, OsCPS2, OsKO2 and OsKAO was remarkably higher in OE-D3 plants, while the NECD2 expression, a key gene involved in ABA biosynthesis, was significantly higher in d3 mutants than in WT and OE-D3 plants. The results indicate that the miR528-D3 module negatively regulates plant height in rice by modulating the GA and ABA homeostasis, thereby further affecting the elongation of internodes, and resulting in lower plant height, which adds a new regulatory role to the D3-mediated plant height controlling in rice."
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