Rice GROWTH-REGULATING FACTOR7 Modulates Plant Architecture through Regulating GA and Indole-3-Acetic Acid Metabolism

Abstract

Plant-specific GROWTH-REGULATING FACTORs (GRFs) participate in central developmental processes, including leaf and root development; inflorescence, flower, and seed formation; senescence; and tolerance to stresses. In rice (Oryza sativa), there are 12 GRFs, but the role of the miR396-OsGRF7 regulatory module remains unknown. Here, we report that OsGRF7 shapes plant architecture via the regulation of auxin and GA metabolism in rice. OsGRF7 is mainly expressed in lamina joints, nodes, internodes, axillary buds, and young inflorescences. Overexpression of OsGRF7 causes a semidwarf and compact plant architecture with an increased culm wall thickness and narrowed leaf angles mediated by shortened cell length, altered cell arrangement, and increased parenchymal cell layers in the culm and adaxial side of the lamina joints. Knockout and knockdown lines of OsGRF7 exhibit contrasting phenotypes with severe degradation of parenchymal cells in the culm and lamina joints at maturity. Further analysis indicated that OsGRF7 binds the ACRGDA motif in the promoters of a cytochrome P450 gene and AUXIN RESPONSE FACTOR12, which are involved in the GA synthesis and auxin signaling pathways, respectively. Correspondingly, OsGRF7 alters the contents of endogenous GAs and auxins and sensitivity to exogenous phytohormones. These findings establish OsGRF7 as a crucial component in the OsmiR396-OsGRF-plant hormone regulatory network that controls rice plant architecture.

Enhancement of Nicotiana tabacum Resistance Against Dehydration-Induced Leaf Senescence via Metabolite/Phytohormone-Gene Regulatory Networks Modulated by Melatonin

“…Accordingly, the expression of MEL biosynthetic genes, such as NtTDC , NtT5H , NtASMT1 , and NtSNAT was upregulated by MEL treatment ( Figure 2I ). Similarly, a recent study in citrus trees also showed that the transcript levels of MEL biosynthetic genes, CsTDC1 , CsT5H , and CsASMTs were upregulated by exogenous MEL supplementation ( Nehela and Killiny, 2020 ). Further, endogenous MEL level is remarkably induced in MEL-pretreated Medicago sativa plants subjected to prolonged drought stress (7 days) ( Antoniou et al, 2017 ).…”

“…There is a close relationship between phytohormone levels and MEL concentration. Accumulating evidence supports that MEL acts synergistically or antagonistically with other phytohormones such as auxin, CTK, GA, ABA, ethylene, and JA during biological processes, particularly in stress responses ( Zhang et al, 2014 ; Arnao and Hernández-Ruiz, 2015 , 2018 ; Fan et al, 2018 ; Tan et al, 2019 ; Nehela and Killiny, 2020 ), with ABA and auxin being particularly interesting. Previous studies have shown that MEL decreases the anabolic capacity for ABA biosynthesis and increases catabolic capacity for ABA metabolism, thereby regulating the functions of stomata in dehydration-treated Malus plants ( Li et al, 2015 ).…”

Construction of a High-Density Genetic Map and Identification of Leaf Trait-Related QTLs in Chinese Bayberry (Myrica rubra)

“…Other genes in this cluster include MrChr5G3156 , which is a predicted chlorophyll a/b-binding protein expressed in green tissues and linked to photosynthesis in Jatropha curcas L., Euphorbiaceae ( Zhao et al, 2020 ). MrChr5G3258 was also in this cluster and was annotated as growth-regulating factor 3, participating in essential processes such as root and leaf development, seed and flower formation, inflorescence, and hormone network regulation in plants ( Chen et al, 2020 ). MrChr5G3089 was annotated as an OVATE family protein, the overexpression of which resulted in altered plant morphology, leaf chlorophyll accumulation, and retarded leaf senescence in tomatoes ( Zhou et al, 2019 ).…”

Spatial control of cell division by GA-OsGRF7/8 module in a leaf explains the leaf length variation between cultivated and wild rice

“…Exogenous GAtreatment, however, increased the leaf length without altering the mature epidermal cell length, suggesting that GA primarily affects rice leaf length via regulation of cell division (Supplemental Table S4 and S5 GRF transcription factors promote cell division activity by directly binding to the promoters of CYCA1;1 and CDC20 (Li et al, 2018). Moreover, GRF7 regulation of GAbiosynthesis and auxin-signaling genes control the rice plant architecture (Chen et al, 2020).…”