https://scholar.dgist.ac.kr/handle/20.500.11750/347 2026-04-05T12:42:40Z https://scholar.dgist.ac.kr/handle/20.500.11750/57390 Title: The genetically programmed rhythmic alteration of diurnal gene expression in the aged Arabidopsis leaves Author(s): Jung, Sukjoon; Kim, Hyunmin; Lee, Juhyeon; Kang, Myeong Hoon; Kim, Jung Yeon; Kim, Jong Kyoung; Lim, Pyung Ok; Nam, Hong Gil Abstract: The circadian clock regulates the daily pattern of temporal gene expression. In Arabidopsis, aging is associated with a shortening of the endogenous period of circadian rhythms under circadian conditions. However, the functional link between the circadian clock and aging under diurnal conditions and its physiological relevance remain elusive. In this study, we investigate and characterize the effect of aging on the waveforms of rhythmic gene expression patterns under light/dark cycles. Our analysis revealed that the diurnal rhythmic patterns of core clock genes undergo significant rhythmic alteration with phase shift and change of waveforms in aged plants compared to younger plants. Transcriptomic analysis indicated that this age-dependent rhythmic alteration occurs not only in core clock genes but also globally. Due to the rhythmic alteration patterns of the diurnal rhythmic gene expression, aged plants experience subjectively a shorter day and longer night. We also observed that genetic mutants of core clock component genes exhibited broadly yet distinctively altered changes in diurnal rhythmic gene expression patterns as aging progresses. Collectively, our findings support that age-dependent rhythmic alteration of diurnal gene expression rhythms reprograms the timetable of daily gene expression, leading to the physiological changes required for plant senescence. Copyright © 2024 Jung, Kim, Lee, Kang, Kim, Kim, Lim and Nam. 2024-10-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/47558 Title: An auxin-mediated ultradian rhythm positively influences root regeneration via EAR1/EUR1 in Arabidopsis Author(s): Vu, Quy Thi; Song, Kitae; Park, Sungjin; Xu, Lin; Nam, Hong Gil; Hong, Sunghyun Abstract: Ultradian rhythms have been proved to be critical for diverse biological processes. However, comprehensive understanding of the short-period rhythms remains limited. Here, we discover that leaf excision triggers a gene expression rhythm with ~3-h periodicity, named as the excision ultradian rhythm (UR), which is regulated by the plant hormone auxin. Promoter–luciferase analyses showed that the spatiotemporal patterns of the excision UR were positively associated with de novo root regeneration (DNRR), a post-embryonic developmental process. Transcriptomic analysis indicated more than 4,000 genes including DNRR-associated genes were reprogramed toward ultradian oscillation. Genetic studies showed that EXCISION ULTRADIAN RHYTHM 1 (EUR1) encoding ENHANCER OF ABSCISIC ACID CO-RECEPTOR1 (EAR1), an abscisic acid signaling regulator, was required to generate the excision ultradian rhythm and enhance root regeneration. The eur1 mutant exhibited the absence of auxin-induced excision UR generation and partial failure during rescuing root regeneration. Our results demonstrate a link between the excision UR and adventitious root formation via EAR1/EUR1, implying an additional regulatory layer in plant regeneration. Copyright © 2023 Vu, Song, Park, Xu, Nam and Hong. 2023-05-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/46519 Title: Concomitant Activation of OsNAS2 and OsNAS3 Contributes to the Enhanced Accumulation of Iron and Zinc in Rice Author(s): Lee, Sichul; Rahman, M d Mizanor; Nakanishi, Hiromi; Nishizawa, Naoko K. Nishizawa; An, Gynheung; Nam, Hong Gil; Jeon, Jong-Seong Abstract: Nicotianamine (NA) is produced by NA synthase (NAS), which contains three genes in rice and is responsible for chelating metals such as iron (Fe) and zinc (Zn), as well as preserving metal homeostasis. In this study, we generated a transgenic plant (23D) that shows simultaneous activation of OsNAS2 and OsNAS3 by crossing two previously identified activation-tagged mutants, OsNAS2-D1 (2D) and OsNAS3-D1 (3D). Concomitant activation of both genes resulted in the highest Fe and Zn concentrations in shoots and roots of the 23D plants grown under normal conditions and Fe and Zn limited growth conditions. Expression of genes for the biosynthesis of mugineic acid family phytosiderophores (MAs) and Fe and Zn uptake were enhanced in 23D roots. Additionally, 23D plants displayed superior growth to other plants at higher pH levels. Importantly, 23D seeds had NA and 2′-deoxymugineic acid (DMA) concentrations that were 50.6- and 10.0-fold higher than those of the WT. As a result, the mature grain Fe and Zn concentrations of the 23D plant were 4.0 and 3.5 times greater, respectively, than those of the WT. Furthermore, 23D plants exhibited the greatest resistance to excess metals. Our research suggests that simultaneous activation of OsNAS2 and OsNAS3 can enhance Fe and Zn accumulation in rice grains while also increasing plant tolerance to growing situations with metal deficiency and excess metal availability. © 2023 by the authors. 2023-03-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/15665 Title: Verticillium dahliae secretory effector PevD1 induces leaf senescence by promoting ORE1-mediated ethylene biosynthesis Author(s): Zhang, Yi; Gao, Yuhan; Wang, Hou-Ling; Kan, Chengcheng; Li, Ze; Yang, Xiufen; Yin, Weilun; Xia, Xinli; Nam, Hong Gil; Li, Zhonghai; Guo, Hongwei Abstract: Leaf senescence, the final stage of leaf development, is influenced by numerous internal and environmental signals. However, how biotic stresses such as pathogen infection regulate leaf senescence remains largely unclear. In this study, we found that the premature leaf senescence in Arabidopsis caused by the soil-borne vascular fungus Verticillium dahliae was impaired by disruption of a protein elicitor from V. dahliae 1 named PevD1. Constitutive or inducible overexpression of PevD1 accelerated Arabidopsis leaf senescence. Interestingly, a senescence-associated NAC transcription factor, ORE1, was targeted by PevD1. PevD1 could interact with and stabilize ORE1 protein by disrupting its interaction with the RING-type ubiquitin E3 ligase NLA. Mutation of ORE1 suppressed the premature senescence caused by overexpressing PevD1, whereas overexpression of ORE1 or PevD1 led to enhanced ethylene production and thereby leaf senescence. We showed that ORE1 directly binds the promoter of ACS6 and promotes its expression for mediating PevD1-induced ethylene biosynthesis. Loss-of-function of ACSs could suppress V. dahliae–induced leaf senescence in ORE1-overexpressing plants. Furthermore, we found thatPevD1 also interacts with Gossypium hirsutum ORE1 (GhORE1) and that virus-induced gene silencing of GhORE1 delays V. dahliae–triggered leaf senescence in cotton, indicating a possibly conserved mechanism in plants. Taken together, these results suggest that V. dahliae induces leaf senescence by secreting the effector PevD1 to manipulate the ORE1-ACS6 cascade, providing new insights into biotic stress-induced senescence in plants. © 2021 The Author 2021-10-31T15:00:00Z