Study on Phenotypes and Agronomical utility of a Rice GT1 (grassy tillers 1, OsGT1) Homologue

Vikranth Kumar,Yuan Hu Xuan,Byoung Il Je,Soon Ju Park,Jin Huang,Jing Miao Liu,Ryza A. Priatama,Vimal Raj K,Sung Hoon Kim,Jin-hee Jeong,Chang-deok Han 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07

Enhancing yield has been a major challenge of agriculture. In rice, tiller number is one of the important biomass and yield components. A maize mutant grassy tillers1 (gt1) increases lateral branches in maize. The GT1 gene encodes a class I homeodomain leucine zipper (HD-Zip) protein. In maize, the gt1 expression is induced by shading and is dependent on the activity of teosinte branched1 (tb1), a major domestication locus controlling tillering and lateral branching. To estimate the biological role and agricultural utility of gt1 in rice, rice homologue (OsGT1) has been isolated and its overexpressors and RNAi lines were generated. Field data showed that OsGT1 overexpressors reduced tillers and panicles while RNAi lines increased them, compared to wild type. Shade signal is an important factor in determining lateral branching. To understand the relationship between OsGT1 and shade avoidance, plants have been grown under 50% shading in the field. Also, double genetic combinations with phytochrome mutants (phyA, B, and C) are being examining for tillering phenotype. These ongoing researches will provide insights in determining the action of OsGT1 on branching and shade avoidance in rice.

Tiller Outgrowth in Rice (Oryza sativa L.) is Controlled by OsGT1, Which Acts Downstream of FC1 in a PhyB‑Independent Manner

Kumar Vikranth,Kim Sung Hoon,ADNAN MOCH ROSYADI,허정,정진희,Priatama Ryza A.,이증주,김철민,제병일,박순주,Xuan Yuan Hu,한창덕 한국식물학회 2021 Journal of Plant Biology Vol.64 No.5

Tillering is one of the most important determinants of biomass and yield in rice (Oryza sativa L.). The capacity of plants to develop tillers from primordial meristems or buds is determined not only by the genotype but also by environmental cues. Here, we characterized the function of rice grassy tiller1 (OsGT1) and its interaction with other genetic and biological factors involved in tiller bud outgrowth in rice by generating OsGT1 RNA interference (RNAi) and overexpression (OX) lines. The tiller number was increased in OsGT1-RNAi mutants but strongly suppressed in OsGT1-OX lines. Expression analysis of OsGT1 in rice phyB mutants and in genotypes carrying various genetic combinations of GT1 RNAi and phyB demonstrated that OsGT1 is not involved in phyB-mediated suppression of tiller development in rice. Expression analysis of fine culm1 (fc1), a rice tb1 homolog, and molecular assays demonstrated that FC1 enhances the expression of OsGT1 by directly binding to its promoter. Comparison of the transcriptomic profiles of fc1 and OsGT1-RNAi mutants revealed differentially expressed genes (DEGs) common to both genotypes. Finally, analysis of tillering phenotypes of OX and RNAi seedlings treated with various phytohormones implied a possible role of OsGT1 in strigolactone-mediated tiller outgrowth. Overall, this study enhances our understanding of the diverse mechanisms of tiller development in grasses.

NH4+ Suppresses NO3–-Dependent Lateral Root Growth and Alters Gene Expression and Gravity Response in OsAMT1 RNAi Mutants of Rice (Oryza sativa)

Vikranth Kumar,Sung Hoon Kim,Ryza A. Priatama,Jin Hee Jeong,Moch Rosyadi Adnan,Bernet Agung Saputra,Chul Min Kim,Byoung Il Je,Soon Ju Park,Ki-Hong Jung,Kyung Min Kim,Yuan Hu Xuan,Chang‑deok Han 한국식물학회 2020 Journal of Plant Biology Vol.63 No.5

The AMT1 family comprises major ammonium transporters in rice roots. In this study, we utilized AMT1 RNAi mutants (amt1) to explore how AMT1 affects NH4+- and NO3–-mediated morphological development and NH4+-responsive gene expression in roots. In the presence of NH4+, amt1 showed inhibition of NO3–- dependent lateral root development. The inhibitory action of NH4+ on lateral root growth was independent of the NO3– concentrations supplied to amt1 roots. The results of split root assays indicated that NH4+ exerts systemic action in inhibiting NO3–-dependent lateral root development in amt1. Further study with NAA and NOA, a potent auxin flux inhibitor, suggested that perturbation of membrane dynamics might not be the primary cause of the inhibitory action of NH4+ on NO3–-mediated lateral root growth in amt1 mutants. RNA-seq analysis of NH4+-responsive genes showed that approximately half of DEGs observed in wild-type roots were not detected in the DEGs of amt1 roots. Gene ontology enrichment analysis suggested that the expression of specific functional gene groups were affected by amt1 during the early response to NH4+. Auxin-responsive gene expression and root gravity responses were altered in amt1. This study demonstrated that AMT1 affects the interactions not only between ammonium and nitrate in lateral root growth but also between auxin and NH4+ in rice roots.

Searching For Transcription Factors Involved In Ammonium Assimilation and Root Growth in Rice Plants

Ryza A. Priatama,Vikranth Kumar,Jin-hee Jeong,Chang-deok Han 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07

Nitrogen in rice paddy soils and utilized as the major source for N-assimilation in rice crops. In roots, transcriptional activities of ammonium uptake and assimilation genes are highly sensitive to the availability of exogenous ammonium. However, little is known about the transcription factor genes that regulated by ammonium supply and its role to roots and plant developments. To study the transcription factor genes that involved in Ammonium response, two weeks old rice seedlings treated using Ammonium from 0 to 3 hours. Total RNA collected from each sample and samples were prepared for Agilent 8x60K microarray system. Based on the microarray data, we select transcription factor genes that highly affected by ammonium and selected knock out mutant candidates that used for phenotype screening.

Effect of suspension parameters on dynamics of a metro coach: A parametric study

Sudhir Kumar Singh,Abhilash Vishwakarma,Sanjay R Singh,Vikranth Racherla 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.6

This work aims to analyse the effect of primary and secondary suspension parameters on the dynamics of a BEML metro coach plying on the Kolkata metro track with short straight segments, sharp curves, rapid acceleration, and deceleration. For this, instrumented field trials were conducted on the metro coach on the newly built track in Kolkata, India. During the trials, vehicle speed, coach acceleration, and primary, secondary springs compressions were recorded. A multibody dynamics model for the BEML metro coach plying on the metro track is built in commercial software Simpack. Vertical and lateral track irregularities, non-linear air spring and rail-wheel contact models are considered in modeling for accurate representation of the coach. The developed multibody dynamics model is validated using the field trials data by matching vertical and lateral ride comfort indices for the coach along with roll, pitch, and equivalent bounce motions of the coach and bogies. Effect of four suspension parameters, namely, effective area of air spring, horizontal stiffness of air spring, damping coefficient of lateral damper and horizontal stiffness of primary spring, on metro coach dynamics is studied. Vehicle output response parameters monitored include average vertical ride comfort, average lateral ride comfort, maximum derailment coefficient, average wear index, and vehicle stability. Central composite design is used to design the simulation runs. Response surface methodology is used to obtain second order polynomial models for output response variables in terms of selected suspension parameters. Significant reduction of around 8 % in average wear index was observed for 20 % reduction in horizontal stiffness of primary and secondary springs. Separately, around 7 % reduction in lateral ride comfort index was observed for 20 % reduction in lateral damping coefficient, secondary spring horizontal stiffness and 20 % increase in primary spring horizontal stiffness.

IDD10 is Involved in the Interaction between NH4+ and Auxin Signaling in Rice Roots

Chang-Deok Han,Yuan Hu Xuan,Vikranth Kumar,Xiao Feng Zhu,Byoung Il Je,Chul Min Kim,Jin Huang,Jun Hyeon Cho,Gihwan Yi 한국식물학회 2018 Journal of Plant Biology Vol.61 No.2

NH4+ is an important nitrogen resource for rice plantsin paddy soil. Therefore, it is likely that NH4+-triggered plantgrowth interacts with phytohormone-mediated developmentalmechanisms. Our previous transcriptomic analysis revealedthat many genes involved in auxin signaling and efflux aresensitive to NH4+. In the current study, we found that NH4+treatment causes a delayed gravity response in rice roots. Tofurther elucidate the interlocking relationship between NH4+and auxin signaling during root development, we utilizedmutants and overexpressors of a key NH4+ signaling transcriptionfactor INDETERMINATE DOMAIN 10 (IDD10), encoding atranscription factor that regulates the expression of NH4+uptake and N-assimilation genes. We obtained several linesof evidence that auxin affects NH4+-mediated gene expressionand root development in rice plants via IDD10. First, thegravity response was delayed in idd10 roots and acceleratedin IDD10 overexpressor (IDD10 OX) roots in the absenceand (especially) presence of NH4+. Second, idd10 plantsshowed strong root coiling only in the presence of NH4+. However, treatment of 1-N-naphthylphthalamic acid (NPA),a polar auxin transport inhibitor suppressed the NH4+-specific root phenotype of idd10. Third, the expression ofNH4+-responsive auxin-related genes was affected in idd10and IDD10 overexpressors. Finally, IDD10 expression wasinduced by IAA and suppressed by NPA. These findingssuggest that the gene expression patterns and phenotypestriggered by NH4+ are influenced by the actions of auxinduring root development, pointing to a regulatory circuitbetween NH4+ and auxin signaling that functions in rootdevelopment in rice.

<i>Loose Plant Architecture1</i> ( <i>LPA1</i> ) determines lamina joint bending by suppressing auxin signalling that interacts with C-22-hydroxylated and 6-deoxo brassinosteroids in rice

Liu, Jing Miao,Park, Soon Ju,Huang, Jin,Lee, Eun Jin,Xuan, Yuan Hu,Je, Byoung Il,Kumar, Vikranth,Priatama, Ryza A.,Raj K, Vimal,Kim, Sung Hoon,Min, Myung Ki,Cho, Jun Hyeon,Kim, Tae Ho,Chandran, Anil K Oxford University Press 2016 Journal of experimental botany Vol.67 No.6

<P>Lamina inclination is a key agronomical character that determines plant architecture and is sensitive to auxin and brassinosteroids (BRs). <I>Loose Plant Architecture1</I> (<I>LPA1</I>) in rice (<I>Oryza sativa</I>) and its Arabidopsis homologues (<I>SGR5/AtIDD15</I>) have been reported to control plant architecture and auxin homeostasis. This study explores the role of <I>LPA1</I> in determining lamina inclination in rice. <I>LPA1</I> acts as a positive regulator to suppress lamina bending. Genetic and biochemical data indicate that <I>LPA1</I> suppresses the auxin signalling that interacts with C-22-hydroxylated and 6-deoxo BRs, which regulates lamina inclination independently of <I>OsBRI1</I>. Mutant <I>lpa1</I> plants are hypersensitive to indole-3-acetic acid (IAA) during the lamina inclination response, which is suppressed by the brassinazole (Brz) inhibitor of C-22 hydroxylase involved in BR synthesis. A strong synergic effect is detected between <I>lpa1</I> and <I>d2</I> (the defective mutant for catalysis of C-23-hydroxylated BRs) during IAA-mediated lamina inclination. No significant interaction between <I>LPA1</I> and <I>OsBRI1</I> was identified. The <I>lpa1</I> mutant is sensitive to C-22-hydroxylated and 6-deoxo BRs in the <I>d61-1</I> (rice <I>BRI1</I> mutant) background. We present evidence verifying that two independent pathways function via either BRs or <I>BRI1</I> to determine IAA-mediated lamina inclination in rice. RNA sequencing analysis and qRT-PCR indicate that <I>LPA1</I> influences the expression of three <I>OsPIN</I> genes (<I>OsPIN1a</I>, <I>OsPIN1c</I> and <I>OsPIN3a</I>), which suggests that auxin flux might be an important factor in <I>LPA1</I>-mediated lamina inclination in rice.</P>