July 2017, Volume 59 Issue 7, Pages 453每522.


Cover Caption: Subcellular localization of OsZFP
Auxin plays a crucial role in lateral root development. In this issue, Cui et al. (pp. 496每505) report in rice that OsZFP as a C2HCtype zinc finger protein participates in IAA signal pathways to control lateral root development by interacting with cyclophilin. The expression of Aux/IAA genes (OsIAA1, 8, 11, 23, 31) was altered in OsZFP-RNAi lines in response to IAA treatments.

 

          Letter to the Editor
Arabidopsis Forkhead-Associated Domain Protein 3 negatively regulates peroxisome division  
Author: Mintu Desai, Ronghui Pan and Jianping Hu
Journal of Integrative Plant Biology 2017 59(7): 454每458
Published Online: March 23, 2017
DOI: 10.1111/jipb.12542
      
    

Peroxisomes are ubiquitous and dynamic eukaryotic organelles capable of altering their abundance in response to environmental and developmental cues, yet the regulatory mechanism of plant peroxisome division/proliferation is unclear. To identify transcriptional regulators of the peroxisome division factor gene PEX11b, we performed a nuclear pull-down experiment and identified Arabidopsis Forkhead-Associated Domain Protein 3 (FHA3) as a novel protein that binds to the promoter of PEX11b. Our data supported the conclusion that, in contrast to the previously identified HY5 HOMOLOG (HYH) protein that promotes the transcription of PEX11b, FHA3 is a negative regulator of PEX11b expression and peroxisome division.

Abstract (Browse 1032)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Peroxisomes are essential and dynamic organelles capable of changing abundance through division and proliferation in response to environmental and developmental cues. This work identified an Arabidopsis transcription factor Forkhead-Associated Domain Protein 3 (FHA3), which negatively regulates peroxisome division by repressing the expression of the peroxisome division factor gene PEX11b.
          Cell and Developmental Biology
Poly(ADP-ribose) polymerases regulate cell division and development in Arabidopsis roots
Author: Caifeng Liu, Qiao Wu, Weiwei Liu, Zongyin Gu, Wenjing Wang, Ping Xu, Hong Ma and Xiaochun Ge
Journal of Integrative Plant Biology 2017 59(7): 459每474
Published Online: March 6, 2017
DOI: 10.1111/jipb.12530
      
    

Root organogenesis involves cell division, differentiation and expansion. The molecular mechanisms regulating root development are not fully understood. In this study, we identified poly(adenosine diphosphate (ADP)-ribose) polymerases (PARPs) as new players in root development. PARP catalyzes poly(ADP-ribosyl)ation of proteins by repeatedly adding ADP-ribose units onto proteins using nicotinamide adenine dinucleotide (NAD+) as the donor. We found that inhibition of PARP activities by 3-aminobenzomide (3-AB) increased the growth rates of both primary and lateral roots, leading to a more developed root system. The double mutant of Arabidopsis PARPs, parp1parp2, showed more rapid primary and lateral root growth. Cyclin genes regulating G1-to-S and G2-to-M transition were up-regulated upon treatment by 3-AB. The proportion of 2C cells increased while cells with higher DNA ploidy declined in the roots of treated plants, resulting in an enlarged root meristematic zone. The expression level of PARP2 was very low in the meristematic zone but high in the maturation zone, consistent with a role of PARP in inhibiting mitosis and promoting cell differentiation. Our results suggest that PARPs play an important role in root development by negatively regulating root cell division.

Abstract (Browse 340)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Understanding the molecular mechanisms regulating root architecture establishment is very important for agriculture. In this study, we present the evidence that poly (ADP-ribose) polymerases play an important role in regulating root cell division and inhibition of their activities promotes lateral root development.
          Metabolism and Biochemistry
Phenolic metabolism and molecular mass distribution of polysaccharides in cellulose-deficient maize cells  
Author: María de Castro, Romina Martínez-Rubio, José L. Acebes, Antonio Encina, Stephen C. Fry and Penélope García-Angulo
Journal of Integrative Plant Biology 2017 59(7): 475每495
Published Online: May 5, 2017
DOI: 10.1111/jipb.12549
      
    
As a consequence of the habituation to low levels of dichlobenil (DCB), cultured maize cells presented an altered hemicellulose cell fate with a lower proportion of strongly wall-bound hemicelluloses and an increase in soluble extracellular polymers released into the culture medium. The aim of this study was to investigate the relative molecular mass distributions of polysaccharides as well as phenolic metabolism in cells habituated to low levels of DCB (1.5 μM). Generally, cell wall bound hemicelluloses and sloughed polymers from habituated cells were more homogeneously sized and had a lower weight-average relative molecular mass. In addition, polysaccharides underwent massive cross-linking after being secreted into the cell wall, but this cross-linking was less pronounced in habituated cells than in non-habituated ones. However, when relativized, ferulic acid and p-coumaric acid contents were higher in this habituated cell line. Feasibly, cells habituated to low levels of DCB synthesized molecules with a lower weight-average relative molecular mass, although cross-linked, as a part of their strategy to compensate for the lack of cellulose.
Abstract (Browse 808)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
In this study, a novel strategy adopted for coping with reduced cellulose levels is provided. Maize cells with reduced cellulose contents synthesize shorter, albeit extensively cross-linked hemicelluloses as part of their coping strategy. This work contributes to enhancing our understanding of hemicellulose metabolism, providing new mechanisms for cell wall plasticity.
          Molecular Physiology
A zinc finger protein, interacted with cyclophilin, affects root development via IAA pathway in rice
Author: Peng Cui, Hongbo Liu, Songlin Ruan, Basharat Ali, Rafaqat Ali Gill, Huasheng Ma, Zhifu Zheng and Weijun Zhou
Journal of Integrative Plant Biology 2017 59(7): 496每505
Published Online: March 7, 2017
DOI: 10.1111/jipb.12531
      
    

The plant hormone auxin plays a crucial role in lateral root development. To better understand the molecular mechanisms underlying lateral root formation, an auxin-responsive gene OsCYP2 (Os02g0121300) was characterized from rice. Compared to the wild type, OsCYP2-RNAi (RNA interference) lines exhibited distinctive defects in lateral root development. Yeast two-hybrid and glutathione S-transferase pull-down results confirmed that OsCYP2 interacted with a C2HC-type zinc finger protein (OsZFP, Os01g0252900) which is located in the rice nucleus. T2 OsZFP-RNAi lines had significantly fewer lateral roots than did wild-type plants, which suggests a role for OsCYP2 and OsZFP in regulating lateral root development. Quantitative real-time polymerase chain reaction showed that the expression of certain Aux/IAA (auxin/indole-3-acetic acid) genes was altered in OsCYP2- and OsZFP-RNAi lines in response to IAA. These findings imply that OsCYP2 and OsZFP participate in IAA signal pathways controlling lateral root development. More importantly, OsIAA11 showed functional redundancy not only in OsCYP2-RNAi lines but also in OsZFP-RNAi lines, which provides important clues for the elucidation of mechanisms controlling lateral root development in response to auxin.

Abstract (Browse 308)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
To better understand the molecular mechanisms underlying lateral root formation, an auxin-responsive gene, OsZFP (Os01g0252900), was characterized from rice. OsZFP encodes a C2HC-type zinc finger protein, which locates in nucleus, and interacts with cyclophilin. OsZFP-RNAi lines exhibited distinctive defects in lateral root development through IAA pathway.
          Plant-environmental Interactions
Unfolded protein response activation compensates endoplasmic reticulum-associated degradation deficiency in Arabidopsis
Author: Qingliang Li, Hai Wei, Lijing Liu, Xiaoyuan Yang, Xiansheng Zhang and Qi Xie
Journal of Integrative Plant Biology 2017 59(7): 506每521
Published Online: April 18, 2017
DOI: 10.1111/jipb.12544
      
    

Abiotic stresses often disrupt protein folding and induce endoplasmic reticulum (ER) stress. There is a sophisticated ER quality control (ERQC) system to mitigate the effects of malfunctioning proteins and maintain ER homeostasis. The accumulation of misfolded proteins in the ER activates the unfolded protein response (UPR) to enhance ER protein folding and the degradation of misfolded proteins mediate by ER-associated degradation (ERAD). That ERQC reduces abiotic stress damage has been well studied in mammals and yeast. However, in plants, both ERAD and UPR have been studied separately and found to be critical for plant abiotic stress tolerance. In this study, we discovered that UPR-associated transcription factors AtbZIP17, AtbZIP28 and AtbZIP60 responded to tunicamycin (TM) and NaCl induced ER stress and subsequently enhanced Arabidopsis thaliana abiotic stress tolerance. They regulated the expression level of ER chaperones and the HRD1-complex components. Moreover, overexpression of AtbZIP17, AtbZIP28 and AtbZIP60 could restore stress tolerance via ERAD in the HRD1-complex mutant hrd3a-2, which suggested that UPR and ERAD have an interactive mechanism in Arabidopsis.

Abstract (Browse 179)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
UPR and ERAD are two related systems for eliminating misfolded proteins caused by stresses. In this study, the bZIP proteins involved in the UPR machinery were found specifically regulated ER chaperone and HRD1 complex components, suggesting that bZIPs could compensate for ERAD deficiency under abiotic stresses.
 

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