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Early View

  Special Issue: Genomics-assisted Germplasm Improvement in Rice
OsIDD2, a zinc finger and INDETERMINATE DOMAIN protein, regulates secondary cell wall formation
Author: Peng Huang, Hideki Yoshida, Kenji Yano, Shunsuke Kinoshita, Kyosuke Kawai, Eriko Koketsu, Masako Hattori, Sayaka Takehara, Ji Huang, Ko Hirano, Reynante Lacsamana Ordonio, Makoto Matsuoka and Miyako Ueguchi-Tanaka
Received: February 8, 2017         Accepted: May 29, 2017
Online Date: June 2, 2017
DOI: 10.1111/jipb.12557
   
      
    

Previously, we found 123 transcription factors (TFs) as candidate regulators of secondary cell wall (SCW) formation in rice by using phylogenetic and co-expression network analyses. Among them, we examined in this work the role of OsIDD2, a zinc finger and indeterminate domain (IDD) family TF. Its overexpressors showed dwarfism, fragile leaves, and decreased lignin content, which are typical phenotypes of plants defective in SCW formation, whereas its knockout plants showed slightly increased lignin content. The RNA-seq and quantitative reverse transcription polymerase chain reaction analyses confirmed that some lignin biosynthetic genes were downregulated in the OsIDD2-overexpressing plants, and revealed the same case for other genes involved in cellulose synthesis and sucrose metabolism. The transient expression assay using rice protoplasts revealed that OsIDD2 negatively regulates the transcription of genes involved in lignin biosynthesis, cinnamyl alcohol dehydrogenase 2 and 3 (CAD2 and 3), and sucrose metabolism, sucrose synthase 5 (SUS5), whereas an AlphaScreen assay, which can detect the interaction between TFs and their target DNA sequences, directly confirmed the interaction between OsIDD2 and the target sequences located in the promoter regions of CAD2 and CAD3. Based on these observations, we conclude that OsIDD2 is negatively involved in SCW formation and other biological events by downregulating its target genes.

Abstract (Browse 150)   |   References   |   Full Text HTML   |   Full Text PDF       
Ectopic expression of fungal EcGDH improves nitrogen assimilation and grain yield in rice
Author: Dongying Tang, Yuchong Peng, Jianzhong Lin, Changqing Du, Yuanzhu Yang, Dan Wang, Cong Liu, Lu Yan, Xiaoying Zhao, Xia Li, Liangbi Chen and Xuanming Liu
Received: December 28, 2016         Accepted: January 5, 2017
Online Date: January 6, 2017
DOI: 10.1111/jipb.12519
   
      
    

NADP(H)-dependent glutamate dehydrogenases (GDH) in lower organisms have stronger ammonium affinity than those in higher plants. Here we report that transgenic rice overexpressing the EcGDH from Eurotium cheralieri exhibited significantly enhanced aminating activities. Hydroponic and field tests showed that nitrogen assimilation efficiency and grain yields were markedly increased in these transgenic plants, especially at the low nitrogen conditions. These results suggest that EcGDH may have potential to be used to improve nitrogen assimilation and grain yield in rice.

Abstract (Browse 360)   |   References   |   Full Text HTML   |   Full Text PDF       
QTL editing confers opposing yield performance in different rice varieties
Author: Lan Shen, Chun Wang, Yaping Fu, Junjie Wang, Qing Liu, Xiaoming Zhang, Changjie Yan, Qian Qian and Kejian Wang
Received: June 1, 2016         Accepted: September 13, 2016
Online Date: September 15, 2016
DOI: 10.1111/jipb.12501
   
      
    

Grain yield is one of the most important and complex trait for genetic improvement in crops; it is known to be controlled by a number of genes known as quantitative trait loci (QTLs). In the past decade, many yield-contributing QTLs have been identified in crops. However, it remains unclear whether those QTLs confer the same yield performance in different genetic backgrounds. Here, we performed CRISPR/Cas9-mediated QTL editing in five widely-cultivated rice varieties and revealed that the same QTL can have diverse, even opposing, effects on grain yield in different genetic backgrounds.

Abstract (Browse 428)   |   References   |   Full Text HTML   |   Full Text PDF       
  Letters to the Editor
Seed dispersal by hornets: An unusual insect-plant mutualism
Author: Gao Chen, Zheng-Wei Wang, Yan Qin and Wei-Bang Sun
Received: June 15, 2017         Accepted: July 10, 2017
Online Date: July 11, 2017
DOI: 10.1111/jipb.12568
   
      
    

Vespicochory, seed dispersal by hornets, is a rare seed dispersal mechanism in angiosperms and, to date, there are few records of this phenomenon. Through field investigations and behavioral assays conducted in four populations of Stemona tuberosa from 2011–2016, we demonstrate that hornets are the primary seed dispersers of S. tuberosa and play an important role in “long-distance” seed dispersal in this species. Furthermore, some ant species act as secondary dispersers and may transport the seeds to safe sites. Hornets and ants provide complementary seed dispersal at different spatial scales. This unique example of insect-plant mutualism may be an underestimated but important strategy to ensure “long-distance” seed dispersal in other myrmecochorous plants.

Abstract (Browse 86)   |   References   |   Full Text HTML   |   Full Text PDF       
THESEUS1 positively modulates plant defense responses against Botrytis cinerea through GUANINE EXCHANGE FACTOR4 signaling
Author: Shaofeng Qu, Xi Zhang, Yutong Song, Jinxing Lin and Xiaoyi Shan
Received: May 9, 2017         Accepted: June 21, 2017
Online Date: June 24, 2017
DOI: 10.1111/jipb.12565
   
      
    

The plant cell wall is an important interface for sensing pathogen attack and activating signaling pathways that promote plant immune responses. THESEUS1 (THE1) acts as a sensor of cell wall integrity that controls cell elongation during plant growth. However, no specific role for THE1 in plant defense responses has been reported. Here, we found that THE1 interacts with GUANINE EXCHANGE FACTOR4 (GEF4) and that both proteins play regulatory roles in plant resistance to the necrotrophic fungus Botrytis cinerea. Genetic analysis showed that THE1 and GEF4 function in the same genetic pathway to mediate plant defense responses. In addition, using transcriptome analysis, we identified various genes (such as defense-related, secondary metabolite-related, and transcription factor genes) that are likely downstream targets in the THE1-GEF4 signaling pathway. Our results suggest that THE1 functions as an upstream regulator of GEF4 signaling to positively regulate defense responses against B. cinerea in Arabidopsis.

Abstract (Browse 118)   |   References   |   Full Text HTML   |   Full Text PDF       
  Plant-abiotic Interactions
Potassium channel AKT1 is involved in the auxin-mediated root growth inhibition in Arabidopsis response to low K+ stress
Author: Juan Li, Wei-Hua Wu and Yi Wang
Received: April 13, 2017         Accepted: August 4, 2017
Online Date: August 7, 2017
DOI: 10.1111/jipb.12575
   
      
    

The changes in external K+ concentration affect plant root growth. However, the molecular mechanism for perceiving a K+ signal to modulate root growth remains unknown. It is hypothesized that the K+ channel AKT1 is involved in low K+ sensing in the Arabidopsis root and subsequent regulation of root growth. Along with the decline of external K+ concentration, the primary root growth of wild-type plants was gradually inhibited. However, the primary root of the akt1 mutant could still grow under low K+ (LK) conditions. Application of NAA inhibited akt1 root growth, but promoted wild-type root growth under LK conditions. By using the ProDR5:GFP and ProPIN1:PIN1-GFP lines, we found that LK treatment reduced auxin accumulation in wild-type root tips by degrading PIN1 proteins, which did not occur in the akt1 mutant. The LK-induced PIN1 degradation may be due to the inhibition of vesicle trafficking of PIN1 proteins. In conclusion, our findings indicate that AKT1 is required for an Arabidopsis response to changes in external K+, and subsequent regulation of K+-dependent root growth by modulating PIN1 degradation and auxin redistribution in the root.

Abstract (Browse 47)   |   References   |   Full Text HTML   |   Full Text PDF       

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