September 2016, Volume 58 Issue 9, Pages 761每812.


Cover Caption: Rice Caryopsis Development
As one of the most important food sources, rice caryopsis has a complex structure that composes of maternal tissues of pericarp and testa, and filial tissues of endosperm and embryo. In this issue, two papers, authored by Wu et al, illustrate in detail the development of maternal (pp. 772每785) and endosperm tissues (pp. 786每798). Results provided show that rice caryopsis undergoes dynamic changes in mitotic divisions, cellularization, cell differentiation and programmed cell death.

 

          Letters to the Editor
Mutation in the gene encoding 1-aminocyclopropane-1-carboxylate synthase 4 (CitACS4) led to andromonoecy in watermelon  
Author: Gaojie Ji, Jie Zhang, Haiying Zhang, Honghe Sun, Guoyi Gong, Jianting Shi, Shouwei Tian, Shaogui Guo, Yi Ren, Huolin Shen, Junping Gao and Yong Xu
Journal of Integrative Plant Biology 2016 58(9): 762每765
Published Online: February 3, 2016
DOI: 10.1111/jipb.12466
      
    

Although it has been reported previously that ethylene plays a critical role in sex determination in cucurbit species, how the andromonoecy that carries both the male and hermaphroditic flowers is determined in watermelon is still unknown. Here we showed that the watermelon gene 1-aminocyclopropane-1-carboxylate synthase 4 (CitACS4), expressed specifically in carpel primordia, determines the andromonoecy in watermelon. Among four single nucleotide polymorphism (SNPs) and one InDel identified in the coding region of CitACS4, the C364W mutation located in the conserved box 6 was co-segregated with andromonoecy. Enzymatic analyses showed that the C364W mutation caused a reduced activity in CitACS4. We believe that the reduced CitACS4 activity may hamper the programmed cell death in stamen primordia, leading to the formation of hermaphroditic flowers.

Abstract (Browse 620)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
In this study, we showed that the watermelon gene 1-aminocyclopropane-1-carboxylate synthase 4 (CitACS4), expressed specifically in carpel primordia, determines the andromonoecy in watermelon. The C364W mutation of CitACS4 caused its reduced activity. We believe our results will be helpful to improve the breeding production in watermelon.
An exon skipping in a SEPALLATA-Like gene is associated with perturbed floral and fruits development in cucumber  
Author: Xin Wang, Dongli Gao, Jinjing Sun, Min Liu, Yaoyao Lun, Jianshu Zheng, Shenhao Wang, Qingzhi Cui, Xiaofeng Wang and Sanwen Huang
Journal of Integrative Plant Biology 2016 58(9): 766每771
Published Online: March 3, 2016
DOI: 10.1111/jipb.12472
      
    
We isolated a mutant showing perturbations in the development of male and female floral organs and fruits. Analysis of the single nucleotide polymorphisms from bulked F2 pools identified the causative variant occurring in Csa4G126690. Csa4G126690 shows high homology to Arabidopsis SEPALLATA2 (SEP2) thus being designated CsSEP2. The causative variant was located on the splicing site of CsSEP2, resulting in the skipping of exon 6 and abolishment of the transcriptional activity. Our data suggest that CsSEP2 is involved in the floral organ and fruits development by conferring transcriptional activity.
Abstract (Browse 586)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
We isolated a mutant showing perturbations in the development of floral organs and fruits in cucumber. We further identified the causative variant occurring in CsSEP2 by whole genome re-sequencing of the mutant. The variant caused the skipping of exon 6 and abolishment of the transcriptional activity, thus perturbing floral organs and fruits development.
          Cell and Developmental Biology
Rice caryopsis development I: Dynamic changes in different cell layers  
Author: Xiaoba Wu, Jinxin Liu, Dongqi Li and Chun-Ming Liu
Journal of Integrative Plant Biology 2016 58(9): 772每785
Published Online: October 16, 2015
DOI: 10.1111/jipb.12440
      
    

Rice caryopsis as one of the most important food sources for humans has a complex structure that is composed of maternal tissues including the pericarp and testa and filial tissues including the endosperm and embryo. Although rice caryopsis studies have been conducted previously, a systematic characterization throughout the entire developmental process is still lacking. In this study, detailed morphological examinations of caryopses were made during the entire 30-day developmental process. We observed some rapid changes in cell differentiation events and cataloged how cellular degeneration processes occurred in maternal tissues. The differentiations of tube cells and cross cells were achieved by 9 days after pollination (DAP). In the testa, the outer integument was degenerated by 3 DAP, while the outer layer of the inner integument degenerated by 7 DAP. In the nucellus, all tissues with the exception of the nucellar projection and the nucellar epidermis degenerated in the first 5 DAP. By 21 DAP, all maternal tissues, including vascular bundles, the nucellar projection and the nucellar epidermal cells were degenerated. In summary, this study provides a complete atlas of the dynamic changes in cell differentiation and degeneration for individual maternal cell layers of rice caryopsis.

Abstract (Browse 1433)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Detailed morphological examinations of maternal tissues in rice caryopsis were made during the entire 30-day developmental process. This study provides a complete atlas of the dynamic changes in cell differentiation and degeneration for individual maternal cell layers of rice caryopsis.
Rice caryopsis development II: Dynamic changes in the endosperm  
Author: Xiaoba Wu, Jinxin Liu, Dongqi Li and Chun-Ming Liu
Journal of Integrative Plant Biology 2016 58(9): 786每798
Published Online: July 22, 2016
DOI: 10.1111/jipb.12488
      
    

The rice endosperm plays crucial roles in nourishing the embryo during embryogenesis and seed germination. Although previous studies have provided the general information about rice endosperm, a systematic investigation throughout the entire endosperm developmental process is still lacking. In this study, we examined in detail rice endosperm development on a daily basis throughout the 30-day period of post-fertilization development. We observed that coenocytic nuclear division occurred in the first 2 days after pollination (DAP), cellularization occurred between 3 and 5 DAP, differentiation of the aleurone and starchy endosperm occurred between 6 and 9 DAP, and accumulation of storage products occurred concurrently with the aleurone/starchy endosperm differentiation from 6 DAP onwards and was accomplished by 21 DAP. Changes in cytoplasmic membrane permeability, possibly caused by programmed cell death, were observed in the central region of the starchy endosperm at 8 DAP, and expanded to the whole starchy endosperm at 21 DAP when the aleurone is the only living component in the endosperm. Further, we observed that a distinct multi-layered dorsal aleurone formed near the dorsal vascular bundle, while the single- or occasionally two-cell layered aleurone was located in the lateral and ventral positions of endosperm. Our results provide in detail the dynamic changes in mitotic divisions, cellularization, cell differentiation, storage product accumulation, and programmed cell death that occur during rice endosperm development.

Abstract (Browse 854)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
In this study, we examined in detail rice endosperm development on a daily basis throughout the 30-day period of post-fertilization development. Our results provide in detail the dynamic changes in mitotic divisions, cellularization, cell differentiation, storage product accumulation, and programmed cell death that occur during rice endosperm development.
Break of symmetry in regenerating tobacco protoplasts is independent of nuclear positioning  
Author: Linda Brochhausen, Jan Maisch and Peter Nick
Journal of Integrative Plant Biology 2016 58(9): 799每812
Published Online: February 22, 2010
DOI: 10.1111/jipb.12469
      
    

Nuclear migration and positioning are crucial for the morphogenesis of plant cells. We addressed the potential role of nuclear positioning for polarity induction using an experimental system based on regenerating protoplasts, where the induction of a cell axis de novo can be followed by quantification of specific regeneration stages. Using overexpression of fluorescently tagged extranuclear (perinuclear actin basket, kinesins with a calponin homology domain (KCH)) as well as intranuclear (histone H2B) factors of nuclear positioning and time-lapse series of the early stages of regeneration, we found that nuclear position is no prerequisite for polarity formation. However, polarity formation and nuclear migration were both modulated in the transgenic lines, indicating that both phenomena depend on factors affecting cytoskeletal tensegrity and chromatin structure. We integrated these findings into a model where retrograde signals are required for polarity induction. These signals travel via the cytoskeleton from the nucleus toward targets at the plasma membrane.

Abstract (Browse 484)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
We addressed the role of nuclear positioning for polarity induction using regenerating protoplasts, where induction of a cell axis de novo can be followed. We integrate our findings into a model, where retrograde signals travelling via the cytoskeleton from the nucleus towards the plasma membrane are required for polarity induction.
 

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