June 2016, Volume 58 Issue 6, Pages 517每609.


Cover Caption: Mechanosensitive Ion Channel and Wounding
Plants release jasmonates (JAs), a class of phytohormones, upon wounding that subsequently activate a variety of protective responses. How plants sense wounding is not known. In this issue, Zou et al. (pp.600每609) show that a gain-of-function mutation in a mechanosensitive ion channel if Arabidopsis triggers elevated JAresponses including accumulation of anthocyanin (as seen in the photo), microscopic cell death, and hyper-accumulation of JAs in response to wounding. These results suggest that perturbation of mechanosensitive ion channels is linked to perception of mechanic damage.

 

          Cell and Developmental Biology
Maize ZmVPP5 is a truncated Vacuole H+-PPase that confers hypersensitivity to salt stress  
Author: Xiaoliang Sun, Weiwei Qi, Yihong Yue, Huiling Ling, Gang Wang and Rentao Song
Journal of Integrative Plant Biology 2016 58(6): 518-528
Published Online: January 5, 2016
DOI: 10.1111/jipb.12462
      
    

In plants, Vacuole H+-PPases (VPPs) are important proton pumps and encoded by multiple genes. In addition to full-length VPPs, several truncated forms are expressed, but their biological functions are unknown. In this study, we functionally characterized maize vacuole H+-PPase 5 (ZmVPP5), a truncated VPP in the maize genome. Although ZmVPP5 shares high sequence similarity with ZmVPP1, ZmVPP5 lacks the complete structure of the conserved proton transport and the inorganic pyrophosphatase-related domain. Phylogenetic analysis suggests that ZmVPP5 might be derived from an incomplete gene duplication event. ZmVPP5 is expressed in multiple tissues, and ZmVPP5 was detected in the plasma membrane, vacuole membrane and nuclei of maize cells. The overexpression of ZmVPP5 in yeast cells caused a hypersensitivity to salt stress. Transgenic maize lines with overexpressed ZmVPP5 also exhibited the salt hypersensitivity phenotype. A yeast two-hybrid analysis identified the ZmBag6-like protein as a putative ZmVPP5-interacting protein. The results of bimolecular luminescence complementation (BiLC) assay suggest an interaction between ZmBag6-like protein and ZmVPP5 in vivo. Overall, this study suggests that ZmVPP5 might act as a VPP antagonist and participate in the cellular response to salt stress. Our study of ZmVPP5 has expanded the understanding of the origin and functions of truncated forms of plant VPPs.

Abstract (Browse 719)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
ZmVPP5 is a truncated Vacuole H+-PPase protein. We demonstrated that overexpressing ZmVPP5 exhibited salt hypersensitivity phenotype in transgenic maize and yeast. We also identified a ZmBag6-like protein as a ZmVPP5-interacting protein. Our study of ZmVPP5 has expanded the understanding of the origin and functions of plant truncated VPPs.
The pleiotropic ABNORMAL FLOWER AND DWARF1 affects plant height, floral development and grain yield in rice  
Author: Deyong Ren, Yuchun Rao, Liwen Wu, Qiankun Xu, Zizhuang Li, Haiping Yu, Yu Zhang, Yujia Leng, Jiang Hu, Li Zhu, Zhenyu Gao, Guojun Dong, Guangheng Zhang, Longbiao Guo, Dali Zeng and Qian Qian
Journal of Integrative Plant Biology 2016 58(6): 529每539
Published Online: October 21, 2015
DOI: 10.1111/jipb.12441
      
    

Moderate plant height and successful establishment of reproductive organs play pivotal roles in rice grain production. The molecular mechanism that controls the two aspects remains unclear in rice. In the present study, we characterized a rice gene, ABNORMAL FLOWER AND DWARF1 (AFD1) that determined plant height, floral development and grain yield. The afd1 mutant showed variable defects including the dwarfism, long panicle, low seed setting and reduced grain yield. In addition, abnormal floral organs were also observed in the afd1 mutant including slender and thick hulls, and hull-like lodicules. AFD1 encoded a DUF640 domain protein and was expressed in all tested tissues and organs. Subcellular localization showed AFD1-green fluorescent fusion protein (GFP) was localized in the nucleus. Meantime, our results suggested that AFD1 regulated the expression of cell division and expansion related genes.

Abstract (Browse 883)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
AFD1 encoded a DUF640 domain protein and loss of its function resulted in the dwarfism, small grains, and abnormal hulls. This work aim to facilitate the understanding of the molecular mechanism of vegetative and reproductive development mediated by AFD1, and provide insight into the functions of AFD1 gene on improving grain yield.
          Molecular Ecology and Evolution
Nonfunctional alleles of long-day suppressor genes independently regulate flowering time  
Author: Xiao-Ming Zheng, Li Feng, Junrui Wang, Weihua Qiao, Lifang Zhang, Yunlian Cheng and Qingwen Yang
Journal of Integrative Plant Biology 2016 58(6): 540每548
Published Online: July 29, 2015
DOI: 10.1111/jipb.12383
      
    

Due to the remarkable adaptability to various environments, rice varieties with diverse flowering times have been domesticated or improved from Oryza rufipogon. Detailed knowledge of the genetic factors controlling flowering time will facilitate understanding the adaptation mechanism in cultivated rice and enable breeders to design appropriate genotypes for distinct preferences. In this study, four genes (Hd1, DTH8, Ghd7 and OsPRR37) in a rice long-day suppression pathway were collected and sequenced in 154, 74, 69 and 62 varieties of cultivated rice (Oryza sativa) respectively. Under long-day conditions, varieties with nonfunctional alleles flowered significantly earlier than those with functional alleles. However, the four genes have different genetic effects in the regulation of flowering time: Hd1 and OsPRR37 are major genes that generally regulate rice flowering time for all varieties, while DTH8 and Ghd7 only regulate regional rice varieties. Geographic analysis and network studies suggested that the nonfunctional alleles of these suppression loci with regional adaptability were derived recently and independently. Alleles with regional adaptability should be taken into consideration for genetic improvement. The rich genetic variations in these four genes, which adapt rice to different environments, provide the flexibility needed for breeding rice varieties with diverse flowering times.

Abstract (Browse 940)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Due to the adaptability to environments, rice varieties with diverse flowering times have been domesticated. Among hundreds of varieties, we found that varieties with nonfunctional alleles flowered significantly earlier than those with functional alleles under long-day conditions. Meanwhile, phylogeographic analysis studies suggested that the nonfunctional alleles were derived recently and independently.
Evolution and protein interactions of AP2 proteins in Brassicaceae: Evidence linking development and environmental responses  
Author: Liping Zeng, Yue Yin, Chenjiang You, Qianli Pan, Duo Xu, Taijie Jin, Bailong Zhang and Hong Ma
Journal of Integrative Plant Biology 2016 58(6): 549每563
Published Online: October 16, 2015
DOI: 10.1111/jipb.12439
      
    

Plants have evolved a large number of transcription factors (TF), which are enriched among duplicate genes, highlighting their roles in complex regulatory networks. The APETALA2/EREBP-like genes constitute a large plant TF family and participate in development and stress responses. To probe the conservation and divergence of AP2/EREBP genes, we analyzed the duplication patterns of this family in Brassicaceae and identified interacting proteins of representative Arabidopsis AP2/EREBP proteins. We found that many AP2/EREBP duplicates generated early in Brassicaceae history were quickly lost, but many others were retained in all tested Brassicaceae species, suggesting early functional divergence followed by persistent conservation. In addition, the sequences of the AP2 domain and exon numbers were highly conserved in rosids. Furthermore, we used 16 A. thaliana AP2/EREBP proteins as baits in yeast screens and identified 1,970 potential AP2/EREBP-interacting proteins, with a small subset of interactions verified in planta. Many AP2 genes also exhibit reduced expression in an anther-defective mutant, providing a possible link to developmental regulation. The putative AP2-interacting proteins participate in many functions in development and stress responses, including photomorphogenesis, flower development, pathogenesis, drought and cold responses, abscisic acid and auxin signaling. Our results present the AP2/EREBP evolution patterns in Brassicaceae, and support a proposed interaction network of AP2/EREBP proteins and their putative interacting proteins for further study.

Abstract (Browse 1001)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
AP2 genes are important for plant development and environmental responses, and their copy numbers have been increased and then reduced during evolution. The complex protein interaction pattern uncovered here suggests numerous cross-talks between developmental regulators and those mediating environmental processes.
Jasmonic acid carboxyl methyltransferase regulates development and herbivory-induced defense response in rice  
Author: Jinfeng Qi, Jiancai Li, Xiu Han, Ran Li, Jianqiang Wu, Haixin Yu, Lingfei Hu, Yutao Xiao, Jing Lu and Yonggen Lou
Journal of Integrative Plant Biology 2016 58(6): 564每576
Published Online: October 15, 2015
DOI: 10.1111/jipb.12436
      
    

Jasmonic acid (JA) and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase (JMT) may be involved in plant defense and development by methylating JA to methyl jasmonate (MeJA) and thus influencing the concentrations of JA and related metabolites. However, no JMT gene has been well characterized in monocotyledon defense and development at the molecular level. After we cloned a rice JMT gene, OsJMT1, whose encoding protein was localized in the cytosol, we found that the recombinant OsJMT1 protein catalyzed JA to MeJA. OsJMT1 is up-regulated in response to infestation with the brown planthopper (BPH; Nilaparvata lugens). Plants in which OsJMT1 had been overexpressed (oe-JMT plants) showed reduced height and yield. These oe-JMT plants also exhibited increased MeJA levels but reduced levels of herbivore-induced JA and jasmonoyl-isoleucine (JA-Ile). The oe-JMT plants were more attractive to BPH female adults but showed increased resistance to BPH nymphs, probably owing to the different responses of BPH female adults and nymphs to the changes in levels of H2O2 and MeJA in oe-JMT plants. These results indicate that OsJMT1, by altering levels of JA and related metabolites, plays a role in regulating plant development and herbivore-induced defense responses in rice.

Abstract (Browse 1114)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Jasmonic acid (JA) and related metabolites play key roles in plant defense and growth. Our study shows that a JA carboxyl methyltransferase, by methylating JA to methyl jasmonate, alters levels of JA and related metabolites and thereby regulates plant development as well as herbivore-induced defense responses in rice.
          Molecular Physiology
Genome-scale analysis of the cotton KCS gene family revealed a binary mode of action for gibberellin A regulated fiber growth  
Author: Guang-Hui Xiao, Kun Wang, Gai Huang and Yu-Xian Zhu
Journal of Integrative Plant Biology 2016 58(6): 577每589
Published Online: September 24, 2015
DOI: 10.1111/jipb.12429
      
    

Production of β-ketoacyl-CoA, which is catalyzed by 3-ketoacyl-CoA synthase (KCS), is the first step in very long chain fatty acid (VLCFA) biosynthesis. Here we identified 58 KCS genes from Gossypium hirsutum, 31 from G. arboreum and 33 from G. raimondii by searching the assembled cotton genomes. The gene family was divided into the plant-specific FAE1-type and the more general ELO-type. KCS transcripts were widely expressed and 32 of them showed distinct subgenome-specific expressions in one or more cotton tissues/organs studied. Six GhKCS genes rescued the lethality of elo2Δelo3Δ yeast double mutant, indicating that this gene family possesses diversified functions. Most KCS genes with GA-responsive elements (GAREs) in the promoters were significantly upregulated by gibberellin A3 (GA). Exogenous GA3 not only promoted fiber length, but also increased the thickness of cell walls significantly. GAREs present also in the promoters of several cellulose synthase (CesA) genes required for cell wall biosynthesis and they were all induced significantly by GA3. Because GA treatment resulted in longer cotton fibers with thicker cell walls and higher dry weight per unit cell length, we suggest that it may regulate fiber elongation upstream of the VLCFA-ethylene pathway and also in the downstream steps towards cell wall synthesis.

Abstract (Browse 746)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
We produced a binary mode of GA action in regulating fiber growth. GAs may act upstream of the VLCFA-ethylene pathway via activation of a large set of GhKCS genes and function concomitantly in downstream steps that result in cellulose biosynthesis by promoting CesA expressions.
A putative 6-transmembrane nitrate transporter OsNRT1.1b plays a key role in rice under low nitrogen  
Author: Xiaorong Fan, Huimin Feng, Yawen Tan, Yanling Xu, Qisong Miao and Guohua Xu
Journal of Integrative Plant Biology 2016 58(6): 590每599
Published Online: July 29, 2015
DOI: 10.1111/jipb.12382
      
    

OsNRT1.1a is a low-affinity nitrate (NO3) transporter gene. In this study, another mRNA splicing product, OsNRT1.1b, putatively encoding a protein with six transmembrane domains, was identified based on the rice genomic database and bioinformatics analysis. OsNRT1.1a/OsNRT1.1b expression in Xenopus oocytes showed OsNRT1.1a-expressing oocytes accumulated 15N levels to about half as compared to OsNRT1.1b-expressing oocytes. The electrophysiological recording of OsNRT1.1b-expressing oocytes treated with 0.25 mM NO3 confirmed 15N accumulation data. More functional assays were performed to examine the function of OsNRT1.1b in rice. The expression of both OsNRT1.1a and OsNRT1.1b was abundant in roots and downregulated by nitrogen (N) deficiency. The shoot biomass of transgenic rice plants with OsNRT1.1a or OsNRT1.1b overexpression increased under various N supplies under hydroponic conditions compared to wild-type (WT). The OsNRT1.1a overexpression lines showed increased plant N accumulation compared to the WT in 1.25 mM NH4NO3 and 2.5 mM NO3 or NH4+ treatments, but not in 0.125 mM NH4NO3. However, OsNRT1.1b overexpression lines increased total N accumulation in all N treatments, including 0.125 mM NH4NO3, suggesting that under low N condition, OsNRT1.1b would accumulate more N in plants and improve rice growth, but also that OsNRT1.1a had no such function in rice plants.

Abstract (Browse 974)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
A full size nitrate transporter usually has 12 transmembrane helixes. In here, we presented that a half size nitrate transporter, one splicing product of OsNRT1.1 gene, can also function well in nitrate transport and even behavior better than its full size product under nitrogen deficiency in rice.
A gain-of-function mutation in Msl10 triggers cell death and wound-induced hyperaccumulation of jasmonic acid in Arabidopsis
Author: Yan Zou, Satya Chintamanani, Ping He, Hirotada Fukushige, Liping Yu, Meiyu Shao, Lihuang Zhu, David F. Hildebrand, Xiaoyan Tang and Jian-Min Zhou
Journal of Integrative Plant Biology 2016 58(6): 600每609
Published Online: September 10, 2015
DOI: 10.1111/jipb.12427
      
    

Jasmonates (JAs) are rapidly induced after wounding and act as key regulators for wound induced signaling pathway. However, what perceives the wound signal and how that triggers JA biosynthesis remains poorly understood. To identify components involved in Arabidopsis wound and JA signaling pathway, we screened for mutants with abnormal expression of a luciferase reporter, which is under the control of a wound-responsive promoter of an ethylene response factor (ERF) transcription factor gene, RAP2.6 (Related to APetala 2.6). The rea1 (RAP2.6 expresser in shoot apex) mutant constitutively expressed the RAP2.6-LUC reporter gene in young leaves. Along with the typical JA phenotypes including shorter petioles, loss of apical dominance, accumulation of anthocyanin pigments and constitutive expression of JA response gene, rea1 plants also displayed cell death and accumulated high levels of JA in response to wounding. The phenotype of rea1 mutant is caused by a gain-of-function mutation in the C-terminus of a mechanosensitive ion channel MscS-like 10 (MSL10). MSL10 is localized in the plasma membrane and is expressed predominantly in root tip, shoot apex and vascular tissues. These results suggest that MSL10 is involved in the wound-triggered early signal transduction pathway and possibly in regulating the positive feedback synthesis of JA.

Abstract (Browse 743)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Wounding response involves perception, transduction of wound signals and activation of wound-responsive genes. We identified a gain-of-function mutation in a mechanosensitive ion channel which is involved in the wound-triggered early signal transduction pathway and possibly in regulating the positive feedback synthesis of JA.
 

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