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October 2018, Volume 60 Issue 10, Pages 909-1015.

Cover Caption: NAB1 in tillering control
Tillering is an important agronomic trait in sorghum, contributing to grain yield and plant architecture. In this issue, Chen et al. (938¨C955) report that a mutation in NAB1 led to activation of axillary buds in sorghum, and NAB1 encodes a carotenoid©\cleavage dioxygenase, homologous to HTD1/D17 in rice and MAX3 in Arabidopsis.

 

          Invited Expert Review
Expanding roles for pectins in plant development
Author: Adam M. Saffer
Journal of Integrative Plant Biology 2018 60(10): 910-923
Published Online: May 4, 2018
DOI: 10.1111/jipb.12662
      
    

Pectins are complex cell wall polysaccharides important for many aspects of plant development. Recent studies have discovered extensive physical interactions between pectins and other cell wall components, implicating pectins in new molecular functions. Pectins are often localized in spatially©\restricted patterns, and some of these non©\uniform pectin distributions contribute to multiple aspects of plant development, including the morphogenesis of cells and organs. Furthermore, a growing number of mutants affecting cell wall composition have begun to reveal the distinct contributions of different pectins to plant development. This review discusses the interactions of pectins with other cell wall components, the functions of pectins in controlling cellular morphology, and how non©\uniform pectin composition can be an important determinant of developmental processes.

Abstract (Browse 144)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Pectins are a class of polysaccharides present in plant cell walls, and each of the different pectins has distinct functions. The specific localization of pectins is an important mechanism to influence plant development. This review discusses the roles of pectins and how they contribute to multiple aspects of development.
          Cell and Developmental Biology
Arabidopsis small ubiquitin©\related modifier protease ASP1 positively regulates abscisic acid signaling during early seedling development  
Author: Qiongli Wang, Gao-Ping Qu, Xiangxiong Kong, Yan Yan, Jigang Li and Jing Bo Jin
Journal of Integrative Plant Biology 2018 60(10): 924-937
Published Online: May 22, 2018
DOI: 10.1111/jipb.12669
      
    

The small ubiquitin©\related modifier (SUMO) modification plays an important role in the regulation of abscisic acid (ABA) signaling, but the function of the SUMO protease, in ABA signaling, remains largely unknown. Here, we show that the SUMO protease, ASP1 positively regulates ABA signaling. Mutations in ASP1 resulted in an ABA©\insensitive phenotype, during early seedling development. Wild©\type ASP1 successfully rescued, whereas an ASP1 mutant (C577S), defective in SUMO protease activity, failed to rescue, the ABA©\insensitive phenotype of asp1©\1. Expression of ABI5 and MYB30 target genes was attenuated in asp1©\1 and our genetic analyses revealed that ASP1 may function upstream of ABI5 and MYB30. Interestingly, ASP1 accumulated upon ABA treatment, and ABA©\induced accumulation of ABI5 (a positive regulator of ABA signaling) was abolished, whereas ABA©\induced accumulation of MYB30 (a negative regulator of ABA signaling) was increased in asp1©\1. These findings support the hypothesis that increased levels of ASP1, upon ABA treatment, tilt the balance between ABI5 and MYB30 towards ABI5©\mediated ABA signaling.

Abstract (Browse 156)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
SUMO E3 ligase©\mediated SUMO conjugation negatively regulates ABA signaling, but SUMO protease(s) regulating ABA signaling remains unknown. This paper established that the SUMO protease ASP1©\mediated deSUMOylation positively regulates ABA signaling during early seedling development by positively and negatively regulating ABA©\induced accumulation of ABI5 and MYB30 respectively.
Non©\dormant Axillary Bud 1 regulates axillary bud outgrowth in sorghum  
Author: Jun Chen, Limin Zhang, Mengjiao Zhu, Lijie Han, Ya Lv, Yishan Liu, Pan Li, Haichun Jing and Hongwei Cai
Journal of Integrative Plant Biology 2018 60(10): 938-955
Published Online: May 9, 2018
DOI: 10.1111/jipb.12665
      
    

Tillering contributes to grain yield and plant architecture and therefore is an agronomically important trait in sorghum (Sorghum bicolor). Here, we identified and functionally characterized a mutant of the Non©\dormant Axillary Bud 1 (NAB1) gene from an ethyl methanesulfonate©\mutagenized sorghum population. The nab1 mutants have increased tillering and reduced plant height. Map©\based cloning revealed that NAB1 encodes a carotenoid©\cleavage dioxygenase 7 (CCD7) orthologous to rice (Oryza sativa) HIGH©\TILLERING DWARF1/DWARF17 and Arabidopsis thaliana MORE AXILLARY BRANCHING 3. NAB1 is primarily expressed in axillary nodes and tiller bases and NAB1 localizes to chloroplasts. The nab1 mutation causes outgrowth of basal axillary buds; removing these non©\dormant basal axillary buds restored the wild©\type phenotype. The tillering of nab1 plants was completely suppressed by exogenous application of the synthetic strigolactone analog GR24. Moreover, the nab1 plants had no detectable strigolactones and displayed stronger polar auxin transport than wild©\type plants. Finally, RNA©\seq showed that the expression of genes involved in multiple processes, including auxin©\related genes, was significantly altered in nab1. These results suggest that NAB1 functions in strigolactone biosynthesis and the regulation of shoot branching via an interaction with auxin transport.

Abstract (Browse 157)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
In sorghum, tillering contributes to grain yield and plant architecture, and therefore is an agronomically important trait. In this study, we cloned a Non©\dormant Axillary Bud 1 (NAB1) gene and demonstrated that NAB1 functions in strigolactone biosynthesis and regulation of tillering via an interaction with auxin transport.
          Functional Omics and Systems Biology
Arabidopsis VQ10 interacts with WRKY8 to modulate basal defense against Botrytis cinerea
Author: Junqiu Chen, Houping Wang, Yang Li, Jinjing Pan, Yanru Hu and Diqiu Yu
Journal of Integrative Plant Biology 2018 60(10): 956-969
Published Online: May 4, 2018
DOI: 10.1111/jipb.12664
      
    

Recent studies in Arabidopsis have revealed that some VQ motif©\containing proteins physically interact with WRKY transcription factors; however, their specific biological functions are still poorly understood. In this study, we confirmed the interaction between VQ10 and WRKY8, and show that VQ10 and WRKY8 formed a complex in the plant cell nucleus. Yeast two©\hybrid analysis showed that the middle region of WRKY8 and the VQ motif of VQ10 are critical for their interaction, and that this interaction promotes the DNA©\binding activity of WRKY8. Further investigation revealed that the VQ10 protein was exclusively localized in the nucleus, and VQ10 was predominantly expressed in siliques. VQ10 expression was strongly responsive to the necrotrophic fungal pathogen, Botrytis cinerea and defense©\related hormones. Phenotypic analysis showed that disruption of VQ10 increased mutant plants susceptibility to the fungal pathogen B. cinerea, whereas constitutive©\expression of VQ10 enhanced resistance to B. cinerea. Consistent with these findings, expression of the defense©\related PLANT DEFENSIN1.2 (PDF1.2) gene was decreased in vq10 mutant plants, after B. cinerea infection, but increased in VQ10©\overexpressing transgenic plants. Taken together, our findings provide evidence that VQ10 physically interacts with WRKY8 and positively regulates plant basal resistance against the necrotrophic fungal pathogen B. cinerea.

Abstract (Browse 155)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
VQ10 is a VQ motif©\containing protein, while WRKY8 is an important positive regulator of plant resistance against the necrotrophic fungal pathogen Botrytis cinerea. In this study, we demonstrated that VQ10 physically interacts with WRKY8 and activates its transcriptional activity, and the over©\expression of VQ10 enhances plant resistance to B. cinerea.
A genome©\wide association study of early©\maturation traits in upland cotton based on the CottonSNP80K array  
Author: Chengqi Li, Yuanyuan Wang, Nijiang Ai, Yue Li and Jiafeng Song
Journal of Integrative Plant Biology 2018 60(10): 970-985
Published Online: June 7, 2018
DOI: 10.1111/jipb.12673
      
    

Genome©\wide association studies (GWASs) efficiently identify genetic loci controlling traits at a relatively high resolution. In this study, variations in major early©\maturation traits, including seedling period (SP), bud period (BP), flower and boll period (FBP), and growth period (GP), of 169 upland cotton accessions were investigated, and a GWAS of early maturation was performed based on a CottonSNP80K array. A total of 49,650 high©\quality single©\nucleotide polymorphisms (SNPs) were screened, and 29 significant SNPs located on chromosomes A6, A7, A8, D1, D2, and D9, were repeatedly identified as associated with early©\maturation traits, in at least two environments or two algorithms. Of these 29 significant SNPs, 1, 12, 11, and 5 were related to SP, BP, FBP, and GP, respectively. Six peak SNPs, TM47967, TM13732, TM20937, TM28428, TM50283, and TM72552, exhibited phenotypic contributions of approximately 10%, which could allow them to be used for marker©\assisted selection. One of these, TM72552, as well as four other SNPs, TM72554, TM72555, TM72558, and TM72559, corresponded to the quantitative trait loci previously reported. In total, 274 candidate genes were identified from the genome sequences of upland cotton and were categorized based on their functional annotations. Finally, our studies identified Gh_D01G0340 and Gh_D01G0341 as potential candidate genes for improving cotton early maturity.

Abstract (Browse 137)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
29 SNPs associated with cotton early©\maturation traits were repeatedly detected in at least two environments or two algorithms by GWAS. Six peak SNPs, TM47967, TM13732, TM20937, TM28428, TM50283, and TM72552, exhibited phenotypic contributions of ∼10%. Two candidate genes, Gh_D01G0340 and Gh_D01G0341, may potentially improve cotton early maturity.
          Molecular Ecology and Evolution
Maintenance of species boundaries in three sympatric Ligularia (Senecioneae, Asteraceae) species
Author: Ningning Zhang, Yongpeng Ma, Ryan A. Folk, Jiaojun Yu, Yuezhi Pan and Xun Gong
Journal of Integrative Plant Biology 2018 60(10): 986-999
Published Online: June 7, 2018
DOI: 10.1111/jipb.12674
      
    

The key process in speciation concerns the formation and maintenance of reproductive isolating barriers between diverging lineages. Although species boundaries are frequently investigated between two species across many taxa, reproductive isolating barriers among multiple species (>2) that would represent the most common phenomenon in nature, remain to be clarified. Here, we use double digest restriction©\site associated DNA (ddRAD) sequencing to examine patterns of hybridization at a sympatric site where three Ligularia species grow together and verify whether those patterns contribute to the maintenance of boundaries among species. The results based on the RAD SNP datasets indicated hybridization Ligularia cyathiceps × L. duciformis and L. duciformis × L. yunnanensis were both restricted to F1s plus a few first©\generation backcrosses and no gene introgression were identified, giving rise to strong reproductive isolation among hybridizing species. Moreover, hybrid swarm simulation, using HYBRIDLAB, indicated the RAD SNP datasets had sufficient discriminatory power for accurate hybrid detection. We conclude that parental species show strong reproductive isolation and they still maintain species boundaries, which may be the key mechanism to maintain species diversity of Ligularia in the eastern Qinghai©\Tibetan Plateau and adjacent areas. Moreover, this study highlights the effectiveness of RAD sequencing in hybridization studies.

Abstract (Browse 123)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Although natural hybridization occurred in three sympatric Ligularia species, these species show strong reproductive isolation and they still maintain species boundaries, which may be the key mechanism to maintain species diversity of Ligularia in the eastern Qinghai©\Tibetan Plateau and adjacent areas.
          Molecular Physiology
Identification of novel cis©\elements bound by BplMYB46 involved in abiotic stress responses and secondary wall deposition  
Author: Huiyan Guo, Liuqiang Wang, Chuanping Yang, Yiming Zhang, Chunrui Zhang, Chao Wang
Journal of Integrative Plant Biology 2018 60(10): 1000-1014
Published Online: June 7, 2018
DOI: 10.1111/jipb.12671
      
    

Transcription factors (TFs) play vital roles in various biological processes by binding to cis©\acting elements to control expressions of their target genes. The MYB TF BplMYB46, from Betula platyphylla, is involved in abiotic stress responses and secondary wall deposition. In the present study, we used a TF©\centered yeast one©\hybrid technology (TF©\centered Y1H) to identify the cis©\acting elements bound by BplMYB46. We screened a short©\insert random library and identified three cis©\elements bound by BplMYB46: an E©\box (CA(A/T/C)(A/G/C)TG) and two novel motifs, a TC©\box (T(G/A)TCG(C/G)) and a GT©\box (A(G/T)T(A/C)GT(T/G)C). Chromatin immunoprecipitation (ChIP) and effector©\reporter coexpression assays in Nicotiana tabacum confirmed binding of BplMYB46 to the TC©\box, GT©\box, and E©\box motifs in the promoters of the phenylalanine ammonia lyase (PAL), peroxidase (POD), and superoxide dismutase (SOD) genes, which function in abiotic stress tolerance and secondary wall biosynthesis. This finding improves our understanding of potential regulatory mechanisms in the response to abiotic stress and secondary wall deposition of BplMYB46 in B. platyphylla.

Abstract (Browse 143)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
The novel cis©\elements bound by BplMYB46 were found by using a transcription factor©\centered yeast one©\hybrid technology. These binds were further proved by chromatin immunoprecipitation and effector©\reporter co©\expression assays. This finding revealed the potential regulatory mechanisms of BplMYB46 in B.platyphylla.
          Corrigendum
Corrigendum
Author:
Journal of Integrative Plant Biology 2018 60(10): 1015-1015
Published Online: October 5, 2018
DOI: 10.1111/jipb.12710
Abstract (Browse 4)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
 
 

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