Latest Accepted Articles

  Letters to the Editor
The circadian clock contributes to diurnal patterns of plant indirect defense in nature
Author: Youngsung Joo, Jay K. Goldberg, Lucille Chretien, Sang-Gyu Kim, Ian T. Baldwin, Meredith C. Schuman
Received: July 1, 2018         Accepted: September 21, 2018
Online Date: September 25, 2018
DOI: 10.1111/jipb.12725
                     
      
    

The plant circadian clock regulates the rhythms of plant metabolism. Many herbivore©\induced plant volatiles (HIPVs) fluctuate, diurnally, but the role of the circadian clock in the emission of HIPVs and their ecological consequences remains largely unknown. Here, we show that the timing of herbivore attack can alter the outcome of tri©\trophic interactions, and this is mediated by the circadian clock, under both field and glasshouse conditions. Although most HIPV emissions did not have a circadian rhythm, the circadian clock modulated HIPV emissions in a time©\dependent manner. HIPVs mediate tri©\trophic interactions, and the circadian clock may affect these interactions by modulating HIPV emission in nature.

Abstract (Browse 18)   |   Full Text
Towards a better recording of microtubule cytoskeletal spatial organization and dynamics in plant cells
Author: Weiwei Liu Chaofeng Wang, Guangda Wang, Yinping Ma, Juan Tian, Yanjun Yu, Li Dong, and Zhaosheng Kong
Received: July 23, 2018         Accepted: September 7, 2018
Online Date: September 18, 2018
DOI: 10.1111/jipb.12721
                     
      
    

Numerous fluorescent marker lines are currently available to visualize microtubule (MT) architecture and dynamics in living plant cells, such as markers expressing p35S::GFP©\MBD or p35S::GFP©\TUB6. However, these MT marker lines display obvious defects that affect plant growth or produce unstable fluorescent signals. Here, a series of new marker lines were developed, including the pTUB6::VisGreen©\TUB6©\expressing line in which TUB6 is under the control of its endogenous regulatory elements and eGFP is replaced with VisGreen, a brighter fluorescent protein. Moreover, two different markers were combined into one expression vector and developed two dual©\marker lines. These marker lines produce bright, stable fluorescent signals in various tissues, and greatly shorten the screening process for generating dual©\marker lines. These new marker lines provide a novel resource for MT research.

Abstract (Browse 20)   |   Full Text
  Special Issue on Plant Synthetic Biology
Optimizing photorespiration for improved crop productivity
Author: Paul F. South, Amanda P. Cavanagh, Patricia E. Lopez-Calcagno, Christine A. Raines and Donald R. Ort
Received: August 3, 2018         Accepted: August 14, 2018
Online Date: August 20, 2018
DOI: 10.1111/jipb.12709
                     
      
    

In C3 plants, photorespiration is an energy©\expensive process, including the oxygenation of ribulose©\1,5©\bisphosphate (RuBP) by ribulose 1,5©\bisphosphate carboxylase/oxygenase (Rubisco) and the ensuing multi©\organellar photorespiratory pathway required to recycle the toxic byproducts and recapture a portion of the fixed carbon. Photorespiration significantly impacts crop productivity through reducing yields in C3 crops by as much as 50% under severe conditions. Thus, reducing the flux through, or improving the efficiency of photorespiration has the potential of large improvements in C3 crop productivity. Here, we review an array of approaches intended to engineer photorespiration in a range of plant systems with the goal of increasing crop productivity. Approaches include optimizing flux through the native photorespiratory pathway, installing non©\native alternative photorespiratory pathways, and lowering or even eliminating Rubisco©\catalyzed oxygenation of RuBP to reduce substrate entrance into the photorespiratory cycle. Some proposed designs have been successful at the proof of concept level. A plant systems©\engineering approach, based on new opportunities available from synthetic biology to implement in silico designs, holds promise for further progress toward delivering more productive crops to farmer's fields.

Abstract (Browse 33)   |   Full Text
Biotechnological approaches in glucosinolate production
Author: Annette Petersen, Cuiwei Wang, Christoph Crocoll and Barbara Ann Halkier
Received: May 5, 2018         Accepted: July 31, 2018
Online Date: August 6, 2018
DOI: 10.1111/jipb.12705
                     
      
    

Glucosinolates (GLSs) are sulfur©\rich, amino acid©\derived defense compounds characteristic of the Brassicales order. In the past, GLSs were mostly known as anti©\nutritional factors in fodder, biopesticides in agriculture, and flavors in condiments such as mustard. However, in recent times, GLSs have received increased attention as promoters of human health. This has spurred intensive research towards generating rich sources of health©\promoting GLSs. We provide a comprehensive overview of the biotechnological approaches applied to reach this goal. This includes optimization of GLS production and composition in native, GLS©\producing plants, including hairy root and cell cultures thereof, as well as synthetic biology approaches in heterologous hosts, such as tobacco and the microbial organisms Escherichia coli and Saccharomyces cerevisiae. The progress using these different approaches is discussed.

Abstract (Browse 68)   |   Full Text
  Special Issue on Seed Biology
Genome©\wide identification of loci affecting seed glucosinolate contents in Brassica napus L
Author: Dayong Wei, Yixin Cui, Jiaqin Mei, Lunwen Qian, Kun Lu, ZhiMin Wang, Jiana Li, Qinglin Tang, Wei Qian
Received: April 9, 2018         Accepted: August 29, 2018
Online Date: September 5, 2018
DOI: 10.1111/jipb.12717
                     
      
    

Glucosinolates are amino acid©\derived secondary metabolites that act as chemical defense agents against pests. However, the presence of high levels of glucosinolates severely diminishes the nutritional value of seed meals made from rapeseed (Brassica napus L.). To identify the loci affecting seed glucosinolate content (SGC), we conducted genome©\wide resequencing in a population of 307 diverse B. napus accessions from the three B. napus ecotype groups, namely, spring, winter, and semi©\winter. These resequencing data were used for a genome©\wide association study (GWAS) to identify the loci affecting SGC. In the three ecotype groups, four common and four ecotype©\specific haplotype blocks (HBs) were significantly associated with SGC. To identify candidate genes controlling SGC, transcriptome analysis was carried out in 36 accessions showing extreme SGC values. Analyses of haplotypes, genomic variation, and candidate gene expression pointed to five and three candidate genes in the common and spring group©\specific HBs, respectively. Our expression analyses demonstrated that additive effects of the three candidate genes in the spring group©\specific HB play important roles in the SGC of B. napus.

Abstract (Browse 23)   |   Full Text
  Special Issue on Barley and Wheat Biology
TaZIM©\A1 negatively regulates flowering time in common wheat (Triticum aestivum L.)
Author: Hong Liu, Tian Li, Yamei Wang, Jun Zheng, Huifang Li, Chenyang Hao and Xueyong Zhang
Received: August 1, 2018         Accepted: September 11, 2018
Online Date: September 18, 2018
DOI: 10.1111/jipb.12720
                     
      
    

Flowering time is a critical determinant of regional adaptation for crops and has strong effects on crop yields. Here, we report that TaZIM©\A1, an atypical GATA©\like transcription factor, is a negative regulator of flowering in wheat. TaZIM©\A1 possessed weak transcriptional repression activity, with its CCT domain functioning as the major inhibitory region. TaZIM©\A1 expression exhibited a typical circadian oscillation pattern under various light regimes. Overexpression of TaZIM©\A1 caused a delay in flowering time and a decrease in thousand©\kernel weight (TKW) in wheat under long©\day conditions. Moreover, TaZIM©\A1 directly bound to the promoters of TaCO©\1 and TaFT©\1 and downregulated their expression. Sequence analysis of a collection of common wheat cultivars identified three and two haplotypes for TaZIM©\A1 and TaZIM©\B1, respectively. Association analysis revealed that TaZIM©\A1©\HapI/©\HapIII and TaZIM©\B1©\HapI have undergone strong positive selection during modern wheat breeding, likely due to their association with earlier heading and higher TKW. Diagnostic markers were developed for these haplotypes that can be used for wheat cultivar improvement, via marker©\assisted breeding.

Abstract (Browse 16)   |   Full Text
  Molecular Physiology
A member of the ALOG gene family has a novel role in regulating nodulation in Lotus japonicus
Author: Yawen Lei, Shihao Su, Liang He, Xiaohe Hu, Da Luo
Received: May 30, 2018         Accepted: August 19, 2018
Online Date: August 21, 2018
DOI: 10.1111/jipb.12711
                     
      
    

Legumes can control the number of symbiotic nodules that form on their roots, thus balancing nitrogen assimilation and energy consumption. Two major pathways participate in nodulation: the Nod factor (NF) signaling pathway which involves recognition of rhizobial bacteria by root cells and promotion of nodulation, and the autoregulation of nodulation (AON) pathway which involves long©\distance negative feedback between roots and shoots. Although a handful of genes have a clear role in the maintenance of nodule number, additional unknown factors may also be involved in this process. Here, we identify a novel function for a Lotus japonicus ALOG (Arabidopsis LSH1 and Oryza G1) family member, LjALOG1, involved in positively regulating nodulation. LjALOG1 expression increased substantially after inoculation with rhizobia, with high levels of expression in whole nodule primordia and in the base of developing nodules. The ljalog1 mutants, which have an insertion of the LORE1 retroelement in LjALOG1, had significantly fewer nodules compared with wild type, along with increased expression of LjCLE©\RS1 (L. japonicus CLE Root Signal 1), which encodes a nodulation suppressor in the AON pathway. In summary, our findings identified a novel factor that participates in controlling nodulation, possibly by suppressing the AON pathway.

Abstract (Browse 32)   |   Full Text
Trehalose phosphate synthase 5©\dependent trehalose metabolism modulates basal defense responses in Arabidopsis thaliana
Author: Xuelan Wang,Yan Du and Diqiu Yu
Received: March 15, 2018         Accepted: July 21, 2018
Online Date: July 30, 2018
DOI: 10.1111/jipb.12704
                     
      
    

Despite the recent discovery that trehalose synthesis is important for plant development and abiotic stress tolerance, the effects of trehalose on biotic stress responses remain relatively unknown. In this study, we demonstrate that TREHALOSE PHOSPHATE SYNTHASE 5 (TPS5)©\dependent trehalose metabolism regulates Arabidopsis thaliana defenses against pathogens (necrotrophic Botrytis cinerea and biotrophic Pseudomonas syringae). Pathogen infection increased trehalose levels and up©\regulated TPS5 expression. The application of exogenous trehalose significantly improved plant defenses against B. cinerea, but increased the susceptibility of plants to P. syringae. We demonstrated that elevated trehalose biosynthesis, in transgenic plants over©\expressing TPS5, also increased the susceptibility to P. syringae, but decreased the disease symptoms caused by B. cinerea. The knockout of TPS5 prevented the accumulation of trehalose and enhanced defense responses against P. syringae. Additionally, we observed that a TPS5©\interacting protein (multiprotein bridging factor 1c) was required for induced expression of TPS5 during pathogen infections. Furthermore, we show that trehalose promotes P. syringae growth and disease development, via a mechanism involving suppression of the plant defense gene, Pathogenesis©\Related Protein 1. These findings provide insight into the function of TPS5©\dependent trehalose metabolism in plant basal defense responses.

Abstract (Browse 75)   |   Full Text
  Cell and Developmental Biology
Rice miR394 suppresses leaf inclination through targeting an F©\box gene, LEAF INCLINATION 4
Author: Li Qu, Li-Bi Lin and Hong-Wei Xue
Received: May 27, 2018         Accepted: August 24, 2018
Online Date: August 25, 2018
DOI: 10.1111/jipb.12713
                     
      
    

Rice leaf inclination is an important agronomic trait, closely related to plant architecture and yield. Identification of genes controlling leaf inclination would assist in crop improvement. Although various factors, including the plant hormones auxin and brassinosteroids, have been shown to regulate lamina joint development, the role of microRNAs in regulating leaf inclination remains largely unknown. Here, we functionally characterize the role of rice miR394 and its target, LEAF INCLINCATION 4 (LC4), which encodes an F©\box protein, in the regulation of leaf inclination. We show that miR394 and LC4 work, antagonistically, to regulate leaf lamina joint development and rice architecture, by modulating expansion and elongation of adaxial parenchyma cells. Suppressed expression of miR394, or enhanced expression of LC4, results in enlarged leaf angles, whereas reducing LC4 expression by CRISPR/Cas9 leads to reduced leaf inclination, suggesting LC4 as candidate for use in rice architecture improvement. LC4 interacts with SKP1, a component of the SCF E3 ubiquitin ligase complex, and transcription of both miR394 and LC4 are regulated by auxin. Rice plants with altered expression of miR394 or LC4 have altered auxin responses, indicating that the miR394©\LC4 module mediates auxin effects important for determining rice leaf inclination and architecture.

Abstract (Browse 41)   |   Full Text
  Molecular Ecology and Evolution
Streptomyces lydicus A01 affects soil microbial diversity, improving growth and resilience in tomato
Author: Qiong Wu, Caige Lu, Mi Ni, Hongli Wang, Weicheng Liu, and Jie Chen
Received: May 29, 2018         Accepted: September 18, 2018
Online Date: September 25, 2018
DOI: 10.1111/jipb.12724
                     
      
    

The actinomycete Streptomyces lydicus A01 promotes tomato seedling growth; however, the underlying mechanism is unclear. In this study, we investigated whether changes in soil microbial diversity, following Streptomyces lydicus A01 treatment, were responsible for the increased tomato seedling growth. Eukaryotic 18S ribosomal DNA (rDNA) sequencing showed that S. lydicus A01©\treated and untreated soil shared 193 operational taxonomic units (OTUs), whereas bacterial 16S rDNA sequencing identified 1,219 shared OTUs between the treated and untreated soil. Of the 42 dominant eukaryotic OTUs, 8 were significantly increased and 6 were significantly decreased after A01 treatment. Of the 25 dominant bacterial OTUs, 12 were significantly increased and 8 were significantly decreased after A01 treatment. Most of the eukaryotes and bacteria that increased in abundance exhibited growth promoting characteristics, which were mainly predicted to be associated with mineralization of nitrogen and phosphorus, phosphate solubilization, nutrient accumulation, and secretion of auxin, whereas some were related to plant protection, such as the degradation of toxic and hazardous substances. Soil composition tests showed that S. lydicus A01 treatment enhanced the utilization of nitrogen, phosphorus, and potassium in tomato seedlings. Thus, microbial fertilizers based on S. lydicus A01 may improve plant growth, without the detriment effects of chemical fertilizers.

Abstract (Browse 11)   |   Full Text
Incomplete reproductive isolation between Rhododendron taxa enables hybrid formation and persistence
Author: Li-Jun Yan, Kevin S. Burgess, Wei Zheng, Zhi-Bin Tao, De-Zhu Li, and Lian-Ming Gao
Received: August 18, 2018         Accepted: September 6, 2018
Online Date: September 7, 2018
DOI: 10.1111/jipb.12718
                     
      
    

The evolutionary consequences of hybridization ultimately depend on the magnitude of reproductive isolation between hybrids and their parents. We evaluated the relative contributions of pre©\ and post©\zygotic barriers to reproduction for hybrid formation, hybrid persistence and potential for reproductive isolation of hybrids formed between two Rhododendron species, R. spiciferum and R. spinuliferum. Our study established that incomplete reproductive isolation promotes hybrid formation and persistence and delays hybrid speciation. All pre©\zygotic barriers to reproduction leading to hybrid formation are incomplete: parental species have overlapping flowering; they share the same pollinators; reciprocal assessments of pollen tube germination and growth do not differ among parents. The absence of post©\zygotic barriers between parental taxa indicates that the persistence of hybrids is likely. Reproductive isolation was incomplete between hybrids and parents in all cases studied, although asymmetric differences in reproductive fitness were prevalent and possibly explain the genetic structure of natural hybrid swarms where hybridization is known to be bidirectional but asymmetric. Introgression, rather than speciation, is a probable evolutionary outcome of hybridization between the two Rhododendron taxa. Our study provides insights into understanding the evolutionary implications of natural hybridization in woody plants.

Abstract (Browse 13)   |   Full Text
Environmental drivers and genomic architecture of trait differentiation in fire©\adapted Banksia attenuata ecotypes
Author: Tianhua He, Byron B. Lamont, Neal J. Enright, Haylee M. D¡¯Agui, William Stock
Received: February 9, 2018         Accepted: July 10, 2018
Online Date: July 11, 2018
DOI: 10.1111/jipb.12697
                     
      
    

Trait divergence between populations is considered an adaptive response to different environments, but to what extent this response is accompanied by genetic differentiation is less clear since it may be phenotypic plasticity. In this study, we analysed phenotypic variation between two Banksia attenuata growth forms, lignotuberous (shrub) and epicormic resprouting (tree), in fire©\prone environments to identify the environmental factors that have driven this phenotypic divergence. We linked genotype with phenotype and traced candidate genes using differential gene expression analysis. Fire intervals determined the phenotypic divergence between growth forms in B. attenuata. Genome©\wide association study identified 69 single nucleotide polymorphisms, putatively associated with growth form, whereas no growth form©\ or phenotype©\specific genotypes were identified. Genomic differentiation between the two growth forms was low (Fst = 0.024). Differential gene expression analysis identified 37 genes/transcripts that were differentially expressed in the two growth forms. A small heat©\shock protein gene, associated with lignotuber presence, was differentially expressed in the two forms. We conclude that different fire regimes induce phenotypic polymorphism in B. attenuata, whereas phenotypic trait divergence involves the differential expression of a small fraction of genes that interact strongly with the disturbance regime. Thus, phenotypic plasticity among resprouters is the general strategy for surviving varying fire regimes.

Abstract (Browse 96)   |   Full Text
  New Resources
New lncRNA annotation reveals extensive functional divergence of the transcriptome in maize
Author: Linqian Han, Zhenna Mu, Zi Luo, Qingchun Pan and Lin Li
Received: July 5, 2018         Accepted: August 6, 2018
Online Date: August 16, 2018
DOI: 10.1111/jipb.12708
                     
      
    

Long non©\coding RNAs (lncRNAs), whose sequences are ∼200 bp or longer and unlikely to encode proteins, may play an important role in eukaryotic gene regulation. Although the latest maize (Zea Mays L.) reference genome provides an essential genomic resource, genome©\wide annotations of maize lncRNAs have not been updated (Jiao et al. 2017). Here, we report on a large transcriptomic dataset collected from 749 RNA sequencing experiments across different tissues and stages of the maize reference inbred B73 line and 60 from its wild relative teosinte. We identified 18,165 high©\confidence lncRNAs in maize, of which 6,873 are conserved between maize and teosinte. We uncovered distinct genomic characteristics of conserved lncRNAs, non©\conserved lncRNAs, and protein©\coding transcripts. Intriguingly, Shannon entropy analysis showed that conserved lncRNAs are likely to be expressed similarly to protein©\coding transcripts. Co©\expression network analysis revealed significant variation in the degree of co©\expression. Furthermore, selection analysis indicated that conserved lncRNAs are more likely than non©\conserved lncRNAs to be located in regions subject to recent selection, indicating evolutionary differentiation. Our results provide the latest genome©\wide annotation and analysis of maize lncRNAs and uncover potential functional divergence between protein©\coding, conserved lncRNA, and non©\conserved lncRNA genes, demonstrating the high complexity of the maize transcriptome.

Abstract (Browse 60)   |   Full Text
  Plant-abiotic Interactions
Rhizosheath formation and involvement in foxtail millet (Setaria italica) root growth under drought stress
Author: Tie-Yuan Liu, Nenghui Ye, Tao Song, Yunying Cao, Bei Gao, Di Zhang, Fuyuan Zhu, Moxian Chen, Yingjiao Zhang, Weifeng Xu and Jianhua Zhang
Received: June 22, 2018         Accepted: September 3, 2018
Online Date: September 5, 2018
DOI: 10.1111/jipb.12716
                     
      
    

The rhizosheath, a layer of soil particles that adheres firmly to the root surface by a combination of root hairs and mucilage, may improve tolerance to drought stress. Setaria italica (foxtail millet), a member of the Poaceae family, is an important food and fodder crop in arid regions and forms a larger rhizosheath under drought conditions. Rhizosheath formation under drought conditions has been studied, but the regulation of root hair growth and rhizosheath size in response to soil moisture remains unclear. To address this question, in this study we monitored root hair growth and rhizosheath development in response to a gradual decline in soil moisture. Here, we determined that a soil moisture level of 10% ©\ 14% (w/w) stimulated greater rhizosheath production compared to other soil moisture levels. Root hair density and length also increased at this soil moisture level, which was validated by measurement of the expression of root hair©\related genes. These findings contribute to our understanding of rhizosheath formation in response to soil water stress.

Abstract (Browse 16)   |   Full Text
Plant lncRNAs are enriched in and move systemically through the phloem in response to phosphate deficiency
Author: Zhaoliang Zhang, Yi Zheng, Byung-Kook Ham, Shupei Zhang, Zhangjun Fei and William J. Lucas
Received: May 16, 2018         Accepted: August 29, 2018
Online Date: September 1, 2018
DOI: 10.1111/jipb.12715
                     
      
    

In response to phosphate (Pi) deficiency, it has been shown that micro©\RNAs (miRNAs) and mRNAs are transported through the phloem for delivery to sink tissues. Growing evidence also indicates that long non©\coding RNAs (lncRNAs) are critical regulators of Pi homeostasis in plants. However, whether lncRNAs are present in and move through the phloem, in response to Pi deficiency, remains to be established. Here, using cucumber as a model plant, we show that lncRNAs are enriched in the phloem translocation stream and respond, systemically, to an imposed Pi©\stress. A well©\known lncRNA, IPS1, the target mimic (TM) of miRNA399, accumulates to a high level in the phloem, but is not responsive to early Pi deficiency. An additional 24 miRNA TMs were also detected in the phloem translocation stream; among them miRNA171 TMs and miR166 TMs were induced in response to an imposed Pi stress. Grafting studies identified 22 lncRNAs which move systemically into developing leaves and root tips. A CU©\rich PTB motif was further identified in these mobile lncRNAs. Our findings revealed that lncRNAs respond to Pi deficiency, non©\cell©\autonomously, and may act as systemic signaling agents to coordinate early Pi deficiency signaling, at the whole©\plant level.

Abstract (Browse 16)   |   Full Text
ZmOST1 mediates ABA regulation of guard cell ion channels and drought stress responses
Author: Qiqi Wu, Mei Wang, Jianlin Shen, Donghua Chen, Yu Zheng, Wei Zhang
Received: May 9, 2018         Accepted: August 26, 2018
Online Date: August 30, 2018
DOI: 10.1111/jipb.12714
                     
      
    

The phytohormone abscisic acid (ABA) is an important mediator in the drought response, participating in, among other processes, stomatal movements. In Arabidopsis thaliana, the serine/threonine protein kinase, OST1, regulates this response, but the function of its maize homolog has yet to be established. Here, we isolated ZmOST1 and show that its encoded protein indeed acts to regulate guard cell movement. ZmOST1 was ubiquitously expressed throughout the plant, being highly expressed in guard cells, and inducible both by exogenous ABA and water stress. Transient expression of a ZmOST1©\GFP fusion protein, in maize mesophyll protoplasts, indicated its subcellular localization in the cytoplasm and nucleus. A Zmost1 loss©\of©\function mutant exhibited reduced sensitivity to ABA©\activated slow anion channels in maize guard cells, and reduced drought tolerance. Constitutive expression of ZmOST1, in an A. thaliana ost1©\1 mutant rescued the phenotype with respect both to the sensitivity of guard cell slow anion currents to ABA treatment and stomatal closure. Our findings indicate a positive regulatory role for ZmOST1 in guard cell ABA signaling and drought response in maize plants.

Abstract (Browse 26)   |   Full Text
  Functional Omics and Systems Biology
Genomic divergence in cotton germplasm related to maturity and heterosis
Author: Shoupu He, Gaofei Sun, Longyu Huang, Daigang Yang, Panhong Dai, Dayun Zhou, Yuzhen Wu, Xiongfeng Ma, Xiongming Du, Shoujun Wei, Jun Peng and Meng Kuang
Received: August 3, 2018         Accepted: September 17, 2018
Online Date: September 25, 2018
DOI: 10.1111/jipb.12723
                     
      
    

Commercial varieties of upland cotton (Gossypium hirsutum) have undergone extensive breeding for agronomic traits, such as fiber quality, disease resistance, and yield. Cotton breeding programs have widely used Chinese upland cotton source germplasm (CUCSG) with excellent agronomic traits. A better understanding of the genetic diversity and genomic characteristics of these accessions could accelerate the identification of desirable alleles. Here, we analyzed 10,522 high©\quality single©\nucleotide polymorphisms (SNP) with the CottonSNP63K microarray in 137 cotton accessions (including 12 hybrids of upland cotton). These data were used to investigate the genetic diversity, population structure, and genomic characteristics of each population and the contribution of these loci to heterosis. Three subgroups were identified, in agreement with their known pedigrees, geographical distributions, and times since introduction. For each group, we identified lineage©\specific genomic divergence regions, which potentially harbor key alleles that determine the characteristics of each group, such as early maturity©\related loci. Investigation of the distribution of heterozygous loci, among 12 commercial cotton hybrids, revealed a potential role for these regions in heterosis. Our study provides insight into the population structure of upland cotton germplasm. Furthermore, the overlap between lineage©\specific regions and heterozygous loci, in the high©\yield hybrids, suggests a role for these regions in cotton heterosis.

Abstract (Browse 67)   |   Full Text
  Plant Reproduction Biology
Brassinosteroids function in spikelet differentiation and degeneration in rice
Author: Weiyang Zhang, Kuanyu Zhu, Zhiqin Wang, Hao Zhang, Junfei Gu, Lijun Liu, Jianchang Yang and Jianhua Zhang
Received: July 2, 2018         Accepted: September 19, 2018
Online Date: September 24, 2018
DOI: 10.1111/jipb.12722
                     
      
    

Brassinosteroids (BRs) play crucial roles in many aspects of plant development. However, their function in spikelet differentiation and degeneration in rice (Oryza sativa L.) remains unclear. Here, we investigated the roles of these phytohormones in spikelet development in field©\grown rice subjected to five different nitrogen (N) fertilization treatments during panicle differentiation. BR levels and expression of genes involved in BR biosynthesis and signal transduction were measured in spikelets. Pollen fertility and the number of differentiated spikelets were closely associated with 24©\epicastasterone (24©\epiCS) and 28©\homobrassinolide (28©\homoBL) levels in spikelets. Enhanced BR biosynthesis and signal transduction, in response to N treatment, enhanced spikelet differentiation, reduced spikelet degeneration, and increased grain yield. Increases in proton©\pumping ATPase activity, ATP concentration, energy charge, and antioxidant system (AOS) levels were consistent with 24©\epiCS and 28©\homoBL concentrations. Exogenous application of 24©\epiCS or 28©\homoBL on young panicles induced a marked increase in endogenous 24©\epiCS or 28©\homoBL levels, energy charge, AOS levels, spikelet differentiation, and panicle weight. The opposite effects were observed following treatment with a BR biosynthesis inhibitor. Our findings indicate that, in rice, BRs mediate the effects of N fertilization on spikelet development and play a role in promoting spikelet development through increasing AOS levels and energy charge during panicle development.

Abstract (Browse 10)   |   Full Text

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