Latest Accepted Articles

  Letters to the Editor
NaMYB8 regulates distinct, optimally distributed herbivore defense traits
Author: Martin Schäfer, Christoph Brütting, Shuqing Xu, Zhihao Ling, Anke Steppuhn, Ian T. Baldwin and Meredith C. Schuman
Received: May 18, 2017         Accepted: August 25, 2017
Online Date: August 26, 2017
DOI: 10.1111/jipb.12593
                     
      
    

When herbivores attack, plants specifically reconfigure their metabolism. Herbivory on the wild tobacco Nicotiana attenuata strongly induces the R2/R3 MYB transcriptional activator MYB8, which was reported to specifically regulate the accumulation of phenolamides (PAs). We discovered that transcriptional regulation of trypsin protease inhibitors (TPIs) and a threonine deaminase (TD) also depend on MYB8 expression. Induced distributions of PAs, TD and TPIs all meet predictions of optimal defense theory: their leaf concentrations increase with the fitness value and the probability of attack of the tissue. Therefore, we suggest that these defensive compounds have evolved to be co-regulated by MYB8.

Abstract (Browse 49)   |   Full Text
Fitness consequences of a clock pollinator filter in Nicotiana attenuata flowers in nature
Author: Felipe Yon, Danny Kessler, Youngsung Joo, Sang-Gyu Kim and Ian T. Baldwin1
Received: June 23, 2017         Accepted: August 17, 2017
Online Date: August 19, 2017
DOI: 10.1111/jipb.12579
                     
      
    

Nicotiana attenuata flowers, diurnally open, emit scents and move vertically to interact with nocturnal hawkmoth and day-active hummingbird pollinators. To examine the fitness consequences of these floral rhythms, we conducted pollination trials in the plant's native habitat with phase-shifted flowers of plants silenced in circadian clock genes. The results revealed that some pollination benefits observed under glasshouse conditions were not reproduced under natural field conditions. Floral arrhythmicity increased pollination success by hummingbirds, while reducing those by hawkmoths in the field. Thus floral circadian rhythms may influence a plant's fitness by filtering pollinators leading to altered seed set from outcrossed pollen.

Abstract (Browse 53)   |   Full Text
  Cell and Developmental Biology
AGO18b negatively regulates determinacy of spikelet meristems on the tassel central spike in maize
Author: Wei Sun, Xiaoli Xiang, Lihong Zhai, Dan Zhang, Zheng Cao, Lei Liu and Zuxin Zhang
Received: July 31, 2017         Accepted: August 31, 2017
Online Date: September 6, 2017
DOI: 10.1111/jipb.12596
                     
      
    

The maize tassel represents an indeterminate male inflorescence. The number of primordia that a given inflorescence meristem produces is related to its determinacy, i.e., capacity for continued meristem activity. Transcription factors (TFs) controlling determinacy in tassel axillary meristems are well studied in maize, and small RNAs are known to influence tassel development by repressing targets including tassel-related TFs. As core components of the RNA-inducible silence complex (RISC), Argonaute (AGO) proteins are required for small RNA-mediated repression. Here, we characterized the biological function of AGO18b, a tassel-enriched AGO. The abundance of AGO18b transcripts gradually increased during tassel development from inception to gametogenesis and were enriched in the inflorescence meristem and axillary meristems of the tassel. Repressing AGO18b expression resulted in more spikelets, which contributed to a longer central spike of the tassel. Additionally, the transcripts of several HD-ZIP III transcription factors that were canonical targets of microRNA166 (miR166) accumulated in the AGO18b-repressed lines. We propose that AGO18b is a negative regulator of the determinacy of inflorescence and axillary meristems, and that it acts by interacting with the miR166-HD-ZIP III TF regulatory pathway.

Abstract (Browse 37)   |   Full Text
Arabidopsis EXO70A1 recruits Patellin3 to the cell membrane independent of its role as exocyst subunit
Author: Chengyun Wu, Lu Tan, Max van Hooren, Xiaoyun Tan, Feng Liu, Yan Li, Yanxue Zhao, Bingxuan Li, Qingchen Rui, Teun Munnik and Yiqun Bao
Received: July 8, 2017         Accepted: August 14, 2017
Online Date: August 16, 2017
DOI: 10.1111/jipb.12578
                     
      
    

The exocyst is a well-known complex to tether vesicles at the cell membrane before fusion. Whether an individual subunit can execute a unique function is largely unknown. Using yeast-two-hybrid (Y2H) analysis, we found that EXO70A1 interacted with the GOLD domain of Patellin3 (PATL3). The direct EXO70A1-PATL3 interaction was supported by in vitro and in vivo experiments. In Arabidopsis, PATL3-GFP colocalized with EXO70A1 predominantly at the cell membrane, and PATL3 localization was insensitive to BFA and TryA23. Remarkably, in the exo70a1 mutant, PATL3 proteins accumulated as punctate structures within the cytosol, which did not colocalize with several endomembrane compartment markers, and was insensitive to BFA. Furthermore, PATL3 localization was not changed in exo70e2, PRsec6, exo84b mutants. These data suggested that EXO70A1, but not other exocyst subunits, was responsible for PATL3 localization, which is independent of its role in secretory/recycling vesicle-tethering/fusion. Both EXO70A1 and PATL3 were found to bind PI4P and PI(4,5)P2 in vitro. Evidence was provided that the other four members of the PATL family bound to EXO70A1 as well, and shared similar localization pattern of PATL3. These results brought us a new appraisal of the exocyst subunit-specific function, and provided data and tools for further characterization of PATL family proteins.

Abstract (Browse 41)   |   Full Text
  Review Articles
Small RNAs in regulating temperature stress response in plants
Author: Qing Liu, Shijuan Yan, Tifeng Yang, Shaohong Zhang, Yue-Qin Chen and Bin Liu
Received: July 5, 2017         Accepted: July 12, 2017
Online Date: July 21, 2017
DOI: 10.1111/jipb.12571
                     
      
    

Due to global climate change, temperature stress has become one of the primary causes of crop losses worldwide. Much progress has been made in unraveling the complex stress response mechanisms in plants, particularly in the identification of temperature stress responsive protein-coding genes. Recently discovered microRNAs (miRNAs) and endogenous small-interfering RNAs (siRNAs) have also been demonstrated as important players in plant temperature stress response. Using high-throughput sequencing, many small RNAs, especially miRNAs, have been identified to be triggered by cold or heat. Subsequently, several studies have shown an important functional role for these small RNAs in cold or heat tolerance. These findings greatly broaden our understanding of endogenous small RNAs in plant stress response control. Here, we highlight new findings regarding the roles of miRNAs and siRNAs in plant temperature stress response and acclimation. We also review current understanding of the regulatory mechanisms of small RNAs in temperature stress response, and explore the outlook for the utilization of these small RNAs in molecular breeding for improvement of temperature stress tolerance in plants.

Abstract (Browse 63)   |   Full Text
  Plant Reproduction Biology
Variation in floral characters, particularly floral scent, in sapromyophilous Stemona species
Author: Gao Chen, Wei-Chang Gong, Jia Ge, Johann Schinnerl, Bin Wang and Wei-Bang Sun
Received: July 12, 2017         Accepted: August 22, 2017
Online Date: August 24, 2017
DOI: 10.1111/jipb.12580
                     
      
    

Flowers or inflorescences often deploy various signals, including visual, olfactory, and gustatory cues, that can be detected by their pollinators. In many plants, these cues and their functions are poorly understood. Deciphering the interactions between floral cues and pollinators is crucial for analyzing the reproductive success of flowering plants. In this study, we examined the composition of the fetid floral scents produced by several Stemona species, including nine S. tuberosa populations from across China, using dynamic headspace adsorption, gas chromatography, and mass spectrometry techniques. We compared variations in floral phenotype, including floral longevity, nectar rewards, pollinator behavior, and flower length and color among the Stemona species. Of the 54 scent compounds identified, the major compounds include fetid dimethyl disulfide, dimethyl trisulfide, 1-pyrroline, butyric acid, p-cresol, isoamyl alcohol, and indole. We detected striking differentiation in floral scent at both the species and population level, and even within a population of plants with different colored flowers. Floral characteristics related to sapromyophily and deceptive pollination, including flower color mimicking livor mortis and a lack of nectar, were found in five Stemona species, indicating that Stemona is a typical sapromyophilous taxon. Species of this monocot genus might employ evolutionary tactics to exploit saprophilous flies for pollination.

Abstract (Browse 44)   |   Full Text
Arabidopsis CPR5 regulates ethylene signaling via molecular association with the ETR1 receptor
Author: Feifei Wang, Lijuan Wang, Longfei Qiao, Jiacai Chen, Maria Belen Pappa, Haixia Pei, Tao Zhang, Caren Chang and Chun-Hai Dong
Received: April 10, 2017         Accepted: June 26, 2017
Online Date: July 14, 2017
DOI: 10.1111/jipb.12570
                     
      
    

The plant hormone ethylene plays various functions in plant growth, development and response to environmental stress. Ethylene is perceived by membrane-bound ethylene receptors, and among the homologous receptors in Arabidopsis, the ETR1 ethylene receptor plays a major role. The present study provides evidence demonstrating that Arabidopsis CPR5 functions as a novel ETR1 receptor-interacting protein in regulating ethylene response and signaling. Yeast split ubiquitin assays and bi-fluorescence complementation studies in plant cells indicated that CPR5 directly interacts with the ETR1 receptor. Genetic analyses indicated that mutant alleles of cpr5 can suppress ethylene insensitivity in both etr1-1 and etr1-2, but not in other dominant ethylene receptor mutants. Overexpression of Arabidopsis CPR5 either in transgenic Arabidopsis plants, or ectopically in tobacco, significantly enhanced ethylene sensitivity. These findings indicate that CPR5 plays a critical role in regulating ethylene signaling. CPR5 is localized to endomembrane structures and the nucleus, and is involved in various regulatory pathways, including pathogenesis, leaf senescence, and spontaneous cell death. This study provides evidence for a novel regulatory function played by CPR5 in the ethylene receptor signaling pathway in Arabidopsis.

Abstract (Browse 67)   |   Full Text
  Functional Omics and Systems Biology
Graft-accelerated virus-induced gene silencing facilitates functional genomics in rose flowers
Author: Huijun Yan, Shaochuan Shi, Nan Ma, Xiaoqian Cao, Hao Zhang, Xianqin Qiu, Qigang Wang, Hongying Jian, Ningning Zhou, Zhao Zhang and Kaixue Tang
Received: July 11, 2017         Accepted: September 10, 2017
Online Date: September 12, 2017
DOI: 10.1111/jipb.12599
                     
      
    

Rose has emerged as a model ornamental plant for studies of flower development, senescence, and morphology, as well as the metabolism of floral fragrances and colors. Virus-induced gene silencing (VIGS) has long since been used in functional genomics studies of rose by vacuum infiltration of cuttings or seedlings with an Agrobacterium suspension carrying TRV-derived vectors. However, VIGS in rose flowers remains a challenge because of its low efficiency and long time to silencing. Here we present a novel and rapid VIGS method that can be used to analyze gene function in rose, called ‘graft-accelerated VIGS’, where axillary sprouts are cut off the rose plant and vacuum infiltrated with Agrobacterium. The inoculated scions are then grafted back onto the plants to flower and silencing phenotypes can be observed within five weeks post infiltration. Using this new method, we successfully silenced the expression of the RhDFR1, RhAG, and RhNUDX1 in rose flowers, and affected their color, petal number, as well as fragrance, respectively. This grafting method will facilitate high-throughput functional analysis of genes in rose flowers. Importantly, it may also be applied to other woody species that are not currently amenable to VIGS by conventional leaf or plantlet/seedling infiltration methods.

Abstract (Browse 22)   |   Full Text
Genetic dissection of top three leaf traits in rice using progenies from one japonicaˇÁindica cross
Author: Changbin Yin, Huihui Li, Zhigang Zhao, Zhiquan Wang, Shijia Liu, Liangming Chen, Xi Liu, Yunlu Tian, Juan Ma, Lidong Xu, Dashuang Zhang, Susong Zhu, Danting Li, Jianmin Wan and Jiankang Wang
Received: June 12, 2017         Accepted: September 4, 2017
Online Date: September 6, 2017
DOI: 10.1111/jipb.12597
                     
      
    

The size of the top three leaves of rice plants is strongly associated with yield; thus, it is important to consider quantitative traits representing leaf size (e.g., length and width) when breeding novel rice varieties. It is challenging to measure such traits on a large scale in the field, and little is known about the genetic factors that determine the size of the top three leaves. In this study, a population of recombinant inbred lines (RILs) and reciprocal single chromosomal segment substitution lines (SSSLs) derived from the progeny of a japonica Asominori × indica IR24 cross were grown under four diverse environmental conditions. Six morphological traits associated with leaf size were measured, namely length and width of the flag leaf, length and width of the second leaf, and length and width of the third leaf. In the RIL population, 49 QTLs were identified that clustered in 30 genomic region. Twenty-three of these QTLs were confirmed in the SSSL population. A comparison with previously reported genes/QTLs revealed eight novel genomic regions that contained uncharacterized ORFs that had not previously been associated with leaf size. The QTLs identified in this study can be used for marker-assisted breeding and for fine mapping of novel genetic elements controlling leaf size in rice.

Abstract (Browse 33)   |   Full Text
  Molecular Ecology and Evolution
Stigmatic exudate in the Annonaceae: pollinator reward, pollen germination medium or extragynoecial compitum?  
Author: Jenny Y. Y. Lau, Chun-Chiu Pang, Lawrence Ramsden and Richard M.K. Saunders
Received: August 25, 2017         Accepted: September 5, 2017
Online Date: September 6, 2017
DOI: 10.1111/jipb.12598
                     
      
    

Although ‘dry-type’ stigmas are widely regarded as ancestral in angiosperms, the early-divergent family Annonaceae has copious stigmatic exudate. We evaluate three putative functions for this exudate: as a nutritive reward for pollinators; as a pollen germination medium; and as an extragynoecial compitum that enables pollen tube growth between carpels. Stigmatic exudate is fructose dominated (72.2%), but with high levels of glucose and sucrose; the dominance of hexose sugars and the diversity of amino acids observed, including many that are essential for insects, supports a nutritive role for pollinators. Sugar concentration in pre-receptive flowers is high (28.2%), falling during the peak period of stigmatic receptivity (17.4%), and then rising again towards the end of the pistillate phase (32.9%). Pollen germination was highest in sugar concentrations < 20%. Sugar concentrations during the peak pistillate phase therefore provide optimal osmolarity for pollen hydration and germination; subsequent changes in sugar concentration during anthesis reinforce protogyny (in which carpels mature before stamens), enabling the retention of concentrated exudate into the staminate phase as a pollinator food reward without the possibility of pollen germination. Intercarpellary growth of pollen tubes was confirmed: the exudate therefore also functions as a suprastylar extragynoecial compitum, overcoming the limitations of apocarpy.

Abstract (Browse 26)   |   Full Text

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