November 2017, Volume 59 Issue 11, Pages 773每839.


Cover Caption: Seed dispersal by hornets
Seed dispersal by hornets is a rare dispersal mechanism in angiosperms. In this issue, Chen et al. (pp. 792每796) demonstrate that hornets are the primary and long-distance seed dispersers in Stemona tuberosa, and ants act as the secondary dispersers and transport seeds to safe sites. This unique example of insect-seed mutualism might be underestimated in myrmecochorous plants.

 

          Invited Expert Review
Small RNAs in regulating temperature stress response in plants  
Author: Qing Liu, Shijuan Yan, Tifeng Yang, Shaohong Zhang, Yue-Qin Chen and Bin Liu
Journal of Integrative Plant Biology 2017 59(11): 774每791
Published Online: 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 (siRN As) 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 the current understanding of the regulatory mechanisms of small RNAs in temperature stress response, and explore the outlook for the use of these small RNAs in molecular breeding for improvement of temperature stress tolerance in plants.

Abstract (Browse 206)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Here, we review the new findings regarding the roles of small RNAs and their regulatory mechanisms in plant temperature stress response. We also explore the outlook for utilization of these small RNAs in molecular breeding for improvement of temperature stress tolerance in plants.
          Letters to the Editor
Seed dispersal by hornets: An unusual insect-plant mutualism  
Author: Gao Chen, Zheng-Wei Wang, Yan Qin and Wei-Bang Sun
Journal of Integrative Plant Biology 2017 59(11): 792每796
Published Online: July 11, 2017
DOI: 10.1111/jipb.12568
      
    

Vespicochory, seed dispersal by hornets, is a rare seed dispersal mechanism in angiosperms and, to date, there are few records of this phenomenon. Through field investigations and behavioral assays conducted in four populations of Stemona tuberosa from 2011–2016, we demonstrate that hornets are the primary seed dispersers of S. tuberosa and play an important role in “long-distance” seed dispersal in this species. Furthermore, some ant species act as secondary dispersers and may transport the seeds to safe sites. Hornets and ants provide complementary seed dispersal at different spatial scales. This unique example of insect-plant mutualism may be an underestimated but important strategy to ensure “long-distance” seed dispersal in other myrmecochorous plants.

Abstract (Browse 144)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Seed dispersal by hornets is a rare seed dispersal mechanism in angiosperms. Chen et al. demonstrate that hornets are the primary seed dispersers of Stemona tuberosa and play an important role in long-distance seed dispersal. This unique example of insect-seed mutualism may be underestimated in other myrmecochorous plants.
THESEUS1 positively modulates plant defense responses against Botrytis cinerea through GUANINE EXCHANGE FACTOR4 signaling  
Author: Shaofeng Qu, Xi Zhang, Yutong Song, Jinxing Lin and Xiaoyi Shan
Journal of Integrative Plant Biology 2017 59(11): 797每804
Published Online: June 24, 2017
DOI: 10.1111/jipb.12565
      
    

The plant cell wall is an important interface for sensing pathogen attack and activating signaling pathways that promote plant immune responses. THESEUS1 (THE1) acts as a sensor of cell wall integrity that controls cell elongation during plant growth. However, no specific role for THE1 in plant defense responses has been reported. Here, we found that THE1 interacts with GUANINE EXCHANGE FACTOR4 (GEF4) and that both proteins play regulatory roles in plant resistance to the necrotrophic fungus Botrytis cinerea. Genetic analysis showed that THE1 and GEF4 function in the same genetic pathway to mediate plant defense responses. In addition, using transcriptome analysis, we identified various genes (such as defense-related, secondary metabolite-related, and transcription factor genes) that are likely downstream targets in the THE1-GEF4 signaling pathway. Our results suggest that THE1 functions as an upstream regulator of GEF4 signaling to positively regulate defense responses against B. cinerea in Arabidopsis.

Abstract (Browse 161)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
THESEUS1, a member of the Catharanthus roseus RLK1-like kinase family, interacts with GUANINE EXCHANGE FACTOR4 (GEF4) and elicits the GEF4 signaling network to regulate defense responses to the necrotrophic fungal pathogen Botrytis cinerea, revealing an important player in defense responses against biotic stresses.
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. Baldwin
Journal of Integrative Plant Biology 2017 59(11): 805每809
Published Online: 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 106)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Circadian rhythms in flowers of a wild tobacco, Nicotiana attenuata, have evolved to interact with day-active pollinators, hummingbirds and night-active pollinators, hawkmoths. Field experiments with floral rhythm-altered plants revealed that floral rhythms play an important role in pollinator selection in nature.
          Plant Reproduction Biology
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
Journal of Integrative Plant Biology 2017 59(11): 810每824
Published Online: 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 187)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
In this study, the authors demonstrate that the Arabidopsis CPR5, an endomembrane-localized protein functioning in pathogenesis, leaf senescence and stress responses, can directly interact with the ETR1, the ethylene receptor, and plays a critical role in the regulation of ethylene signaling.
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
Journal of Integrative Plant Biology 2017 59(11): 825每839
Published Online: 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 78)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Floral phenotype and fetid floral scent composition (dimethyl disulfide, dimethyl trisulfide, 1-pyrroline, butyric acid, p-cresol, and indole, etc.) of several Stemona species were investigated. Striking differentiation in floral scent at both the species and population level was detected in this study. Floral characteristics related to sapromyophily and deceptive pollination of Stemona were also identified.
 

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