Epigenetic Variations in Plant Hybrids and Their Potential Roles in Heterosis

Heterosis,one of the most important biological phenomena,refers to the phenotypic superiority of a hybrid over its genetically diverse parents with respect to many traits such as biomass,growth rate and yield.Despite its successful application in breeding and agronomic production of many crop and animal varieties,the molecular basis of heterosis remains elusive.The classic genetic explanations for heterosis centered on three hypotheses:dominance (Davenport,1908;Bruce,1910;Keeble and Pellew,1910;Jones,1917),overdominance (East,1908;Shull,1908) and epistasis (Powers,1944;Yu et al.,1997).However,these hypotheses are largely conceptual and not connected to molecular principles,and are therefore insufficient to explain the molecular basis of heterosis (Birchler et al.,2003).Recently,many studies have explored the molecular mechanism of heterosis in plants at a genome-wide level.These studies suggest that global differential gene expression between hybrids and parental lines potentially contributes to heterosis in plants (e.g.,Swanson-Wagner et al.,2006;Zhang et al.,2008;Wei et al.,2009;Song et al.,2010).Research suggests that genetic components,including cis-acting elements and trans-acting factors,are critical regulators of differential gene expression in hybrids (Hochholdinger and Hoecker,2007;Springer and Stupar,2007;Zhang et al.,2008).However,other research indicates that epigenetic components,the regulators of chromatin states and genome activity,also have the potential to impact heterosis (e.g.,Ha et al.,2009;He et al.,2010;Groszmann et al.,2011;Barber et al.,2012;Chodavarapu et al.,2012;Greaves et al.,2012a;Shen et al.,2012).     

Genome-Wide Analysis and Expression Patterns of the YUCCA Genes in Maize

<正>Auxin plays important roles in various aspects of plant growth and development(Zhao,2010).In Arabidopsis,a number of YUCCA(YUC)genes,which are involved in auxin biosynthesis,have been identified(Zhao et al.,2001;Woodward et al.,2005;Cheng et al.,2006,2007;Kim et al.,2007;Chen et al.,2014).YUC genes encode flavin monooxygenases(FMOs)that convert indole-3-pyruvate(IPA)to indole-3-acetic acid(IAA)(Zhao,2012).The Arabidopsis YUC family is comprised of 11 members(Zhao et al.,2001;     

Elymus sibiricus populations drive the community of root-associated arbuscular mycorrhizal fungi in a monoculture agroecosystem

正Dear Editor,Arbuscular mycorrhizal fungi (AMF) belonging to phylum Glomeromycota,form symbiotic associations with roots of over 80%of land plant species in terrestrial ecosystems (van der Heijden et al.,2015).A growing body of evidence shows that symbiotic AMF are important for plant growth and health (van der Heijden et al.,2015).A plant root is commonly associated with a complex AMF community in terrestrial ecosystems (Pivato et al.,2007;Davison et al.,2015;     

Rare variants in novel and known genes associated with primary angle closure glaucoma based on whole exome sequencing of 549 probands

<正>Primary angle closure glaucoma(PACG)is one of the most common causes of irreversible blindness in Asia and about 80%of PACG are present in Asia(Song et al.,2017).Genetics plays an important role in the development of PACG(Gramer et al.,2014).Recently,eight common SNPs were found to be strongly associated with PACG(Vithana et al.,2012;Khor et al.,2016)and mutations in MYRF cause high hyperopia accompanied with PACG(Xiao et al.,2019).However,the genetic defects underlying PACG are still     

Highly efficient genome editing using oocyte-specific zcas9 transgenic zebrafish

正Since its first application to induce mutations in mammalian cells (Cong et al., 2013; Mali et al., 2013), CRISPR/Cas9 has rapidly become a routine technique to perform genome editing in a variety of biological systems due to its facile, robust, and multiplexable features (Hwang et al., 2013; Wang et al., 2013; Guo et al., 2014; Liu,     

Acute paralysis viruses of the honey bee

<正>The alarming decline of honey bee(Apis mellifera)colonies in the last decade drove the attention and research to several pathogens of the honey bee including viruses.Viruses challenge the development of healthy and robust colonies since they manage to prevail in an asymptomatic mode and reemerge in acute infections following external stresses,as well as they are able to infect new healthy colonies(de Miranda J R,et al.,2010a;de Miranda J R,et al.,2010b;Di Prisco G,et al.,2013;Nazzi F,et al.,2012;Yang X L,et al.,2005).     

Rapid breeding of pink-fruited tomato hybrids using the CRISPR/Cas9 system

<正>As one of the most important vegetables,tomato (Solanum lycopersicum) is extensively produced and consumed worldwide and substantially contributes to human nutrition and health (The Tomato Genome Consortium,2012).Although red tomatoes are the most common,pink tomatoes are more popular in Asia,particularly in China and Japan,because of their better taste (Ballester et al.,2010;Zhu et al.,2018).Compared with red tomatoes,pink tomatoes fail to accumulate the yellow-colored flavonoid pigment,naringenin chalcone (NarCh),in their peels,resulting in a colorless peel phenotype (Adato et al,2009;Ballester et al.,2010).Genetic     

Evolutionary selection on MDA5 and LGP2 in the chicken preserves antiviral competence in the absence of RIG-I

<正>The pattern recognition receptors (PRRs) act as the first line of defense against pathogens and are common molecular targets in the conflict between viruses and their host (Tan et al.,2018).The RIG-I-like receptors (RLRs),including RIG-I (Yoneyama et al.,2004),MDA5 (Andrejeva et al.,2004),and LGP2 (Saito et al.,2007),are PRRs and reside in the cytoplasm.These proteins recognize the RNA structures of different viral RNA species.All RLRs have an intermediate RNA helicase domain that catalyzes ATP hydrolysis and a C-terminal domain (CTD).RIG-I and MDA5,but not LGP2,contain tandem caspase recruitment domains at their N-termini     

Interspecies embryo transfer between rhesus and cynomolgus monkeys

正Nonhuman primates (NHPs) present significant advantages over rodents for physiological and pharmacological investigations because of their higher genetic and physiological similarity to humans. Both rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) monkeys are considered ideal animal models in biomedical research (Phillips et al., 2014), especially in modeling normal development and diseases in the nervous system (Izpisua Belmonte et al., 2015; Ng et al., 2015; Niu et al., 2015; Poo et al.,     

PIK-75 promotes homology-directed DNA repair

Homo!ogy-directed repair(HDR)is one of two major DNA repair pathways to mend the double-strand breaks(DSBs)formed in the genome(Liang et al.,1998;Pardo et al.,2009).Although less efficient compared with another DNA repair pathway,nonhomologous end joining(NHEJ),HDR is a type of precise repair to restore DNA damage and sustain genomic stability(Pardo et al.,2009;Ceccaldi et al.,2016).By contrast,NHEJ usually introduces mutations into the repaired site,thus probably harming the genomic integrity(Lieber et al.,2003).The error-free property enables HDR to be harnessed to correct a faulty mutation for therapeutic purpose in cells or in the body(Wu et al.,2013).In add让ion,HDR possesses great potential in the generation of genome-edited animals with precise genetic modifications,such as point mutation,DNA replacement,and DNA insertion in a specific genomic site(Wang et al.,2013).However,the low repair frequency mediated by HDR significantly limits让s application for efficient gene correction or establishment of various genetically modified animal models.Currently,multiple site-specific endonucleases have emerged as highly efficient tools to create targeted DSBs and markedly promote subsequent DNA repair either via HDR or NHEJ(Gaj et al.,2013).Nonetheless,the HDR-mediated modifications following the cleavage of engineering nucleases are still inefficient,usually with an efficiency less than 20%in cultured mammalian cells and embryos(Mali et al..2013;Wang et al.,2013;Yang et al.,2013).     

Gut microbiota from end-stage renal disease patients disrupt gut barrier function by excessive production of phenol

<正>End stage renal disease (ESRD), an advanced stage of chronic kidney disease, has received increasing attention as a leading public health problem (Webster et al., 2017). Chronic kidney disease (CKD) and ESRD are invariably accompanied by chronic systemic inflammation which plays central roles in CKD progression (Cachofeiro et al., 2008) and the increased mortality due to cardiovascular disease (Landray et al., 2004). Accumulating evidence in humans and     

Engrafted newborn neurons could functionally integrate into the host neuronal network

The limited capability to regenerate new neurons following injuries of the central neural system (CNS) still remains a major challenge for basic and clinical neuroscience.Neural stem cells (NSCs) could nearly have the potential to differentiate into all kinds of neural cells in vitro.Previous studies verified that exogenous transplanted NSCs are capable of differentiating into neurons and projecting onto the host neurons in the rat brain (Tabar et al.,2005;Dong JR et al.,2012),which could lead to behavioral recovery from neuronal damages such as spinal cord injury (McDonald et al.,1999),Parkinson's disease (Gonzalez et al.,2015;Kim et al.,2002;Lindvall,2001),and stroke (Zhang et al.,2016).     

Lack of an Additive Effect between the Deletions of Klf5 and Nkx3-1 in Mouse Prostatic Tumorigenesis

Prostate cancer is one of the most common malignancies.The development and progression of prostate cancer are driven by a series of genetic and epigenetic events including gene amplification that activates oncogenes and chromosomal deletion that inactivates tumor suppressor genes.Whereas gene amplification occurs in human prostate cancer,gene deletion is more common,and a large number of chromosomal regions have been identified to have frequent deletion in prostate cancer,suggesting that tumor suppressor inactivation is more common than oncogene activation in prostatic carcinogenesis (Knuutila et al.,1998,1999;Dong,2001).Among the most frequently deleted chromosomal regions in prostate cancer,target genes such as NKX3-1 from 8p21,PTENfrom 10q23 andATBF1 from 16q22 have been identified by different approaches (He et al.,1997;Li et al.,1997;Sun et al.,2005),and deletion of these genes in mouse prostates has been demonstrated to induce and/or promote prostatic carcinogenesis.For example,knockout of Nkx3-1 in mice induces hyperplasia and dysplasia (Bhatia-Gaur et al.,1999;Abdulkadir et al.,2002) and promotes prostatic tumorigenesis (Abate-Shen et al.,2003),while knockout of Pten alone causes prostatic neoplasia (Wang et al.,2003).Therefore,gene deletion plays a causal role in prostatic carcinogenesis (Dong,2001).     

New cytosine base editor for plant genome editing

正A large number of beneficial agronomic traits in crops are associated with single nucleotide polymorphisms (SNPs) or point mutations (Jiao et al., 2010; Li et al., 2017; Ma et al.,2015). In the past, site-specific point mutations in a target gene can only be achieved through the CRISPR/Cas9-mediated gene replacement via the homology-directed repair(HDR). However, the intrinsically low HDR activity in plant cells and the lack of efficient way to supply abundant HDR templates in plant nucleus have greatly limited the success     

Generation of marker-free transgenic rice using CRISPR/Cas9 system controlled by ?oral speci?c promoters

Recently, the CRISPR/Cas9 system has been used as a powerful tool for genome editing in many species (Jinek et al., 2012;Cong et al., 2013;Wright et al., 2016;Li et al., 2017;Deng et al., 2018). The CR1SPR/Cas9 system can not only be used as a useful technology to disrupt endogenous genes but also expand numerous other applications, such as precise base editing (Komor et al., 2016;Zong et al., 2017), regulation of gene expression (Gilbert et al., 2013), and gene replacement or insertion (Wang et al., 2017).     

What can we Learn from Oxygen and Hydrogen Isotope Compositions of Tree-ring Cellulose in Higher Plants (英文)

Stable isotope ratios in tree-ring cellulose have been shown to be reliable recorders of changes in the ambient climate (Leuenberger et al., 1998). Thus, isotopic fractionations associated with both physical and biochemical processes during cellulose synthesis in higher plants (Epstein & Krishnaumurthy, 1990; Roden et al., 2000; Saurer et al., 1997a; 1997b; 2000) can be used as archives for past climatic indicators. Superimposed on the climatic induced isotopic signal are the long-term responses of plant physiological processes to past changes in environmental conditions including CO2 enrichment.     

Functional non-homologous end joining patterns triggered by CRISPR/Cas9 in human cells

正CRISPR/Cas9-mediated genome engineering technologies are now widely applied in various organisms,including mouse and human cells(Cong et al.,2013;Mali et al.,2013;Yang et al.,2013;Hsu et al.,2014).The most widely used customized CRISPR/Cas9(Sp Cas9)is derived from Streptococcus pyogenes(Cong et al.,2013).The CRISPR/Cas9 system creates site-specific double-     

Fox- and raccoon-dog–associated rabies outbreaks in northern China

正Dear Editor,Rabies is a generally fatal disease caused by the rabies virus(RABV),and is transmitted mainly by Carnivora and Chiroptera(Fooks A R,et al.,2014;Tao X,et al.,2013).In China,stray dogs and some wild animals(e.g.,Chinese ferret badgers,foxes,and raccoon dogs)are the principal reservoirs for RABV(Hu R L,et al.,2009).Historically,rabies in wild foxes and raccoon dogs(Nyctereutes procyonoides)was recorded in the early     

Synaptobrevin-2 facilitates the trafficking and function of atrial SK2 channel

正Dear Editor,Small conductance Ca2+-activated potassium (SK) channels are widely expressed in various tissues and play a unique role in regulating cell function by integrating cytosolic Ca2+ levels and membrane potential (Adelman et al., 2012). Xu et al. first identified SK channels in the heart and found that SK channels, particularly the SK2 channel, are preferentially expressed in human and mouse atrial myocytes but not in ventricular myocytes (Xu et al., 2003). This suggests that the SK     

A new record of the capped langur (Trachypithecus pileatus) in China

DEAR EDITOR, The distribution of the capped langur (Trachypithecus pileatus)in China has become controversial since Shortridge's langur (Trachypithecus shortridgei) was upgraded to a full species.The capped langur is considered to be distributed in northeast India,Bangladesh,Bhutan,and northwest Myanmar only (Brandon-Jones et al.,2004;Choudhury,2008,2014;Das et al.,2008;Groves,2001).In our field survey,however,we obtained photos of the capped langur,demonstrating its existence in China. Following the species promotion of Shortridge's langur (Brandon-Jones et al.,2004;Groves,2001) and the delimiting of its distribution range to northwestern Yunnan in China and northeastern Myanmar (Brandon-Jones et al.,2004;Cui et al.,2016;Das et al.,2008;Groves,2001;Htun et al.,2008),with a new record in southeastern Tibet (Wu et al.,2016),the capped langur has been deleted from the checklist of mammals in China (Jiang et al.,2015).Despite this,Dr.George Schaller has suggested that capped langurs might exist in the northeastern section of the Yarlung-Zangbo River (Choudhury,2008).