Jingjue ZengYi DengShahid IqbalJiarui Zhang...
556-572页查看更多>>摘要：Hippeastrum,a highly diverse genus in the Amaryllidaceae family,is a valuable ornamental bulbous flowering plant.Somatic embryogenesis(SE)is an efficient method for mass production of Hippeastrum plantlets.Previous studies have been devoted to the in vitro propagation of Hippeastrum,but the SE and its regulatory networks are rarely reported.In this study,we established a direct SE method of Hippeastrum'Bangkok Rose'using leaf bases as explants.MS supplemented with 1.00 mg·L-1 NAA+1.00 mg·L-1 KT+0.25 mg·L-1 TDZ was the optimal medium for SE.Histological observations showed that the bipolar somatic embryo originated from the epidermal cell layer and underwent initiation,globular,scutellar and coleoptile stages.During SE,endogenous hormones of IAA,CTK,ABA,and SA were highly accumulated.Transcriptomic analysis revealed the genes encoding auxin biosynthesis/metabolic enzymes and efflux carriers were induced,while the auxin receptor of TIR1 and ARF transcriptional repressor of Aux/IAA were down-regulated and up-regulated,respectively,leading to suppression of auxin signaling.In contrast,cytokine signaling was promoted at the early stage of SE,as biosynthesis,transport,and signaling components were up-regulated.Various stress-related genes were up-regulated at the early or late stages of SE.Chromatin remodeling could also be dynamically regulated via distinct expression enzymes that control histone methylation and acetylation during SE.Moreover,key SE regulators,including WOXs and SERKs were highly expressed along with SE.Overall,the present study provides insights into the SE regulatory mechanisms of the Hippeastrum.
Bin DongQianqian WangDan ZhouYiguang Wang...
573-585页查看更多>>摘要：Sweet osmanthus(Osmanthus fragrans)is a having general approval aromatic tree in China that is widely applied to landscaping and gardening.However,the evergreen tree adaptability is limited by many environmental stresses.Currently,limited information is available regarding the genetic analysis and functional identification of expansin genes in response to abiotic stress in sweet osmanthus.In this study,a total of 29 expansin genes were identified and divided into four groups by genome-wide analysis from the sweet osmanthus genome.Tran-scriptome and quantitative Real-time PCR analysis showed that the cell wall-localized protein expansin-like A(OfEXLA1)gene was significantly induced by salt and drought treatment.Histochemical GUS staining of transgenic Arabidopsis lines in which GUS activity was driven with the OfEXLA1 promoter,GUS activity was significantly induced by salt,drought,and exogenous abscisic acid(ABA).In yeast,we found OfEXLA1 overexpression significantly improved the population of cells compared with wild-type strains after NaCl and polyethylene glycol(PEG)treatment.Additionally,OfEXLA1 overexpression not only promoted plant growth,but also improved the salt and drought tolerance in Ara-bidopsis.To gain insight into the role of ABA signaling in the regulation of OfEXLA1 improving abiotic tolerance in sweet osmanthus,four differentially expressed ABA Insensitive 5(ABI5)-like genes(OfABL4,OfABL5,OfABL7,and OfABL8)were identified from transcriptome,and dual-luciferase(dual-LUC)and yeast one hybrid(Y1H)assay showed that OfABL4 and OfABL5 might bind to OfEXLA1 promoter to accumulate the OfEXLA1 expression by responding to ABA signaling to improve abiotic tolerance in sweet osmanthus.These results provide the information for understanding the molecular functions of expansin-like A gene and molecular breeding of sweet osmanthus in future.
Wenying LiJingzhen ChenXiang DongMeilan Liu...
586-600页查看更多>>摘要：The mu oil tree(Vernicia montana Lour.)is a dioecious species,but the genetic mechanisms underlying its phenotypic sexual dimorphism are unclear.In this study,we determined two pivotal phases of sex differentiation of mu oil tree via morphological and histological analyses of unisexual flowers:(Ⅰ)differentiation of male or female primordia to produce staminate flowers(SFs)or transient hermaphrodite flowers(HFs),and(Ⅱ)complete abortion of stamens in transient HFs to generate pistillate flowers(PFs).A total of 1621 sex-biased genes were identified by comparative transcriptome analysis which exhibited elevated rates of protein evolution than unbiased genes.The female-biased genes were enriched in the production of defense compounds while male-biased genes were focused on the production of viable pollens.Transcriptome-based analysis revealed that the differentially expressed genes(DEGs)between PFs and SFs in phase Ⅰ involved in abscisic acid(ABA),auxin(AUX),cytokinin(CK),ethylene(ET),and gibberellin(GA)biosynthesis and signaling showed higher expression levels in males than in females in general,whereas the DEGs involved in jasmonic acid(JA)and salicylic acid(SA)pathways displayed opposite expression patterns.Moreover,differentially expressed endogenous ABA,AUX,GAs,JA,and SA exhibited consistent biased expression patterns with the DEGs by UPLC-MS-based analysis.Exogenous application of an anti-ethylene plant growth regulator could promote the development of stamens in PFs and generated HFs.Comparative transcriptomic and hormonal analyses of PFs and SFs in phase Ⅱ indicated an increase in ET concentration when abortion of stamens in PFs occurred.This study suggested that phytohormones play key roles in sex dimorphism and ET may determine the development of stamens in PFs of mu oil tree,which provides an insight into plant sex differentiation mechanisms.
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