摘""要:本研究以白肉火龍果(Hylocereus"undatus)為材料,研究茉莉酸甲酯(MeJA)處理調(diào)控白肉火龍果采后成熟的機(jī)制。利用高通量測(cè)序的數(shù)字基因表達(dá)譜(DEGs)技術(shù),對(duì)MeJA處理16"d的白肉火龍果果實(shí)和對(duì)照組的樣品進(jìn)行差異基因表達(dá)譜分析。結(jié)果顯示,MeJA處理導(dǎo)致15"596個(gè)基因差異表達(dá),其中上調(diào)表達(dá)基因6135個(gè),下調(diào)表達(dá)基因9461個(gè)。GO功能顯著性富集分析表明,差異表達(dá)基因主要涉及細(xì)胞過(guò)程、生物調(diào)節(jié)、物質(zhì)合成、催化活性、結(jié)合活性和轉(zhuǎn)運(yùn)活性等。KEGG基因通路富集分析發(fā)現(xiàn),差異表達(dá)基因富集于多條代謝通路上,主要涉及光合作用、植物激素信號(hào)轉(zhuǎn)導(dǎo)、蛋白質(zhì)加工、淀粉和糖類(lèi)代謝等代謝途徑。進(jìn)一步分析發(fā)現(xiàn),MeJA處理導(dǎo)致多個(gè)參與乙烯信號(hào)途徑和細(xì)胞壁代謝途徑的基因表達(dá)量顯著下調(diào),如ERF、EIN、XTH、PG和PME家族成員等。上述結(jié)果表明,MeJA處理可能抑制了乙烯信號(hào)轉(zhuǎn)導(dǎo)和細(xì)胞壁代謝過(guò)程,從而延緩白肉火龍果采后成熟,延長(zhǎng)果實(shí)的貯藏時(shí)間。本研究結(jié)果將為熱帶特色水果采后保鮮技術(shù)的開(kāi)發(fā)與應(yīng)用奠定基礎(chǔ)。
關(guān)鍵詞:白肉火龍果;茉莉酸甲酯;果實(shí)采后成熟;差異表達(dá)基因中圖分類(lèi)號(hào):S667.9""""""文獻(xiàn)標(biāo)志碼:A
Transcriptome"Profiles"of"Postharvest"White-Fleshed"Pitaya"(Hylocereus"undatus)"in"Response"to"Methyl"Jasmonate"Treatment
ZHU"Shengnan1,"LIN"Hairong2,"MO"Yuxing1,"LI"Haili1,"WANG"Jindi1,"LIU"Kaidong1*
1."Life"Science"and"Technology"School,"Lingnan"Normal"University,"Zhanjiang,"Guangdong"524048,"China;"2."Zhanjiang"Agrotechnical"Extension"Center,"Zhanjiang,"Guangdong"524043,"China
Abstract:"The"molecular"mechanism"underlying"white-fleshed"pitaya"(Hylocereus"undatus)"in"response"to"MeJA"treatment"during"the"fruit"postharvest"ripening"was"investigated."The"differentially"expressed"genes"(DEGs)"response"to"MeJA"treatment"were"analyzed"by"the"digital"gene"expression"profiling"technology."The"results"showed"that"compared"with"the"control,"a"total"of"15"596"DEGs,"including"6135"up-regulated"genes"and"9461"down-regulated"genes,"were"identified."Gene"ontology"analysis"showed"that"most"DEGs"were"involved"in"cell"metabolism,"biological"regulation,"biosynthesis,"catalysis,"binding"activities"and"transport"activities."KEGG"pathway"enrichment"analysis"revealed"that"all"DEGs"were"assigned"in"many"pathways,"mainly"involving"in"photosynthesis,"plant"hormone"signal"transduction,"protein"processing"and"starch"and"carbohydrate"metabolism."Moreover,"the"transcripts"of"most"genes"involved"in"ethylene-signaling"transduction"and"cell-wall"degradation,"belonging"to"ERF,"EIN,"XTH,"PG"and"XTH"family,"were"found"to"be"significantly"down-regulated."These"results"strongly"suggest"that"MeJA"treatment"may"be"involved"in"delaying"the"softening"of"white-pitaya"by"restraining"the"ethylene-signaling"transduction"and"retarding"the"degradation"of"cell"wall"during"postharvest"ripening."The"results"would"lay"a"foundation"for"further"research"on"developing"the"more"efficient"postharvest"preservation"technology"for"tropical"fruits.
Keywords:"pitaya"(Hylocereus"undatus);"methyl"jasmonate;"postharvest"ripening;"differentially"expressed"gene
DOI:"10.3969/j.issn.1000-2561.2025.02.002
白肉火龍果(Hylocereus"undatus)又名紅龍果、仙蜜果和情人果等,是仙人掌科(Cactaceae)量天尺屬(Hylocereus)植物[1]。火龍果作為一種新型的保健水果,富含膳食纖維、蛋白質(zhì)和維生素等營(yíng)養(yǎng)物質(zhì),其花中也含有大量的藥效成分[2-3]。20世紀(jì)90年代,火龍果被引種至我國(guó)臺(tái)灣、廣東、四川和云南等地區(qū)并大規(guī)模種植,加速了火龍果產(chǎn)業(yè)發(fā)展[4]。由于火龍果的含水量大,在運(yùn)送期間極易發(fā)生劣變,出現(xiàn)果皮皺縮、果肉褐變和腐爛變質(zhì)等現(xiàn)象[5]。研究發(fā)現(xiàn),火龍果在常溫狀態(tài)下儲(chǔ)存3"d左右就會(huì)出現(xiàn)鱗片黃化、萎蔫和果實(shí)腐爛等現(xiàn)象,造成巨大的經(jīng)濟(jì)損失[6]。此外,隨著火龍果種植面積不斷擴(kuò)大,火龍果的病蟲(chóng)害也日趨嚴(yán)重,對(duì)產(chǎn)量和質(zhì)量都造成了嚴(yán)重不利影響[7]。因此,通過(guò)利用化學(xué)生物保鮮劑維持采后火龍果的品質(zhì),延長(zhǎng)火龍果果實(shí)的貯藏期,對(duì)火龍果產(chǎn)業(yè)的可持續(xù)性發(fā)展具有重要意義。
茉莉酸甲酯(methyl"jasmonate,"MeJA)是一種天然植物生長(zhǎng)調(diào)節(jié)物質(zhì),在植物的應(yīng)激反應(yīng)和次生代謝過(guò)程中作為一種信號(hào)分子,調(diào)控著植物體的生長(zhǎng)發(fā)育和各種抗逆反應(yīng)[8]。WANG等[8]發(fā)現(xiàn)MeJA處理不僅能夠激發(fā)植物防御基因的表達(dá),還能夠改變揮發(fā)性信號(hào)化合物的釋放以吸引害蟲(chóng)的捕食者或天敵,從而提高植物對(duì)病蟲(chóng)害的抗性。此外,研究發(fā)現(xiàn)外源MeJA處理番茄(Solanum"lycopersicum)[9]、葡萄(Vitis"vinifera)[10]、香蕉(Musa"nana)[11]、蘋(píng)果(Malus"pumila)[12]、柿子(Diospyros"kaki)[13]、藍(lán)莓(Vaccinium"uliginosum)[8]和杧果(Mangifera"indica)[14]等果實(shí),能夠增強(qiáng)果實(shí)抗性,減少腐爛,有效地延長(zhǎng)果實(shí)儲(chǔ)藏期。如HASAN等[13]發(fā)現(xiàn)MeJA處理能夠改變柿果的色澤及果實(shí)中抗氧化物酶等的活性;唐偉杰等[12]證實(shí)低濃度的MeJA能夠通過(guò)減緩膜脂過(guò)氧化,降低果實(shí)采后褐變,進(jìn)而維持蘋(píng)果常溫貯藏品質(zhì)。盡管MeJA在水果保鮮方面的應(yīng)用研究相對(duì)較多,但主要集中在對(duì)果實(shí)的生理變化方面的影響,而有關(guān)MeJA調(diào)控果實(shí)保鮮的分子機(jī)理的研究在國(guó)內(nèi)外仍相對(duì)較少。
基于轉(zhuǎn)錄組測(cè)序(RNA-seq)的數(shù)字基因表達(dá)譜(DGE)技術(shù)是指通過(guò)利用新一代高通量測(cè)序技術(shù)快速檢測(cè)生物體的基因表達(dá)情況,篩選出不同條件下的差異表達(dá)基因,從而揭示差異表達(dá)基因功能及參與的生物代謝途徑[15]。目前此技術(shù)因?yàn)榫_性高、重復(fù)性好和通量高等優(yōu)點(diǎn)已經(jīng)在基礎(chǔ)醫(yī)學(xué)和生物科學(xué)研究等領(lǐng)域廣泛應(yīng)用。學(xué)者們利用該技術(shù)對(duì)西瓜(Citrullus"lanatus)[16]、桃(Amygdalus"persica)[17]、哈密瓜(Cucumis"melo)[18]和甘蔗(Saccharum"officinarum)[19]等進(jìn)行了基因表達(dá)模式的轉(zhuǎn)錄水平分析。本研究通過(guò)利用DGE技術(shù)對(duì)MeJA處理的白肉火龍果果實(shí)總RNA測(cè)序,篩選出MeJA處理后的差異表達(dá)基因,并將差異表達(dá)基因進(jìn)行GO、KEGG富集分析,明確差異表達(dá)基因的功能與表達(dá)情況,旨在揭示MeJA處理下影響白肉火龍果果實(shí)采后成熟的分子調(diào)控機(jī)制。
1.1""材料
白肉火龍果購(gòu)于廣東省湛江市麻章果樹(shù)種植場(chǎng)。挑選質(zhì)量、果皮顏色、大小一致且無(wú)機(jī)械損傷的白肉火龍果果實(shí),用1%(V/V)NaClO滅菌5"min,用自來(lái)水充分清洗干凈。將滅菌后的果實(shí)分為MeJA處理組(MeJA)和對(duì)照組(CK),每組設(shè)置4個(gè)重復(fù)。MeJA組用濃度為1.0"mmol/L的MeJA浸泡30"min,CK組則用蒸餾水浸泡30"min,待其表面干燥后,再將所有的火龍果密封于同樣條件的保鮮盒中,置于常溫保存。16"d后從每組中收取4個(gè)果實(shí)樣品,用錫箔紙包好再放入樣品袋中,做好標(biāo)記,隨后利用液氮快速冰凍處理以防止酶對(duì)組織的降解,儲(chǔ)存在超低溫冰箱中,用于總RNA提取。
1.2""方法
1.2.1""RNA提取、純度檢測(cè)和文庫(kù)構(gòu)建""用植物總RNA提取試劑盒提取處理后火龍果果實(shí)的總RNA,將提取的總RNA樣品送至廣州基迪奧生物科技有限公司進(jìn)行RNA純度的檢測(cè),將檢測(cè)合格的RNA樣品進(jìn)行mRNA的富集、雙鏈cDNA的合成和文庫(kù)構(gòu)建,采用Illumina"HiSeqTM"2500平臺(tái)進(jìn)行轉(zhuǎn)錄組測(cè)序[20-22]。利用RSEM軟件的bowtie2將Trinity拼接得到的轉(zhuǎn)錄組作為參考序列。為保證測(cè)序得到的原始數(shù)據(jù)的質(zhì)量,對(duì)raw"reads數(shù)據(jù)進(jìn)行過(guò)濾,剔除低質(zhì)量數(shù)據(jù),將過(guò)濾后的clean"reads與參考轉(zhuǎn)錄組進(jìn)行比對(duì)。
1.2.2""基因富集和差異表達(dá)基因可視化分析""對(duì)read"count數(shù)據(jù)進(jìn)行標(biāo)準(zhǔn)化處理,然后利用DESeq技術(shù)對(duì)處理組和對(duì)照組序列進(jìn)行差異分析[22]。對(duì)差異基因進(jìn)行GO功能富集分析,篩選條件為P≤0.05;KEGG富集分析,篩選條件為Q≤0.05。利用FDR與log2FC來(lái)篩選差異基因,篩選條件為FDR≤0.05且|log2FC|gt;1。使用GOseqR軟件對(duì)差異表達(dá)基因進(jìn)行GO富集分析,使用KOBASs軟件對(duì)差異表達(dá)基因進(jìn)行KEGG富集分析,使用TBtools軟件制作熱圖。
2.1""表型分析
為探究茉莉酸甲酯對(duì)白肉火龍果采后成熟的影響,本研究對(duì)處理16"d的白肉火龍果果實(shí)硬度和可溶性固形物含量進(jìn)行分析,結(jié)果如圖1所示。與對(duì)照組相比,MeJA處理導(dǎo)致白肉火龍果果實(shí)硬度增加了17.1%,果實(shí)內(nèi)部可溶性固形物減少了20.8%,表明MeJA處理可能通過(guò)調(diào)控火龍果果實(shí)硬度和可溶性固形物含量影響火龍果采后成熟。
2.2""測(cè)序基因質(zhì)量評(píng)估
CK和MeJA處理的測(cè)序數(shù)據(jù)經(jīng)過(guò)過(guò)濾低質(zhì)量數(shù)據(jù)后分別獲得19"847"126和22"263"172條有效序列,分別占原始序列總數(shù)的95.53%和96.73%。CK和MeJA處理的低質(zhì)量reads數(shù)的占比分別為4.45%和3.24%。將過(guò)濾后的數(shù)據(jù)與參考基因組序列進(jìn)行比對(duì),發(fā)現(xiàn)CK和MeJA處理中可以比對(duì)到唯一基因上的reads數(shù)分別占總reads數(shù)的10.90%和18.17%,表明白肉火龍果基因組注釋信息相對(duì)較少。此外,分析利用測(cè)序飽和度檢測(cè)白肉火龍果的測(cè)序量和檢測(cè)到的基因數(shù)量之間的協(xié)同性,結(jié)果發(fā)現(xiàn)MeJA處理中被檢測(cè)基因數(shù)量飽和曲線較CK更快達(dá)到飽和,因此測(cè)序數(shù)據(jù)足以滿足后續(xù)分析的要求。
2.3""MeJA處理白肉火龍果的差異表達(dá)基因分析
對(duì)CK與MeJA處理的白肉火龍果果實(shí)組織中的差異表達(dá)基因分析,結(jié)果顯示MeJA處理導(dǎo)致15"596個(gè)基因差異表達(dá),其中6135個(gè)基因上調(diào),9461個(gè)基因下調(diào),差異表達(dá)基因中下調(diào)基因的數(shù)目明顯高于上調(diào)基因數(shù),下調(diào)基因數(shù)目占總差異基因數(shù)目的60.66%,這說(shuō)明MeJA處理可能通過(guò)在分子水平上影響多個(gè)基因的表達(dá),進(jìn)而影響果實(shí)采后成熟(圖2)。
2.4""差異表達(dá)基因的GO功能顯著性富集分析
利用COG(Cluster"of"Orthologous"Groups"of"proteins)數(shù)據(jù)庫(kù)對(duì)MeJA處理的白肉火龍果差異表達(dá)基因進(jìn)行功能分類(lèi),其中GO分為3個(gè)大類(lèi),分別是生物過(guò)程(biological"process)、細(xì)胞組分(cellular"component)和分子功能(molecular"function)。由圖3可知,MeJA處理16"d后,差異表達(dá)基因共涉及45個(gè)GO分類(lèi)條目,其中參與生物過(guò)程、分子功能和細(xì)胞組分相關(guān)的GO條目分別有18、12和15條,分別占總數(shù)的40.0%、26.7%和33.3%。參與生物過(guò)程的差異基因主要主要包括代謝過(guò)程(2124個(gè)上調(diào),2495個(gè)下調(diào))、多組織過(guò)程(122個(gè)上調(diào),122個(gè)下調(diào))、單一組織過(guò)程(1555個(gè)上調(diào),1951個(gè)下調(diào))和生物調(diào)節(jié)(670個(gè)上調(diào),698個(gè)下調(diào))等;參與細(xì)胞組分的差異基因主要包括細(xì)胞組分(1646個(gè)上調(diào),2018個(gè)下調(diào))、膜及膜組分(1120個(gè)上調(diào),1652個(gè)下調(diào))和細(xì)胞器及其組分(1529個(gè)上調(diào),2249個(gè)下調(diào))等相關(guān)過(guò)程的基因;參與分子功能的差異基因主要包括催化活性(1888個(gè)上調(diào),2207個(gè)下調(diào))、結(jié)合活性(1752個(gè)上調(diào),1793個(gè)下調(diào))和轉(zhuǎn)運(yùn)活性(168個(gè)上調(diào),215個(gè)下調(diào))等。從顯著富集的GO分類(lèi)條目可知,MeJA處理16"d后火龍果的差異表達(dá)基因主要參與多組織過(guò)程、發(fā)育過(guò)程、生物節(jié)律、細(xì)胞連接、膜及膜組分、電子載體活性和催化活性等,其中下調(diào)表達(dá)的差異基因均多于上調(diào)表達(dá)差異基因。
2.5""差異基因的KEGG基因通路富集分析
利用KEGG數(shù)據(jù)庫(kù)對(duì)差異表達(dá)基因進(jìn)行代謝通路富集分析,白肉火龍果在MeJA處理16"d的差異表達(dá)基因被注釋到125條代謝通路(KEGG"Pathway)上,富集最為顯著的前20條通路如圖4所示。其中,富集差異基因數(shù)目最多的途徑主要包括核糖體途徑(ko03010)、碳循環(huán)途徑(ko01200)、氧化磷酸化(ko00190)、光合碳固定(ko00710)、氨糖和核糖代謝(ko00520)和乙醛酸代謝(ko00630)等途徑。擁有差異表達(dá)基因數(shù)目最多的是核糖體途徑,該途徑中鑒定出103個(gè)上調(diào)表達(dá)基因和221個(gè)下調(diào)表達(dá)基因。同時(shí),碳循環(huán)途徑所含的差異表達(dá)基因僅次于核糖體途徑,分別有106個(gè)上調(diào)表達(dá)基因和156個(gè)下調(diào)表達(dá)基因。此外,參與氧化磷酸化和TCA循環(huán)途徑的差異表達(dá)基因分別為161(117個(gè)下調(diào)表達(dá)基因,44個(gè)上調(diào)表達(dá)基因)和70個(gè)(19個(gè)上調(diào)表達(dá)基因,51個(gè)下調(diào)表達(dá)基因)。
KEGG基因通路富集分析與GO功能富集分析結(jié)果一致,表現(xiàn)為差異表達(dá)基因主要參與細(xì)胞內(nèi)三羧酸循環(huán)、氧化磷酸化過(guò)程、有機(jī)體碳循環(huán)和氨基酸代謝等過(guò)程。上述結(jié)果表明,MeJA可能通過(guò)影響白肉火龍果果實(shí)內(nèi)能量代謝和物質(zhì)循環(huán)等過(guò)程,進(jìn)而影響白肉火龍果果實(shí)的采后成熟。
2.6""MeJA處理下白肉火龍果果實(shí)生長(zhǎng)素和乙烯通路相關(guān)基因的表達(dá)變化
植物激素是一類(lèi)對(duì)植物代謝和生長(zhǎng)發(fā)育具有重要調(diào)控作用的化學(xué)物質(zhì)。為進(jìn)一步探究MeJA調(diào)控白肉火龍果采后成熟的機(jī)制,本研究分析MeJA處理16"d的白肉火龍果果實(shí)的轉(zhuǎn)錄組數(shù)據(jù),并對(duì)轉(zhuǎn)錄組中激素信號(hào)途徑響應(yīng)相關(guān)的蛋白編碼基因的轉(zhuǎn)錄水平進(jìn)行比較分析,包括15個(gè)生長(zhǎng)素響應(yīng)因子ARF(auxin-response"factor)、5個(gè)生長(zhǎng)素外排轉(zhuǎn)運(yùn)蛋白PIN(auxin"efflux"carrier"component)、3個(gè)生長(zhǎng)素結(jié)合蛋白ABP(auxin-binding"protein)"以及乙烯信號(hào)轉(zhuǎn)導(dǎo)途徑中3個(gè)乙烯上游受體因子ETR(ethylene"receptor)、5個(gè)EIN成員(ethylene"insensitive"protein)和24個(gè)乙烯響應(yīng)因子ERF/ABI4/CRF(ethylene-responsive"transcription"factor)等。由圖5可知,與CK相比,MeJA處理導(dǎo)致13個(gè)生長(zhǎng)素代謝途徑相關(guān)基因的表達(dá)量明顯上調(diào),且至少上調(diào)1.2倍。其中IAA16(Unigene0000823)、ARF(Unigene0013726)、ARF18(Unigene0017453)以及PIN(Unigene 0053295)等基因的表達(dá)量甚至上調(diào)約13倍。同時(shí),MeJA也導(dǎo)致20個(gè)生長(zhǎng)素相關(guān)基因的表達(dá)量顯著下調(diào)。此外,MeJA導(dǎo)致4個(gè)乙烯相關(guān)基因(Unigene0011639、Unigene0028216、Unigene00 40632和Unigene0044750)的表達(dá)量上調(diào)12倍,8個(gè)乙烯信號(hào)途徑基因的表達(dá)量下調(diào)10倍以上,包括EIN3(Unigene0012846)、ERF(Unigene 0015368、Unigene0019345和Unigene0037933)、CRF(Unigene0022674)、ABI(Unigene0016273)、ABR(Unigene0017926)和ERS(Unigene0028469)。以上結(jié)果表明MeJA通過(guò)影響生長(zhǎng)素和乙烯信號(hào)途徑來(lái)影響白肉火龍果采后成熟過(guò)程。
2.7""MeJA處理下白肉火龍果果實(shí)生長(zhǎng)素和乙烯通路相關(guān)基因的轉(zhuǎn)錄差異
對(duì)MeJA處理的白肉火龍果果實(shí)中差異表達(dá)基因進(jìn)行進(jìn)一步篩選,其中與細(xì)胞壁代謝相關(guān)的基因共篩選到58個(gè),主要包括果膠酶(pectinase)家族基因PE、多聚半乳糖醛酸酶(polygalact uronase)基因PG、木葡聚糖內(nèi)糖基轉(zhuǎn)移酶(xyloglucan"endotransglucosylase)基因XTH和細(xì)胞壁水解酶(cell"wall-associated"hydrolase)基因CWH等(圖6)。其中,有22個(gè)細(xì)胞壁代謝相關(guān)編碼基因的表達(dá)量約降低10倍,如3個(gè)PE基因(Unigene0010738、Unigene0017116和Uni gene0029700)和11個(gè)PG基因(Unigene0007056、Unigene0011523、Unigene0011809和Unigene 0012855等);此外,13個(gè)細(xì)胞壁代謝相關(guān)基因的表達(dá)量顯著上調(diào),包括11個(gè)XTH(Unigene"0006676、Unigene0013995、Unigene0015122和Unigene0029787等)、1個(gè)PE(Unigene0013690)和1個(gè)PG(Unigene0018581)。綜上可知,MeJA可能通過(guò)降低細(xì)胞壁代謝相關(guān)基因的轉(zhuǎn)錄,進(jìn)而保持果實(shí)采后成熟階段細(xì)胞壁結(jié)構(gòu)的完整性,延緩果實(shí)軟化進(jìn)程。
2.8""MeJA處理對(duì)白肉火龍果果實(shí)內(nèi)呼吸代謝途徑關(guān)鍵基因的差異調(diào)控
采后果實(shí)的衰老受果實(shí)內(nèi)呼吸代謝途徑影響,而糖酵解(glycoslysis,"EMP)、檸檬酸循環(huán)(tricarboxylic"acid,"TCA)和磷酸戊糖途徑(pentose"phosphate"pathway,"PPP)是植物內(nèi)重要的呼吸代謝途徑。其中磷酸果糖激酶(phosphofructoskinase,PFK)、異檸檬酸脫氫酶(isocitrate"dehydrogenase,"IDH)、葡萄糖-6-磷酸脫氫酶(glucose-6-phosphate"dehydrogenase,"G6PDH)和6-磷酸葡萄糖酸脫氫酶(6-phosphogluconate"dehydrogenase,"6PGDH)是上述呼吸代謝過(guò)程中的關(guān)鍵限速酶,調(diào)控整個(gè)呼吸代謝過(guò)程的速率和呼吸代謝類(lèi)型的轉(zhuǎn)變。MeJA處理對(duì)白肉火龍果果實(shí)內(nèi)PFK、IDH、G6PDH和6PGDH等基因表達(dá)的調(diào)控如表1所示,與CK相比,MeJA處理16"d顯著抑制果實(shí)中PFK的轉(zhuǎn)錄,抑制果實(shí)內(nèi)EMP途徑,進(jìn)而降低了呼吸過(guò)程中底物的消耗。同時(shí),MeJA處理也導(dǎo)致2個(gè)IDH(Unigene0005502和Unige ne0008291)的表達(dá)量明顯下調(diào)和2個(gè)IDH(Unigene0028329和Unigene0030950)的表達(dá)量顯著上調(diào),進(jìn)而影響TCA循環(huán)的速率。此外,PPP途徑中多個(gè)G6PDH和6PGDH的表達(dá)量均明顯下調(diào)。綜上可知,MeJA可能通過(guò)影響呼吸代謝速率延緩果實(shí)衰老。
近年來(lái),水果保鮮技術(shù)是一個(gè)研究熱點(diǎn)。以前常用的保鮮方法是低溫冷藏,但是通過(guò)外源激素處理延長(zhǎng)果實(shí)的儲(chǔ)藏時(shí)間已經(jīng)成為保鮮技術(shù)的探索熱點(diǎn)。部分研究發(fā)現(xiàn),外源赤霉素處理有效延緩香蕉果實(shí)衰老進(jìn)程,保持果實(shí)品質(zhì),延長(zhǎng)了果實(shí)的貯藏期[23-25]。ZHOU等[25]發(fā)現(xiàn)0.5"mmol/L"IAA處理能夠調(diào)控抗氧化酶活性和細(xì)胞壁代謝相
關(guān)基因的表達(dá),維持芒果的采后品質(zhì)。火龍果作為我國(guó)熱帶亞熱帶地區(qū)重要的經(jīng)濟(jì)型水果,具有較高的經(jīng)濟(jì)價(jià)值和食用價(jià)值?;瘕埞麑?shí)主要于夏秋季節(jié)采收,這2個(gè)季節(jié)雨水較多,且火龍果果實(shí)水分多、含糖量高,不耐儲(chǔ)藏,一般在采后3"d出現(xiàn)黃化、萎蔫等現(xiàn)象,7"d后果皮出現(xiàn)皺縮,12"d后果實(shí)開(kāi)始出現(xiàn)腐爛[26]。研究發(fā)現(xiàn),MeJA處理能夠顯著影響番茄[27]、荔枝(Litchi"chinensis)[28]、獼猴桃(Actinidia"deliciosa)[29]和桃(Prunus"persica)[30]等果實(shí)的品質(zhì),明顯延長(zhǎng)果實(shí)儲(chǔ)藏時(shí)間,減少果實(shí)腐爛的機(jī)率。盡管多個(gè)研究均證實(shí)MeJA能改變果實(shí)的生理生化特性,延緩果實(shí)采后腐爛,但有關(guān)具體機(jī)制的報(bào)道仍不清楚[31-36]。
近年來(lái),隨著高通量測(cè)序技術(shù)的應(yīng)用,轉(zhuǎn)錄組測(cè)序分析技術(shù)逐步用來(lái)揭示植物響應(yīng)逆境脅迫和采后水果保鮮的機(jī)制。本研究通過(guò)利用轉(zhuǎn)錄組技術(shù)對(duì)MeJA處理的白肉火龍果果實(shí)進(jìn)行差異表達(dá)結(jié)果分析。高通量測(cè)序結(jié)果顯示,與CK相比,MeJA處理導(dǎo)致15"596個(gè)基因的表達(dá)量有顯著變化,其中上調(diào)表達(dá)基因有6135個(gè),下調(diào)表達(dá)基因有9461個(gè)。與對(duì)照組相比,火龍果響應(yīng)MeJA處理的差異表達(dá)基因分布于多個(gè)代謝途徑,具有功能多樣性。GO功能顯著性富集分析顯示,差異基因分布的范圍很廣,主要包括細(xì)胞代謝過(guò)程、生物調(diào)節(jié)、發(fā)育過(guò)程、催化活性、結(jié)合活性和轉(zhuǎn)運(yùn)活性等,這說(shuō)明MeJA調(diào)控白肉火龍果成熟過(guò)程的轉(zhuǎn)錄系統(tǒng)是一個(gè)高度開(kāi)放且敏感的表達(dá)系統(tǒng),其中大量基因的差異性表達(dá)影響果實(shí)內(nèi)眾多生物化學(xué)反應(yīng)過(guò)程。進(jìn)一步利用KEGG數(shù)據(jù)庫(kù)對(duì)差異基因進(jìn)行Pathway顯著性富集分析發(fā)現(xiàn),這些差異基因主要參與果實(shí)成熟過(guò)程中的生物代謝途徑,如TCA循環(huán)途徑、氧化磷酸化途徑和有機(jī)體碳循環(huán)途徑等,這與柿果和番茄中的研究結(jié)果相一致[37-38],表明MeJA能通過(guò)影響果實(shí)內(nèi)物質(zhì)代謝與循環(huán)影響果實(shí)成熟。
果實(shí)在成熟過(guò)程中會(huì)發(fā)生一系列生理改變,如果實(shí)顏色、內(nèi)容物、香氣物質(zhì)的含量變化[39]。果實(shí)的成熟是一個(gè)復(fù)雜的過(guò)程,涉及多種植物激素的參與,如生長(zhǎng)素和乙烯等。艾辛梓[38]發(fā)現(xiàn)外源生長(zhǎng)素2,"4-D能夠抑制櫻桃番茄果實(shí)中乙烯的產(chǎn)生和類(lèi)胡蘿卜素的積累,從而延緩果實(shí)成熟。本研究發(fā)現(xiàn)MeJA處理影響多個(gè)生長(zhǎng)素代謝途徑中相關(guān)基因的轉(zhuǎn)錄,表明MeJA通過(guò)影響生長(zhǎng)素的合成與降解影響果實(shí)成熟。在番茄中,敲除突變體ein3表現(xiàn)出果實(shí)不成熟的表型[39-40]。在番木瓜中,乙烯誘導(dǎo)的生長(zhǎng)素轉(zhuǎn)錄因子CpARF2被證實(shí)能夠與乙烯信號(hào)因子CpEIL1發(fā)生互作,增強(qiáng)CpEIL1對(duì)下游細(xì)胞壁代謝基因CpXTH12和CpPE51的表達(dá),進(jìn)而促進(jìn)果實(shí)成熟[41]。本研究發(fā)現(xiàn)8個(gè)乙烯信號(hào)途徑相關(guān)基因(如EIN3、ERF、CRF和ABR等)的表達(dá)水平受MeJA處理顯著抑制,表明MeJA可能通過(guò)抑制乙烯的生成延緩果實(shí)衰老。細(xì)胞壁代謝相關(guān)酶類(lèi)在促進(jìn)果實(shí)成熟方面發(fā)揮重要作用,如果膠甲酯酶、多聚半乳糖醛酸酶和木葡聚糖內(nèi)糖基轉(zhuǎn)移酶等[41]。本研究發(fā)現(xiàn),MeJA處理導(dǎo)致多個(gè)參與細(xì)胞壁代謝的基因表達(dá)量呈現(xiàn)出差異變化,其中22個(gè)細(xì)胞壁代謝相關(guān)基因的表達(dá)量下調(diào)約10倍,而13個(gè)相關(guān)基因的表達(dá)量上調(diào),這與WANG等[42]在藍(lán)莓和蘋(píng)果中的研究結(jié)果相一致,表明MeJA能夠影響細(xì)胞壁降解相關(guān)基因的表達(dá)量以延緩果實(shí)的軟化。
綜上,通過(guò)對(duì)MeJA處理組和CK對(duì)照組的果實(shí)樣品進(jìn)行RNA-seq分析,比較2組的差異基因可知,大量與果實(shí)生長(zhǎng)發(fā)育、生物代謝過(guò)程和激素信號(hào)轉(zhuǎn)導(dǎo)途徑有關(guān)的基因均參與了白肉火龍果對(duì)MeJA處理的響應(yīng)。MeJA通過(guò)調(diào)控白肉火龍果果實(shí)中激素(如生長(zhǎng)素和乙烯)信號(hào)途徑以及細(xì)胞壁代謝過(guò)程中相關(guān)基因的表達(dá),抑制白肉火龍果果實(shí)軟化,延長(zhǎng)果實(shí)的貯藏期。本研究初步探討了MeJA處理對(duì)白肉火龍果采后成熟的分子調(diào)控機(jī)制,為火龍果采后保鮮的研究奠定理論基礎(chǔ)。
參考文獻(xiàn)
[2]"SHAH"K,"CHEN"J"Y,"CHEN"J"X,"QIN"Y"H."Pitaya"nutrition,"biology,"and"biotechnology:"a"review[J]."International"Journal"of"Molecular"Sciences."2023,"24(18):"13986.
[9]"YU"W"Q,"ZHAO"R"R,"SHENG"J"P,"SHEN"L."SlERF2"is"associated"with"Methyl"jasmonate-mediated"defense"response"aganist"Botrytis"cinerea"in"tomato"fruit[J]."Journal"of"Agricultural"and"Food"Chemistry,"2018,"66(38):"9923-9932.
[10]"汪開(kāi)拓,"鄭永華,"唐文才,"李廷君,張卿."茉莉酸甲酯處理對(duì)葡萄果實(shí)NO和H2O2水平及植保素合成的影響[J]."園藝學(xué)報(bào),"2012,"39(8):"1559-1566.WANG"K"T,"ZHENG"Y"H,"TANG"W"C,"LI"T"J,"ZHANG"Q."Effects"of"methyl"jasmonate"treatment"on"levels"of"nitric"oxide"and"hydrogen"peroxide"and"phytoalexin"synthesis"in"postharvest"grape"berries[J]."Acta"Horticulturae"Sinica,"2012,"39(8):"1559-1566."(in"Chinese)
[11]"麻寶成,"朱世江."苯并噻重氮和茉莉酸甲酯對(duì)采后香蕉果實(shí)抗病性及相關(guān)酶活性的影響[J]."中國(guó)農(nóng)業(yè)科學(xué),"2006(6):"1220-1227.MA"B"C,"ZHU"S"J."Induction"of"disease"resistance"by"benzothiadiazole"and"methyl"jasmonate"in"relation"to"activities"of"defense-related"enzymes[J]."Scientia"Agricultura"Sinica,"2006(6):"1220-1227."(in"Chinese)
[12]"唐偉杰,"張瀠支,"張良,"呂靜祎,"孫明宇,"葛永紅,"陳敬鑫."不同濃度茉莉酸甲酯處理對(duì)“金冠”蘋(píng)果保鮮效果的影響[J]."包裝與食品機(jī)械,"2004,"42(1):"12-18.TANG"W"J,"ZHANG"Y"Z,"ZHANG"L,"LYU"J"Y,"SUN"M"Y,"GE"Y"H,"CHEN"J"X."Effects"of"different"concentrations"of"methy"jasmonate"treatment"on"preservation"of"'Jinguan'"apple"fruits[J]."Packaging"and"Food"Machinery,"2004,"42(1):"12-18."(in"Chinese)
[13]"HASAN"M"U,"SINGH"Z,"SHAH"H"M"S,"WOODWARD"A,"AFRIFA-YAMPAH"E."Methyl"jasmonate"advancs"fruit"ripening,"colour"development,"and"improves"antioxidant"quality"of"'Yoho'"and"'Jiro'"persimmon[J]."Food"Chemistry,"2024,"459:"140360.
[14]"弓德強(qiáng),"谷會(huì),"張魯斌,"洪克前,"朱世江."杧果采前噴施茉莉酸甲酯對(duì)其抗病性和采后品質(zhì)的影響[J]."園藝學(xué)報(bào),"2013,"40(1):"49-57.GONG"D"Q,"GU"H,"ZHANG"L"B,"HONG"K"Q,"ZHU"S"J."Effects"of"preharvest"methyl"jasmonate"spraying"on"disease"resistance"and"postharvest"quality"of"mango"fruits[J]."Acta"Horticulturae"Sinica,"2013,"40(1):"49-57."(in"Chinese)
[15]"孟麗,"張?zhí)m增,"周和云,"周森,"李玉."數(shù)字基因表達(dá)譜解析草菇子實(shí)體的生長(zhǎng)發(fā)育[J]."北方園藝,"2018(8):"149-154.MENG"L,"ZHANG"L"Z,"ZHOU"H"Y,"ZHOU"S,"LI"Y."Expression"profiling"reveals"volvariella"volvacea"fruiting"body"development[J]."Noethern"Horticulture,"2018(8):"149-154."(in"Chinese)
[16]"GUO"S"G,"LIU"J"G,"ZHENG"Y,"HUANG"M"Y,"ZHANG"H"Y,"GONG"G"Y,"HE"H"G,"REN"Y,"ZHONG"S"L,"FEI"Z"J,"XU"Y."Characterization"of"transcriptome"dynamics"during"watermelon"fruit"development:"sequencing,"assembly,"annotation"and"gene"expression"profiles[J]."BMC"Genomics,"2011,"12:"454.
[17]"李雄偉."桃種質(zhì)資源群體遺傳分析及果實(shí)數(shù)字基因表達(dá)譜構(gòu)建[D]."杭州:"浙江大學(xué),"2013.LI"X"W."Population"genetic"analysis"of"peach"germplasm"and"the"construction"of"digital"gene"expression"profilings"of"fruit[D]."Hangzhou:"Zhejiang"University,"2013."(in"Chinese)
[18]"杜紅鳳."冷脅迫下哈密瓜基因表達(dá)譜及相關(guān)抗性酶分析[D]."石河子:"石河子大學(xué),"2017."DU"H"F."Study"on"gene"expression"profile"and"the"related"resistant"enzymes"of"hami"melon"under"cold"stress[D]."Shihezi:"Shihezi"University,"2017."(in"Chinese)
[19]"李穆,"程志遠(yuǎn),"何麗蓮,"王先宏,"李富生."甘蔗印度種響應(yīng)干旱脅迫的數(shù)字基因表達(dá)譜[J]."分子植物育種,"2018,"16(7):"2099-2106."LI"M,"CHENG"Z"Y,"HE"L"L,"WANG"X"H,"LI"F"S."Digital"gene"expression"profiling"of"S."barberi"J."response"to"drought"stress[J]."Molecular"Plant"Breeding,"2018,"16(7):"2099-2106."(in"Chinese)
[20]"LIU"H"J,"YANG"X"R,"LIAO"X"H,"ZUO"T,"QIN"C,"CAO"S"L,"DONG"L,"ZHOU"H"K,"ZHANG"Y"Z,"LIU"S"S,"SHEN"Y"O,"LIN"H"J,"LüBBERSTEDT"T,"ZHANG"Z"M,"PAN"G"T."Genome-wide"comparative"analysis"of"digital"gene"expression"tag"profiles"during"maize"ear"development[J]."Genomics,"2015,"106(1):"52-60.
[21]"楊慧菊,"郭華春."低溫脅迫下馬鈴薯的數(shù)字基因表達(dá)譜分析[J]."作物學(xué)報(bào),"2017,"43(3):"454-463."YANG"H"J,"GUO"H"C."Digital"gene"expression"profiling"analysis"of"potato"under"low"temperature"stress[J]."Acta"Agronomica"Sinica,"2017,"43(3):"454-463."(in"Chinese)
[22]"ANDERS"S,"HUBER"W."Differential"expression"analysis"for"sequence"count"data[J]."Genome"Biology,"2010,"11(10):"R106.
[23]"尹培培,"包日雙,"戴佳錕,"尉亞輝."植物激素對(duì)植物器官發(fā)生影響的研究進(jìn)展[J]."江西農(nóng)業(yè)學(xué)報(bào),"2012,"24(6):"37-41."YIN"P"P,"BAO"R"S,"DAI"J"K,"WEI"Y"H."Research"advance"in"impact"of"phytohormone"on"plant"organogenesis[J]."Acta"Agriculturae"Jiangxi,"2012,"24(6):"37-41."(in"Chinese)
[24]nbsp;周傳悅,"程謙偉,"張定宇."外源赤霉素處理對(duì)采后香蕉生理生化的影響[J]."中國(guó)南方果樹(shù),"2023,"52(2):"78-83."ZHOU"C"Y,"CHENG"Q"W,"ZHANG"D"Y."Effects"of"exogenous"gibberellin"treatment"on"physiology"and"biochemistry"of"postharvest"banana[J]."South"China"Fruits,"2023,"52(2):"78-83."(in"Chinese)
[25]"ZHOU"Y,"LIU"J"M,"ZHUO"Q"Y,"ZHANG"K"Y,"YAN"J"L,"TANG"B"M,"WEI"X"Y,"LIN"L"J,"LIU"K"D."Exogenous"glutathione"maintains"the"postharvest"quality"of"mango"fruit"by"modulating"the"ascorbate-glutathione"cycle[J]."PeerJ,"2023,"11:"e15902.
[26]"王生有,"陳于隴,"徐玉娟,"吳繼軍,"肖更生."火龍果采后生理和保鮮技術(shù)的研究進(jìn)展[J]."食品工業(yè)科技,"2014,"35(13):"396-400."""""WANG"S"Y,"CHEN"Y"L,"XU"Y"J,"WU"J"J,"XIAO"G"S."Progress"in"postharvest"physiology"and"preservative"technology"of"pitaya[J]."Science"and"Technology"of"Food"Industry,"2014,"35(13):"396-400."(in"Chinese)
[27]"RIVERO"MEZA"S"L,"DE"CASTRO"TOBARUELA"E,"BENEDETTI"PASCOAL"G,"LOURO"MASSARETTO"I,"PURGATTO"E."Post-Harvest"treatment"with"methyl"jasmonate"impacts"lipid"metabolism"in"tomato"pericarp"(Solanum"lycopersicum"L."cv."Grape)"at"different"ripening"stages[J]."Foods,"2021,"10(4):"877.
[28]"HE"M"Y,"YIN"F"L,"PAK"DEK"M,"LIAO"L"Y,"LIU"Y"F,"LIANG"Y"L,"CAI"W,"HUANG"L"L,"SHUAI"L."Methyl"jasmonate"delays"the"browning"of"litchi"pericap"by"activating"the"phenylpropanoid"metabolismnbsp;during"cold"storage[J]."Postharvest"Biology"and"Technology,"2025,"219:"113278.
[29]"PAN"L"Y,"ZHAO"X"Y,"CHEN"M,"FU"Y"G,"XIANG"M,"CHEN"J"Y."Effect"of"exogenous"methyl"jasmonate"treatment"on"disease"resistance"of"postharvest"kiwifruit[J]."Food"Chemistry,"2020,"305:"125483.
[30]"JIN"P,"ZHU"H,"WANG"J,"CHEN"J"G,"WANG"X"L,"ZHENG"Y"H."Effect"of"methyl"jasmonate"on"energy"metabolism"in"peach"fruit"during"chilling"stress[J]."Science"of"Food"and"Agriculture."2013,"93(8):"1827-1832.
[31]"DING"X"Y,"WANG"B,"GONG"Y"B,"YAN"X"Q,"CHEN"X"X,"ZHONG"Y"W,"ZHAO"Z"Y."Exogenous"methyl"jasmonate"(MeJA)"improves"‘Ruixue’"apple"fruit"quality"by"regulating"cell"wall"metabolism[J]."Foods,"2023,"13(11):"1594.
[32]"CAO"S"F,"CAI"Y"T,"YANG"Z"F,"JOYCE"D"C,"ZHENG"Y"H."Effect"of"MeJA"treatment"on"polyamine,"energy"status"and"anthracnose"rot"of"loquat"fruit[J]."Food"Chemistry,"2014,"145:"86-89.
[33]"DESHI"V,"HOMA"F,"GHATAK"A,"AFTAB"M"A,"MIR"H,"OZTURK"B,"SIDDIQUI"M"W."Exogenous"methyl"jasmonate"modulates"antioxidant"activities"and"delays"pericarp"browning"in"litchi[J]."Physiology"and"Molecular"Biology"of"Plants,"2022,"28(8):"1561-1569.
[34]"LIU"G"Y,"LI"B,"LI"X"Q,"WEI"Y"X,"LIU"D"B,"SHI"H"T."Comparative"physiological"analysis"of"methyl"jasmonate"in"the"delay"of"postharvest"physiological"deterioration"and"cell"oxidative"damage"in"cassava[J]."Biomolecules,"2019,"9(9):"451.
[35]"LI"J"Z,"MIN"D"D,"LI"Z"L,"FU"X"D,"ZHAO"X"M,"WANG"J"H,"ZHANG"X"H,"LI"F"J,"LInbsp;X"A,"GUO"Y"Y."Regulation"of"sugar"metabolism"by"methyl"jasmonate"to"improve"the"postharvest"quality"of"tomato"fruit[J]."Journal"of"Plant"Growth"Regulation,"2022,"41:"1615-1626.
[36]"WANG"S"Y,"SHI"X"C,"LIU"F"Q,"PEDRO"L."Effects"of"exogenous"methyl"jasmonate"on"quality"and"preservation"of"postharvest"fruits:"a"review[J]."Food"Chemistry,"2021,"353:"129482.
[37]"LIU"M"P,"WANG"R,"SUN"W"W,"HAN"W"J,"LI"G,"ZONG"W,"FU"J"M."Effects"of"postharvest"calcium"treatments"on"the"firmness"of"persimmon"(Diospyros"kaki)"fruit"based"on"a"decline"in"WSP[J]."Scientia"Horticulturae,"2023,"307:"111490.
[38]"艾辛梓."外源生長(zhǎng)素對(duì)番茄采后成熟過(guò)程中蔗糖代謝和芳香物質(zhì)的影響[D]."杭州:"浙江大學(xué),"2019."AI"X"Z."Effect"of"exogenous"auxin"on"surcose"metabolism"and"aroma"volatiles"of"cherry"tomato"(Solanum"lycopersicum"L.)"fruit"during"postharvest"ripening[D]."Hanghzou:"Zhejiang"University,"2019."(in"Chinese)
[39]"HUANG"W,"HU"N,"XIAO"Z,"QIU"Y"P,"YANG"Y,"YANG"J,"MAO"X,"WANG"Y"H,"LI"Z"G,"GUO"H"W."A"molecular"framework"of"ethylene-mediated"fruit"growth"and"ripening"processes"in"tomato[J]."Plant"Cell,"2022,"34(9):"3280-3300.
[40]"DENG"L,"YANG"T"X,"LI"Q,"CHANG"Z"Q,"SUN"C"L,"JIANG"H"L,"MENG"X"W,"HUANG"T"T,"LI"C"B,"ZHONG"S"L,"LI"C"Y."Tomato"MED25"regulates"fruit"ripening"by"interacting"with"EIN3-"like"transcription"factors[J]."Plant"Cell,"2023,"35(3):"1038-1057.
[41]"ZHANG"T,"LI"W"J,"XIE"R"X,"XU"L,"ZHOU"Y,"LI"H"L,"YUAN"C"C,"ZHENG"X"L,"XIAO"L"T,"LIU"K"D."CpARF2"and"CpEIL1"interact"to"mediate"auxin-ethylene"interaction"and"regulate"fruit"ripening"in"papaya[J]."The"Plant"Journal,"2020,"103(4):"1318-1337.
[42]"WANG"H"B,"CHENG"X,"WU"C,"FAN"G"J,"LI"T"T,"DONG"C."Retardation"of"postharvest"softening"of"blueberry"fruit"by"methyl"jasmonate"is"correlated"with"altered"cell"wall"modification"and"energy"metabolism[J]."Scientia"Horticulturase,"2021,"276:"109752.