孔凡江,趙曉暉,劉寶輝
(中國(guó)科學(xué)院 東北地理與農(nóng)業(yè)生態(tài)研究所 大豆分子設(shè)計(jì)育種重點(diǎn)實(shí)驗(yàn)室,黑龍江 哈爾濱 150081)
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大豆光周期調(diào)控開(kāi)花與產(chǎn)量性狀的研究進(jìn)展
孔凡江,趙曉暉,劉寶輝
(中國(guó)科學(xué)院 東北地理與農(nóng)業(yè)生態(tài)研究所 大豆分子設(shè)計(jì)育種重點(diǎn)實(shí)驗(yàn)室,黑龍江 哈爾濱 150081)
摘要:大豆作為重要的經(jīng)濟(jì)作物,是人類植物油和植物蛋白的主要來(lái)源,但目前我國(guó)大豆產(chǎn)業(yè)面臨嚴(yán)峻的挑戰(zhàn)。大豆光周期開(kāi)花不僅影響大豆的種植適應(yīng)性,而且決定著大豆的產(chǎn)量。文章闡述了大豆特有的光周期開(kāi)花調(diào)控途徑PhyA-E1-FT,同時(shí)論述了光周期開(kāi)花調(diào)控基因間的相互作用關(guān)系。大豆光周期反應(yīng)中重要基因的克隆為理解開(kāi)花期和生育期分子機(jī)理提供理論基礎(chǔ),同時(shí)對(duì)大豆分子育種和提高大豆產(chǎn)量具有重要意義。圖1,參53。
關(guān)鍵詞:大豆;光周期;生育期;開(kāi)花期;產(chǎn)量
0引言
在植物生命循環(huán)過(guò)程中,開(kāi)花是一個(gè)很重要的標(biāo)志,它標(biāo)志著植物由營(yíng)養(yǎng)生長(zhǎng)向生殖生長(zhǎng)的重要轉(zhuǎn)變,是在整合外界環(huán)境因子(如光、溫度)和植物本身內(nèi)源信號(hào)基礎(chǔ)上的外在表現(xiàn)[1-2]。對(duì)開(kāi)花起重要調(diào)控作用的是光周期[3- 4],植物能夠隨著日照長(zhǎng)短的變化而改變的現(xiàn)象被稱為光周期現(xiàn)象(Photoperiodism)[5]。大豆是典型的短日照作物,即在短日照條件下(小于12小時(shí)光照)比在長(zhǎng)日照條件下(大于16小時(shí)光照)開(kāi)花明顯提前,而且韓天富證明了大豆的光周期反應(yīng)不僅存在于開(kāi)花前,而且在開(kāi)花后的鼓粒期至成熟期都存在[6]。大豆光周期的研究不僅具有重要的理論意義,而且在農(nóng)業(yè)上對(duì)指導(dǎo)大豆開(kāi)花及產(chǎn)量提高具有重要的實(shí)踐意義。文章綜述了大豆主要生育期基因的研究現(xiàn)狀及目前所揭示的大豆光周期調(diào)控途徑,并分析了光周期對(duì)大豆產(chǎn)量性狀的調(diào)控作用。
1大豆主要生育期基因的研究現(xiàn)狀
大豆生育期(開(kāi)花期和開(kāi)花后期)特別是開(kāi)花期是大豆光周期反應(yīng)的重要指標(biāo),是重要的農(nóng)藝性狀,對(duì)大豆的產(chǎn)量、品質(zhì)和適應(yīng)性至關(guān)重要。根據(jù)經(jīng)典遺傳學(xué)的研究方法,對(duì)近等基因系進(jìn)行比較,已發(fā)現(xiàn)了10個(gè)控制大豆開(kāi)花期和成熟期基因位點(diǎn),分別是E1、E2[7]、E3[8]、E4[9]、E5[10]、E6[11]、E7[12]、E8[13]、E9[14]和J[15],這些基因位點(diǎn)如果是顯性,則在自然晝長(zhǎng)的情況下表現(xiàn)為延遲花期與延長(zhǎng)成熟期的作用,但是每個(gè)基因影響的程度卻不一樣[16]。在已知的這些E系列基因位點(diǎn)中,E1-E4和E9研究較為深入,均已被分子克隆。
大豆生育期基因E3和E4不但與大豆開(kāi)花期和成熟期有關(guān),同時(shí)也與光周期的敏感性有關(guān)。大豆植株在人工控制的不同紅光∶遠(yuǎn)紅光(R∶FR)量子比的光質(zhì)量下會(huì)產(chǎn)生不同的反應(yīng)[17]。通過(guò)用熒光燈以較高的R∶FR比延長(zhǎng)至20小時(shí),第一次證實(shí)了E3位點(diǎn),其隱形純合體在長(zhǎng)日照條件下早花[8]。通過(guò)用白熾燈以低的R∶FR比延長(zhǎng)自然光至20小時(shí),又發(fā)現(xiàn)了E4位點(diǎn)[9],e4e4隱性等位基因并不能單獨(dú)的對(duì)光周期產(chǎn)生不敏感性。因此,大豆植株在長(zhǎng)日照條件下提前開(kāi)花,必須攜帶隱性純合基因e3[9,17-18]。因此,E3和E4雙顯性基因型延遲開(kāi)花和成熟,對(duì)光周期反應(yīng)敏感;而純合雙隱性基因型提早開(kāi)花和成熟,對(duì)光周期反應(yīng)不敏感。E3基因的效應(yīng)大于E4,并且對(duì)E4具有上位性作用[18]。2009年Watanabe等利用圖位克隆方法將E3基因克隆出來(lái),E3基因是大豆光敏色素A基因的一個(gè)拷貝(GmphyA3)。此外,還發(fā)現(xiàn)E3位點(diǎn)在栽培品種中存在兩種自然突變類型,一種是光敏色素第四個(gè)外顯子缺失的Harosoy-e3類型,另一種是在第三個(gè)外顯子上氨基酸置換的Misuzudaizu類型[19]。Liu等首次將E4基因克隆出來(lái)并證明其為大豆光敏色素A基因之一(GmphyA2),e4突變型是由于在GmphyA2基因第一個(gè)外顯子上插入一個(gè)LTR型的反轉(zhuǎn)錄轉(zhuǎn)座子SORE1,因此造成該基因失活。光敏色素A基因的另一個(gè)拷貝GmphyA1基因被定位在連鎖群O,與連鎖群I的E4位點(diǎn)區(qū)域是同源的。在連續(xù)的遠(yuǎn)紅光下,純合體e4等位基因的植株表現(xiàn)出黃化,也有部分非黃化的植株,表明e4單突變并不能促使GmphyA功能的完全喪失[20]。
大豆生育期基因E2為擬南芥GIGANTEA(GI)的同源基因GmGIa。Watanabe等成功克隆了E2基因,并發(fā)現(xiàn)大豆品種Misuzudaizu以及Harosoy近等基因系材料的DNA序列第10個(gè)外顯子上有單堿基突變,恰好導(dǎo)致終止密碼子產(chǎn)生,使E2基因的翻譯提前終止,以至于功能發(fā)生了改變。在自然光照條件下e2基因型的開(kāi)花期明顯提前,并且e2突變體中的開(kāi)花整合因子GmFT2a基因被上調(diào)表達(dá)。大豆E2及其近等基因系材料(e2)在高緯度43°N和中緯度36°N的開(kāi)花時(shí)間相近,表明E2基因?qū)Υ蠖归_(kāi)花期的調(diào)控可能不依賴于光周期,以至于地理適應(yīng)性更強(qiáng)[21]。E2基因?qū)ι谪暙I(xiàn)大,對(duì)光周期反應(yīng)影響小,而且受外在環(huán)境影響較小。因此,E2基因在育種實(shí)踐上具有廣闊的應(yīng)用前景。
大豆生育期基因E1對(duì)開(kāi)花期及成熟期影響最大[7,22-25]。Xia等用Harosoy-E1(E1e2E3E4e5)與 Harosoy(e1e2E3E4e5)建立的群體,成功地實(shí)現(xiàn)了該基因的克隆。E1基因含有一個(gè)雙邊核定位信號(hào)和DNA結(jié)合位點(diǎn),并含有一個(gè)B3結(jié)構(gòu)域,其編碼蛋白定位在細(xì)胞核中,而且E1是豆科植物特有的轉(zhuǎn)錄因子。在短日照條件下E1基因的表達(dá)受到明顯抑制,而長(zhǎng)日照條件下則表現(xiàn)出雙峰的晝夜節(jié)律模式,表明E1基因受光周期調(diào)控,且長(zhǎng)日照條件誘導(dǎo)E1的表達(dá)。然而,在e3/e4遺傳背景下E1被長(zhǎng)日照誘導(dǎo)表達(dá)的作用卻被消除,表明E1基因受控于E3和E4。以早花品種Kariyutaka為受體材料進(jìn)行大豆轉(zhuǎn)基因,超表達(dá)E1的轉(zhuǎn)基因株系與對(duì)照相比大大延遲開(kāi)花,并且下調(diào)關(guān)鍵開(kāi)花基因GmFT2a和GmFT5a的表達(dá)[26]。即便是在e3/e4遺傳背景下,E1基因也表現(xiàn)出抑制開(kāi)花的作用,尤其在遠(yuǎn)紅光豐富的長(zhǎng)日照條件及R∶FR量子比小于1的條件下[17]。最近Xu等對(duì)E1家族基因E1-like-a(E1La)和E1Lb在大豆光周期方面的分子基礎(chǔ)進(jìn)行研究,通過(guò)光暗轉(zhuǎn)移試驗(yàn)(Transitionbetween light and dark phases)和暗中斷試驗(yàn)(Night-break experiment)研究發(fā)現(xiàn),E1家族基因僅僅在有光的條件下表達(dá),而且前一天黃昏前的光照誘導(dǎo)對(duì)E1家族基因的表達(dá)起關(guān)鍵作用。進(jìn)一步研究發(fā)現(xiàn)E1-like基因和E1在功能上是相同的,把E1家族基因沉默掉以后大豆植株表現(xiàn)出早花以及成熟期提前[27]。這些結(jié)果表明E1及其同家族基因在抑制大豆開(kāi)花期和成熟期方面起關(guān)鍵作用。隨著E1基因的成功克隆、同家族基因的功能分析及對(duì)其作用機(jī)制的深入研究,可進(jìn)一步揭示大豆特有的光周期反應(yīng)及開(kāi)花調(diào)控機(jī)制。
在隱性純合e1-nl背景下,利用兩個(gè)回交雜交群體,Kong等發(fā)現(xiàn)了E9基因,顯性純合的E9E9基因控制早花,隱性純合的e9e9基因控制晚花[14]。通過(guò)圖位克隆的方法,Zhao等克隆了E9基因,證明E9由大豆GmFT2a基因編碼,隱性e9基因由于在GmFT2a基因的第一個(gè)內(nèi)含子插入了反轉(zhuǎn)錄轉(zhuǎn)座子SORE1,導(dǎo)致GmFT2a基因的表達(dá)量降低,從而使其功能受到抑制,延遲大豆開(kāi)花。進(jìn)一步研究表明,反轉(zhuǎn)錄轉(zhuǎn)座子SORE1插入GmFT2a基因內(nèi)含子兩側(cè)DNA區(qū)域存在著甲基化現(xiàn)象,GmFT2a基因的內(nèi)含子序列中可能存在該基因的順式調(diào)控元件,這一區(qū)域的甲基化影響了GmFT2a基因的表達(dá)[28]。
2大豆光周期調(diào)控途徑
隨著分子生物學(xué)技術(shù)的不斷進(jìn)步和更新,擬南芥中對(duì)開(kāi)花貢獻(xiàn)起關(guān)鍵作用的基因已被鑒定和分離,對(duì)這些基因的研究,使人們對(duì)植物開(kāi)花調(diào)控的分子機(jī)制得以不斷深入。對(duì)模式植物擬南芥的光周期開(kāi)花途徑研究的較為透徹,首先通過(guò)光受體(Photoreceptors)感受光信號(hào),然后傳遞此信號(hào)給生物節(jié)律鐘(Circadian clock),由其產(chǎn)生生物節(jié)律(Circadian rhythm),但也并不是所有光受體調(diào)控的開(kāi)花都是通過(guò)生物鐘來(lái)實(shí)現(xiàn)的[29-30]。然后將節(jié)律輸出給下游的節(jié)律調(diào)節(jié)基因(Circadian regulated genes)GI。GI的表達(dá)以及功能發(fā)揮還會(huì)受到光受體的直接調(diào)控。節(jié)律調(diào)節(jié)基因通過(guò)輸出基因CO(CONSTANS)調(diào)控下游的開(kāi)花時(shí)間基因(Flowering time genes),如成花途徑整合因子(Floral integrators)FT基因,從而調(diào)控花分生組織識(shí)別基因(Floral meristem identity genes)的表達(dá),最終控制擬南芥的開(kāi)花時(shí)間。因此,擬南芥開(kāi)花轉(zhuǎn)變的光周期途徑為GI-CO-FT模式。其中CO基因在光周期調(diào)控中起重要的調(diào)節(jié)作用,由Putterill采用圖位克隆的方法分離得到,CO編碼鋅指蛋白轉(zhuǎn)錄因子[31],是植物生物鐘與開(kāi)花之間的橋梁。在韌皮部表達(dá)的CO能夠激活開(kāi)花植物FT的表達(dá),而且有實(shí)驗(yàn)證明FT是CO蛋白的直接作用底物[32]。擬南芥FT蛋白轉(zhuǎn)移至莖尖生長(zhǎng)點(diǎn),促使SOC1、LFY、AP1等基因表達(dá),誘導(dǎo)植物開(kāi)花[33]。然而,Jung等研究發(fā)現(xiàn)在擬南芥的光周期途徑中GI除了調(diào)控CO基因表達(dá)以外,還調(diào)控miR172及其靶基因TOE1,即便是在缺失功能的co突變體中過(guò)表達(dá)miR172,無(wú)論長(zhǎng)日照還是短日照條件植株都會(huì)提前開(kāi)花,但最終也作用于FT基因[34]。因此,表明擬南芥miR172促進(jìn)光周期調(diào)控的開(kāi)花是不依賴于CO基因的一條獨(dú)特途徑,即GI-miR172-TOE1-FT模式。擬南芥miR172途徑的發(fā)現(xiàn)是對(duì)光周期調(diào)控開(kāi)花途徑的一個(gè)完善,具有重要意義。
在大豆光周期調(diào)控途徑中,目前已經(jīng)揭示了包括生育期基因E1-E4在內(nèi)的部分光周期調(diào)控大豆開(kāi)花網(wǎng)絡(luò),見(jiàn)圖1。Xu等在E3和E4基因型的大豆Harosoy近等基因系中分析E1及E1-like基因的表達(dá),結(jié)果顯示雖然在Harosoy-e3/e4材料中E1的表達(dá)模式與Harosoy(E3/E4)相同,但表達(dá)量卻顯著降低,甚至幾乎不表達(dá),充分證明E1及其同家族基因受到光受體基因E3和E4的調(diào)控,與Xia和Cao等的研究結(jié)果一致,Cao等還發(fā)現(xiàn)E3對(duì)E1影響比E4基因強(qiáng)烈[26-27,35]。通過(guò)大豆轉(zhuǎn)基因以及病毒誘導(dǎo)基因沉默技術(shù)(Virusinducedgene silencing,VIGS)鑒定E1及其家族基因的功能,結(jié)果顯示它們均是大豆開(kāi)花抑制因子,強(qiáng)烈延遲大豆開(kāi)花期及成熟期,但最終也是通過(guò)調(diào)控開(kāi)花基因GmFT2a和GmFT5a實(shí)現(xiàn)對(duì)開(kāi)花時(shí)間的控制[26-27]。GmFT2a和GmFT5a是大豆關(guān)鍵的開(kāi)花整合因子,在光周期途徑中協(xié)同調(diào)控開(kāi)花[36],但對(duì)下游基因的調(diào)控又是不同的[37],表明二者在功能上產(chǎn)生了分化,冗余且協(xié)調(diào)的發(fā)揮作用。其同源基因GmFT4功能與之相反,為大豆開(kāi)花抑制因子[38]。三個(gè)GmFT2a/5a/4基因均受到E1的調(diào)控。于是在大豆的光周期反應(yīng)中形成了以生育期基因E1為核心的調(diào)控開(kāi)花的主途徑,即E3/E4-E1-GmFT。由于E1基因是豆科作物特有的轉(zhuǎn)錄因子,在擬南芥和水稻等物種中沒(méi)有同源基因,所以E1基因的研究結(jié)果揭示了大豆基因組中獨(dú)特的控制開(kāi)花期與成熟期的調(diào)控途徑。
隨著對(duì)大豆光周期反應(yīng)研究的深入,在后續(xù)的研究中發(fā)現(xiàn)光周期調(diào)控開(kāi)花途徑中的很多基因都與E1存在相互調(diào)節(jié)作用。擬南芥CO-like基因GmCOL1a過(guò)表達(dá)的大豆轉(zhuǎn)基因株系在長(zhǎng)日照條件和自然光照條件下表現(xiàn)出延遲開(kāi)花,gmcol1b突變體與非轉(zhuǎn)基因的對(duì)照相比為早花表型,表明大豆CO-like基因是大豆開(kāi)花抑制因子,并且調(diào)控下游開(kāi)花基因GmFT2a/5a和GmFT4的表達(dá)。當(dāng)GmCOL1a過(guò)表達(dá)時(shí)下調(diào)大豆生育期基因E1和E2,而在E1和E2的近等基因系材料中GmCOL1a卻被上調(diào)表達(dá),所以極有可能在GmCOL1a、E1和E2基因之間存在反饋調(diào)節(jié)環(huán),但仍需要進(jìn)一步試驗(yàn)驗(yàn)證。同時(shí),研究還發(fā)現(xiàn)E3和E4促進(jìn)E2和GmCOL1a/1b的表達(dá)[35]。然而,CO基因在調(diào)控植物開(kāi)花方面的功能是相對(duì)保守的,在很多物種中起到誘導(dǎo)開(kāi)花的作用,如擬南芥、水稻[39]、牽?;╗40-41]及小麥[42]等,而大豆GmCOL1a和GmCOL1b的功能卻與之相反,這可能與GmCOL1a/1b受到大豆特有轉(zhuǎn)錄因子E1的調(diào)控有關(guān),也可能與大豆基因組的復(fù)雜性有關(guān)。根據(jù)Cao等的研究結(jié)果不難發(fā)現(xiàn)GmCOL1a/1b基因受到GI同源基因E2的調(diào)控,并且調(diào)控GmFT2a/5a的表達(dá),所以大豆GmCOL1a/1b參與調(diào)控的光周期途徑也是相對(duì)保守的,與模式植物擬南芥相同為GI(E2)-CO-FT模式;又因E1基因?yàn)槎箍谱魑锼赜?,所以受E1調(diào)控的GmCOL1a/1b光周期途徑又是獨(dú)特的。
圖1 大豆光周期調(diào)控開(kāi)花網(wǎng)絡(luò)模式圖Fig.1 Proposed model for molecular network in the regulation of flowering time in soybean
植物miR172及其靶基因在生長(zhǎng)發(fā)育過(guò)程中發(fā)揮調(diào)控作用,并且miR172作用于miR156的下游促進(jìn)植物成年特征(Adult epidermal identity)的出現(xiàn)[43]。在光周期調(diào)控的大豆開(kāi)花網(wǎng)絡(luò)中miR156延遲開(kāi)花,而且E1基因也參與到miR156/GmSPL通路中[44]。miR156通過(guò)其靶基因GmSPL3/9調(diào)控miR172的表達(dá),miR172又通過(guò)靶基因GmTOE4a對(duì)miR156和GmSPL3/9進(jìn)行反饋調(diào)控[45]。因此,miR156和miR172之間可能存在著一定的平衡關(guān)系,從而調(diào)控植物在適當(dāng)?shù)臅r(shí)間發(fā)育并完成發(fā)育階段的時(shí)相轉(zhuǎn)換,進(jìn)而繁殖產(chǎn)生后代,以保證物種的延續(xù)。大豆miR172靶基因GmTOE4a過(guò)表達(dá)以后,轉(zhuǎn)基因大豆株系延遲開(kāi)花。研究發(fā)現(xiàn)GmTOE4a延遲從營(yíng)養(yǎng)生長(zhǎng)到生殖生長(zhǎng)期的轉(zhuǎn)換是通過(guò)抑制開(kāi)花相關(guān)基因GmFT2a、GmFT5a、GmAP1、GmLFY和miR156的靶基因GmSPL3/9的表達(dá),而促進(jìn)GmFT4和miR156的表達(dá)實(shí)現(xiàn)的。同時(shí)研究發(fā)現(xiàn)miR172與其靶基因GmTOE4a之間存在著負(fù)反饋調(diào)控關(guān)系。進(jìn)一步研究發(fā)現(xiàn)GmTOE4a參與的大豆光周期調(diào)控開(kāi)花途徑是在生育期基因E3和E4的作用下,依賴于GmCOL1a的表達(dá),并且其轉(zhuǎn)錄水平不受GI同源基因E2的調(diào)控[45]。這是有別于模式植物擬南芥miR172途徑的一種調(diào)控方式,再次表明大豆的光周期途徑既有保守的一面,又有其獨(dú)特性的一面。這可能與大豆經(jīng)歷了2次基因組復(fù)制成為具有復(fù)雜基因組的古四倍體物種有關(guān)。
大豆的光周期反應(yīng)是一個(gè)極為復(fù)雜的過(guò)程,需要多基因間相互協(xié)調(diào)的發(fā)揮作用才能最終實(shí)現(xiàn)開(kāi)花。目前所揭示的以E1為中心的開(kāi)花網(wǎng)絡(luò)僅僅處在轉(zhuǎn)錄水平,基因間的互作關(guān)系及分子機(jī)制有待于學(xué)者們深入研究,需要大量的工作來(lái)補(bǔ)充和完善。
3光周期對(duì)大豆產(chǎn)量性狀的調(diào)控
大豆光周期反應(yīng)不僅對(duì)開(kāi)花誘導(dǎo)有顯著影響,還對(duì)開(kāi)花后的營(yíng)養(yǎng)生長(zhǎng)和生殖生長(zhǎng)具有調(diào)控作用。韓天富利用原產(chǎn)自中國(guó)主要生態(tài)區(qū)、生育期不同的代表品種研究了大豆開(kāi)花后的光周期反應(yīng)問(wèn)題,結(jié)果表明,不同成熟期的大豆品種開(kāi)花后普遍存在著對(duì)光照長(zhǎng)度的反應(yīng),這種反應(yīng)屬于典型的光周期現(xiàn)象;開(kāi)花后的光周期反應(yīng)不僅存在于大豆花莢期還存在于鼓粒期至近成熟期;并且提出光敏色素參與到控制開(kāi)花后的光周期反應(yīng)中[46-47]。大豆生育期基因E3和E4分別為大豆光敏色素A基因GmPhyA3和GmphyA2[19-20],二者不但調(diào)控大豆開(kāi)花期,同時(shí)還決定開(kāi)花后期的主莖節(jié)數(shù)、豆莢發(fā)育及莖的生長(zhǎng)習(xí)性[48]。而大豆結(jié)莢習(xí)性、主莖節(jié)數(shù)、莖粗、株高、節(jié)間距、葉片大小和分枝數(shù)等是與產(chǎn)量相關(guān)的重要農(nóng)藝性狀,表明E3和E4基因不僅影響大豆開(kāi)花期,對(duì)產(chǎn)量形成也具有重要作用。
大豆結(jié)莢習(xí)性又叫大豆莖生長(zhǎng)習(xí)性,是指大豆開(kāi)花和結(jié)莢的方式,是大豆的一個(gè)重要生態(tài)性狀,光周期是影響大豆頂端花序發(fā)育的重要因素[46,48-49]。Bernard等依據(jù)花期長(zhǎng)短、莖生長(zhǎng)狀態(tài)、莖粗細(xì)變化、節(jié)間數(shù)、葉大小變化及莖頂端結(jié)莢情況等綜合性狀的表現(xiàn)將大豆品種劃分為有限結(jié)莢習(xí)性、亞有限結(jié)莢習(xí)性和無(wú)限結(jié)莢習(xí)性3種類型[50]。大豆在低緯度地區(qū)種植,表現(xiàn)出植株矮小、開(kāi)花期及成熟期提前,產(chǎn)量降低。這可能與低緯度地區(qū)的短日照有關(guān),影響大豆頂端花序的發(fā)育[47]。目前大豆結(jié)莢習(xí)性控制基因已克隆了Dt1[51]和Dt2[52],分別控制無(wú)限結(jié)莢習(xí)性和亞有限結(jié)莢習(xí)性。結(jié)莢習(xí)性是重要的株型性狀之一,是聯(lián)系大豆開(kāi)花期與產(chǎn)量性狀的橋梁。
E3和E4基因下游的GmTOE4a轉(zhuǎn)基因大豆株系表現(xiàn)出明顯的延遲開(kāi)花、株高降低、節(jié)間縮短、葉片變小及主莖增粗等表型,該基因?qū)Υ蠖归_(kāi)花期和多個(gè)株型性狀均有調(diào)控作用。同時(shí),研究還發(fā)現(xiàn)GmTOE4a基因與調(diào)控生長(zhǎng)發(fā)育時(shí)相轉(zhuǎn)換的miR156及其靶基因GmSPL之間存在著反饋調(diào)控關(guān)系[45,53]。GmTOE4a屬于AP2(APETALA2)家族基因,具有轉(zhuǎn)錄因子活性,對(duì)開(kāi)花期和株型性狀的調(diào)控作用表明該基因是參與大豆多個(gè)生長(zhǎng)發(fā)育過(guò)程的多效基因,而且是適應(yīng)環(huán)境壓力和提高產(chǎn)量很有潛質(zhì)的基因,在一定程度上能夠?yàn)榇蠖估硐胫晷偷臉?gòu)建提供分子元件。但目前GmTOE4a基因?qū)χ晷托誀钫{(diào)控的分子機(jī)制還不清楚,有可能與大豆生育期基因E3和E4的調(diào)控有關(guān)系,也有可能該基因處在多個(gè)調(diào)控網(wǎng)絡(luò)的交叉點(diǎn),見(jiàn)圖1。隨著測(cè)序技術(shù)的不斷更新和生物信息學(xué)的迅猛發(fā)展,對(duì)光周期調(diào)控網(wǎng)絡(luò)中關(guān)鍵基因的克隆及分子機(jī)制的揭示對(duì)大豆分子設(shè)計(jì)育種和產(chǎn)量的提高具有現(xiàn)實(shí)的指導(dǎo)意義,處于大數(shù)據(jù)時(shí)代背景下的大豆光周期研究將會(huì)有突破性的進(jìn)展。
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Research Progresses on Photoperiodic Flowering and Yield Traits in Soybean(GlycinemaxMerr.)
KONG Fanjiang,ZHAO Xiaohui,LIU Baohui
(KeyLaboratoryofSoybeanMolecularDesignBreeding,NortheastInstituteofGeographyandAgroecology,CAS,Harbin
150081,China)
Abstract:Soybean as an important industrial crop,which is a predominant plant source for human vegetable oil and protein.But now our country′s soybean industry faces severe challenges.Soybean photoperiod regulated flowering not only influences soybean adaptation but also affects soybean grain yield.In this review,we demonstrated that soybean contains a specific photoperiod regulated flowering pathway PhyA-E1-FT.We also elucidated the genetically regulation relationship between identified flowering genes in soybean.The clone of key genes in soybean photoperiod response will serve as a theoretical basis for flowering and maturity molecular mechanism,and will be of great importance in soybean molecular breeding and yield improvement.
Key words:soybean; photoperiod; maturity; flowering time; yield
中圖分類號(hào):S565.1
文獻(xiàn)標(biāo)識(shí)碼:A
作者簡(jiǎn)介:第一作者及通訊孔凡江(1972-),男,黑龍江哈爾濱人,研究員,博士生導(dǎo)師,長(zhǎng)期從事大豆光周期調(diào)控開(kāi)花研究.
基金項(xiàng)目:國(guó)家自然科學(xué)基金(31430065,31371643,31571686).
收稿日期:2016-03-15.
文章編號(hào):2095-2961(2016)02 -0065 -07
doi:10.11689/j.issn.2095-2961.2016.02.001