水稻矮稈基因克隆研究進(jìn)展

陳文娟,劉亞男,孫亞利,李萬昌 ,李景原

(河南師范大學(xué) 生命科學(xué)學(xué)院,河南 新鄉(xiāng) 453007)

水稻矮稈基因克隆研究進(jìn)展

陳文娟,劉亞男,孫亞利,李萬昌*,李景原

(河南師范大學(xué) 生命科學(xué)學(xué)院,河南 新鄉(xiāng) 453007)

矮稈是水稻育種中最重要的農(nóng)藝性狀之一,對(duì)增強(qiáng)水稻抗倒伏性、提高水稻產(chǎn)量有重要作用。綜述了水稻矮稈基因的分類,并從參與油菜素內(nèi)酯、赤霉素、獨(dú)角金內(nèi)酯、生長(zhǎng)素等生物合成或信號(hào)傳導(dǎo)途徑方面闡述了水稻矮稈基因的克隆情況,為矮稈突變基因在水稻育種中的應(yīng)用提供理論依據(jù)。

水稻； 矮稈基因； 克隆

水稻(OryzasativaL．)是世界上最重要的糧食作物之一,其株型改良對(duì)提高產(chǎn)量至關(guān)重要[1]。矮稈是水稻育種中最重要的農(nóng)藝性狀之一,它可以增強(qiáng)水稻抗倒伏性并提高產(chǎn)量[2]。目前,已經(jīng)克隆了多個(gè)矮稈基因,其中半矮稈基因sd1(semi-dwarf 1)是唯一用于水稻育種的,被稱為“綠色革命”基因,它的成功運(yùn)用,使水稻單產(chǎn)提高了20%～30%[3]。但為了避免依賴單一半矮稈基因,需要繼續(xù)加大對(duì)水稻矮稈基因的研究,找到更多有利的矮稈基因資源,用于水稻育種,進(jìn)一步提高水稻產(chǎn)量。研究表明,水稻株高的降低是由于植物內(nèi)源激素如赤霉素(GA)、油菜素內(nèi)酯(BR)、獨(dú)角金內(nèi)酯(SLs)的缺乏或者他們的信號(hào)傳導(dǎo)途徑的改變?cè)斐傻腫4]。目前，尚未見從這幾方面具體闡述矮稈基因克隆情況的報(bào)道。為此,綜述了水稻矮稈基因的分類,并從參與BR、GA、SLs、生長(zhǎng)素(IAA)等生物合成或信號(hào)傳導(dǎo)途徑方面闡述了水稻矮稈基因的克隆情況,為矮稈突變基因在水稻育種中的應(yīng)用提供理論依據(jù)。

1 水稻矮稈基因的分類

水稻矮稈基因有多種分類方法。根據(jù)株高可分為半矮稈、矮稈和極矮稈3種類型[5]。矮稈常指成熟時(shí)植株高度等于或低于原正常植株高度一半的矮稈突變系；半矮稈則是指株高介于矮稈和正常植株高度之間的突變系；極矮稈是指極其矮化的矮稈突變系。在具體劃分時(shí),盧永根等[6]把半矮稈株高定在75～102 cm,而馬良勇等[7]把株高小于50 cm的定為矮稈,根據(jù)原株高或親本的株高不同,將50～70 cm的定為矮稈或半矮稈,超過70 cm時(shí)一般歸為半矮稈。根據(jù)矮稈基因?qū)A的反應(yīng),將矮稈基因分為在發(fā)芽期時(shí)α-淀粉酶顯著增加而芽伸長(zhǎng)較少的N型(normal type)；內(nèi)源GA較少但對(duì)外源GA敏感的T型(Tan-ginbozu type)；對(duì)GA不敏感的D 型(Daikoku type)；內(nèi)源GA正常,對(duì)外源GA敏感的E 型(Ebisu type)[8]。根據(jù)矮稈基因的表型,將眾多矮源分為多蘗矮生、小粒矮生、畸形矮生和半矮生等4類[9]。正常的水稻植株,成花誘導(dǎo)的完成伴隨著末梢4或5個(gè)節(jié)間的伸長(zhǎng),而底部其他節(jié)間基本不伸長(zhǎng)。水稻植株的矮化是節(jié)間長(zhǎng)度縮短或節(jié)間數(shù)減少的結(jié)果,也可能是兩者共同作用的結(jié)果。根據(jù)水稻植株矮化與節(jié)間的關(guān)系,以節(jié)間長(zhǎng)度占株高的比例為指數(shù),將矮稈分為dn、dm、d6、nl和sh 等5種基本類型,而將節(jié)間比例正常的品種標(biāo)定為N型[10]。 dn型的特征是節(jié)間比例與N型相同,即各節(jié)間按相同比例同時(shí)縮短；dm型的特征是倒2節(jié)間特別短；d6型的特征是只有穗下節(jié)間伸長(zhǎng),其他節(jié)間不伸長(zhǎng)；nl型的特征是有頸葉,倒1節(jié)間短而第4節(jié)間長(zhǎng),偶爾第6節(jié)間伸長(zhǎng)；sh型的特征是倒1節(jié)幾乎不伸長(zhǎng),穗子包藏在劍葉葉鞘中。其中,除dn型外,所有矮稈類型都存在某一節(jié)間顯著縮短的特征,不同的矮稈基因作用于水稻植株的不同伸長(zhǎng)節(jié)間,其矮化作用只發(fā)生在某一特定生長(zhǎng)時(shí)期,導(dǎo)致某些節(jié)間顯著縮短。

2 水稻矮稈基因的克隆

株高是由復(fù)雜的遺傳途徑?jīng)Q定的,矮稈來自BR、GA、SLs、IAA等的生物合成或信號(hào)傳導(dǎo)途徑的缺陷突變。目前,研究者利用圖位克隆等方法得到多個(gè)矮稈相關(guān)基因,其參與不同的生物合成途徑或信號(hào)傳導(dǎo)途徑。

2.1 參與BR生物合成或信號(hào)傳導(dǎo)途徑的矮稈基因

BR是重要的植物激素,在植物生長(zhǎng)發(fā)育中起重要作用,能促進(jìn)植物莖稈伸長(zhǎng)和細(xì)胞分裂。BR缺陷矮稈突變體一般分為2種,一種是信號(hào)傳導(dǎo)缺陷突變,另一種是自身合成缺陷突變。無論是哪一種都會(huì)導(dǎo)致矮稈表型。

BR自身合成缺陷突變的矮稈基因有d2(dwarf 2)[11]、d11[12]、CPB1(clustered primary branch 1)[13]、SDG725(set domain group 25)[14]、brd1(BR-deficient dwarf 1)[15]。其中,前3個(gè)基因都屬于細(xì)胞色素P450(CYP450)家族,編碼BR生物合成過程中的一種關(guān)鍵酶。d2編碼CYP90D2蛋白,它的隱性突變導(dǎo)致BR生物合成受阻,致使水稻植株矮化[11]。d11編碼CYP724B1蛋白,其突變體產(chǎn)生移碼突變,不能合成此蛋白質(zhì)[12]。CPB1是d11的一個(gè)新等位基因,編碼CYP724B1蛋白,其突變體中His360亮氨酸取代了保守的CPB1/D11區(qū)域,此區(qū)域控制突變體的穗結(jié)構(gòu)和種子大小[13]。水稻SDG725基因編碼H3K36甲基轉(zhuǎn)移酶,其下調(diào)引起表型缺陷,包括矮稈、節(jié)間縮短、葉片直立、小粒[14]。brd1是BR合成缺陷突變體,在突變體中導(dǎo)入野生型OsDWARF基因可以使突變體恢復(fù)正常表型[15]。OsDWARF編碼水稻中的BR合成酶C-6氧化酶,此酶的缺失會(huì)抑制葉和莖中細(xì)胞的有序排列和極性生長(zhǎng)分裂,使植株矮化[15]。

另外,還有BR合成補(bǔ)充途徑缺失突變的矮稈基因brd2(BR-deficient dwarf 2)[16]和OsDWARF4[17]。brd2編碼DIM(DIMINUTO)/DWF1蛋白,催化BR生物合成早期的24-亞甲基膽固醇(24-MC)到菜油甾醇(CR)的反應(yīng),與擬南芥DIM1/DWF1基因有同源序列,brd2中一個(gè)外顯子的單堿基G缺失導(dǎo)致移碼突變,BR合成受阻,造成成熟植株嚴(yán)重矮化[16]。OsDWARF4基因編碼CYP90B2蛋白,催化BR生物合成后期步驟的C-22 的羥基化,該基因突變后,致使BR合成量減少,植株略矮、葉片直立,產(chǎn)量增加[17]。

BR信號(hào)傳導(dǎo)缺陷突變的矮稈基因有d1352[18]、TUD1(Taihu dwarf)[19]、編碼LRR(leucine-rich repeat)激酶的基因XIAO[20]、OsBLE3(brassinolide-enhanced 3)[21]、SG1(short grain 1)和SGL1(short grain like 1)[22]、DLT(dwarf and low tillering)[23]、OsBZR1(brassinosteroid resistant 1)[24]、d61和OsBRI1(brassinosteroid insensitive 1)[25]、OsDof12(DNA binding with one finger)[26]、OsMDP1(MADS-domain-containing protein 1)[27]、OsBRL1(brassinosteroid insensitive like 1)和OsBRL3[28]、BU1(brassinosteroid upregulated 1)[29]。基因d1352在U-box E3泛素連接酶區(qū)插入一個(gè)24 bp的片段 ,故在U-box保守結(jié)構(gòu)域插入了8個(gè)氨基酸,使其失去識(shí)別BR的功能[18]。TUD1基因編碼U-Box E3泛素連接酶,它和異源三聚體G蛋白α亞基一起共同調(diào)節(jié)BR介導(dǎo)的水稻生長(zhǎng)；TUD1是d1的上位基因,二者協(xié)同互作對(duì)BR信號(hào)途徑進(jìn)行調(diào)節(jié),二者的雙突變體呈現(xiàn)植株第2節(jié)間變短、葉直立、谷粒變短的表型[19]?；騒IAO對(duì)BR 信號(hào)傳遞和細(xì)胞分裂起調(diào)控作用,其T-DNA插入突變體的表型為植株矮化、葉直立且結(jié)實(shí)率下降[20]。OsBLE3基因編碼蕓苔素內(nèi)酯(BL)上調(diào)蛋白,是一個(gè)BR增強(qiáng)型基因,可通過對(duì)BL和IAA的雙重調(diào)節(jié)參與細(xì)胞伸長(zhǎng),導(dǎo)致植株生長(zhǎng)緩慢、矮化[21]。SG1和SGL1分別編碼SG1蛋白和類SG1蛋白,SG1降低了對(duì)BR的應(yīng)答,SG1和SGL1過表達(dá)會(huì)產(chǎn)生短粒和矮化表型[22]?；駾LT編碼一個(gè)新的GRAS[GAI(GA insensitive)、RGA(repressor of gal-3)、SCR(SCARECROW)]家族蛋白,參與BR合成基因表達(dá)的反饋抑制, 其突變體dlt表現(xiàn)為矮化、少分蘗[23]。OsBZR1 基因編碼擬南芥BZR1同源蛋白,經(jīng)過RNAi技術(shù)沉默該基因后,BR信號(hào)傳遞受阻,產(chǎn)生矮化、葉直立表型[24]。d61和OsBRI1是等位基因,單堿基的突變就導(dǎo)致了BR受體,即OsBRI1激酶結(jié)構(gòu)域中的1834F被替換,從而使OsBRI1活性大大降低,而OsBRI1活性對(duì)BR調(diào)節(jié)水稻植株的正常生長(zhǎng)和發(fā)育是必需的[25]。OsDof12編碼Dof蛋白,OsDof12過表達(dá)時(shí),BR信號(hào)的2個(gè)信號(hào)正調(diào)節(jié)因子OsBR1 和OsZR1顯著下調(diào),表明OsDof12在水稻中是一個(gè)負(fù)調(diào)節(jié)因子,通過抑制BR信號(hào)傳導(dǎo)使植株形態(tài)發(fā)生改變[26]。另外一個(gè)編碼BR信號(hào)負(fù)調(diào)節(jié)因子的基因是OsMDP1,它編碼MADS-box轉(zhuǎn)錄因子。OsMDP1缺陷導(dǎo)致主根系變短、胚芽鞘伸長(zhǎng)、葉節(jié)傾角變大,還可導(dǎo)致編碼木葡聚糖轉(zhuǎn)葡糖苷酶的基因OsXTR1表達(dá)增強(qiáng)[27]。OsBRL1和OsBRL3在根中高度表達(dá),在嫩枝中表達(dá)量較少,其編碼蛋白是BR信號(hào)途徑中的正調(diào)控因子；同時(shí),OsBRL1 和OsBRL3也會(huì)部分參與根中BR的感知過程,二者的轉(zhuǎn)基因反義植株表現(xiàn)出不同程度的矮化現(xiàn)象[28]。BU1編碼螺旋-環(huán)-螺旋蛋白質(zhì)BU1,參與BR信號(hào)傳導(dǎo)并控制葉的彎曲度；BU1蛋白也是BR反應(yīng)的正調(diào)節(jié)因子,通過OsBRI1和 RGA1參與BR反應(yīng)的2個(gè)通路,BU1過表達(dá)會(huì)使株高變矮、種子變大、葉的彎曲度增大、育性降低[29]。

2.2 參與GA生物合成或信號(hào)傳導(dǎo)途徑的矮稈基因

GA在高等植物生長(zhǎng)和發(fā)育的多個(gè)階段是至關(guān)重要的。它促進(jìn)莖的伸長(zhǎng)、開花、種子萌發(fā)、種子和果實(shí)的生長(zhǎng)。GA缺陷矮稈突變體一般也分為2種,一種是信號(hào)傳導(dǎo)缺陷突變,另一種是自身合成缺陷突變。

GA信號(hào)傳導(dǎo)缺陷突變的矮稈基因有d89[30]、dwt1(dwarf tiller 1)[31]、d1[32]、gid1(GA-insensitive dwarf 1)[33]、gid2[34]、OsGAI(GA-insensitive)[35]、EUI1(elongated uppermost internode 1)[36]。d89編碼異源三聚體G蛋白的α亞基,D89中1個(gè)堿基的替換(A—G)使蘇氨酸突變?yōu)楸彼?致使α螺旋變短,不能與GSP結(jié)合,故導(dǎo)致了G蛋白的失活,GA信號(hào)傳導(dǎo)受阻,最終表現(xiàn)為植株矮化[30]。dwt1編碼WUSCHEL相關(guān)同源框(WOX)轉(zhuǎn)錄因子,與擬南芥WOX8和WOX9同源,dwt1與GA的信號(hào)傳導(dǎo)有關(guān),在突變體中細(xì)胞分裂和細(xì)胞伸長(zhǎng)受抑,主枝的穗長(zhǎng)發(fā)育正常,矮化分蘗的穗長(zhǎng)變短[31]。d1編碼GTP 結(jié)合蛋白的α 亞基,在突變體HO541中該位點(diǎn)上有833 bp的缺失,造成G蛋白失活,抑制了GA的信號(hào)傳導(dǎo),節(jié)間的細(xì)胞分裂減少,導(dǎo)致植株矮化[32]。GID1編碼GA 受體,其類似于激素敏感的脂肪酶,是核定位蛋白質(zhì),突變體gid1中GA信號(hào)傳遞受阻,導(dǎo)致植株矮化[33]。GID2蛋白是GA信號(hào)傳導(dǎo)中的正調(diào)節(jié)因子,調(diào)節(jié)抑制因子SLR1(slender rice 1)的降解,突變體gid2中SLR1不能正常降解,從而抑制GA信號(hào)向下游的傳導(dǎo),致使植株嚴(yán)重矮化、不育等[34]。OsGAI與EUI1編碼蛋白則是負(fù)調(diào)節(jié)因子,OsGAI即SLR1,編碼水稻GA負(fù)調(diào)控因子DELLA蛋白,屬于GRAS基因超家族,OsGAI的過表達(dá)可阻礙GA的信號(hào)傳導(dǎo),致使植株矮化[35,37]?；駿UI1編碼細(xì)胞色素P450單加氧酶,其通過改變水稻中GA的反應(yīng)進(jìn)而負(fù)調(diào)節(jié)節(jié)間的伸長(zhǎng),過表達(dá)該基因可導(dǎo)致植株極度矮化[36]。

GA自身合成缺陷突變的矮稈基因有sd1[5]、ph1(plant height 1)[38]、pad(plant architecture determinant)[39]、sgd1(t)(small-grain dwarf mutant 1)[40]、OsDOG(dwarf rice with overexpression of gibberellin-induced gene)[41]、d35[42]、OsKO2(ent-kaurene oxidase 2)[43]、dit1(dwarf increased tillering 1)[44]、d18[45]、OsGA2ox6(Oryzasativagibberellin 2-oxidase 6)[46]、OsWOX3A(WUSCHEL-related homeobox 3A)[47]、BC12(brittle culm 12)/GDD1(gibberellin-deficient dwarf 1)[48]。半矮稈基因sd1,編碼由389個(gè)氨基酸組成的GA20氧化酶(GA20ox),GA20ox是GA合成途徑中的關(guān)鍵酶,sd1突變將導(dǎo)致植株不同程度的矮化[5]?；騪h1與sd1緊密連鎖,編碼幾丁質(zhì)誘導(dǎo)GA應(yīng)答蛋白(CIGR),屬于GRAS家族,ph1可調(diào)控株高,且對(duì)株高有很大的遺傳效應(yīng)[38]。pad基因編碼由SNP導(dǎo)致的單個(gè)氨基酸改變的細(xì)胞質(zhì)膜蛋白OsMCA1,該基因可能參與GA代謝與信號(hào)傳導(dǎo)的調(diào)控,且能降低GA的生物活性,產(chǎn)生矮化、小葉的株型[39]。sgd1(t)與BC12/GDD1是等位基因,編碼kinesin-4亞家族驅(qū)動(dòng)蛋白,該基因第4個(gè)外顯子上發(fā)生由G到T的堿基突變,使第186位保守氨基酸由甘氨酸突變?yōu)槔i氨酸,影響該蛋白質(zhì)的功能,sgd1(t)對(duì)外源GA敏感,呈現(xiàn)植株矮化、穗及各節(jié)間顯著縮短的表型[40]。OsDOG基因編碼GA誘導(dǎo)的A20/AN1型鋅指蛋白,其調(diào)節(jié)GA穩(wěn)態(tài),并負(fù)調(diào)節(jié)水稻植物細(xì)胞伸長(zhǎng)[41]。d35與OsKO2位于同一基因位點(diǎn),d35編碼貝殼杉烯氧化酶,該酶催化GA生物合成早期步驟,D35缺失植株嚴(yán)重矮化[42]；OsKO2還影響糊粉層細(xì)胞程序化死亡進(jìn)程,并促進(jìn)種子萌發(fā)[43]?；騞it1編碼類胡蘿卜素裂解酶7(CCD7),是htd1(high tillering dwarf 1)的等位基因,dit1的第6個(gè)外顯子中CC置換AA,使終止密碼子取代絲氨酸,形成截短的蛋白質(zhì),喪失功能,dit1為外源GA敏感型基因,可產(chǎn)生矮化多分蘗表型[44]?；駾18編碼GA 3β羥化酶,其突變體GA活性下降,產(chǎn)生矮稈表型[45]?；騉sGA2ox6編碼GA2氧化酶(GA2ox),GA2ox通過2β-羥基化作用使有活性的GA失活,過量表達(dá)OsGA2ox6后植株表現(xiàn)為半矮稈性狀[46]。OsWOX3A是GA響應(yīng)基因,其編碼的OsWOX3A參與GA生物合成通路的負(fù)反饋調(diào)節(jié),保持GA的穩(wěn)態(tài)。OsWOX3A直接與編碼貝殼杉烯酸的基因KAO(ent-kuarenoic acid oxidase)的啟動(dòng)子相互作用,過表達(dá)OsWOX3A的植株中GA合成量下降,導(dǎo)致植株極度矮化[47]。基因BC12/GDD1編碼驅(qū)動(dòng)蛋白類似蛋白BC12,與GA生物合成基因啟動(dòng)子結(jié)合,抑制內(nèi)源性GA的生成,使細(xì)胞伸長(zhǎng)受阻,使植株產(chǎn)生矮化表型[48]。

2.3 參與SLs生物合成或信號(hào)傳導(dǎo)途徑的矮稈基因

SLs生物合成或信號(hào)傳導(dǎo)缺陷突變的矮稈基因有d27[49]、D10[50]、D3[51]、D53[52]、HTD2/D88/D14[53]、HTD1/D17[54]、OsTB1(teosinte branched 1)[55]、FIE1(fertilization-independent endosperm 1)[56]。d27參與MAX/RMS/D通路,編碼位于葉綠體的含鐵蛋白質(zhì),是BL生物合成的一個(gè)新成員,d27突變體呈現(xiàn)多分蘗、矮稈的表型[49]。D10編碼類胡蘿卜素裂解雙加氧酶,參與SLs/SLs衍生物的生物合成,隱性突變導(dǎo)致SLs合成受阻,致使植株矮化[50]。D3編碼擬南芥MAX2(more axillary branches 2)/ORE9(oresara 9) 同源的D3蛋白,對(duì)SL信號(hào)是必需的,D3組裝成一個(gè)SCFD3[SKP(S-phase kinase-associated protein)、cullin、F-box protein dwarf 3]復(fù)合體,并與D14聯(lián)合抑制水稻分枝,d3突變體呈現(xiàn)株高變矮、分蘗增多的表型[51]。D53編碼SCFD3泛素復(fù)合物中的一種底物,是SLs信號(hào)途徑的抑制子,SLs可誘導(dǎo)其降解,D53負(fù)調(diào)節(jié)SLs信號(hào)傳導(dǎo),其過表達(dá)可使植株矮化[52]?；騂TD2、HTD1/D17和OsTB1都對(duì)水稻分蘗數(shù)進(jìn)行負(fù)調(diào)節(jié)。HTD2也稱D88或D14,編碼酯酶/脂肪酶,抑制水稻分枝發(fā)生,D14可能是SLs信號(hào)途徑的一個(gè)組分,在其下游起作用,其突變體呈現(xiàn)多蘗、矮稈表型[53]。HTD1/D17編碼擬南芥MAX3的同源蛋白胡蘿卜素裂解雙加氧酶OsCCD7,參與SLs的生物合成,突變體htd1中SLs合成受阻,產(chǎn)生多蘗矮稈表型[54]。OsTB1編碼轉(zhuǎn)錄因子,此轉(zhuǎn)錄因子攜帶與DNA啟動(dòng)子結(jié)合的螺旋-環(huán)-螺旋結(jié)構(gòu),命名為TCP結(jié)構(gòu)域,參與SLs信號(hào)傳遞；OsTB1過表達(dá),導(dǎo)致側(cè)枝明顯減少,說明OsTB1負(fù)調(diào)節(jié)側(cè)枝生長(zhǎng)[55]。此外,DNA甲基化和去甲基化,也能阻斷遺傳信息的傳遞過程,從而影響植株正常生長(zhǎng)發(fā)育,例如：FIE1基因甲基化后使植株呈現(xiàn)矮稈、多蘗的Epi-df(epi-allele)的突變表型[56]。

2.4 參與IAA生物合成或信號(hào)傳導(dǎo)途徑的矮稈基因

IAA在許多植物的側(cè)根起始、維管束分化、細(xì)胞伸長(zhǎng)、細(xì)胞分裂、胚的形成、芽伸長(zhǎng)和根尖形成等重要發(fā)育過程中起關(guān)鍵作用。IAA自身合成或信號(hào)傳導(dǎo)缺陷突變的矮稈基因有NAL1(narrow leaf 1)[57]、OsIAA1[58]、tdd1(tryptophan deficient dwarf 1)[59]。nal1-2(narrow leaf 1-2)是NAL1的無義等位基因突變,因整個(gè)啟動(dòng)子和NAL1的第一外顯子404 bp的片段被刪除,而使得NAL1無法編碼特定的胰蛋白酶樣絲氨酸和半胱氨酸蛋白酶,阻礙IAA的信號(hào)傳導(dǎo),產(chǎn)生矮稈、窄葉表型[57]。OsIAA1編碼Aux/IAA蛋白,OsIAA1在IAA和BR的信號(hào)通路的相互作用中及植株的形態(tài)建成中起重要作用,OsIAA1過表達(dá)會(huì)造成植株矮化、株型松散[58]。TDD1編碼鄰氨基苯甲酸合酶β亞基同源蛋白,參與IAA合成,催化色氨酸生物合成途徑的第一步，并在色氨酸依賴性IAA生物合成的上游起作用,突變體tdd1中由于色氨酸和IAA的不足,導(dǎo)致植株出現(xiàn)矮化、窄葉、花異常等表型[59]。

2.5 與其他生物合成或信號(hào)傳導(dǎo)途徑有關(guān)的矮稈基因

雖然控制水稻矮稈相關(guān)基因的大多是激素相關(guān)基因,但也有一些控制其他因素導(dǎo)致水稻矮稈的基因,如Psd1(photoperiod sensitive dwarf 1)[60]、OsCESA7(cellulose synthase A subunit 7)[61]、RLS2(rapid leaf senescence 2)[62]、d6/OSH15(homeobox 15)[63]。在長(zhǎng)日照條件下,顯性矮稈突變體Psd1出現(xiàn)嚴(yán)重矮化表型,但短日照時(shí)接近正常生長(zhǎng)。突變位點(diǎn)在編碼特定的脂質(zhì)轉(zhuǎn)移蛋白的基因中,突變后蛋白質(zhì)C末端縮短,不能發(fā)揮正常功能,使細(xì)胞分裂和伸長(zhǎng)受損,導(dǎo)致矮稈[60]。基因OsCESA7編碼纖維素酶A的第七亞基,錯(cuò)義突變改變?cè)撁镐\指結(jié)構(gòu)域中高度保守的C40為Y,造成莖中厚壁細(xì)胞細(xì)胞壁增厚有缺陷且纖維素含量減少,使植株呈現(xiàn)脆稈和矮化等表型[61]。RLS2基因編碼OsEXO70A1,rls2突變觸發(fā)EXO70同源基因轉(zhuǎn)錄波動(dòng),并影響到與大量元素的吸收和運(yùn)輸有關(guān)的基因,造成維管束不規(guī)則和礦質(zhì)營(yíng)養(yǎng)同化的紊亂,產(chǎn)生矮稈等性狀[62]?；騉SH15 編碼含有同源異型結(jié)構(gòu)域的蛋白質(zhì),屬于KNOX(knotted-like homeobox) 家族Ⅰ類。其與Oskn3是同一基因,參與調(diào)節(jié)SAM(shoot apicalm eristem) 的形成,控制水稻節(jié)間的發(fā)育,OSH15缺失會(huì)造成植株矮化[63]。d6突變體植株矮化,表現(xiàn)為第2、3、4 節(jié)間變短,而稻穗和第1節(jié)間沒有變短,導(dǎo)入OSH15基因可以使突變體恢復(fù)正常表型[63]。

3 展望

水稻矮稈基因的研究已經(jīng)有了很大進(jìn)展,發(fā)現(xiàn)了很多有利突變體,但是現(xiàn)在能真正應(yīng)用到生產(chǎn)中并發(fā)揮重要作用的只有水稻半矮稈基因sd1。因此，為了避免依賴單一半矮稈基因,需要找到更多的可用基因,培育理想株型,以應(yīng)對(duì)人口的增加和更加多變的環(huán)境條件。首先,應(yīng)該注重野生稻的發(fā)展和利用。親本材料遺傳背景狹窄，便得不到理想的產(chǎn)量、質(zhì)量和抗性材料,而野生稻提供了豐富的具有優(yōu)良性狀的遺傳資源,如病蟲害強(qiáng)抗性和脅迫耐受性等。其次,利用人工誘變,如空間誘變、射線誘變等，選育出具有優(yōu)良性狀的矮稈品系。同時(shí)，考慮到環(huán)境因素如光、溫等對(duì)水稻生長(zhǎng)的影響。最后,要克隆出具有優(yōu)良性狀的基因,搞清楚其調(diào)控網(wǎng)絡(luò)。確保新品種在產(chǎn)量、谷粒質(zhì)量、抗逆性等方面具有優(yōu)良農(nóng)藝性狀,有助于進(jìn)一步保護(hù)國(guó)家糧食安全。

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Research Advances in Cloning of Dwarf Genes in Rice

CHEN Wenjuan,LIU Ya’nan,SUN Yali,LI Wanchang*,LI Jingyuan

(College of Life Sciences,Henan Normal University,Xinxiang 453007,China)

Dwarf is one of the most important agricultural traits in rice(OryzasativaL.) breeding,which plays an important role in enhancing the lodging resistance and production of rice.Here,classification and cloning of rice dwarf genes were reviewed from the aspects of the biosynthesis and signal transduction pathways of brassinosteroid,gibberellins,strigolactones and auxins,which could provide a theoretical basis for the application of dwarf mutant genes in rice breeding.

rice(OryzasativaL．); dwarf gene; clone

2016-09-04

國(guó)家自然科學(xué)基金項(xiàng)目(U1304317)

陳文娟(1992-)，女，河南商丘人，在讀碩士研究生，研究方向：作物遺傳育種。E-mail：1273298205@qq.com

*通訊作者：李萬昌(1974-),男,河南汝州人，教授，博士，主要從事水稻遺傳育種研究。E-mail：li_wan_chang@163.com

S511

A

1004-3268(2017)03-0001-07