2012年第1期《遗传》封面说明

株高是水稻重要的株型组成因子,水稻矮秆基因是株型改良的重要遗传基础,其大多参与植物内源激素赤霉素和油菜素内酯的合成或信号传导途径,一般具有"一因多效"的遗传性状表现,造成植株矮化的同时也会改变其他性状。通过对所构建的水稻突变体库进行大规模筛选,我们获得一个稳定遗传的矮秆突变体dtl1。与野生型相比,dtl1表现为     

水稻长穗颈基因eui紧密连锁SSR标记获得

02428h是从半矮秆材料02428体细胞培养后代中发现的隐性高秆突变体, 其株高性状由1对长穗颈基因eui和1对半矮秆基因sd-1共同控制。以02428h与半矮秆材料南京11杂交的F₂为作图群体, 利用Gramene公布的SSR标记和根据NCBI中的BAC序列自己新开发的SSR标记, 将eui基因定位在第5染色体上的RM3673和RM0012之间, 两侧遗传距离分别为0.3 cM和1.0 cM, 为该基因的分子标记辅助选择奠定了基础。     

一个水稻显性高秆突变体的遗传分析和基因定位

从水稻(Oryza sativa L.)的两个半矮秆籼稻品种6442S-7和蜀恢881杂交F2代群体中发现一个高秆突变体D111,其株高和秆长分别比亲本蜀恢881增加63.0%和87.0%.用205个微卫星标记分析D¨1及其原始亲本6442S-7和蜀恢881之间的基因组DNA多态性,结果未发现D111具有2个原始亲本都没有的新带型,证明D1¨的确是6442S-7和蜀恢881的杂交后代发生基因突变产生的.将D111分别与蜀恢881、蜀恢527、明恢63、9311、IR68、G46B等6个半矮秆品种和高秆对照品种南京6号杂交,分析F1和F2代株高的遗传行为,结果表明D1¨的高秆性状由一对显性基因控制,且该基因与南京6号的高秆基因紧密连锁或等位.以蜀恢527/D111 F2群体为定位群体,运用微卫星标记将D111显性高秆突变基因定位于水稻第一染色体长臂,与RM212、RM302和RM472的遗传距离分别是27.7 cM、25.5 cM和6.0 cM,该基因暂命名为LC(t).认为D111是首例从半矮秆品种自然突变产生的水稻显性高秆突变体,LC(t)为首次定位的水稻显性高秆突变基因.此外,将上述基因定位结果与Causse等(1994)和Temnykh等(2000,2001)发表的水稻分子连锁图谱进行比较,发现LC(t)基因恰巧位于与水稻"绿色革命基因"sd1相同或十分相近的染色体区域,因此,还就LC(t)基因与sd1基因之间的可能关系进行了讨论.     

一个水稻显性高秆突变体的遗传分析和基因定位

从水稻(Oryza sativa L.)的两个半矮秆籼稻品种6442S-7和蜀恢881杂交F2代群体中发现一个高秆突变体D111,其株高和秆长分别比亲本蜀恢881增加63.0%和87.0%。用205个微卫星标记分析D111及其原始亲本6442S-7和蜀恢881之间的基因组DNA多态性,结果未发现D111具有2个原始亲本都没有的新带型,证明D111的确是6442S-7和蜀恢881的杂交后代发生基因突变产生的。将D111分别与蜀恢881、蜀恢527、明恢63、9311、IR68、G46B等6个半矮秆品种和高秆对照品种南京6号杂交,分析F1和F2代株高的遗传行为,结果表明D111的高秆性状由一对显性基因控制,且该基因与南京6号的高秆基因紧密连锁或等位。以蜀恢527/D111 F2群体为定位群体,运用微卫星标记将D111显性高秆突变基因定位于水稻第一染色体长臂,与RM212、RM302和RM472的遗传距离分别是27.7 cM、25.5 cM和6.0 cM,该基因暂命名为LC(t)。认为D111是首例从半矮秆品种自然突变产生的水稻显性高秆突变体,LC(t)为首次定位的水稻显性高秆突变基因。此外,将上述基因定位结果与Causse等(1994)和Temnykh等(2000; 2001)发表的水稻分子连锁图谱进行比较,发现LC(t)基因恰巧位于与水稻“绿色革命基因”sd1相同或十分相近的染色体区域,因此,还就LC(t)基因与sd1基因之间的可能关系进行了讨论。     

一个水稻矮秆突变体的遗传分析及基因定位

水稻（Oryza sativa）是我国重要的粮食作物之一。水稻矮秆材料的引入掀起了第1次＂绿色革命＂。但近年来,在水稻育种中矮生基因遗传单一的问题越来越突出,已经严重影响到水稻产量的持续提高。利用60Co-γ射线辐照籼稻亲本材料M804获得了一个性状能够稳定遗传的矮秆突变体MU101。对该矮秆突变体和台粳16号杂交获得的F2代的遗传分析表明,该矮秆性状受1对隐性单基因控制,并暂命名为ds1。利用已有的SSR分子标记将DS1基因定位在水稻第5号染色体上,通过扩大群体和开发新的Indel标记,进一步将DS1基因定位在2个Indel标记之间,两者间的物理距离大约为384kb。该研究为DS1基因的克隆及其在生产中的应用奠定了基础。     

一个玉米矮秆突变体K123d的遗传鉴定

矮秆已被广泛用于改良作物的抗倒伏性状,培育理想株型,从而提高作物产量。玉米矮秆突变体K123d由自交系K123自然突变产生。本研究比较该突变体与野生型主要农艺性状差异及其对赤霉素的敏感性;用K123d与株高不同的3个自交系分别构建F1、BC和F2群体,分析矮秆性状的遗传模式;以K169/K123d-F2为定位群体,采用集团分离分析法(BSA),运用SSR标记定位矮秆基因d123;参照br-2序列信息分段设计特异引物,同源克隆d123。结果表明,与野生型相比K123d株高降低35.59%,穗位高降低、节间缩短、叶片较直立,但结实率差,对赤霉素敏感;在F2群体和BC1群体中,正常植株与矮秆植株分离比例分别符合3∶1和1∶1,说明矮秆性状受1对隐性基因控制;其矮秆基因d123定位于第一条染色体上SSR标记umc1278和bnlg1564之间,遗传距离分别为12.8 c M和7.3 c M;同源克隆显示d123与br-2存在12个碱基替换,其中第4个外显子编码的一个谷氨酸被替换为赖氨酸。由此可见,矮秆突变体K123d为br-2的一个突变类型,对矮化育种具有进一步研究利用价值。     

一个新的水稻小粒矮秆基因的分子标记定位及效应分析

从水稻(Oryza safjva L．)半矮秆品种蜀恢I62中发现一份小粒矮秆突变体“I62d”。对I62d与4个半矮秆品种杂交F1和F2代的遗传分析表明,I62d的矮生性由一对隐性基因控制。以II-32B／162d F2代作定位群体,用分子标记将I62d突变基凶定位丁水稻第3染色体短臂,该基因与微卫星标记RM218和RMI57之间的遗传距离分别为3．5cM和10．0cM。同时,利用近等基因系分析了该基因的表型效应,结果表明它可使株高降为正常高度的1／4左右,籽粒降为正常大小的1／4左右,并使叶片显著缩短、加宽,结实率显著降低。我们认为162d突变基因是一个新的水稻小粒矮秆某因,暂命名为dI62(t）。     

水稻Dwarf1移码突变的新突变体鉴定

从一批水稻品种"中花11"组织培养苗里分离到一个矮化突变株"C6PS",它的T2代群体株高呈现3:1分离。利用该群体矮化单株与"珍汕97"、"牡丹江8"构建2个F2群体F2(CZ)、F2(CM),两个群体中高株与矮株均呈现3:1分离,证明该性状变异为单基因控制。"C6PS"表现型与已经报道的Dwarf1隐性突变体"d1"相似,以D1附近标记RM430检测F2(CZ)群体基因型,结果显示群体表型与RM430基因型呈极显著相关(P=0.0001),将该基因初步定位于Dwarf1附近。对"C6PS"及"中花11"进行D1序列分析显示,突变株中D1基因在其第九个外显子与第九个内含子的剪接位点上发生6个碱基的缺失,根据缺失两侧序列设计C6PS-D1L/R标记,在T2代群体该标记与表型呈现共分离,表明"C6PS"是一种新的Dwarf1突变体。cDNA测序显示突变体d1基因转录产物发生26个碱基的缺失,导致移码产生终止突变,从而无法翻译出有功能的Gα蛋白,因此,它是一个Gα功能缺失突变体。叶倾斜度检测显示"C6PS"对油菜素内酯响应比野生型"中花11"弱。     

一个新的水稻矮秆突变体的遗传分析和基因定位

新的水稻矮秆基因的发掘,对深入研究植物株高的调控途径及株型育种有非常重要的作用。我们报道了从日本特早熟粳稻品种Kitaake的组织培养后代获得的一个矮秆突变体dm,该突变体植株细小,紧凑,机械强度降低,结实率下降,籽粒变窄,千粒重降低等。利用分离群体中的矮秆株,最终将目标基因定位在第4染色体长臂末端InDel标记EL-72和L-1之间,物理距离为168 Kb的区间内,该区间内无已报道的水稻矮秆基因,该基因可能是一个尚未被克隆的新的株高决定基因。     

一个新的水稻卷叶突变体的遗传分析与基因定位

水稻叶片发育异常的突变体是研究水稻叶片发育分子机理的重要材料．本研究在IR64的EMS突变体库中发现了一个新的卷叶突变体材料w32,在整个生育期过程叶片都表现高度卷曲．突变体w32与IR24、培矮64杂交构建F2群体进行遗传分析,结果表明,卷叶性状受一个隐性基因控制,选用w32/PA64F2群体中的1846个卷叶单株进行基因定位,在卷叶和正常叶的DNA池中筛选到两个多态性标记RM6697和RM20781,并确定该卷叶基因位于第7染色体短臂上,是一个尚未报道过的基因,暂命名为r111（t）．利用新发展的11个SSR标记和19个InDel标记,最终将r111（t）基因定位在一个约52kb的区段上,为最终克隆该卷叶基因奠定了基础。     

Analysis of the rice mutant dwarf and gladius leaf 1. Aberrant katanin-mediated microtubule organization causes up-regulation of gibberellin biosynthetic genes independently of gibberellin signaling

Molecular genetic studies of plant dwarf mutants have indicated that gibberellin (GA) and brassinosteroid (BR) are two major factors that determine plant height; dwarf mutants that are caused by other defects are relatively rare, especially in monocot species. Here, we report a rice (Oryza sativa) dwarf mutant, dwarf and gladius leaf 1 (dgl1), which exhibits only minimal response to GA and BR. In addition to the dwarf phenotype, dgl1 produces leaves with abnormally rounded tip regions. Positional cloning of DGL1 revealed that it encodes a 60-kD microtubule-severing katanin-like protein. The protein was found to be important in cell elongation and division, based on the observed cell phenotypes. GA biosynthetic genes are up-regulated in dgl1, but the expression of BR biosynthetic genes is not enhanced. The enhanced expression of GA biosynthetic genes in dgl1 is not caused by inappropriate GA signaling because the expression of these genes was repressed by GA3 treatment, and degradation of the rice DELLA protein SLR1 was triggered by GA3 in this mutant. Instead, aberrant microtubule organization caused by the loss of the microtubule-severing function of DGL1 may result in enhanced expression of GA biosynthetic genes in that enhanced expression was also observed in a BR-deficient mutant with aberrant microtubule organization. These results suggest that the function of DGL1 is important for cell and organ elongation in rice, and aberrant DGL1-mediated microtubule organization causes up-regulation of gibberellin biosynthetic genes independently of gibberellin signaling.     

一个籼稻脆性突变体的生物学特性及基因定位研究

水稻脆性突变体是研究细胞壁组分结构形成机制的重要材料。通过离子束诱变籼稻9311获得1个茎秆、叶片均脆的突变体,命名为bc9311-1。bc9311-1突变体与野生型9311相比,分蘖数减少,结实率显著降低,其他农艺性状无明显差异。叶片和茎秆的细胞壁成分分析表明,与野生型相比,bc9311-1突变体茎秆中的纤维素和木质素含量明显降低,半纤维素和SiO2含量显著增加;叶片中的纤维素含量降低,半纤维素和木质素含量增加,SiO2含量无明显差异。遗传分析表明,该脆性突变体脆性性状受单隐性基因控制。以bc9311-1突变体与02428杂交的F2群体为基因定位群体,利用SSR标记将bc9311-1突变位点定位在水稻第1染色体上,位于SSR分子标记的RM1095和RM3632之间,遗传距离分别为0.6cM和3.4cM,与其中的标记RM1183表现共分离。这些结果为进一步克隆突变基因,揭示脆性性状的分子机制奠定坚实基础。     

Overexpression of constitutive differential growth 1 gene, which encodes a RLCKVII-subfamily protein kinase, causes abnormal differential and elongation growth after organ differentiation in Arabidopsis

To better understand genetic regulation of differential growth of plant organs, a dominant and semidwarf mutant, constitutive differential growth 1-Dominant (cdg1-D), was isolated utilizing the technique of activation tagging. cdg1-D showed pleiotropic phenotype including dwarfism, exaggerated leaf epinasty, and twisted or spiral growth in hypocotyl, inflorescence stem, and petiole. Hypocotyls of cdg1-D were longer than those of wild type under light conditions. The phenotype was caused by activation tagging of CDG1 gene that encodes a receptor-like cytoplasmic kinase of RLCKVII subfamily. When treated with high concentrations of brassinolide, light-grown wild-type seedlings showed long hypocotyls and strong leaf epinasty as observed in cdg1-D seedlings. Treatment of cdg1-D with brassinazole, a specific inhibitor of brassinosteroid (BR) biosynthesis, did not rescue the mutant phenotype. Gene expression of CONSTITUTIVE PHOTOMORPHOGENESIS AND DWARFISM involved in BR biosynthesis and phyB ACTIVATION-TAGGED SUPPRESSOR1 that inactivates BR was repressed and induced, respectively, in cdg1-D plants, suggesting constitutive activation of BR signaling in the mutant. CDG1 was expressed at a very low level in all the organs of the wild type tested. We isolated two independent intragenic suppressors of cdg1-D. However, they showed normal morphology and responded to BR in a similar manner to wild type. Taken together, CDG1 gene may interfere with signal transduction of BR when overexpressed, but is not an essential factor for it in the wild type.     

BIN2, a new brassinosteroid-insensitive locus in Arabidopsis

Brassinosteroids (BRs) play important roles throughout plant development. Although many genes have been identified that are involved in BR biosynthesis, genetic approaches in Arabidopsis have led to the identification of only one gene, BRI1, that encodes a membrane receptor for BRs. To expand our knowledge of the molecular mechanism(s) of plant steroid signaling, we analyzed many dwarf and semidwarf mutants collected from our previous genetic screens and identified a semidwarf mutant that showed little response to exogenous BR treatments. Genetic analysis of the bin2 (BR-INSENSITIVE 2) mutant indicated that the BR-insensitive dwarf phenotype was due to a semidominant mutation in the BIN2 gene that mapped to the middle of chromosome IV between the markers CH42 and AG. A direct screening for similar semidwarf mutants resulted in the identification of a second allele of the BIN2 gene. Despite some novel phenotypes observed with the bin2/+ mutants, the homozygous bin2 mutants were almost identical to the well-characterized bri1 mutants that are defective in BR perception. In addition to the BR-insensitive dwarf phenotype, bin2 mutants exhibited BR insensitivity when assayed for root growth inhibition and feedback inhibition of CPD gene expression. Furthermore, bin2 mutants displayed an abscisic acid-hypersensitive phenotype that is shared by the bri1 and BR-deficient mutants. A gene dosage experiment using triploid plants suggested that the bin2 phenotypes were likely caused by either neomorphic or hypermorphic gain-of-function mutations in the BIN2 gene. Thus, the two bin2 mutations define a novel genetic locus whose gene product might play a role in BR signaling.     

蒺藜苜蓿株高控制基因COSTIN的克隆及功能研究

株高是影响植物株型建成的重要农艺性状之一,直接决定作物的倒伏性和生物产量,但目前关于苜蓿等豆科牧草株高性状形成的分子调控机制尚不清楚。通过定向筛选豆科模式植物蒺藜苜蓿Tnt1逆转座子插入突变体库,分离鉴定了一个蒺藜苜蓿矮化突变体compact stalk internodes(costin),该突变体的矮化表型是由于茎节伸长受到抑制所致。通过基因表型连锁分析成功克隆了COSTIN基因,该基因编码一个钙离子交换蛋白,与拟南芥的CALCIUM EXCHANGER 7(CAX7) 基因高度同源。qRT-PCR检测发现COSTIN基因在茎、叶和果荚等组织中有较高的表达。进一步研究发现在costin突变体中赤霉素合成途径关键基因MtCPS、MtKAO1、MtGA20ox4、MtGA20ox7和MtGA3ox1表达下调;外施赤霉素GA3可以恢复costin突变体的矮化表型。上述研究表明COSTIN基因通过影响植物激素赤霉素的生物合成来调控蒺藜苜蓿的茎节伸长。     

Proteomic study identifies proteins involved in brassinosteroid regulation of rice growth

Brassinosteroids (BRs) are essential hormones for growth and development of plant. In rice, BRs regulate multiple developmental processes and affect many important traits such as height, leaf angle, fertility and seed filling. We identified brassinosteroid-regulated proteins in rice using proteomic approaches and performed functional analysis of some BR-regulated proteins by overexpression experiments. Using two-dimensional difference gel electrophoresis (2-D DIGE) followed by protein identification by mass spectrometry, we compared proteomic differences in the shoots and roots of the BR-insensitive mutant d61-4 and BR-deficient mutant brd1-3. We identified a large number of proteins differentially expressed in the mutants compared with wild type control. These include a glycine-rich RNA-binding protein (OsGRP1) and a DREPP2 protein, which showed reduced levels in the BR mutants. Overexpression of these two proteins partially suppressed the dwarf phenotype of the Arabidopsis BR-insensitive mutant bri1-5. In contrast to the reduced protein level, the RNA level of OsGRP1 was not significantly affected in the BR mutants or by BR treatment, suggesting BR regulation of OsGRP1 at the posttranslational level. This study identifies many BR-regulated proteins and demonstrates that OsGRP1 functions downstream in the BR signal transduction pathway to promote cell expansion.     

一个新的水稻叶形突变体（tll1）的遗传分析与精细定位

利用甲基磺酸乙酯（ethylmethane sulphonate,EMS）诱变粳稻品种日本晴获得了一个遗传稳定的叶形突变体thread-like leaf1（tll1）。该突变体在杭州表现为矮化、窄叶,极端时仅剩主脉,呈细丝状。将该突变体分别与籼稻品种南京6号、浙辐802和9311进行正反交配组,遗传分析表明该突变体性状由1对隐性单基因控制。通过SSR和STS分子标记对F2代分离群体进行遗传定位,将该基因初步定位在第12染色体SSR标记RM247和RM101之间。随后利用已公布的粳稻品种日本晴和籼稻品种9311的基因组序列,发展了7对有多态的STS标记,最终将该基因定位在FL13和FL14之间约94.3kb的区间内,为进一步克隆TLL1基因奠定了基础。     

Loss-of-function of a rice brassinosteroid biosynthetic enzyme,C-6 oxidase,prevents the organized arrangement and polar elongation of cells in the leaves and stem

Molecular genetic and physiological studies on brassinosteroid (BR)-related mutants of dicot plants have revealed that BRs play important roles in normal plant growth and development. However, little is known about the function of BR in monocots (grasses), except for the phenotypic analysis of a rice mutant partially insensitive to BR signaling. To investigate the function of BR in monocots, we identified and characterized BR-deficient mutants of rice, BR-deficient dwarf1 (brd1). The brd1 mutants showed a range of abnormalities in organ development and growth, the most striking of which were defects in the elongation of the stem and leaves. Light microscopic observations revealed that this abnormality was primarily owing to a failure in the organization and polar elongation of the leaf and stem cells. The accumulation profile of BR compounds in the brd1 mutants suggested that these plants may be deficient in the activity of BR C-6 oxidase. Therefore, we cloned a rice gene, OsDWARF, which has a high sequence similarity to the tomato C-6 oxidase gene, DWARF. Introduction of the wild-type OsDWARF gene into brd1 rescued the abnormal phenotype of the mutants. The OsDWARF gene was expressed at a low level in all of the examined tissues, with preferential expression in the leaf sheath, and the expression was negatively regulated by brassinolide treatment. On the basis of these findings, we discuss the biological function of BRs in rice plants.     

一个新矮生玉米种质资源的发现与遗传鉴定

玉米矮生种质资源在育种工作中具有重要的利用价值。2002年在玉米种质资源扩繁与鉴定过程中,从玉米自交系K36中发现一株矮生突变体。随后通过连续自交,获得了纯合一致、稳定的矮生自交系,命名为矮2003。该矮秆材料在北京表现株高62．1cm,植株清秀,茎秆坚硬,结实正常。于不同时期用不同浓度赤霉素处理该材料显示其对赤霉素反应不敏感。矮2003与正常玉米自交系测交F1呈现高秆,F2与BC1高、矮秆分离比例分别符合3：1与1：1,遗传分析表明其矮生性状受一对主效单基因控制,表现为隐性遗传。所携带的矮生基因不同于已报道的玉米Dwarf8等。