水稻矮秆突变体dtl1的分离鉴定及其突变基因的精细定位

文章通过对所构建的水稻突变体库进行大规模筛选,获得一个稳定遗传的矮秆突变体,与野生型日本晴相比,该突变体表现为植株矮化、叶片卷曲、分蘖减少和不育等性状,命名为dtl1(dwarf and twist leaf 1)。dtl1属于nl型矮秆,激素检测表明,矮秆性状与赤霉素和油菜素内酯无关。遗传分析显示,突变性状受单一隐性核基因控制。利用dtl1与籼稻品种Taichung Native 1杂交构建F2群体,将该突变基因DTL1定位于水稻第10染色体长臂2个SSR标记RM25923和RM6673之间约70.4 kb区域内,并与InDel标记Z10-29共分离,在该区域预测有13个候选基因,但未见调控水稻株高相关基因的报道,因此,认为DTL1基因是一个新的控制水稻株高的基因。     

水稻矮秆小粒突变体dsg7的图位克隆

水稻是世界上最重要的作物之一,株高是决定水稻产量的重要因素,不断发掘新的水稻株高调控基因,阐明水稻株高调控机理具有重要的意义。本研究在Kitaake的EMS(甲基磺酸乙酯)诱变后代中筛选到一个矮秆小粒突变体dsg7,与Kitaake相比,dsg7株高变矮,千粒重下降。通过叶鞘切片观察证实,由于细胞数目减少导致小粒表型的出现。利用图位克隆,将DSG7定位到第7染色体长臂237kb的区间内,经过生物信息学分析和测序证实Os07g0616000为突变基因,编码一个植物中广泛存在的蛋白。本研究证实DSG7参与水稻株高发育调控,为阐明水稻株高调控提供新的理论基础,有助于水稻株高发育分子机制的进一步阐释。     

水稻多分蘖矮秆突变体htd1-2的遗传分析和基因定位

文章所采用的多分蘖矮秆突变体为htd1-2(high-tillering dwarf 1-2), 是野生型籼稻品种9311经350Gy的60Co- g射线辐射处理后产生的后代中选育出来的稳定多分蘖矮秆突变体。遗传分析表明, 突变体htd1-2多分蘖矮秆性状是由一对隐性核基因的突变造成的。文章利用简单重复序列(Simple sequence repeat, SSR)、酶切扩增多态性序列(Cleaved amplified polymorphic sequence, CAPS)和衍生型CAPS(derived CAPS, dCAPS)等分子标记的方法, 最终将多分蘖矮秆基因HIGH-TILLERING DWARF1-2(HTD1-2)定位在水稻第4号染色体116 kb的物理区间内。在该物理区间内有一个已经克隆的控制水稻分蘖的基因HIGH-TILLERING DWARF1(HTD1), 经过测序比对和dCAPS特异性分析, 认为HTD1就是HTD1-2基因。尽管突变体htd1与突变体htd1-2是等位基因的不同位点发生突变, 但是由于遗传背景的不同, 两者表型并不完全相同。此外, 通过去除分蘖芽的实验证明了突变体htd1-2的矮化部分是由于分蘖过多造成的。     

水稻矮化基因WLD1的图位克隆

水稻(Oryza sativa)矮化是与光合效率及产量等密切相关的重要农艺性状。发掘更多的水稻矮秆资源,不仅能够进一步加深对水稻株高分子遗传机制的认识,而且还能为水稻新品种培育提供新的种质资源。在水稻T-DNA插入突变体库中筛选到1个矮化、宽叶小粒突变体(wld1)。经图位克隆将WLD1基因定位在第5号染色体长臂,位于分子标记In Del37与InDel48之间,基因编号为LOC_Os05g32270,属于AP2转录因子家族。该基因第6外显子处胸腺嘧啶缺失,造成转录提前终止。石蜡切片观察结果显示,茎部第2节间横向细胞数目增加,而纵向细胞数目未变。RT-PCR检测结果表明,LOC_Os05g32270在突变体wld1中不表达,造成功能缺失。该基因与已报道的水稻OsSMOS1(SMALL ORGAN SIZE1)为等位基因。水稻突变体wld1的矮秆遗传效应可直接应用于育种中。该研究结果进一步明确了突变体wld1的表型特征与遗传基础,为解析其参与的信号途径提供参考。     

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）。     

拟南芥雄性不育突变体ms1142的遗传定位与功能分析

经EMS诱变野生型拟南芥（Arabidopsis thaliana）群体筛选得到一株雄性不育突变体ms1142,突变体的果荚短小,不含种子。细胞学观察和扫描电镜结果表明,突变体花药发育过程中,花药中小孢子外壁异常、破裂,最后没有花粉形成。遗传分析表明,该突变体为隐性单核基因突变所致;利用图位克隆的方法将MS1142基因定位于第1条染色体的BAC克隆F16P17上44kb区间内,目前尚未见该区间内有雄性不育基因的报道。以上结果结合生物信息学分析表明,MS1142是一个新的调控花药发育的关键基因。该工作为花药发育关键基因MS1142的克隆及功能分析奠定了基础。     

拟南芥雄性不育突变体ms1142的遗传定位与功能分析

经EMS诱变野生型拟南芥(Arabidopsis thaliana)群体筛选得到一株雄性不育突变体ms1142, 突变体的果荚短小, 不含种子。细胞学观察和扫描电镜结果表明, 突变体花药发育过程中, 花药中小孢子外壁异常、破裂, 最后没有花粉形成。遗传分析表明, 该突变体为隐性单核基因突变所致; 利用图位克隆的方法将MS1142基因定位于第1条染色体的BAC克隆F16P17上44 kb区间内, 目前尚未见该区间内有雄性不育基因的报道。以上结果结合生物信息学分析表明, MS1142是一个新的调控花药发育的关键基因。该工作为花药发育关键基因MS1142的克隆及功能分析奠定了基础。     

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。     

拟南芥雄性不育突变体fne的遗传与定位分析

在T-DNA插入突变体Salk_118481株系的群体中,筛选到一株雄性不育突变体,用T-DNA序列上的一对引物进行PCR鉴定表明其基因组中没有T DNA插入。通过背景纯化与遗传分析发现该雄性不育突变体是由单个隐性基因控制的,引起不育的主要原因是在花药发育的第13~14期,花丝不能伸长以完成授粉,故该突变体命名为fne （filament no elongation）。利用图位克隆的方法对FNE基因进行了定位,结果表明FNE基因位于第五条染色体上分子标记MBD2和MMG4之间的97kb区间内。目前该区间内尚未见到控制花丝伸长基因的报道,因此,FNE基因是一个控制花丝伸长的新基因。     

水稻矮杆突变体D814基因图位克隆与功能分析

水稻株高对作物产量有着重要的影响,在水稻整个生长发育过程中,株高受到多因素的调控,而植物激素乙烯就是重要的影响因素之一。用10 mg/m3乙烯处理水稻幼苗,对水稻突变体库进行筛选,获得了3个根伸长生长对乙烯敏感性降低的突变体,其中1个突变体D814表现出植株矮化、分蘖数减少、千粒重下降等特征。图位克隆将其定位在1号染色体上1 c M的区间内,该区间有6个已报道的矮杆突变基因,通过对这6个基因测序,发现其中1个基因Os BRI1(LOC_Os01g52050)发生了点突变(编码区第1 837位G突变为T)。并在D814中分别对Os BRI1的2个同源基因(Os BRL1和Os BRL3)进行测序,发现这2个基因均无突变。利用已报道的Os BRI1等位突变体gsor300084进行乙烯处理,发现gsor300084与D814一样,表现出根对乙烯敏感性降低。Os BRI1是植物激素油菜素内酯(brassinosteroid,BR)的信号受体,经检测,BR信号途径响应基因在D814突变体中的表达也有变化,说明D814是Os BRI1的1个等位突变体。功能分析发现,D814参与乙烯信号转导调控途径和植物盐胁迫应答途径。研究结果为探究乙烯调控水稻生长发育及耐逆性的分子机理提供了研究材料,也为进一步探讨油菜素内酯与乙烯协同调控水稻生长发育机制奠定了理论基础。     

Genetic analysis and fine-mapping of a dwarfing with withered leaf-tip mutant in rice

A dwarf mutant of rice(Oryza.sativa L.)by mutagenesis of ethylene methylsulfonate(EMS)treatment from Nipponbare was identified.The mutant exhibited phenotypes of dwarfism and withered leaf tip(dwll).Based on the internode length of dwl1,this mutant be longs to the dm type of dwarfing.Analysis of elongation of the second sheath and α-amylase activity in endosperm showed that the phenotype caused by dwll was insensitive to gibberellin acid treatment.Using a large F2 population derived from a cross between the dwll and an indica rice variety,TN1,the DWLl gene was mapped to the terminal region of the long arm of chromosome 3.Fine-mapping de-limited it into a 46 kb physical distance between two STS markers,HL921 and HL944,where 6 open reading frames were predicted.Cloning of DWL1 will contribute to dissecting molecular mechanism that regulates plant height in rice,which will be beneficial to molecular assisted selection of this important trait.     

一份水稻矮杆小粒突变体的形态特征和基因定位

从水稻T-DNA插入突变体库中鉴定出一个矮杆小粒突变体t129,该突变体与野生型植株相比,植株明显矮化,籽粒粒长明显缩短,千粒重下降。遗传分析表明,t129的突变性状由一对隐性核基因控制,该基因(T129)经图位克隆定位于水稻第5染色体长臂上,引物InDel43和InDel57之间,物理距离为430 kb,并与标记InDel51共分离。本研究明确了该矮杆小粒突变体的表型特征及遗传规律,为进一步研究调控水稻株高和粒型基因奠定基础。     

Characterization and fine mapping of <Emphasis Type="Italic">osh15</Emphasis>(<Emphasis Type="Italic">t</Emphasis>), a novel dwarf mutant gene in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Plant height is one of the most important agronomic traits of plant architecture, and also affects grain yield in rice. In this study, we obtained a novel dwarf rice mutant of japonica variety Shennong9816, designated Shennong9816d. Compared with wild-type, the Shennong9816d plant height was significantly reduced, and the tiller number significantly increased. Additionally, the mutant yield component, and the number of large and small vascular bundles were significantly decreased compared with wild-type. Genetic analysis indicated that the Shennong9816d dwarf phenotype was controlled by a recessive nuclear gene, while the plant was shown to be sensitive to gibberellic acid. Using a large F₂ population derived from a cross between Shennong9816d and the indica rice variety Habataki, the osh15(t) gene was fine mapped between RM20891 and RM20898, within a physical distance of 73.78 kb. Sequencing analysis showed that Shennong9816d carries a 1 bp mutation and a 30 bp insertion in the OSH15 region. These results suggest that osh15(t) is a novel allelic mutant originally derived from japonica variety Shennong9816, which may be useful for introducing the semi-dwarf phenotype to improve plant architecture in rice breeding practice.     

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.     

<i>DWARF</i> and <i>SMALL SEED1</i>, a Novel Allele of <i>OsDWARF</i>, Controls Rice Plant Architecture,Seed Size,and Chlorophyll Biosynthesis

Plant architecture is a vital agronomic trait to control yield in rice (Oryza sativa L.). A dwarf and small seed 1 (dss1) mutant were obtained from the ethyl methanesulfonate (EMS) mutagenized progeny of a Guizhou glutinous landrace cultivar, Lipingzabianhe. The dss1 mutant displayed phenotypes similar to those of brassinosteroid (BR) deficient mutants, such as dwarfing, dark green and rugose erect leaves, small seeds, and loner neck internode panicles with primary branching. In our previous study, the underlying DSS1 gene was isolated, a novel allele of OsDWARF (OsBR6ox) that encodes a cytochrome P450 protein involved in the BR biosynthetic pathway by MutMap technology. In this work, we confirmed that a Thr335Ile amino acid substitution residing in DSS1/OsDWARF was responsible for the dwarf, panicle architecture, and small seed phenotypes in the dss1 mutants by genetic transformation experiments. The overexpression of OsDWARF in the dss1 mutant background could not only recover dss1 to the normal plant height and panicle architecture but also rescued normal leaf angles, seed size, and leaf color. Thus, the specific mutation in DSS1/OsDWARF influenced plant architecture, seed size, and chlorophyll biosynthesis.     

A substitution mutation in OsCCD7 cosegregates with dwarf and increased tillering phenotype in rice

Dwarf plant height and tillering ability are two of the most important agronomic traits that determine the plant architecture, and have profound influence on grain yield in rice. To understand the molecular mechanism controlling these two traits, an EMS-induced recessive dwarf and increased tillering1 (dit1) mutant was characterized. The mutant showed proportionate reduction in each internode as compared to wild type revealing that it belonged to the category of dn-type of dwarf mutants. Besides, exogenous application of GA3 and 24-epibrassinolide, did not have any effect on the phenotype of the mutant. The gene was mapped on the long arm of chromosome 4, identified through positional candidate approach and verified by cosegregation analysis. It was found to encode carotenoid cleavage dioxygenase7 (CCD7) and identified as an allele of htd1. The mutant carried substitution of two nucleotides CC to AA in the sixth exon of the gene that resulted in substitution of serine by a stop codon in the mutant, and thus formation of a truncated protein, unlike amino acid substitution event in htd1. The new allele will facilitate further functional characterization of this gene, which may lead to unfolding of newer signalling pathways involving plant development and architecture.     

Characterization and genetic mapping of a Photoperiod-sensitive dwarf 1 locus in rice (Oryza sativa L.)

Plant height is an important agronomic trait for crop architecture and yield. Most known factors determining plant height function in gibberellin or brassinosteroid biosynthesis or signal transduction. Here, we report a japonica rice (Oryza sativa ssp. japonica) dominant dwarf mutant, Photoperiod-sensitive dwarf 1 (Psd1). The Psd1 mutant showed impaired cell division and elongation, and a severe dwarf phenotype under long-day conditions, but nearly normal growth in short-day. The plant height of Psd1 mutant could not be rescued by gibberellin or brassinosteroid treatment. Genetic analysis with R₁ and F₂ populations determined that Psd1 phenotype was controlled by a single dominant locus. Linkage analysis with 101 tall F₂ plants grown in a long-day season, which were derived from a cross between Psd1 and an indica cultivar, located Psd1 locus on chromosome 1. Further fine-mapping with 1017 tall F₂ plants determined this locus on an 11.5-kb region. Sequencing analysis of this region detected a mutation site in a gene encoding a putative lipid transfer protein; the mutation produces a truncated C-terminus of the protein. This study establishes the genetic foundation for understanding the molecular mechanisms regulating plant cell division and elongation mediated by interaction between genetic and environmental factors.