Characterization of dwarf mutants and molecular mapping of a dwarf locus in soybean

Plant height is one of the most important traits in soybean. The semi-dwarf soybean cultivars could improve the ability of lodging resistance to obtain higher yield. To broaden the dwarfism germplasm resources in soybean, 44 dwarf mutants were identified from a gamma rays mutagenized M-2 population. Two of these mutants, Gmdwf1（Glycine max dwarf 1） and Gmdwf2（Glycine max dwarf 2）, were investigated in this study. Genetic analysis showed that both mutants were inherited in a recessive manner and their mutated regions were delimited to a 2.610-Mb region on chromosome 1 by preliminary mapping. Further fine mapping study proved that the two mutants had a common deletion region of 1.552 Mb in the target region, which was located in a novel locus site without being reported previously. The dwarfism of Gmdwf1 could not be rescued by gibberellin（GA） and brassinolide（BR） treatments, which indicated that the biosynthesis of these hormones was not deficient in Gmdwf1.

Isolation and Characterization of Storage Protein Subunit-null-dwarf Mutants in Soybean(Glycine max(L.) Merr.)

Dwarfing is useful to reduce plant height,when breeding high-yielding and non-lodging crops.In this study,a set of natural storage protein subunit-null dwarf mutants of soybean was reported that showed strongly reduced plant stature and deficiency in various 7S and 11S subunits,designated as snd1 mutants.Under normal growth conditions,the snd1 mutants showed a severe dwarf phenotype,with plant height of about 25 cm.Compared with wild-type DN47,the mutant snd1 exhibited no obvious morphological differences at the early stage of development.All the snd1 mutants examined had fewer nodes and shorter than normal internodes;the leaves were similar in shape to normal parents,but were dark-green at the mature stage.The flower size was similar to DN47;however,the flowering period was shorter than in the wild-type.Significant variation was noted for protein content,oil content of the seeds and size of seeds(weight of 100 seeds)among 17 snd1 dwarf lines.Genetic analysis indicated that the dwarfism of snd1 was controlled by a single recessive gene.The snd1 dwarf mutant had markedly different dynamic levels of the endogenous hormones gibberellin(GA),brassinosteroid,indole-3-acetic acid and abscisic acid,at the seedling stage.Exogenous GA3 treatment led to recovery of the plant height phenotype of the snd1 mutant;GA3 at 0.1 mm had the largest effect on enhancing plant height.Using molecular markers,snd1 gene was approximately mapped in an interval of 603 kb between markers Satt166 and Satt561 on chromosome 19.Snd1 mutant provided valuable material for hypoallergenic soybean breeding and the snd1 gene might be a novel gene related to plant height in soybean.

Genetic Analysis and Gene Mapping of Multi-tiller and Dwarf Mutant d63 in Rice

A spontaneous mutation, tentatively named d63, was derived from the twin-seedling progenies of rice crossed by diploid SARIII and Minghui 63. Compared with wild-type plants, the d63 mutant showed multiple abnormal phenotypes, such as dwarfism, more tillers, smaller flag leaf and reduced seed-setting rate and 1000-grain weight. In this study, two F2 populations were developed by crossing between d63 and Nipponbare, d63 and 93-11. Genetic analysis indicated that d63 was controlled by a single recessive gene, which was located on the short arm of chromosome 8, within the genetic distance of 0.40 cM from RM22195. Hence, D63 might be a new gene as there are no dwarf genes reported on the short arm of chromosome 8.

Investigation on Agronomic Characters of Dwarf Mutant 778 in Broomcorn Millet(Panicum miliaceum L.)and Analysis of Its Sensitivity to GA

In order to investigate the differences between agronomic traits of dwarf mutant and original material 260 and whether the cause of dwarf is related to GA synthesis or signaling pathway,this experiment used dwarf mutant 778 and its original material 260 as experimental materials.Morphological observation and determination were performed for agronomic traits on plant height,ear length,internode length,internode number,seed length,seed width and number of seeds in different growth periods and different concentrations.The plants were treated by GA spraying,and the changes of plant height,root length,stem width,leaf length and leaf width were measured.The results are as follows:①The plant height of the dwarf mutant material was significantly different from that of the original high material,which was mainly caused by the difference between above-ground basal part and the length of the first and second elongation joints.②Comparing and analyzing the differences of traits between dwarf mutant material 778 and original high material 260,it was found that the plant height,ear length,internode number,grain number per ear and internode length of dwarf mutant 778 were significantly lower than that of high stalk 260(P<0.01),and the seed length of dwarf mutant 778 was significantly higher than that of high stalk 260(P<0.05).③Different concentrations of gibberellin(0,50,100,200 mg/L)had no significant effect on plant height and root length of dwarf mutant 778(P>0.05).Different concentrations of gibberellin had significant effects on plant height,root length and sensitivity coefficient of high stalk 260(P<0.05).And compared with the control group,all high materials 260 treated with different concentrations of gibberellin performed differently in plant morphology and growth potential.④Under the conditions of 100 and 200 mg/L GA,the difference of plant height between the dwarf mutant and the high stalk control decreased with time,and there was no difference at the end.There were no differences in sensitivity coefficient GRI between different concentrations of gibberellin treatment groups,indicating that the external gibberellin could restore the scorpion dwarf mutant to the original high stalk,and the gene that causes the mutation might be related with the gibberellin synthesis pathway.

Genetic Analysis of a Novel Dwarf Mutant,AISHENG98,from Upland Cotton

Cotton(Gossypium hirsutum L.) is the most important textile fiber and the second most important oil seed source in the world.To control excessive growth of cotton plant height,which may result in shading and lodging,farmers and researchers have used plant growth regulators that

Characterization and Expression Profiling of Genes Encoding the Gibberellin 3-oxidase in Dasypyrum villosum Dwarf Mutant

Gibberellin 3-oxidase catalyzes the conversion of inactive gibberellin(GA) species into GAs with biological activity and it is subjected to strict developmental controls in the life cycle of a plant. In this study, 33 gene sequences, encoding the gibberellin 3-oxidase(GA3ox) from Dasypyrum villosum and its dwarf mutant, were obtained. Each contained a 1 107 bp coding sequence(CDS) that encoded a putative protein containing 369 amino acids. The GA3ox protein showed 77% to 97% homology and shared the major conserved structural domains of GA3ox proteins with rice, sorghum bicolor, oat, barley, and wheat. Sequence alignment showed that there were 20 single nucleotide polymorphisms(SNPs) and 22 Insertion/deletions(In Dels) among these sequences, which could be divided into 2 haplotypes, haplotypes Ⅰ and Ⅱ. Haplotype Ⅰ was found in the wild type and was1 495 bp in length, and haplotype Ⅱ was found in the dwarf mutant and was 1 485 bp in length. The Q-PCR results showed that GA3ox was expressed in the leaves, roots, internodes, and stem nodes, and that there was a significant difference in the transcript level of the GA3ox between the wild type and dwarf mutant. The transcript levels of GA3ox in the leaves at the seedling stage, stem elongation stage and the heading stage, in the root and stem nodes at the stem elongation stage and in the internodes at the heading stage of the wild type, were significantly higher than those in the dwarf mutant. However, GA3ox expression in the rest of the wild type tissues at the 3 stages was slightly higher than or not different from the dwarf mutant.The results suggested that the wild type and mutant allele sequences of GA3ox in D. villosum showed 2 amino acid changes in exons and variations in the lengths of introns or the SNPs in introns, which most probably impaired the function of the enzyme,affected the GA3ox expression level, and eventually gave rise to dwarfing.

Cloning and Expression of Gene Responsible for High-Tillering Dwarf Phenotype in Indica Rice Mutant gsor23

High-tillering dwarf mutant gsor23 was generated from an indica rice variety Indica9 radiatied by y-ray. Genetic analysis showed that this phenotype was controlled by one single recessive gene, which was mapped within a physical distance of 386 kb between two insertion-deletion （InDel） markers CI-WT2 and C1-WT4 on the long arm of chromosome 1. There is a known gene DIO within this region, the mutation of which causes high-tillering in rice. Sequence analysis of the DIO allele in gsor23 revealed that the base cytosine （C） at the 404th position in the coding region was deleted, which would cause frameshift mutation after the 134th amino acids. The mutation site and indica background of gsor23 were different from the previously reported japonica mutants d10-1 and d10-2. Therefore, gsor23 is a novel allelic mutant of D10 which encodes the carotenoid-cleaving dioxygenase 8 （CCD8）, a key enzyme involved in the biosynthesis of the new plant hormone strigolactones （SLs）. After treatment with GR24, a synthetic analogue of SLs, the high-tillering phenotype of gsor23 was restored to normal. Real-time RT-PCR analysis showed that D10 expression was high in roots, but low in leaves. Compared with the wild type Indica9, the expression of the SL biosynthesis gene DIO was upregulated, while genes likely involved in the SL signal transduction pathway such as D3 and D14 were down-regulated in the gsor23 mutant.

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 intemode length of dwll, this mutant belongs to the dm type of dwarfing. Analysis of elongation of the second sheath and m-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 DWL1 gene was mapped to the terminal region of the long arm of chromosome 3. Fine-mapping delimited 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.

Identifi cation of a novel male sterile wheat mutant dms conferring dwarf status and multi-pistils

Plant height and fertility are two important traits of wheat (Triticum aestivum L.), whose mutants are ideal materials for studies on molecular mechanisms of stem and lforal organ development. In this study, we identiifed a dwarf, multi-pistil and male sterile (dms hereafter) wheat mutant from Zhoumai 18. Simple sequence repeat (SSR) marker assay with 181 primer pairs showed that only one locus of GWM148-2B was divergent between Zhoumai 18 and dms. There were three typical phenotypes in the progeny of dms, tal (T;ca. 0.8 m), semi-dwarf (M;ca. 0.6 m) and dwarf (D;under 0.3 m) plants. Morphological investigation indicated that the internode length of M was shortened by about 20–50 mm each;the internode number of D was 2 less than that of T and Zhoumai 18, and its internode length was shorter also. The pol en vigor and hybridization test demonstrated that dms mutant was male sterility. Segregated phenotypes in progeny of M suggested that the multi-pistils and sterility were control ed by one recessive gene locus which was designated as dms temporarily, and the plant height was control ed by a semi-dominant gene locus Dms. Therefore, progeny individuals of the dms had three genotypes, DmsDms for tal plants, Dmsdms for semi-dwarf plants and dmsdms for dwarf plants. The mutant progenies were individual y selected and propagated for more than 6 generations, thus a set of near isogenic lines of T, M and D for dms were developed. This study provides a set germplasms for studies on molecular mechanisms of wheat stem and spike development.

玉米矮秆突变体20F421的表型鉴定及遗传分析

矮秆资源是农作物矮化育种的物质基础,发掘矮秆基因资源对培育矮秆新品种具有重要作用。为了明确^(252)CF裂变快中子辐射诱变玉米自交系KWS49筛选得到的矮秆突变体20F421的遗传特性和矮化机理,以20F421为材料分别与玉米自交系PH6WC、B73、Mo17及KWS49杂交构建F_(1)和F_(2)分离群体,分析矮秆性状的遗传模式,并以(20F421/B73)F_(2)为定位群体,采用混池转录组测序(bulked segregant RNA-seq,BSR-seq)方法初步定位突变基因。结果表明,与KWS49相比,20F421的植株高度为95.2 cm,降低47.89%;穗位高度为23.9 cm,降低64.54%;茎秆节间长度显著缩短、叶片较直立密生,自交结实良好。遗传分析表明,F2分离群体野生型(高秆)与突变型(矮秆)植株性状分离比例符合3∶1,表明该突变体受单个核隐性基因控制;BSR-seq结果将突变基因定位在1号染色体177~255 Mb之间。通过与B73参考基因组进行比对发现,该区间内含有矮秆基因Br2,将20F421与br2突变体杂交进行等位性检测,F_(1)和F_(2)的株高均没有发生性状分离,表现为突变体20F421和br2表型,推测20F421的矮秆突变基因为矮秆基因Br2的等位突变。研究结果为进一步精细定位、克隆突变基因奠定基础,也为解析玉米矮化机理和培育矮秆玉米新品种提供重要基因资源和理论支撑。

两个新水稻 Dwarf18 基因强等位突变体的表型分析及分子鉴定

通过EMS诱变日本晴获得了s2-9和s1-146a两个矮秆突变体,其植株矮小,成熟期株高分别为日本晴的26.3%和19.2%;苗期叶片较宽,叶色深绿;穗型仍为散穗但穗长变短,粒型未发生改变。对水稻胚乳的α-淀粉酶诱导实验表明,这2个矮秆突变体与GA的信号传导途径无关,外源活性GA3对水稻幼苗株高的促进实验显示它们应与赤霉素的生物合成有关。利用突变体与籼稻品种Dular分别杂交构建了F2群体,精细定位表明这2个突变体的表型与水稻Dwarf18(D18)基因紧密连锁。序列分析发现这2个矮秆突变体的D18基因均发生了突变,在s2-9突变体中D18基因的内含子3'拼接点发生单碱基突变,s1-146a中D18基因编码区的单碱基突变导致提前终止密码子的出现。RT-PCR结果显示,在s1-146a中D18基因表达明显增强,但在s2-9中未检测到D18基因的表达。

外源GA_(3)处理对辣椒半矮秆突变体表型和生理特征的影响

分别用1.0、2.0、4.0、8.0 mg/L的GA_(3)处理辣椒半矮秆突变体E483的种子,分别用2.0、4.0、6.0、8.0、10.0、12.0 mg/L的GA_(3)喷施E483幼苗,以0.0 mg/L的GA_(3)处理的野生型6421(CK1)和E483(CK2)为对照,调查GA_(3)处理下E483种子萌发情况和植株表型,并测定幼苗叶片内源GA、可溶性糖、可溶性蛋白、MDA含量以及SOD、CAT、POD、GR活性。结果表明:E483种子萌发速度低于野生型6421的,GA_(3)处理可提高E483种子发芽势,且在2.0、4.0、8.0 mg/L GA_(3)处理下,E483种子发芽能力可恢复至野生型6421种子的发芽能力;E483植株较6421矮,叶片较6421小,喷施GA_(3)处理可促使E483幼苗茎秆节间伸长、茎增粗、叶面积增大,但不会改变其节位数;8.0 mg/L GA_(3)处理的E483的株高与6421的株高无显著差异;2.0 mg/L GA_(3)处理的E483茎粗与6421茎粗无显著差异;6.0 mg/L GA_(3)处理的E483的叶宽、叶面积与6421幼苗的叶面积无显著差异;E483幼苗中GA1、GA_(3)、GA20、GA29、GA_(3)4含量显著低于6421相应的值,推测该突变体属于GA合成缺陷突变体;E483叶片中可溶性糖、可溶性蛋白含量及SOD、CAT、POD、GR活性均显著高于6421的,MDA含量显著低于6421的;10.0 mg/L GA_(3)处理的E483叶片中可溶性糖、可溶性蛋白含量和SOD、CAT、POD活性达到最大值。

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。

化学诱变获得甘蓝型油菜矮秆突变新种质

油菜矮秆种质资源的发掘与创制对于培育株高适度矮化、抗倒性强、高产稳产、适合于机收的新品种具有重要意义。本研究利用化学诱变剂甲基磺酸乙酯处理甘蓝型油菜品种浙油50种子诱发获得两个矮秆突变体3060和4036,其株高分别为74.5 cm和72.0 cm,株型紧凑直立,苗期和成熟期诸多表型特征以及种子脂肪酸组成和含油量等品质性状发生了显著变化。遗传分析结果初步表明,两矮秆突变受单个隐性基因或隐性主基因控制,不存在细胞质效应。光暗处理条件下,两突变体幼苗形态建成正常,推测其矮化机制不涉及油菜素内酯途径。喷施不同浓度外源赤霉素可显著促进两突变体幼苗下胚轴伸长,但均不能使下胚轴长度恢复到原亲本的水平,表明矮秆突变的发生可能与赤霉素信号传导过程中的变异有关。两突变体所具有的一些重要特征特性赋予其一定的利用价值。

小麦矮秆突变体Xu1801的鉴定及其矮化效应分析

在徐麦35原种繁育过程中发现1株天然矮秆突变体,经连续多代单株选择,该突变体株高性状稳定遗传,将其命名为Xu1801(徐1801)。为研究Xu1801矮化原因,进行了农艺性状调查、倒伏指数分析、苗期赤霉素处理和矮秆相关基因检测。调查发现,Xu1801平均株高68.16 cm,较野生型徐麦35株高降低24.05%,其矮化效应表现为节间减少和各节间极显著缩短;其中,第5节间效应值最大,达44.16%。Xu1801的旗叶宽度、叶绿素含量、小穗密度极显著高于徐麦35,其他农艺性状与徐麦35差异较小。Xu1801产量达8604.17kghm^(–2),低于徐麦35;而蛋白质含量、湿面筋、沉降值等品质指标均显著优于徐麦35。Xu1801茎秆粗壮,各节间充实度较好,倒伏指数47.73,极显著低于徐麦35。GA3处理可知,Xu1801和徐麦35同属于赤霉素反应不敏感型种质。分子标记检测发现,Xu1801可能含有Rht-D1b、Rht4、Rht8、Rht9和Rht12等矮秆相关基因;WMC317(Rht4)和BARC102(Rht5)在Xu1801和徐麦35之间呈现出不同条带,其他标记扩增条带在两者之间较为一致。综上,Xu1801株高偏矮、抗倒伏能力强,产量和品质性状协调,具有一定的生产应用潜力,同时携带多个矮秆基因,可作为小麦株高遗传分析的种质资源。

衡谷12号高矮异株突变体稳定性鉴定

衡谷12号是河北省农林科学院旱作农业研究所培育的矮秆、极早熟、分蘖性强的谷子新品种。2019年从衡谷12号繁种田获得高矮异株突变体,对该材料进行两年一点、一年两点和错期播种,为鉴定该突变体的稳定性以及深入研究株高、分蘖、抽穗期提供可靠试验材料。结果表明,衡谷12号高矮异株突变体具有稳定遗传特性,农艺性状表型不受时间、地点、播种期的影响,可作为稳定遗传材料使用。

OsCYP 96B4等位突变体的抗病性分析

优良抗病性是水稻绿色生产的重要需求,在当前水稻育种中有着举足轻重的地位.矮秆水稻具有耐倒伏、适合密植等优良特性,但其存在较高秆水稻生物产量低、密植易发生严重病害等问题,多年来困扰着水稻育种的研究,因此挖掘矮秆抗病资源成了育种家们一直研究的热点.从EMS诱变处理的西农1B突变体库中鉴定到4个水稻矮化易感纹枯病突变体(Dwarf and susceptibility to sheath blight 1 mutants,dssb1s),遗传分析发现:这4个突变体均是在LOC_Os03g04680编码框中的不同位置发生突变,LOC_Os03g04680编码一个细胞色素酶OsCYP 96B4,接种水稻白叶枯病菌和纹枯病菌后发现这4个突变体均感病,qRT-PCR发现突变体中病程相关基因(NPR1,PR10,PR1a和WRKY45)表达量降低.组织切片和扫描电镜分析发现:突变体的叶片发育异常,叶表面硅化细胞的数量明显增多,分布密集、杂乱.对叶片和叶鞘的细胞壁成分测定发现:突变体中的木质素和纤维素质量分数均显著或极显著低于野生型.实验结果表明:OsCYP 96B4是通过调控植物的叶片等发育和细胞壁的组分,进而增强了对水稻病害的耐受性.

利用体细胞无性系变异筛选水稻光温敏核不育系株1S矮秆突变体

以幼穗和成熟胚为外植体经组织培养成功建立了体细胞无性系 ,结合愈伤组织多代培养和化学物质诱导 ,获得了高达 4 0 %以上的体细胞无性系变异 ,并从中选育出遗传稳定的株 1S矮秆突变体 SV5、SV10和 SV14。鉴定结果表明矮秆突变体 SV14是矮化了的光温敏核不育系 ,具有优良的光温敏不育特性 ,配合力强 ,杂种优势明显 ,较对照可以增产 10 %以上 。

EMS诱变水稻矮生资源的鉴定评价

用甲基磺酸乙酯(EMS)处理水稻优良籼型恢复系缙恢10号,获得了24份半矮化突变体,其中4份较为特别。与其他半矮化突变体相比,d11和d24的包穗程度较轻,分别为-2.7和-2.6cm,农艺性状变化较小,有效穗与原始材料相比无变化;缙恢10号对GA3敏感,d9和d18对GA3钝感,d9是全节间缩短型突变体,d18则为顶节缩短型突变体,其平均穗颈长仅为0.31cm,整个穗子被完全包裹在剑叶叶鞘中,包穗度为-24.4cm。遗传分析表明,d9、d11、d18和d24的半矮化性状均受单隐性核基因控制,为水稻矮化基因资源的丰富和GAs信号传导途径的深入研究创造了条件。

植物赤霉素矮化突变体研究进展

赤霉素(GAs)在植物种子萌发、茎的伸长和花的发育等方面起着非常重要的作用。近年来,随着研究手段和技术不断进步,对赤霉素(GA)生物合成和信号传导过程中相关基因的研究取得了惊人的进展。与GA有关的矮化突变体主要有GA缺陷型和不敏感型两类,对与GA生物合成和信号传导过程有关的这两类矮突变体的研究进展进行综述。对这些突变体的研究促进了对赤霉素生物合成和信号传导途径的认识,同时为赤霉素更好地利用提供了科学依据。