水稻直立穗突变体抗倒伏性的遗传力分析

为研究直立穗突变体R1338和R334在抗倒伏特性方面的遗传力与配合力,选用弯曲穗型不育系川农1A、ABG15s和2个含有DEP1直立穗基因的直立穗不育系E69A、E102A,与蜀恢498及其直立穗突变体R1338、R334进行不完全双列杂交,比较F1基部各节的抗倒伏特性。发现F1基部各节抗折力与倒伏指数呈极显著负相关性,抗折力与茎节的直径和茎壁厚度呈极显著正相关;通过回归分析发现影响水稻基部节抗倒伏能力的主要影响因子为茎节的抗折力和弯曲力矩,抗折力越大、弯曲力矩越小其倒伏指数也就越低;2个直立穗突变体基部节倒伏指数的一般配合力效应值均低于野生型,其中R1338的倒伏指数的一般配合力效应值更低一些。因此利用直立穗亲本配组可以显著改良杂交后代的抗倒伏能力。     

高粱穗部主要性状的配合力分析

以4个高粱不育系13163A、1358A、128A和407A,以及6个恢复系9.1R、213R、272R、381R、矮182R和早21R为试验材料,按照不完全双列杂交设计(NCII),对其F1的穗部主要性状进行配合力分析。结果表明:亲本穗部主要性状存在显著的遗传差异,主要表现为加性基因效应遗传的性状有:穗长、一级枝梗数、二级枝梗数、穗粒数;狭义遗传力大小顺序分别为:二级枝梗数一级枝梗数穗长穗粒数穗粒重千粒重。不同亲本的一般配合力(GCA)和特殊配合力(SCA)在不同穗部性状间存在较大差异。不育系407A和恢复系早21R、9.1R是综合性状较好的亲本材料,利用它们可组配出产量较高的杂交组合。恢复系272R组配的杂交种具有穗粒数较多、千粒重较小的特点,能满足市场上对小粒高粱的需求。深入分析高粱杂交亲本穗部主要性状表现,有利于对亲本材料的进一步了解和利用。     

抗赤霉病小麦地方品种黄方柱和海盐种EMS突变体的变异分析

突变体对增加小麦资源的遗传多样性,克隆和解析重要农艺、产量和抗性相关基因具有重要的意义。本研究以高抗赤霉病小麦品种黄方柱(HFZ)及其11个甲磺酸乙酯(EMS)诱导的纯合突变体(F2~F12,Mu4),以及海盐种(HYZ)及其12个EMS纯合突变体(Y2~Y13,Mu4)为材料,在扬花期利用单花滴注鉴定赤霉病扩展抗性,灌浆期测定了分蘖数、株高、旗叶长、旗叶宽、叶绿素含量,收获后测定千粒重、粒长、粒宽、每穗小穗数和每穗粒数共计11个性状。每一个突变体至少在一个性状上与野生型存在显著差异。黄方柱突变系F6、F9和F12以及海盐种突变系Y6、Y7和Y9病小穗率均显著高于相应野生型,达中感或高感水平,因此,这6个突变体是研究赤霉病扩展抗性的理想材料。此外,海盐种突变体株高、千粒重、每穗粒数和粒宽均低于或显著低于野生型。对野生型和突变体采用了基于最小组内平方和距离的动态聚类分析方法,综合评价了野生型与突变体以及突变体相互之间的相似情况。株高等农艺性状显著优于野生型但赤霉病抗性与野生型类似的突变体(如F2、F7、Y2、Y3、Y4、Y8、Y10和Y12)可为农艺性状的遗传研究和抗赤育种亲本选配提供重要的资源。     

贵州地方粳稻‘黎平杂边禾’矮秆小粒突变体dss1鉴定与基因定位

本研究从贵州地方粳稻(Oryza sativa ssp.japonica)品种‘黎平杂边禾’甲基磺酸乙酯(EMS)突变体库中筛选获得一份能稳定遗传的矮秆小粒突变体,暂命名为dss1(dwarf and small seed 1)。与野生型相比,dss1表现为植株矮化、株型直立、叶色深绿、籽粒变小、第二节间严重缩短、穗长增加等典型油菜素内酯(BR)缺陷突变体的性状。显微观察结果表明dss1叶鞘表皮细胞的长度变短,可能是突变体第二叶鞘长度比野生型短的原因。对突变体的暗形态建成与BR敏感性研究表明,黑暗条件下突变体表现为去黄化表型,对外源BR敏感。遗传特性分析证明dss1突变体由一个隐性单基因位点控制。利用Mut Map技术将dss1基因定位于3号染色体上,筛选获得一个候选基因,测序结果表明,dss1候选基因为BR合成途径关键酶基因Os DWARF,dss1是由于该基因第5个外显子上第335位的氨基酸由苏氨酸(ACT)突变为异亮氨酸(ATT)所引起的。定位得到的矮化小粒基因DSS1为一个新的Os DWARF等位基因。     

两种水稻短穗突变体的形态特征、遗传分析和基因定位

通过辐射诱变籼稻品种明恢86,获得两种短穗突变体,分别命名为rpl1(reduced panicle length 1)和rpl2(reduced panicle length 2)。两突变体都表现为穗变短、枝梗数和穗粒数减少、枝梗缩短,但其再生植株的穗长有所恢复,与野生型的差异明显减少。等位性测验表明,rpl1和rpl2是等位突变。利用M4分离群体和基于高通量测序的分离体混合分析(BSA-seq)方法,发现rpl2中LOC_Os11g12740基因的剪接位点发生了单碱基置换突变。进一步对rpl1测序分析,发现该基因完全缺失。这说明rpl1和rpl2都是LOC_Os11g12740突变引起的,由此证实它就是目标基因。该基因与已报道的SP1是同一个基因,因此rpl1和rpl2是SP1的新等位突变,但二者的表型与已报道的3种短穗突变体并不完全相同,说明不同突变和遗传背景会影响基因功能的表现。本研究进一步验证了SP1的功能,并为深入研究其分子作用机理提供新材料。     

长穗颈水稻的内源GA1、IAA和ABA含量变化

分别以携有长穗颈基因eui1、eui2和野生型基因Eui的协青早不育系和保持系6个水稻品种为材料,测定它们在抽穗始期植株中内源GA1、IAA和ABA含量的变化。结果表明,携有eui1和eui2基因的水稻可以在植株体内产生大量内源GA1,携有eui1基因的GA1含量比携有eui2基因的高。携有eui1基因的ABA含量最高,携有eui2基因的其次,而携有Eui基因的最低。IAA含量也表现出同样的趋势。表明长穗颈基因主要是通过调节内源GA1含量促进水稻最上节间的剧烈伸长。     

水稻矮化小穗突变d18新等位基因的发现及生理功能分析

株高和穗型是决定水稻产量密切相关的农艺性状.本研究从粳稻品种台北309经甲基磺酸乙酯诱变的群体中分离出一个能稳定遗传的矮化小穗突变体,主要表现矮化、粒长增加而宽度变小和穗型变小等特点.遗传分析表明,该突变体受单隐性核基因控制.定位于水稻第1号染色体的Indel标记P4和P5之间,物理距离约为20 kb.由于该区间只有一个已经克隆的矮化基因Dwarf18(d18),其功能编码赤霉素3β-羟化酶(GA3ox2).所以,表明突变基因与d18可能等位.测序比对发现,该突变基因的第2个外显子发生了1个碱基(G)的缺失,造成无义突变,实时荧光定量PCR结果显示,OsGA3ox2基因在突变体中表达量显著下降.因此,将该突变基因暂命名为d18-1.组织切片观察结果显示,与野生型相比,突变体的茎部倒三节间纵向细胞长度显著变短,但细胞数目增多.生理功能结果分析表明,突变体对外源激素GA更敏感,但对外源激素BR不如野生型敏感.检测与GA和BR生物合成与信号传导途径相关基因的表达结果发现,与野生型相比,在突变体中参与GA失活基因OsGA2ox3出现了下调表达,GA生物合成相关基因OsGA20ox2和OsGA3ox2也出现了下调表达,GA信号传导途径中的关键基因都没有明显的差异表达变化.另外,参与BR的合成或者信号传导途径的大部分相关基因在突变体中的表达都出现了下调.由此证明,突变体矮化是由于GA激素的不能正常合成所导致,并且对外源活性BR的响应通路受损而造成对BR激素的低敏感反应.另外,对孕穗期的野生型和突变体的幼穗进行转录组测序分析表明,与野生型相比,突变体检测到1497个差异表达基因,这些差异基因涉及苯丙素的生物合成、糖代谢和碳代谢等.因此,推测突变体中的OsGA3ox2基因发生了无义突变影响了GA和BR生物合成与信号传导途径以及穗型发育相关调控途径,这为更深入研究调控水稻矮化以及穗型的遗传网络提供了新的信息.     

水稻矮脆突变体dwf1的特性与基因定位

矮脆突变体dwf1(dwarf and fragile 1)来源于EMS诱变处理的籼型恢复系缙恢10号,主要表现为根、茎、叶、叶鞘、子粒等器官特别脆,同时植株变矮、叶片披垂。株高、穗长、结实率、节间长以及千粒重有不同程度降低,细胞壁中纤维素和木质素含量下降、半纤维素含量增加,机械强度下降。茎秆表面锯齿状突起尖锐,薄壁细胞较野生型小、细胞大小不一致、排列紊乱,细胞形状不规则、长度稍有变短。该突变性状受一对隐性核基因控制,位于第9染色体上标记Ind6与Ind4之间,dwf1相对于野生型在LOC_Os09g25490第7外显子上有一个碱基的错义突变,导致氨基酸由半胱氨酸突变为精氨酸,该突变发生在基因的高度保守区域内。dwf1对深入研究水稻变矮变脆机制具有重要意义。     

DUF640基因BEAK-SHAPED GRAIN1/TRIANGULAR HULL1影响水稻粒形和粒重

种粒的形状和大小都会影响其重量并最终影响产量,然而对于种粒形状和大小的分子调控机制仍然未被研究清楚.最近本研究组分离到一株粒形呈鸟嘴状的水稻突变体beak-shaped grain1(bsg1),其粒长、粒厚和粒重都有所减少,内外颖也发生弯曲而导致其无法完全闭合.与野生型相比,突变体种子的淀粉粒呈现不规则状.组织切片显示bsg1内外颖的外薄壁细胞层细胞变小且数目减少,与粒形的表型一致.图位克隆表明,BSG1基因编码一个DUF640蛋白TRIANGULAR HULL1(TH1).定量PCR和启动子活性分析表明,BSG1主要在幼穗和茎杆中表达.BSG1的突变影响细胞分裂相关基因以及粒宽基因GW2的表达.实验结果表明,BSG1可能通过调控细胞分裂和扩展来影响种粒形状及大小.     

γ-射线辐射诱导水稻黄化转绿叶色突变体X611的特性研究

利用60Coγ-射线辐照粳稻秀水11愈伤组织,在诱变后代中发现了一份黄化转绿叶色突变体X611,并对其表型特征、温度敏感性、生理特性以及农艺性状进行研究。在较低温度17℃条件下,该突变体X611幼苗叶色呈浅黄绿色;在温度为25℃时,X611幼苗叶色呈黄绿色;温度升高至30℃,突变体叶色转为浅绿色。突变体的这种叶色变化特性说明其叶色性状具有低温敏感性。在不同播种时期,突变体X611幼苗期叶片光合色素含量均较野生型秀水11明显下降;但在抽穗期突变体与野生型叶片光合色素含量相接近,净光合速率也表现出同样的趋势。与野生型相比,突变体X611株高平均值降低;剑叶长、剑叶宽、穗长、有效穗数、穗粒数、结实率和千粒重差异不显著。此叶色突变体农艺性状良好,在水稻育种中有较好的育种利用价值。     

Fine mapping and candidate gene analysis of dense and erect panicle 3, DEP3, which confers high grain yield in rice (Oryza sativa L.)

Architecture of the rice inflorescence, which is determined mainly by the morphology, number and length of primary and secondary inflorescence branches, is an important agronomical trait. In the current study, we characterized a novel dense and erect panicle (EP) mutant, dep3, derived from the Oryza sativa ssp. japonica cultivar Hwacheong treated with N-methyl-N-nitrosourea. The panicle of the dep3 mutant remained erect from flowering to full maturation, whereas the panicle of the wild type plant began to droop after flowering. The dep3 mutation also regulated other panicle characteristics, including panicle length, grain shape and grain number per panicle. Anatomical observations revealed that the dep3 mutant had more small vascular bundles and a thicker culm than wild type plants, explaining the EP phenotype. Genetic analysis indicated that the phenotype with the dense and EP was controlled by a single recessive gene, termed dep3. The DEP3 gene was identified as the candidate via a map-based cloning approach and was predicted to encode a patatin-like phospholipase A2 (PLA2) superfamily domain-containing protein. The mutant allele gene carried a 408?bp genomic deletion within LOC_Os06g46350, which included the last 47?bp coding region of the third exon and the first 361?bp of the 3??-untranslated region. Taken together, our results indicated that the patatin-like PLA2 might play a significant role in the formation of vascular bundles, and that the dep3 mutant may provide another EP resource for rice breeding programs.     

Map-based cloning of the ERECT PANICLE 3 gene in rice

Panicle architecture in rice can have a strong influence on yield. Using N-methyl-N-nitrosourea mutagenesis, we isolated an erect panicle mutant, Hep, from Hwasunchalbyeo, a glutinous japonica rice cultivar. Genetic analysis revealed that the erect panicle phenotype was controlled by a single recessive mutation designated erect panicle 3 (ep3). Genetic mapping revealed that the ep3 mutation was located on the short arm of chromosome 2 in a 0.1 cM region delimited by the STS markers STS5803-5 and STS5803-7. The ep3 locus corresponded to 46.8 kb region and contained six candidate genes. Comparison of the DNA sequences of the candidate genes from wild-type and erect panicle plants revealed a single base-pair change in the second exon of LOC_Os02g15950, which is predicted to result in a nonsense mutation. LOC_Os02g15950 encodes a putative F-box protein containing 515 amino acids and is expressed throughout the plant during all growth stages. A line carrying a T-DNA insertion in LOC_ Os02g15950 was obtained and shown to have the same phenotype as the ep3 mutant, thus confirming the identification of LOC_Os02g15950 as the ERECT PANICLE 3 (EP3) gene. The ep3 mutation causes a significant increase in the number of small vascular bundles as well as the thickness of parenchyma in the peduncle, which results in the erect panicle phenotype.     

不同穗型粳稻品种产量和品质性状的比较分析

利用不同穗型粳稻品种,在不同氮肥水平下对产量性状和品质性状进行了比较.试验结果表明,随着施氮水平的提高,直立穗型品种产量增加幅度大于半直立和弯曲穗型品种,但产量构成因素的变化趋势,在各种穗型品种间变化基本一致.随着施氮量的增加,3种穗型品种的糙米率、精米率和整精米率均增加,而垩白率的变化在不同穗型品种间不相一致.直立穗型品种较半直立和弯曲穗型品种,胶稠度相对较硬,蛋白质含量较高,并且对氮素的反应较敏感.     

一份水稻叶片反卷突变体的遗传分析及电镜显微观察

叶片是植物进行光合作用的重要器官。叶片适度卷曲能够提高水稻(Oryza sativa)生长中后期群体基部的光能利用率, 因而有利于水稻产量的提高。该研究首先在水稻T-DNA插入突变体库中发现一份叶片反卷的突变体。遗传分析表明, 该性状受到1对隐性核基因控制。扫描电镜观察结果显示, 突变体成熟叶片上下表皮的气孔发生了畸变; 且叶片上表皮气孔数目增多, 而下表皮气孔数目与野生型基本相同。叶片横切面电镜观察结果表明, 与野生型相比, 突变体叶片的泡状细胞数目和面积在早期(二叶期)就开始增加, 在成熟期更加明显, 这可能是导致叶片反卷的主要原因。     

Morphological alteration caused by brassinosteroid insensitivity increases the biomass and grain production of rice

The rice (Oryza sativa) dwarf mutant d61 phenotype is caused by loss of function of a rice BRASSINOSTEROID INSENSITIVE1 ortholog, OsBRI1. We have identified nine d61 alleles, the weakest of which, d61-7, confers agronomically important traits such as semidwarf stature and erect leaves. Because erect-leaf habit is considered to increase light capture for photosynthesis, we compared the biomass and grain production of wild-type and d61-7 rice. The biomass of wild type was 38% higher than that of d61-7 at harvest under conventional planting density because of the dwarfism of d61-7. However, the biomass of d61-7 was 35% higher than that of wild type at high planting density. The grain yield of wild type reached a maximum at middensity, but the yield of d61-7 continued to increase with planting density. These results indicate that d61-7 produces biomass more effectively than wild type, and consequently more effectively assimilates the biomass in reproductive organ development at high planting density. However, the small grain size of d61-7 counters any increase in grain yield, leading to the same grain yield as that of wild type even at high density. We therefore produced transgenic rice with partial suppression of endogenous OsBRI1 expression to obtain the erect-leaf phenotype without grain changes. The estimated grain yield of these transformants was about 30% higher than that of wild type at high density. These results demonstrate the feasibility of generating erect-leaf plants by modifying the expression of the brassinosteroid receptor gene in transgenic rice plants.     

江苏省直立穗型粳稻品种主要农艺性状和品质性状分析

通过对江苏省淮北稻区种植的主要粳稻品种品质状况和近十年来育成的直立穗型粳稻品种(系)主要品质和农艺性状的分析,发现前期育成直立穗型粳稻品种相时半直立穗型粳稻品种加工品质低,垩白率高和垩白度大,蛋白质含量高;而近期育成直立穗型粳稻品种在上述品质指标上有了较大改进,食味品质也有了显著提高.在主要农艺性状中,近期育成品种呈现每穗总粒数上升、穗长变长、着粒密度下降趋势,产量水平的提高与每穗粒数的增加有着紧密相关.     

水稻穗型与抗倒伏性关系的初步分析

理论分析和物理模拟测定的结果表明,穗型通过使茎秆弯曲的力矩-弯矩和重心高度影响抗倒伏性:弯矩增大和重心升高,抗倒伏性降低;反之,则抗倒伏性升高.弯矩随颈穗弯曲度变化的幅度明显大于重心,因此,弯曲穗型弯矩增加的幅度大而重心降低的幅度小,对抗倒伏性的影响明显大于直立穗型,这可能是北方粳稻直立穗型品种一般抗倒伏性较强的力学基础.     

Erect leaves caused by brassinosteroid deficiency increase biomass production and grain yield in rice

New cultivars with very erect leaves, which increase light capture for photosynthesis and nitrogen storage for grain filling, may have increased grain yields. Here we show that the erect leaf phenotype of a rice brassinosteroid-deficient mutant, osdwarf4-1, is associated with enhanced grain yields under conditions of dense planting, even without extra fertilizer. Molecular and biochemical studies reveal that two different cytochrome P450s, CYP90B2/OsDWARF4 and CYP724B1/D11, function redundantly in C-22 hydroxylation, the rate-limiting step of brassinosteroid biosynthesis. Therefore, despite the central role of brassinosteroids in plant growth and development, mutation of OsDWARF4 alone causes only limited defects in brassinosteroid biosynthesis and plant morphology. These results suggest that regulated genetic modulation of brassinosteroid biosynthesis can improve crops without the negative environmental effects of fertilizers.