一个显性卷叶突变体z2的遗传分析与精细定位

叶片的适度卷曲对水稻理想株型育种具有重要意义。在水稻T-DNA插入突变体库中获得一个叶片外卷突变体z2,突变体表型出现在分蘖期;与野生型相比,农艺性状无明显差异,光合作用效率高于野生型。对突变体和野生型的石蜡切片研究表明,突变体叶片泡状细胞数量(8-9个)明显多于野生型(4-5个)。z2卷叶性状遗传稳定,由一对显性核基因控制。以z2纯合突变体为母本,籼稻Dular为父本进行杂交构建F2代定位群体,利用图位克隆的方法,将该基因初定位于水稻第2号染色体的In Del1812与In Del1870标记之间,物理距离为580 kb。     

一个大豆理想株型突变体it1的表型和生理鉴定

突变体是基因功能研究和品种改良的重要材料。本研究对一个中品661 EMS诱变的株型突变体(it1)进行了表型和生理鉴定,旨在为该突变体的利用提供参考。结果表明:与野生型相比,突变体株型紧凑,节间缩短,叶片变小呈深绿色且皱缩;突变体高度降低为野生型的2/3,但节间数目与野生型无显著差别,说明it1株高降低是由每个节间长度缩短造成的,与节间数目无关;突变体的分枝数、荚数、粒数、叶柄长度及夹角、百粒重等产量性状均显著或极显著低于野生型。与野生型相比,突变体叶片叶绿素相对含量和木质素的含量显著高于野生型。本研究结果为控制突变相关基因的定位、图位克隆和功能分析以及育种利用提供了优良种质和理论依据。     

控制水稻叶形基因CLF1的图位克隆

分蘖、株高、植株形态是水稻理想株型的3个主要农艺性状。目前对水稻理想株型的分子调控机制认识还非常有限。而叶片形态建成是决定植株形态特征的主要因子,鉴定控制水稻叶片形态建成的关键基因至关重要。本研究通过筛选水稻突变体库,获得一份光合效率显著提高的突变体(curly leaf 1,clf1),其形态学特征表现为叶片适度卷曲,经石蜡细胞学切片发现,突变体clf1近轴面的泡状细胞明显增多是导致叶片卷曲和光合效率提高的主要原因。利用图位克隆,将CLF1基因缩小在2个分子标记In Del51与In Del57之间,该区间包含44个基因。通过生物信息学分析,确定了LOC_OS02G45250为CLF1的候选基因。对LOC_OS02G45250基因进行测序,在clf1突变体中,LOC_OS02G45250基因的第六外显子缺失20 bp,造成编码产物提前终止。该基因与已报道的水稻卷叶基因Roc5(Rice outermost cell-specific gene5)为等位基因,Roc5编码产物为一个具有GL2类同源异型结构域的转录因子,不同于已报道的突变体oul1(对应于Roc5基因),突变体clf1农艺性状表现优良,具有较大的生产应用潜力。     

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。     

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。     

叶绿素b含量低的水稻突变体的光合功能衰退及其与活性氧的关系

研究了一个在田间发现的水稻叶绿素b含量低的突变体叶片的光合功能衰退。和野生型相比,突变体的光合功能在叶片一生中较稳定;超氧阴离子和H2O2含量低,但活性氧清除系统的SOD和CAT酶活性差异不显著。由于突变体叶片中还原态辅酶Ⅱ和氧化态辅酶Ⅱ的比值低于野生型,因而认为其光合电子传递速率和羧化反应消耗电子速率之间比野生型更加平衡,是其光合功能较野生型稳定的原因。     

水稻茎秆脆性及叶尖枯死突变体fld1的鉴定与基因定位

用EMS诱变籼型水稻(Oryza sativa)恢复系缙恢10号, 获得稳定遗传的脆性叶尖枯死突变体fld1, 苗期植株呈现脆性和叶尖枯死, 机械强度显著下降, 一直持续到成熟。突变体fld1茎秆中的纤维素和木质素含量仅分别为野生型的67.92%和50.16%, 差异达极显著水平。与野生型相比, fld1叶片中的光合色素含量呈现一定程度的下降。其中, 类胡萝卜素含量在衰老和正常部位均极显著降低, 净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r)也极显著降低, 胞间CO₂浓度(C_i)则极显著升高。遗传分析表明, fld1的脆性和叶尖枯死性状共分离, 且受1对隐性核基因调控。利用西农1A/fld1和fld1/日本晴的F₂群体, 最终将FLD1定位在第9染色体Indel标记Ind09-2与Ind09-3之间215 kb的物理距离内, 包含33个注释基因。研究结果为下一步基因的克隆和功能研究奠定了基础。     

一个新的水稻叶绿素缺失黄叶突变体的特征及基因分子定位

从粳稻“嘉花1号”⁶⁰Coγ射线辐照的后代中筛选到一个叶绿素缺失黄叶突变体(yl11), 与野生型“嘉花1号”相比该突变体表现为全生育期植株叶片呈黄色, 叶绿素含量以及净光合速率明显下降, 叶绿体发育不完善, 并且伴随着株高等主要农艺性状的变化。遗传分析表明, 该突变性状受一对隐性核基因(yl11)控制。该突变体与籼稻“培矮64S”杂交生产的F₂、F₃群体中的分离出突变体型920个单株作为定位群体, 利用SSR和InDel分子标记将yl11基因定位在水稻第11染色体长臂上的MM2199和ID21039分子标记之间, 其物理距离约为110 kb, 目前该区域内没有发现与水稻叶绿素合成/叶绿体发育相关已知功能基因。研究结果为今后对该基因的克隆和功能分析奠定了基础。     

一个新的水稻叶绿素缺失黄叶突变体的特征及基因分子定位

从粳稻"嘉花1号"60Coγ射线辐照的后代中筛选到一个叶绿素缺失黄叶突变体(yl11),与野生型"嘉花1号"相比该突变体表现为全生育期植株叶片呈黄色,叶绿素含量以及净光合速率明显下降,叶绿体发育不完善,并且伴随着株高等主要农艺性状的变化。遗传分析表明,该突变性状受一对隐性核基因(yl11)控制。该突变体与籼稻"培矮64S"杂交生产的F2、F3群体中的分离出突变体型920个单株作为定位群体,利用SSR和InDel分子标记将yl11基因定位在水稻第11染色体长臂上的MM2199和ID21039分子标记之间,其物理距离约为110kb,目前该区域内没有发现与水稻叶绿素合成/叶绿体发育相关已知功能基因。研究结果为今后对该基因的克隆和功能分析奠定了基础。     

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。     

NARROW AND ROLLED LEAF 2 regulates leaf shape,male fertility,and seed size in rice

Grain yield in rice(Oryza sativa L.) is closely related to leaf and flower development. Coordinative regulation of leaf, pollen, and seed development in rice as a critical biological and agricultural question should be addressed. Here we identified two allelic rice mutants with narrow and semirolled leaves, named narrow and rolled leaf 2-1(nrl2-1) and nrl2-2. Map-based molecular cloning revealed that NRL2 encodes a novel protein with unknown biochemical function. The mutation of NRL2 caused pleiotropic effects, including a reduction in the number of longitudinal veins, defective abaxial sclerenchymatous cell differentiation, abnormal tapetum degeneration and microspore development, and the formation of more slender seeds compared with the wild type(WT). The NRL2 protein interacted with Rolling-leaf(RL14),causing the leaves of the nrl2 mutants to have a highercellulose content and lower lignin content than the WT, which may have been related to sclerenchymatous cell differentiation and tapetum degeneration. Thus, this gene is an essential developmental regulator controlling fundamental cellular and developmental processes, serving as a potential breeding target for high-yielding rice cultivars.     

Isolation and characterization of a rice mutant with narrow and rolled leaves

Appropriate leaf shape has proved to be useful in improving photosynthesis and increasing grain yield. To understand the molecular mechanism of leaf morphogenesis, we identified a rice mutant nrl1, which was characterized by a phenotype of narrow and rolled leaves. Microscopic observation showed that the mutation significantly decreased the number of vascular bundles of leaf and stem. Genetic analysis revealed that the mutation was controlled by a single nuclear-encoded recessive gene. To isolate the nrl1 gene, 756 F₂ and F₃ mutant individuals from a cross of the nrl1 mutant with Longtepu were used and a high-resolution physical map of the chromosomal region around the nrl1 gene was made. Finally, the gene was mapped in 16.5 kb region between marker RL21 and marker RL36 within the BAC clone OSJNBa0027H05. Cloning and sequencing of the target region from the mutant showed that there was a 58 bp deletion within the second exon of the cellulose synthase-like D4 gene (TIGR locus Os12g36890). The nrl1 mutation was rescued by transformation with the wild-type cellulose synthase-like D4 gene. Accordingly, the cellulose synthase-like D4 gene was identified as the NRL1 gene. NRL1 was transcribed in various tissues and was mainly expressed in panicles and internodes. NAL7 and SLL1 were found to be upregulated, whereas OsAGO7 were downregulated in the nrl1 mutant. These findings suggested that there might be a functional association between these genes in regulating leaf development.     

Identification and characterization of NARROW AND ROLLED LEAF 1, a novel gene regulating leaf morphology and plant architecture in rice

Leaf morphology is an important agronomic trait in rice breeding. We isolated three allelic mutants of NARROW AND ROLLED LEAF 1 (nrl1) which showed phenotypes of reduced leaf width and semi-rolled leaves and different degrees of dwarfism. Microscopic analysis indicated that the nrl1-1 mutant had fewer longitudinal veins and smaller adaxial bulliform cells compared with the wild-type. The NRL1 gene was mapped to the chromosome 12 and encodes the cellulose synthase-like protein D4 (OsCslD4). Sequence analyses revealed single base substitutions in the three allelic mutants. Genetic complementation and over-expression of the OsCslD4 gene confirmed the identity of NRL1. The gene was expressed in all tested organs of rice at the heading stage and expression level was higher in vigorously growing organs, such as roots, sheaths and panicles than in elsewhere. In the mutant leaves, however, the expression level was lower than that in the wild-type. We conclude that OsCslD4 encoded by NRL1 plays a critical role in leaf morphogenesis and vegetative development in rice.     

不同遗传背景下杂交籼稻功能叶与产量构成因素的相关性

为明确水稻功能叶与产量构成因素间的相关性,以不同遗传背景下籼稻的10个不育系和16个恢复系为亲本,按照NCII设计配制两套双列杂交组合,对水稻12个功能叶性状与8个产量性状构成因素进行了相关分析,结果表明：3片功能叶叶长与叶面积、剑叶宽、倒2叶宽等性状之间均存在极显著正相关,功能叶夹角之间也存在极显著正相关,但不同遗传背景对夹角性状与9个形态性状之间的相关性则存在明显差异,在第1套组合中,其相关系数均为负值,且相关均不显著;而第2套组合则相反。8个产量构成因素中,单株穗数与平均穗长、着粒密度、穗实粒数以及穗着粒数之间存在极显著负相关,平均穗长与穗着粒数、结实率与单株产量呈显著或极显著正相关,遗传背景对产量组成上有较大影响,在第1套组合中单株产量主要由结实率、单株穗数以及穗实粒数等性状决定,而在第2套中则主要由穗实粒数和结实率等性状决定。在功能叶与产量构成因素的相关中,叶长、叶面积、剑叶宽、倒2叶宽与着粒密度、穗实粒数以及穗着粒教等3个性状之间存在显著或极显著正相关。12个水稻功能叶性状与8个产量构成因素之间的主成分分析表明,在不同的遗传背景下,产量构成因素均主要受叶面积和叶夹角影响,两种不同遗传背景中其累积贡献率分别为69．8％和84．0％。     

Characterization and molecular cloning of a serine hydroxymethyltransferase 1 (OsSHM1) in rice

Serine hydroxymethyltransferase(SHMT) is important for one carbon metabolism and photorespiration in higher plants for its participation in plant growth and development,and resistance to biotic and abiotic stresses. A rice serine hydroxymethyltransferase gene, Os SHM1, an ortholog of Arabidopsis SHM1, was isolated using map-based cloning. The osshm1 mutant had chlorotic lesions and a considerably smaller,lethal phenotype under natural ambient CO2 concentrations,but could be restored to wild type with normal growth under elevated CO2levels(0.5% CO2), showing a typical photorespiratory phenotype. The data from antioxidant enzymes activity measurement suggested that osshm1 was subjected to signi fi cant oxidative stress. Also, Os SHM1 was expressed in allorgans tested(root, culm, leaf, and young panicle) but predominantly in leaves. Os SHM1 protein is localized to the mitochondria. Our study suggested that molecular function of the Os SHM1 gene is conserved in rice and Arabidopsis.     

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.     

NaCl胁迫下抗盐突变体和野生型小麦Na~ 、K~ 累积的差异分析

对抗盐突变体和野生型小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．）在盐胁迫下Ｎａ＋、Ｋ＋的累积状况进行了比较研究。结果表明,ＮａＣｌ胁迫下突变体根和叶中Ｎａ＋的相对累积较野生型显著地少,同时Ｎａ＋的净累积速率显著地低。这种Ｎａ＋相对累积少的状况在叶中表现尤为明显。两者叶中Ｋ＋含量随盐浓度的增加显著下降,但突变体的含量均高于野生型。突变体根中Ｋ＋的含量也显著高于野生型,且这种差异随盐浓度的提高而增大。分别统计突变体和野生型根和叶中Ｎａ＋的含量以及每株幼苗的Ｎａ＋总量以分析二者Ｎａ＋在根和叶中的分布差异,结果表明３００ｍｍｏｌ／ＬＮａＣｌ胁迫９６ｈ后,突变体根中Ｎａ＋的累积量占其整株幼苗Ｎａ＋累积总量的４４４％,而野生型根中含量占其总量的２４３％。相对于野生型而言,在盐胁迫下突变体根中Ｎａ＋分布比例的提高可有效地减少根中Ｎａ＋向地上部分转运。     

Mutation in a novel gene SMALL AND CORDATE LEAF 1 affects leaf morphology in cucumber

Plant species exhibit substantial variation in leaf morphology.VWe isolated a recessive mutant gene termed small and cordate leaf 1(sclh)that causes alteration in both leaf size and shape of cucumber.Compared to wild type leaves,the sclh mutant had fewer numbers of epidermal pavement cells.A single nucleotide polymorphism was associated with this leaf phenotype,which occurred in a putative nucleoside bisphosphate phosphatase.RNA-seq analysis of the wild type and sclh mutant leaves suggested that SCL_1 regulation may not involve known hormonal pathways.Our work identified a candidate gene for SCL_1 that may play a role in leaf development.     

OsARG encodes an arginase that plays critical roles in panicle development and grain production in rice

Nitrogen is a crucial nutrient for plant growth and development. Arginine is considered to be an important amino acid for nitrogen transport and storage, playing a crucial role during plant seedling development. However, little is known about the role of arginine in nitrogen remobilization at the reproductive stage. We isolated a rice mutant nglf‐1 with reduced plant height, small panicle and grain size, and low seed‐setting rate (10% in nglf‐1 compared to 93% in wild‐type). Map‐based cloning revealed that the mutant phenotype was caused by loss of function of a gene (OsARG) encoding an arginine hydrolysis enzyme, which is consistent with arginine accumulation in the mutant. The phenotype was partially corrected supplying exogenous nitrogen, and fully corrected by expression of a wild‐type OsARG transgene. Over‐expression of OsARG in rice (cv. Kitaake) increased grain number per plant under nitrogen‐limited conditions. OsARG was ubiquitously expressed in various organs, but most strongly in developing panicles. The OsARG protein was localized in the mitochondria, consistent with other arginases. Our results suggest that the arginase encoded by OsARG, a key enzyme in Arg catabolism, plays a critical role during panicle development, especially under conditions of insufficient exogenous nitrogen. OsARG is a potential target for crop improvement.     

Developmental and genetic characterization of a short leaf mutant of sorghum (Sorghum bicolor L. (Moench.))

Changes in plant architecture, specifically conversion to compact canopy for cereal crops, have resulted in significant increases in grain yield for wheat (Triticum aestivum) and rice (Oryza sativa). For sorghum (Sorghum bicolor L. Moench.) a versatile crop with an open canopy, plant architecture is an important feature that merits strong consideration for modification. Here, we report the genetic, developmental, and physiological characterization of a sorghum genetic stock, KFS2061, a stable mutant (in the Western Black Hull Kafir background) which exhibit short and erect leaves resulting in compact plant architecture. Genetic study of an F₂ population derived from the cross of KFS2061 to BTx623 showed that the short leaf is recessive and appeared to be controlled by a single gene. The expression of the short leaf trait commenced with the 3rd leaf and is propagated through the entire leaf hierarchy of the canopy. The short leaf mutant exhibited consistent steep leaf angle, 43° (with the main culm as reference), and greener leaves than wild type. Biochemical analyses indicated significantly higher chlorophyll and cellulose content per leaf area in the mutant than wild type. Histological studies revealed reduction in cell length along the longitudinal axis and enlargement of bulliform cells in the adaxial surface of the mutant leaf. Further evaluation of agronomic traits indicated that this mutation could increase harvest index. This study provides information on a short leaf genetic stock that could serve as a vital resource in understanding how to manipulate plant canopy architecture of sorghum.