辐射诱变创制水稻新种质研究进展及浙粳99突变体库的建立

辐射诱变育种所需年限短、变异率高、后代性状稳定快,在作物遗传育种中已广泛应用.本文统计了我国近10年来利用辐射诱变技术培育的在生产应用上发挥重要作用的部分优良新品种18个,说明通过辐射诱变可加速水稻变异,丰富水稻遗传图谱,为培育高产、优质、抗病水稻新品种提供更多类型种质资源.此外总结了利用辐射诱变获得的各种类型突变,包...     

小麦异源易位系诱致方法及应用研究进展

小麦属内遗传基础狭窄和多样性种质资源匮乏是小麦遗传改良的瓶颈,利用近缘物种有益基因拓宽小麦遗传资源,是发掘小麦新种质的重要途径。染色体工程是将小麦外源靶向基因渗入小麦的有效方法,部分同源重组诱导体系和电离辐射是创制小麦异源易位系的两种高效技术,可以在短期内诱致大量染色体结构变异,得到了广泛研究和应用。本文重点综述了中国春ph1b突变体和⁶⁰Co-γ射线辐射两种常用的诱变方法及特点,并简述了其在小麦种质创新上的应用进展。上述诱变技术与寡核苷酸探针FISH相结合将加快外源基因向小麦中的渐渗与精准鉴定,提高染色体工程效率。本研究为进一步发掘和利用外源优异基因,拓宽栽培小麦种质资源并开展相关遗传学和基因组学研究提供了重要参考。     

离子束在生命科学中的应用

低能离子在生命科学中应用是道德在中国兴起的１９８６年,中国的科技工作者研究了低能哼子对生物的诱变效应,并成功地将其应用于植物育种。现在,离子注入技术已被应用于生物改良、生命起源和进化以及环境辐射生物学效应等多个理论和应用研究领域。其中,在植物遗传转化、创造新种质资源方面的成果尤其为突出：通过离子束介导转化法获得了高蛋白小麦、高光效水稻,抗病小麦、水稻、棉花新品质。通过诱变技术获得了多穗型玉米、无融     

作物诱变育种研究进展

作物新品种的培育能保持粮食稳产增收,利用自然和诱变获得遗传变异是作物育种的基础。随着栽培作物基因库的日益贫乏,诱变育种技术已成为目前种质资源创新和挖掘新基因的一个重要途径。本文综述了植物诱变育种的发展简史,物理诱变、化学诱变的主要类型、特点、异同及其在农业育种上的应用。由于诱变育种存在的主要问题是有益突变频率仍然较低,变异的方向和性质尚难控制,因此提高诱变效率,迅速鉴定和筛选突变体以及探索定向诱变的途径,是今后研究的重要课题。     

TILLING在水稻育种中的应用前景

TILLING(Targeting Induced Local Lesions in Genomes)是功能基因组研究中应用的一种反向遗传学技术。它能高通量低成本地在EMS诱变群体中鉴定出发生在特定基因上的点突变。在其基础上发展出的EcoTILLING技术则可发现种质资源中的SNP位点及小插入或缺失多态性位点。水稻是非常重要的粮食作物, 也是已经完成了全基因组序列测定,有丰富的生物信息学资源可以利用的基因组研究模式植物。水稻的分子标记辅助育种将在育种中扮演越来越重要的角色。在这样的背景下,本文从基于特定基因的种质资源鉴定、EMS诱变育种、及水稻功能标记开发等方面论述了其在水稻育种中的应用前景。     

高能电子束对水稻的诱变效应

为提高水稻诱变育种的突变频率及效果,本研究采用新型诱变源高能电子束(EB)辐照2种不同基因型水稻品种产生突变效应,并与传统~(60)Co-γ射线处理相比较,探索了高能电子束应用于水稻诱变育种的最适辐照剂量,分析了其M1代的生物损伤特点并统计了M2代部分可见农艺性状表型突变频率,探讨了高能电子束处理不同基因型水稻品种的损伤效应和诱变效应。本研究为水稻的高能电子束诱变育种工作提供了参考。     

“卫星灵芝”让人类更健康

1什么是太空诱变育种 自1987年以来,我国利用返回式卫星和飞船搭载了各种植物种子、微生物菌种、动物等生物材料进行太空生命科学的研究。太空诱变育种是利用返回式卫星等所能到达的空间环境对生物体诱变作用产生的变异,在地面选育新种质、新材料,培育新品种的一种新型的诱变育种方法,称为航天诱变育种或空间诱变育种也称太空诱变育种。     

"培两优7 21"的选育兼谈高空诱变育种

利用高空搭载粳稻品种“中作59”,处于海拔30-35km的高空,8h后回收种植,以后再用γ-射线进行处理,其后代变异类型更为丰富,变异频率增加,从中选育出了很多有利用价值的优良新种质,通过广泛测交、试种、区试、测产,选配出了一个优质、高产的两系杂交水稻新组合-培两优721。本文介绍了该组合的选育经过、组合的特征特性,并探讨了育种的体会及对高空诱变的作用机理。     

植物诱变技术的研究进展

植物诱变技术是指利用外界因素加快物种遗传变异,在短期内获得有利用价值的突变体,为培育新种质、新品种及基因功能的研究等创造条件。相对于自然的选择,诱变技术具有高频率、广突变、周期短等特性。主要论述了常用的化学诱变、物理诱变、空间诱变和生物诱变等诱变手段,并详细介绍了上述诱变技术的诱变机理、生物学效应、常用的诱变方式及其在植物应用中的研究现状。针对现行各种诱变技术的不足提出了今后努力的方向。     

来源于疣粒野生稻的越冬性新种质SH5的鉴定

低温冷害是影响水稻稳产的重要限制因子之一,鉴定和发掘利用优异的耐寒水稻种质资源是选育耐冷水稻品种以减少因低温对水稻生产不利影响的一条经济有效的策略。本研究通过让正季种植的水稻植株自然越冬翌年观察是否长出再生苗的方式鉴定了一份来源于疣粒野生稻的越冬性水稻新种质SH5;0℃低温处理结果表明,SH5的越冬性与其地上部植株的耐寒性无关;田间越冬性观察表明,SH5以地表及其以下的茎越冬;SH5越冬再生苗的扦插种植具有与正季种植的SH5相近的农艺性状。越冬性水稻新种质SH5的鉴定,为选育生产上应用的耐冷水稻品种提供宝贵的新种质资源。     

水稻香味基因分子标记的开发及应用

根据香稻材料在Badh2基因(甜菜碱醛脱氢酶基因)第7外显子的突变位点,设计了分子标记YY5-YY8用来区分这种突变类型的香稻材料。同时结合已报道的针对Badh2在第2、4、5外显子处突变设计的功能标记InDel-E2和FMbadh2-E4-5,对80份不同生态区香稻材料进行了标记检测。结果表明,26份材料属于第7外显子突变类型,37份材料属于第2外显子突变类型,无第4、5外显子突变类型材料。该研究构建了针对Badh2突变的新的分子标记YY5-YY8,并且鉴定了上述香稻材料的突变类型,为优质香稻分子育种奠定基础。     

Tissue Culture-Induced Heritable Genomic Variation in Rice,and Their Phenotypic Implications

Background

Somaclonal variation generally occurs in plants regenerated from tissue culture. However, fundamental issues regarding molecular characteristics, mutation rates and mutation spectra of plant somatic variation as well as their phenotypic relevance have been addressed only recently. Moreover, these studies have reported highly discrepant results in different plant species and even in the same plant genotype.

Methodology/principal findings

We investigated heritable genomic variation induced by tissue culture in rice by whole genome re-sequencing of an extensively selfed somaclonal line (TC-reg-2008) and its wild type (WT) donor (cv. Hitomebore). We computed the overall mutation rate, single nucleotide polymorphisms (SNPs), small scale insertions/deletions (Indels) and mobilization of transposable elements (TEs). We assessed chromosomal distribution of the various types of genomic variations, tested correlations between SNPs and Indels, and examined concomitancy between TE activity and its cytosine methylation states. We also performed gene ontology (GO) analysis of genes containing nonsynonymous mutations and large-effect mutations, and assayed effects of the genomic variations on phenotypes under both normal growing condition and several abiotic stresses. We found that heritable somaclonal genomic variation occurred extensively in rice. The genomic variations distributed non-randomly across each of the 12 rice chromosomes, and affected a large number of functional genes. The phenotypic penetrance of the genomic variations was condition-dependent.

Conclusions/significance

Tissue culture is a potent means to generate heritable genetic variations in rice, which bear distinct difference at least in space (chromosomal distribution) from those occurred under natural settings. Our findings have provided new information regarding the mutation rate and spectrum as well as chromosomal distribution pattern of somaclonal variation in rice. Our data also suggest that rice possesses a strong capacity to canalize genetic variations under normal growing conditions to maintain phenotypic robustness, which however can be released by certain abiotic stresses to generate variable phenotypes.     

CRISPR/Cas9 in rice can induce new mutations in later generations,leading to chimerism and unpredicted segregation of the targeted mutation

CRISPR/Cas9 is a novel tool for targeted mutagenesis and is applicable to plants, including rice. Previous reports on CRISPR/Cas9 in rice have demonstrated that target mutations are transmitted to the next generation in accordance with Mendelian law, but heritability of the target mutation and the role of inherited Cas9 gene have not been fully elucidated. Here, we targeted the rice phytoene desaturase gene, mutants of which exhibit an albino phenotype, by using CRISPR/Cas9 and analyzed segregation of target mutations. Agrobacterium-mediated methods using immature embryos successfully transformed a CRISPR/Cas9 system into five rice cultivars and subsequently induced mutation. Unpredicted segregations, with more mutants than theoretically predicted, were frequently found in T₁ plants from monoallelic T₀ mutants. Chimeric plants with both biallelic and monoallelic mutated cells were also observed in the T₁. Next, we followed segregation of a target mutation in the T₂ from monoallelic T₁ mutants. When T₁ mutants possessed Cas9, unpredicted segregations of the target mutation and chimeric plants were observed again in the T₂. When T₁ mutants did not possess Cas9, segregation of the target mutations followed Mendelian law and no chimeric plants appeared in the T₂. T₂ mutants with Cas9 had mutations different from the original ones found in T₀. Our results indicated that inherited Cas9 was still active in later generations and could induce new mutations in the progeny, leading to chimerism and unpredicted segregation. We conclude that Cas9 has to be eliminated by segregation in T₁ to generate homozygous mutants without chimerism or unpredicted segregation.     

A natural mutation in rc reverts white-rice-pericarp to red and results in a new, dominant, wild-type allele: Rc-g

The Rc locus regulates pigmentation of the rice bran layer, and selection for the rc allele (white pericarp) occurred during domestication of the crop. White bran is now ubiquitous among cultivated varieties throughout rice growing regions of the world. We identified a new allele that arose by natural mutation within the rc pseudogene of the cultivar 'Wells'. The mutation restored the reading frame of the gene, and reverted the bran layer pigmentation to red (wild-type). By sequencing the Rc locus in plants derived from red seeds, and linkage analysis in a segregating population, we were able to demonstrate that mutation within rc resulted in the new, dominant, wild-type allele Rc-g.     

Characterization of a new allelic mutant of DWARF3 in rice and analysing its function and stability in the presence of strigolactone

Strigolactones (SLs) are important intrinsic growth regulators that control plant architecture by coordinating shoot and root development. Recent studies demonstrate that SL signals act via targeting the degradation protein DWARF53 (D53) family of chaperonin-like proteins. This process requires DWARF14 (D14) as strigolactones signal receptor and DWARF3 (D3) forming Skp-Cullin-F-box (SCF) complex as ubiquitin E3 ligase. Although the interactions of these signal components can be expected, where and how the SLs signalling occur within cells in a tissue-specific manner is still uncertain. In this study, we characterize a rice high-tillering dwarf mutant, ext.-M1B, displaying resistance to synthetic strigolactone mixture rac-GR24. Through genetic analysis, we find that ext.-M1B is a new allelic mutant of D3 with a nucleotide mutation resulting in a truncated protein of wide-type D3. We demonstrate that the mutation affects neither gene expression level nor the protein sub-cellular localization, whereas it disrupts the perception of SLs signal in ext.-M1B mutant. Moreover, we find that overexpression of D3 in wild type background causes no significant phenotype, but suppression of D3 by RNA interfering results in a clear phenocopy of SL mutants. By expressing fluorescent D3 fusion protein in rice, we first show that D3 is stable consistently in the nucleus with or without strigolactone treatment. Taken together, our data indicates that D3 encoding an F-box protein in nucleus, as a stable signal component response to strigolactone regulating rice shoot architecture.     

含维生素A功能稻紫宝香糯1号的选育与利用

紫宝香糯1号是江西省玉山县特种水稻研究中心利用紫香糯诱变产生的突变体与地方品种八月香糯杂交配组选育而成的新型水稻品种。糙米中富含钙、硒、维生素E、维生素B1和维生素B6等功能营养成分;且糙米中维生素A含量为11 IU/100g,是目前世界上第一个栽培稻内源基因型含天然维生素A的水稻品种,对人类具有较高的营养及保健功能,2006年通过江西省品种审定委员会审定,命名为赣晚糯6号。     

Genetic interaction between 2 tillering genes, reduced culm number 1 (rcn1) and tillering dwarf gene d3, in rice

Mutant genes, reduced culm number 1 (rcn1) and bunketsuwaito tillering dwarf (d3), affect tiller number in rice (Oryza sativa L.) in opposite directions. The d3 mutant was reported to increase tiller number and reduce plant stature. Our objective was to compare the phenotype of the d3rcn1 double mutant with each single mutant and parental rice cultivar "Shiokari" and to clarify whether the Rcn1 gene interacted with the D3 gene. We recovered a new rcn1 mutant from Shiokari and developed d3rcn1 double mutant with Shiokari genetic background. A new rcn1 mutant, designated as "S-97-61" exhibited a reduction in tiller number and plant stature to about the same level as the previously reported original rcn1 mutant. Three near-isogenic lines, rcn1 mutant, d3 mutant, and d3rcn1 double mutant, were grown together with the parental Shiokari. The reduction in tillering by the rcn1 mutation was independent of the d3 genotype, and tillering number of d3rcn1 double mutant was between those of the d3 and rcn1 mutants. These results demonstrated that the Rcn1 gene was not involved in the D3-associated pathway in tillering control.