水稻橙红色突变体的遗传分析与基因定位

从水稻材料H9808航天诱变的后代中筛选出1株与色素相关的突变体,该突变植株在幼穗分化期新出幼叶的叶脉为橙红色,到拔节后期植株节间及下部约1/3的茎秆均呈现橙红色,在茎杆节底部中心有一橙红色的原点,抽穗时颖壳为橙红色,并保持到种子成熟,遗传分析表明突变体受1对隐性基因控制。在突变体与9311杂交的F2代隐性群体中,利用SSR标记将橙红色基因定位在2号染色体RM5350和RM12601标记之间,遗传距离分别为0.55cM和1.38cM。再利用新设计的InDel标记,进一步将该基因定位在S1和S2之间,遗传距离分别为0.41和0.25,为克隆水稻橙红色基因奠定了基础。     

水稻叶色突变体ygr的遗传分析与基因定位

叶色突变体是研究水稻叶绿体发育、光合色素合成与降解的理想材料。前期研究在水稻保持系大面积繁殖时发现一株转绿型淡黄叶突变体ygr,为了阐明其叶色调控机理,本试验比较了ygr与野生型的主要农艺性状和光合色素含量,并对该突变体进行了遗传分析和基因定位。结果表明,与野生型相比,ygr的始穗期推迟2 d,株高、单株有效穗数、穗长、穗粒数、结实率和千粒重等主要农艺性状均无显著差异,而苗期和抽穗期的叶绿素a、叶绿素b、总叶绿素和类胡萝卜素等光合色素含量均显著降低。遗传分析表明,ygr叶色突变性状受单隐性核基因控制,暂时将其命名为YGR。以ygr与日本晴杂交的F_2群体作为定位群体,将YGR基因定位在水稻第1号染色体分子标记WY8到WY20之间,其遗传距离分别为0.2 cM和0.5 cM。本研究结果为该基因的克隆和功能分析以及解析其突变机制奠定了基础。     

水稻突变体des2和des5的研究和定位(英文)

小穗发育是决定水稻产量的主要农艺性状,鉴定控制小穗发育的关键基因对研究和分析调控农艺性状的分子机理是至关重要的。本文中,我们鉴定了一组小穗数目明显减少的突变体,命名为decreased spikelets(des),这里详细研究des2和des5两个突变体。结果显示des2是由单基因隐性位点控制,图位克隆将此位点定位到6号染色体的长臂上,并最终克隆了此基因,发现des2是moc1的一个新的等位突变体。定位克隆和序列分析显示在des5中,LAX基因的编码HLH(螺旋-环-螺旋)结构域的区域发生了一个点突变,暗示des5是lax的一个新的等位突变体。我们的结果暗示小穗和水稻叶腋分枝的发育受相同的遗传途径调控。     

水稻脆秆褐穗突变体fb1的鉴定与基因定位

为鉴定新的脆杆突变体,从籼型水稻恢复系缙恢10号的甲基磺酸乙酯(EMS)诱变体库中鉴定了一个全生育期植株变脆且开花后稻穗呈褐色的突变体,暂命名为脆秆褐穗突变体fb1,对其进行了机械强度、光合色素含量、木质素和纤维素含量等测定,并开展了遗传分析和基因定位等研究。结果表明,与野生型相比,fb1茎秆和叶片的最大载荷分别下降了43.3%和63.1%,茎秆的纤维素和木质素含量分别为野生型的76.5%和66.6%,叶片的纤维素和木质素含量则分别为野生型的91.0%和95.5%,均显著降低。开花前,fb1的穗部性状与野生型相比无变化,开花后颖壳逐渐褐化,成熟后呈灰褐色。fb1的叶绿素a、叶绿素b和类胡萝卜素含量分别为野生型的74.8%、90.5%和85.3%,均呈显著或极显著下降。遗传分析表明,该性状受一对隐性核基因调控,基于西农1A/fb1的F2群体,利用SSR等分子标记最终将调控基因FB1精细定位在第1染色体SSR标记RM1268和RM11669之间42 kb的物理范围内,包含7个注释基因。该研究结果不仅为FB1基因的图位克隆奠定了基础,也为植物细胞壁发育分子机理研究和新能源水稻育种提供了材料。     

~(60)Co-γ射线诱导水稻卷叶突变体基因组缺失的分析

为探明60Co-γ射线诱导水稻卷叶突变体γ-rl产生的原因,对早期研究中分子标记定位区间内的4个候选基因进行PCR扩增分析,发现其中的OsF MO(t)基因在γ-rl突变体中不能扩增出特异条带。通过PCR扩增和Southern杂交进一步分析,证明γ-rl基因组中存在1个包含OsF MO(t)基因的最大范围约为16.47 kb的缺失区间,该结果为电离辐射可致植物基因组DNA产生较大范围的缺失提供了一个新的确凿证据。利用FGENESH软件对此缺失区间的DNA序列进行基因预测,发现除了OsF MO(t)基因外,该缺失区间内可能还包含1个编码类似拟南芥中假设的核糖核酸酶H基因、1个编码类似人类中E2调节蛋白基因和2个未知功能基因。这些基因的缺失可能是突变体γ-rl产生的主要原因。本研究结果为γ-rl突变体相关基因的克隆及功能分析提供了理论依据。     

GENETIC ANALYSIS AND GENE FINE MAPPING FOR MUTATION OF YELLOW-GREEN LEAF IN RICE

通过甲基磺酸乙酯（EMS）诱变晚粳稻品种秀水09,获得了1个稳定遗传的全生育期黄绿叶突变体Ygl,遗传分析表明该突变性状由1对隐性核基因控制。利用突变体与籼稻品种珍汕97杂交,构建F2群体对突变基因进行定位,发现目的基因与第11号染色体上的SSR标记RM2459连锁,在该标记附近发展了14对InDel标记,将突变基因定位在约82kb区间内。通过在线最新水稻注释系统的基因功能预测分析,寻找候选基因,经测序发现突变体发生单碱基突变。     

水稻窄叶突变体zy103突变基因鉴定

为通过叶形相关基因定位与克隆解析水稻叶形变异的分子机制,本研究以籼稻品种9311与粳稻品种豫粳6号的杂交F₇株系中发现的窄叶突变体zy103为试验材料,应用(zy103/9311)F₂、F₃分离群体对窄叶基因进行精细定位及候选基因预测。表型分析表明,突变体zy103出现全生育期叶片变窄微卷、株高及结实率降低、成熟种子弯曲变形等变异表型。遗传分析和基因定位结果表明,突变体zy103受1对隐性核基因控制,该基因被定位于第12号染色体195.4 kb的区间内,此区间内共预测了28个编码基因。对区间内与水稻叶形态建成相关的OsCSLD4(LOC_Os12g36890.1)基因进行测序,结果表明,突变体中OsCSLD4基因的编码区第2外显子第3 472~第3 479处有8个核苷酸(TGTGCCAC)缺失,造成移码突变,导致原编码蛋白第Ⅶ和第Ⅷ跨膜区保守功能结构域丢失,推测OsCSLD4是引起突变体zy103窄叶突变的目的基因。本研究结果为解析水稻窄叶形成的分子机理和水稻理想株型育种奠定了一定的理论基础。     

水稻白化转绿突变体albg的鉴定和基因精细定位

为丰富水稻白化转绿突变体的基因资源,利用甲基磺酸乙酯(EMS)诱变粳稻品种日本晴,获得一个白化转绿突变体,命名为albg。albg在三叶期前,未完全展开叶片时出现白化现象,待叶片完全展开之后逐渐转绿,三叶期以后新出叶片均无白化现象,至六叶期所有叶片恢复绿色。与野生型植株相比,突变体albg的结实率和株高显著降低,每穗总粒数也有减少,而千粒重和有效分蘖数在野生型和突变体albg之间无显著差异。突变体albg的叶色变化与叶绿素含量和叶绿体发育有关,并受一对隐性基因控制。利用图位克隆技术,将该基因定位于水稻3号染色体上In Del标记3G5和3G3之间,2个标记间相距约163.1 kb,该区间共有28个候选基因,其中Os03g0597200基因编码一个三角五肽(PPR)蛋白。序列分析表明,该基因从ATG开始第1 387位发生了一个碱基G的插入,推测其可能为目的基因。本研究结果为水稻育种提供了应用理论依据。     

一个新的水稻温敏感叶色突变体基因定位分析

粳稻品种嘉花1号种子经60Coγ射线辐照后,筛选得到一个温敏感叶色突变体MR20。该突变体的幼苗叶色在较低温度(20℃)下呈黄白色,并随着温度升高叶色由黄白逐渐转绿,其临界温度约为22.5℃,在低温(20℃)和高温(32℃)条件下叶绿素含量也存在显著差异,表明该突变体为低温导致叶绿素合成受阻的温敏感叶色突变体。遗传分析表明该突变体性状受一对隐性核基因控制,暂命名为tsc(t)。以该突变体与籼稻9311杂交的F2群体作为定位群体,利用SSR分子标记将tsc(t)基因初步定位在水稻第3染色体短臂上的分子标记RM231和RM14407之间,其遗传距离分别为1.5cM和0.5cM。随后,进一步扩大F2群体将该tsc(t)基因定位在分子标记MM0541和RM14407之间的约440kb内。     

一个水稻黄绿叶突变体ygl15的鉴定和基因定位

由籼稻品系杂交后代中发现1个黄绿叶突变体,命名为ygl15。为揭示突变体ygl15叶色变异机制,对其进行了表型鉴定和基因定位分析。结果表明,突变体ygl15从苗期开始表现为黄绿叶,叶片中的叶绿素和类胡萝卜素含量较野生型显著下降,并最终导致其农艺性状受到影响,表现为株高、有效穗数、单株总粒数和单株实粒数显著下降,穗长、每穗粒数和结实率的变化不显著,千粒重略有提高;基因表达分析表明,突变体ygl15叶片中,叶绿素合成和光合系统相关的基因表达上调,但血红素合成相关的基因表达下调或不变。遗传分析表明,ygl15的突变表型受1对细胞核隐性基因控制。以突变体ygl15和中花11杂交的F_2群体为定位群体,经过初步定位和精细定位,将ygl15基因定位在水稻第3号染色体上的分子标记M08124～M08175之间,物理距离约79 kb。本研究结果为进一步克隆ygl15突变基因和研究基因功能奠定了一定的理论基础。     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.