Development and utilization of novel SSRs in foxtail millet [Setaria italica (L.) P. Beauv.]

Although the foxtail millet [Setaria italica (L.) P. Beauv.] is recently regarded as a model crop for studying functional genomics of biofuel grasses, its genetic improvement to some extent was limited due to the non‐availability of molecular markers, particularly the microsatellite markers and the saturated genetic linkage map. Considering this, we attempted to generate a significant number of microsatellite markers in cultivar ‘Prasad’. Two hundred and fifty‐six clones were sequenced to generate 41.82‐kb high‐quality sequences retrieved from genomic library enriched with dinucleotide repeat motifs. Microsatellites were identified in 194 (76%) of the 256 positive clones, and 64 primer pairs (pp) were successfully designed from 95 (49%) unique SSR‐containing clones. The 67.4% primer designing ability, 100% PCR amplification efficiency and 45.3% polymorphic potential in the parents of F₂ mapping population established the efficacy of genomic microsatellites. All the 64 microsatellite markers displayed high level of cross‐species amplification (~67%) in 10 millets and non‐millets species. These experimental findings suggest the utility and efficacy of SSRs in diverse genotyping applications, resolving QTLs, phylogenetic relationships and transferability in several important grass species.     

Traditional maintenance and multiplication of foxtail millet (Setaria italica (L.) P. Beauv.) landraces in China

Summary Foxtail millet (Setaria italica L. P. Beauv.) has been one of the most important cereals in northern China. A large number of landraces have formed under natural and man-made selection since domestication. Farmers in China have developed various traditional methods of maintenance and multiplication of foxtail millet seeds for next generation. Panicle selection was often done in fields. The selected seeds were generally stored at dry places. Archaeological and historical evidence of the origin of foxtail millet in China and the geographical distribution of landraces is also presented.     

Mitochondrial DNA variation in foxtail millet, Setaria italica (L.) P. Beauv.

Mitochondrial DNA (mtDNA) wascharacterized by RFLPs in 94 strains offoxtail millet, Setaria italica (L.)P. Beauv. Three RFLP patterns wereobserved by using rice atp6 as aprobe, and were designated as types I-III. Difference between types I and II seems tobe attributed to recombination between twoatp6 genes. In East and SoutheastAsia and Afghanistan, both of types I andII were found, while type I was predominantin India, Central Asia and Europe. InChina, type III was also found. Chinesestrains showed higher gene diversity thanthose from other regions. This resultcoincided the previous studies on isozymesand nuclear RFLPs.     

Breeding strategy in foxtail millet,Setaria italica (L.P. Beauv.), following interspecific hybridization

Summary An interspecific cross between foxtail millet Setaria italica and its wild relative Setaria viridis was undertaken in order to introduce from the latter triazine resistance in the cultivated plant. Four backcross generations obtained with S. italica as recurrent parent were studied. Results show that only two backcross generations associated with selection are enough to eliminate weedy characters and to return to the cultivated type. S. viridis could thus be an interesting source for improvement of foxtail millet without a complex and time consuming breeding strategy.     

Genetic variability in foxtail millet, Setaria italica (L.) P. Beauv.: Identification and classification of lines with RAPD markers

The DNA of 37 lines of Setaria italica, representative of Eurasian diversity, were used for the detection of polymorphism using the random amplified polymorphic DNA (RAPD) method. Four 10-mer primers, differing from each other by one or two G-C inversions, were used. Each one gave specific RAPD products. Twenty-five bands were polymorphic and allowed the identification of 33 different genotypes. A factorial analysis of correspondence was performed on the presenc-absence data, through which three genetic groups could be identified. These genetic groups were closely related to the geographical origin of the different lines: one central European and two Asiatic groups (the first Asiatic lines originating in latitudes below 35°N and the second comprising the Asiatic lines originating in latitudes above 35° N). The lines originating from western Europe were very variable and were dispersed in the three genetic groups described previously.     

Genetic variability in foxtail millet, Setaria italica (L.) P. Beauv. - RFLP using a heterologous rDNA probe

Ribosomal DNA was surveyed in a world collection (43 lines) of Setaria italica for variation in repeat unit length and restriction enzyme site variability using a non-radioactive wheat rDNA probe. Only two lengths of repeat units of about 7.9 or 7.6 kb were observed. The fact that these two repeat unit lengths were not randomly dispersed throughout the world collection suggests the existence of three genetic groups. The central European lines and most western European accessions have only the 7.6 kb repeat unit and most Asiatic lines have a 7.9 kb repeat unit. Lines originating from the north or the south of Asia showed different numbers of Bam HI fragments. The fact that the difference between the Asiatic and European pool is not continuous (7.9 or 7.6 kb) excludes the hypothesis of domestication being based on the spread of an initial population over Eurasia.     

Indentification of true genetic dwarfing sources in foxtail millet (Setaria italica Beauv.)

Summary True genetic dwarfs hither-to not reported have been located in foxtail millet. The dwarfs as a group distinguished themselves from the talls in having altered constellation of characters. The morphological differences were highly significant for plant height, internodal length, and tillering potential. The talls had elongated internodes compared to dwarfs while there was no difference for node number on the main stem suggesting that short internodal length was primarily responsible for dwarfism. The dwarfs also showed slightly higher leaf number per plant, leaf area and harvest index compared to talls. The dwarfs were insensitive to exogenous GA₃ application indicating that GA₃ synthesis is not impaired. This suggests that dwarfing gene sources presently identified are true genetic dwarfs and their behaviour is similar to dwarfs derived from Norin 10 in wheat and Dee-geo-woo-gen in rice. The superior morphological frame makes these dwarfs ideal as far as plant type is concerned and offers immense potentialities in breeding high yielding foxtail millets.     

谷子叶绿体基因RNA编辑位点的鉴定与分析

RNA编辑是高等植物叶绿体基因转录后加工修饰的现象,它会影响叶绿体发育,导致植株叶片出现黄化或白化等表型。本研究以长农35号及其2份叶色突变体(E752和E1005)为试验材料,利用紫外分光光度计测定了苗期叶绿素含量,通过透射电镜观察了叶绿体结构;利用在线工具Prep-Cp对谷子叶绿体基因RNA编辑位点进行了预测,通过PCR、RT-PCR及测序等方法对预测到的编辑位点进行了验证,并与其他单子叶作物的编辑位点进行了比较分析;进一步利用荧光实时定量方法,分析rpoB及依赖PEP转录的光合途径相关基因(ndhG、psaA、psbA和rbcL)在不同发育时期的表达水平;最后,利用生物信息学分析ropB编辑前后蛋白二级结构的变化。结果表明,与长农35号相比,2份叶色突变体叶绿素含量显著降低,叶绿体发育异常;在谷子中,有10个叶绿体基因共计20个位点发生RNA编辑,所有编辑位点均为胞嘧啶(C)和尿嘧啶(U)的转换,不同基因的编辑位点存在数量差异,其中ndhB编辑位点数量最多,共计6个; 20个编辑位点中,有19个位点在物种进化上具有较高保守性,只有rpoC1-2753为谷子中特有的编辑位点;在长农...     

不同光温条件谷子光温互作模式研究及SiCCT基因表达分析

光周期和温度是影响作物生长发育、生态适应性和产量的2个重要环境因素,揭示光温互作对作物生长发育的效应及其分子机制对育种实践和理论研究具有重要意义。本研究设置长日照高温、长日照低温、短日照高温、短日照低温4个光温处理,调查‘黄毛谷’抽穗期、株高、叶片数和穗长。结果表明,光周期对谷子的发育起关键作用,温度的改变不影响长日照比短日照延迟谷子生殖生长的效应,温度的作用随光周期的不同而异,短日照条件下,高温缩短谷子营养生长期而低温延长营养生长期,长日照条件下则相反;对谷子生殖生长的促迚作用是短日照高温>短日照低温>长日照低温>长日照高温。利用RT-PCR技术从‘黄毛谷’叶片兊隆了一个CCT结构域基因(SiCCT),该基因编码286个氨基酸,属于CMF亚家族成员,基于CCT域基因氨基酸序列的系统迚化分析,谷子与高粱、玉米亲缘关系较近。实时荧光定量PCR分析发现, SiCCT基因在‘黄毛谷’叶片中高表达,其次为幼穗和叶鞘;长日照、短日照处理SiCCT基因均表现24h昼夜节律性特点,短日照七叶期表达水平最高,八叶期(抽穗)及穗后表达迅速降低,长日照七叶至十叶期‘黄毛谷’处于营养生长期...     

杀雄剂SQ-1诱导谷子雄性不育研究

选取3个不同的谷子品种, 以杀雄剂SQ-1为雄性不育诱导剂, 采用3种不同杀雄剂浓度, 在3个不同发育时期对谷子喷施处理, 以喷水为对照。杀雄剂SQ-1在适宜喷施剂量与时期下, 供试品种五九爪软谷和香谷能被诱导产生95%~100%的雄性不育率, 对黄金谷杀雄效果尚未达到90%。五九爪软谷和香谷的喷药适宜时期分别为七叶期和八叶期, 喷施剂量同为4~5 kg hm^–2, 以5 kg hm^–2的杀雄效果最佳。     

Starch properties of native foxtail millet, Setaria italica Beauv.

Properties of foxtail millet (Setaria italica Beauv.) starches have been studied. Amylose content ranged between 3.3 and 11.4%. Starch content was from 67.5 to 68.7%. The onset temperature (To) of all samples ranged from 66.4 to 69.6°C, peak temperature (Tp) ranged 71.0 to 74.2°C, and their gelatinization enthalpy varied from 0.44 to 8.22 J/g, respectively. A highest gelatinization temperature was obtained for Bongseongjaerae (69.6°C). The enthalpy of the gelatinization (Δ H _gel ) was highest in Andongjaerae. The highest peak, highest breakdown, very high final viscosity, and very low setback were noted in Jucheonjaerae. The starch granule sizes ranged 10.1–25.0 in length and 4.7–12.5μm in diameter. X-ray diffraction angles indicated that all starch samples possess a typical A-type crystallinity.     

Molecular evidence of biased inheritance of trifluralin herbicide resistance in foxtail millet

Inheritance of trifluralin herbicide resistance was investigated for phenotype and genotype (molecular identification) in 12 segregating populations derived from crosses between resistant green foxtail (Setaria viridis) and foxtail millet cultivars (S. italica). Combining a herbicide bioassay and a bidirectional allele‐specific polymerase chain reaction (PCR) assay, the trifluralin resistance in foxtail millet was proved to be conferred by a recessive α2‐tubulin gene mutation at Ile‐239, the allele transferred by green foxtail. However, a distorted segregation ratio in F₂ populations was confirmed, with 16.9% resistant plants on average instead of the 25% expected for a single gene recessive mutation. This was not due to non‐germinating seed and the distortion was also observed in the next generations, indicating a heritable phenomenon. After further crosses and self‐fertilization, however, more advanced generations did not show the same pattern of skewed inheritance as in the early generations. These results suggest the possibility of linkage between the α2‐tubulin gene and a modifier gene to explain the distorted segregation, which might be broken by crossing over.     

谷子SiPRR37基因对光温、非生物胁迫的响应特点及其有利等位变异鉴定

从谷子品种延谷11号克隆生物钟基因SiPRR37,通过生物信息学分析、组织特异性表达分析、4种不同光温组合条件的昼夜表达模式分析以及对NaCl、ABA、PEG、低温、Fe 5种非生物胁迫的响应特点分析,揭示SiPRR37参与谷子光温互作调控以及应对非生物胁迫的作用机制;并对160份谷子材料重测序检测SiPRR37基因的突变位点进行单倍型分析,探究该基因对谷子主要农艺性状的影响。结果表明,SiPRR37基因蛋白质编码区(sequence coding for amino acids in protein,CDS)全长2247 bp,编码748个氨基酸,含有REC和CCT 2个结构域,基于PRR37蛋白的系统进化分析发现,谷子与糜子、高粱、玉米亲缘关系最近;启动子预测分析发现,SiPRR37启动子区存在光、温、生长素、赤霉素、脱落酸、茉莉酸甲酯、干旱和盐胁迫等多种应答元件。SiPRR37相对表达量从高到低依次为根、穗颈、穗、顶叶、次顶叶、茎秆;4个光温组合条件SiPRR37均只在光照期出现1个表达峰,无论高温(27℃)还是低温(22℃),短日照相比长日照表达峰均要提前,无论长日照还是短日照,低温(22℃)相比高温(27℃)表达峰均要提前;NaCl、低温(15℃)胁迫能够抑制SiPRR37表达,PEG模拟干旱胁迫和Fe胁迫能够诱导SiPRR37基因表达,SiPRR37参与了ABA信号传导过程。位于SiPRR37 CDS区的10个SNP将160份谷子材料分为19个单倍型,其中3个单倍型(Hap_7、Hap_10、Hap_19)是改善穗部性状的有利单倍型。谷子SiPRR37基因表达具有昼夜节律性,同时受光周期和温度调控,并且参与了谷子对盐胁迫、低温胁迫、干旱胁迫和铁胁迫的应答反应,同时SiPRR37与抽穗期和多个穗部性状相关,在开展谷子高产分子辅助选育中具有一定应用潜力。     

谷子品种遗传差异的RAPD标记分析

利用RAPD标记对来自春、夏谷区不同育种单位的23份谷子品种进行了多态性和聚类分析。结果表明,23份品种的RAPD标记的多态性较低,13个引物共扩增出56条多态性带,平均每个引物扩增多态性带为4.31条,引物S30和S45都有7条多态性带,能够鉴别的品种最多为13个。聚类分析表明,当遗传相似性系数为0.75时,23个品种可分为4类,不同生态区的品种可以归为一类,而同一生态区的品种也可以归为不同的类,基于RAPD的遗传相似性和品种来源地没有必然的一致性。     

夏谷群体光合作用特性及其影响因素

在试验大田,利用Li-Cor6200光合测定系统,以中秆大穗型品种鲁谷10号和矮秆紧凑型品种矮88为材料,初步研究了夏谷群体光合作用特性及其影响因素。结果表明,夏谷光合日变化呈单峰曲线,上午11时前后群体光合达最大值,其趋势与光照强度的变化基本吻合。两品种的群体光补偿点为180～190μE.m-2.s-1,鲁谷10号对高光强的利用     

谷子近缘野生种的亲缘关系及其利用研究

谷子在约1万年前由青狗尾草驯化而来,我国是谷子的起源中心。谷子所属的狗尾草属在全世界约有125个种,其中中国有15个种,从二倍体到八倍体均有。目前利用染色体原位杂交技术鉴定出狗尾草属6个基因组,利用分子标记分析发现狗尾草属是多起源的,与其多样性的基因组一致。系统演化分析发现,青狗尾草和谷子亲缘关系最近,其次是法式狗尾草和轮生狗尾草;基因组比较分析发现, S. adhaerans的B基因组和S. grisebachii的C基因组与谷子和青狗尾草的A基因具有相对近的亲缘关系,而其他基因组和谷子亲缘较远。在野生资源的利用方面,谷子育种工作者已成功将近缘野生种自然发生的抗除草剂基因转育到谷子中,培育成功了可化学除草的新品种并在生产上利用。本文对谷子野生种的分类、基因组构成、系统进化关系和遗传育种的研究进展进行了综述,重点讨论了谷子近缘野生种在谷子起源与驯化、遗传育种中起到的作用,并对谷子近缘野生种在谷子驯化及育种中的进一步利用做了展望。     

谷子抗除草剂“拿捕净”基因的AFLP标记

对由一对显性核基因(Srf)控制的谷子抗除草剂拿捕净(Sethoxydim)种质抗性进行了分子标记的研究.通过采用F2代群分法,在谷子F2代抗感池间随机筛选了330对AFLP引物,找到了与谷子抗除草剂基因连锁的两个AFLP标记AP1284(M55/15)和AP2350(M55/14).它们位于抗除草剂基因的一侧,与该基因的遗传图距分别为6.3 cM和2.9 cM.二者间的遗传     

6种除草剂对谷子的安全性和杂草防效

为筛选对谷子安全的除草剂,采用室内生物测定法,使用嗪草酮、二氯异噁草酮、丙炔氟草胺、唑嘧磺草胺、砜吡草唑、特丁津6种除草剂,分别在谷子苗前和苗后2个时期用药。采用田间小区试验研究室内生物试验所筛选得到的特丁津的杂草防治效果和安全性。室内生物测定结果表明,6种除草剂苗前用药对谷子的鲜重抑制率均超过20%,并出现死苗;除草剂同剂量下苗后茎叶处理对谷子株高和鲜重的抑制程度均低于其土壤处理,其中嗪草酮、丙炔氟草胺和砜吡草唑对谷子的鲜重抑制率均超过20%;50%特丁津悬浮剂1500、1800 g/hm²对谷子的鲜重抑制率分别为0.76%、2.99%,对反枝苋的防效达98.42%、100%。田间小区试验表明,50%特丁津悬浮剂1500、1800 g/hm²对阔叶杂草的鲜重防效分别为93.46%、95.84%,较空白对照增产41.40%、41.82%。嗪草酮等6种除草剂苗前土壤处理对谷子的安全性低,特丁津有在谷田作为茎叶处理剂防除阔叶杂草的应用前景。     

Intraspecific differentiation and geographical distribution of Wx alleles for low amylose content in endosperm of foxtail millet, Setaria italica (L.) Beauv.

To clarify the genetic mechanism which controls the variation in amylose content among nonwaxy landraces of foxtail millet, the inheritance of different starch types in endosperm was examined by I₂-KI staining. The level of starch granule bound protein in foxtail millet endosperm was also analyzed using SDS-PAGE. The segregation for starch types in F₂ and F₃ seeds determined by I₂-KI staining showed that there are three different alleles at the waxy (wx) locus. A major protein bound to starch granules was detected in nonwaxy endosperm but it was absent in most of the waxy endosperm, suggesting that the protein is the Wx gene product which is responsible for the synthesis of amylose in endosperm. The level of Wx protein proportionally corresponded to the amylose content among nonwaxy landraces. This implies that two different Wx alleles regulate quantitative levels of Wx protein. Landraces with the allele for low amylose content are from Taiwan, the Philippines, Indonesia and Thailand. This revised version was published online in July 2006 with corrections to the Cover Date.