The Ultrastructure and Analytical Microscopy of Silicon Deposition in the Aleurone Layer of the Caryopsis of Setaria italica (L.) Beauv.

Silicon deposition in the caryopsis of foxtail millet (Setariaitalica (L.) Beauv.) from Lin Xian, Northern China was investigatedusing transmission electron microscopy and energy dispersiveX-ray analysis. The highest silicon count rates were obtained from the pericarpand outer aleurone cell walls, and particularly from a granularelectron-opaque layer external to the outer aleurone cell wall.Silicon was not detected in tissues interior to the aleurone. A possible mechanism for silicon deposition in the caryopsisis suggested, and the results are discussed with respect tothe high incidence of oesophageal cancer in Lin Xian, NorthernChina. Setaria italica (L.) Beauv., foxtail millet, silicon deposition, alcurone layer, caryopsis, ultrastructure, X-ray analysis     

Silicon Deposition in the Inflorescence Bristles and Macrohairs of Setaria italica (L.) Beauv.

Silicon deposits in the inflorescence bristles subtending eachspikelet, and in the macrohairs of foxtail millet (Setaria italica(L.) Beauv.) were investigated using scanning electron microscopyand electron-probe microanalysis. High concentrations of silicon were detected in the pricklehairs which covered the bristles. In the unicellular macrohairscovering the inflorescence axis and its branches, silicon wasdeposited along the whole length of the hairs. The mechanisms by which silicification may have taken place,and the possibility that the bristles and macrohairs are involvedin the aetiology of oesophageal cancer in N. China are discussed. Setaria italica (L.) Beauv., foxtail millet, millet, silicon deposits, silicification, prickle hairs, scanning electron microscopy, electron-probe microanalysis     

谷子穗分化的扫描电镜观察

利用扫描电镜对复合品种冀谷１１号的穗分化进行了系统观察,比较了夏谷和春谷穗分化的异同。提出了谷子穗分化划分为穗分化前期、生长锥伸长期、枝梗分化期、小穗和刚毛分化期以及小花分化期共５个时期,就谷子刚毛起源穗分化与栽培育种的关系等问题进行了讨论。     

Phytolith analysis for differentiating between foxtail millet (Setaria italica) and green foxtail (Setaria viridis)

Foxtail millet (Setaria italica) is one of the oldest domesticated cereal crops in Eurasia, but identifying foxtail millets, especially in charred grains, and differentiating it from its wild ancestor, green foxtail (Setaria viridis), in the archaeobotanical remains, is still problematic. Phytolithic analysis provides a meaningful method for identifying this important crop. In this paper, the silicon structure patterns in the glumes, lemmas, and paleas from inflorescence bracts in 16 modern plants of foxtail millet and green foxtail from China and Europe are examined using light microscopy with phase-contrast and a microscopic interferometer. Our research shows that the silicon structure of ΩIII from upper lemmas and paleas in foxtail millet and green foxtail can be correspondingly divided into two groups. The size of ΩIII type phytolith of foxtail millet is bigger than that from green foxtail. Discriminant function analysis reveals that 78.4% of data on foxtail millet and 76.9% of data on green foxtail are correctly classified. This means certain morphotypes of phytoliths are relatively reliable tools for distinguishing foxtail millet from green foxtail. Our results also revealed that the husk phytolith morphologies of foxtail millets from China and Eastern Europe are markedly different from those from Western Europe. Our research gives a meaningful method of separating foxtail millet and green foxtail. The implications of these findings for understanding the history of foxtail millet domestication and cultivation in ancient civilizations are significant.     

Genetic structure of landraces in foxtail millet (Setaria italica (L.) P. Beauv.) revealed with transposon display and interpretation to crop evolution of foxtail millet

Although the origin and domestication process of foxtail millet (Setaria italica subsp. italica (L.) P. Beauv.) has been studied by several groups, the issue is still ambiguous. It is essential to resolve this issue by studying a large number of accessions with sufficient markers covering the entire genome. Genetic structures were analyzed by transposon display (TD) using 425 accessions of foxtail millet and 12 of the wild ancestor green foxtail (Setaria italica subsp. viridis (L.) P. Beauv.). We used three recently active transposons (TSI-1, TSI-7, and TSI-10) as genome-wide markers and succeeded in demonstrating geographical structures of the foxtail millet. A neighbor-joining dendrogram based on TD grouped the foxtail millet accessions into eight major clusters, each of which consisted of accessions collected from adjacent geographical areas. Eleven out of 12 green foxtail accessions were grouped separately from the clusters of foxtail millet. These results indicated strong regional differentiations and a long history of cultivation in each region. Furthermore, we discuss the relationship between foxtail millet and green foxtail and suggest a monophyletic origin of foxtail millet domestication.     

Infraspecific variation and systematics of cultivatedSetaria italica,foxtail millet (Poaceae)

Foxtail millet (Setaria italica,) is grown as a cereal in southern Europe and in temperate, subtropical, and tropical Asia. Its closest wild relative isS. italica ssp.viridis (green foxtail). Green foxtail is native to temperate Eurasia, but was introduced and became widely established as a weed in temperate and warmer parts of the Americas. Spontaneous and cultivatedS. italica cross to produce fertile hybrids. Derivatives of such crosses, resembling foxtail millet in some inflorescence traits but with efficient natural seed dispersal, accompany the cereal across its range of cultivation. Giant green foxtail of Europe and the American corn belt is a weed of hybrid origin. Foxtail millet was domesticated in the highlands of central China; remains of cultivated foxtail millet are known from the Yang-shao culture period dating back some 5,000 yrs. Comparative morphology suggests that foxtail millet spread to Europe and India as a cereal soon after its domestication. Three cultivated races are recognized. Moharia, from Europe and southwestern Asia, includes cultivars with 5–52 culms, each bearing several, small, more or less erect inflorescences. Cultivars in race maxima are characterized by plants with 1–8 usually unbranched culms that bear large inflorescences; they occur in Transcaucasian Russia and the Far East. Race indica is intermediate in culm number (ave. 6.6) and inflorescence size between races moharia and maxima, and is cultivated in southern Asia.     

A Ser–Gly substitution in plastid-encoded photosystem II D1 protein is responsible for atrazine resistance in foxtail millet (<Emphasis Type="Italic">Setaria italica</Emphasis>)

A foxtail millet (Setaria italica L. Beauv.) line resistant to atrazine was obtained through interspecific hybridization between wild S. viridis L. Beauv. and cultivated S. italica. The resistance was proved to be controlled by a chloroplast-inherited gene and it has further been utilized in foxtail millet production. However, the sequence information of the putative atrazine resistance gene, psbA in foxtail millet’s chloroplast genome encoding photosystem II D1 protein (32 kDa thylakoid membrane protein) (photosystem Q_B protein) and the mutation site responsible for the resistance are not known. In this paper the psbA sequences of six atrazine susceptible/resistant foxtail millet varieties were obtained and compared. The results indicated that there was only one amino acid difference between susceptible and resistance gene, resulting from a single base substitution. It was concluded that a mutant allele of photosystem II protein D1 encoding a Gly residue instead of a Ser residue at position 264 is a major gene of resistance to atrazine. Moreover, the phylogenetic tree based on the psbA coding region of thirty-five plant species was carried out. The phylogenetic relationship between S. italica and other plants and the related evolutionary issues were discussed and it was suggested that psbA sequences could be used in phylogenetic studies in plants. Xiaoping Jia and Jincheng Yuan have equal contribution.     

Construction of RFLP-based maps of foxtail millet, Setaria italica (L.) P. Beauv.

 An RFLP-based map consisting of 160 loci was constructed in an intervarietal cross of foxtail millet [Setaria italica (L.) P. Beauv.], Longgu 25×Pagoda Flower Green. The map comprises nine linkage groups, which were aligned with the nine foxtail millet chromosomes using trisomic lines, and spans 964 cM. The intraspecific map was compared to an interspecific map, constructed in a S. italica×S. viridis cross. Both the order of the markers and the genetic distances between the loci were highly conserved. Deviations from the expected 1 : 2 : 1 Mendelian segregation ratios were observed in both the intra- and inter-specific populations. The segregation data indicate that chromosome VIII in the Longgu 25×Pagoda Flower Green cross carries a gene that strongly affects gamete fertility. Received: 18 December 1996 / Accepted: 4 August 1997     

The archaeobotanical significance of immature millet grains: an experimental case study of Chinese millet crop processing

We present evidence from ethnography and experimental processing of foxtail millet (Setaria italica (L.) P. Beauv.) in China that spikelets containing incompletely filled (or immature) grains constitute a significant portion of typical millet harvests and are removed along with other by-products after threshing and winnowing. This study provides a baseline for the identification of immature foxtail grains in archaeobotanical assemblages. Immature millet grains are a frequent component of archaeobotanical assemblages in Neolithic and Bronze Age China, and criteria for their recognition are presented based on our modern experimental result and illustrated with archaeobotanical examples from Shandong and Henan. It is seed morphology rather than size that plays a determinative role in the identification of foxtail millet. It is suggested that those grains with a narrow egg-shaped embryo, which is about 5/6 of the whole grain, and having a round shape can be classed as foxtail millet even though they are small, flat and squashed. While different grades of immaturity in millet grains might be defined, the interpretative potential of these appears to be negligible as all immature grains are concentrated in winnowing waste. This study confirms the suggestion that the ratio of immature to mature millet grains can be employed in archaeobotany in considering whether or not early stage crop processing (threshing and winnowing) contributed to the formation of particular archaeological millet assemblages.     

谷子幼苗对土壤铅、铬的生长响应及吸收积累的差异性

采用盆栽土培试验,研究了谷子幼苗对土壤中不同含量铅（Pb）、铬（Cr）的生长响应和吸收积累的差异性。结果表明,在所试浓度（50～800 mg·kg^-1）范围内,Pb、Cr在谷子幼苗地上部和地下部的积累量存在较大差异,幼苗重金属的吸收富集和转运系数均为Pb大于Cr、Pb、Cr胁迫对幼苗生物量的影响表现为低浓度的促进和高浓度的抑制作用,但Cr对生物量的影响比Pb更强。相同处理条件下,幼苗茎叶中可溶性蛋白质、DNA含量和增色效应对Pb、Cr的响应也有明显差别,Cr对幼苗的生理毒性和DNA损伤效应的作用强度大于Pb。     

Nucleotide Sequence Diversity and Linkage Disequilibrium of Four Nuclear Loci in Foxtail Millet (Setaria italica)

Foxtail millet (Setaria italica (L.) Beauv) is one of the earliest domesticated grains, which has been cultivated in northern China by 8,700 years before present (YBP) and across Eurasia by 4,000 YBP. Owing to a small genome and diploid nature, foxtail millet is a tractable model crop for studying functional genomics of millets and bioenergy grasses. In this study, we examined nucleotide sequence diversity, geographic structure, and levels of linkage disequilibrium at four nuclear loci (ADH1, G3PDH, IGS1 and TPI1) in representative samples of 311 landrace accessions across its cultivated range. Higher levels of nucleotide sequence and haplotype diversity were observed in samples from China relative to other sampled regions. Genetic assignment analysis classified the accessions into seven clusters based on nucleotide sequence polymorphisms. Intralocus LD decayed rapidly to half the initial value within ~1.2 kb or less.     

Electron-probe Microanalysis Studies of Silica Distribution in Barley (Hordeum sativum L.)

Silicon occurence has been investigated by means of epidermalpeels, cryostat, and ultrathin sections of the internode, nodes,leaves, inflorescence bracts, and caryopsis of Hordeum sativumL. (cultivar Deba Abed) using the electron probe microanalyser.Analyses were made on growth stages during ear emergence andat maturity. The results indicate that silicon is present inthe internode with the highest concentration associated withthe opaline deposits. Detectable quantities are also found inthe outer tangential walls of the long cells, in the walls ofstomata, the sclerenchyma, and all vascular bundle regions.In mature upper internodes, silicifiation is confined to theupper third region, but this limit extends closer to the basalmeristem with increasing age of internode. The nodes have agreater concentration in the radial than in outer tangentialwalls. Heavy deposits are found in the leaves but with considerablevariation between blade and sheath, abaxial and adaxial surfaces,and the leaf position. The flag leaf contained the highest accumulations. In the inflorescence bracts (lemma and palea), silicon is detectableonly in the abaxial epidermis and hypodermis. Awns are alsoheavily silicified with the highest concentrations in the sclerenchymaand trichomes.     

Phytoliths Analysis for the Discrimination of Foxtail Millet (Setaria italica) and Common Millet (Panicum miliaceum)

Foxtail millet (Setaria italica) and Common millet (Panicum miliaceum) are the oldest domesticated dry farming crops in Eurasia. Identifying these two millets in the archaeobotanical remains are still problematic, especially because the millet grains preserve only when charred. Phytoliths analysis provides a viable method for identifying this important crop. However, to date, the identification of millet phytoliths has been questionable, because very little study has been done on their morphometry and taxonomy. Particularly, no clear diagnostic feature has been used to distinguish between Foxtail millet and Common millet. Here we examined the anatomy and silicon structure patterns in the glumes, lemmas, and paleas from the inflorescence bracts in 27 modern plants of Foxtail millet, Common millet, and closely related grasses, using light microscopy with phase-contrast and microscopic interferometer. Our research shows that five key diagnostic characteristics in phytolith morphology can be used to distinguish Foxtail millet from Common millet based on the presence of cross-shaped type, regularly arranged papillae, Ω-undulated type, endings structures of epidermal long cell, and surface ridgy line sculpture in the former species. We have established identification criteria that, when used together, give the only reliable way of distinguishing between Foxtail millet and Common millet species based on their phytoliths characteristics, thus making a methodological contribution to phytolith research. Our findings also have important implications in the fields of plant taxonomy, agricultural archaeology, and the culture history of ancient civilizations.     

谷子全生育期抗旱性鉴定及抗旱指标筛选

作物全生育期抗旱性对发掘和利用抗旱品种和抗旱基因至关重要,但谷子全生育期抗旱鉴定至今未有报道,抗旱鉴定缺乏鉴定指标。本试验在干旱池模拟干旱条件下,对苗期抗旱性表现不同的谷子品种进行了全生育期抗旱性研究,调查分析了根干重等形态和生理性状在干旱胁迫条件下的变化;采用相关和灰色关联度等方法,分析这些指标与抗旱性(DRI)的关系。结果表明,相对根冠比、相对单穗粒重和灌浆期光合速率、蒸腾速率同抗旱性表现极显著相关,可以作为谷子全生育期抗旱性鉴定的指标;而相对根干重、相对单穗重、相对株高和气孔导度则可以作为谷子全生育期抗旱性鉴定的参考指标;在供试的品种中,红根谷和大齐头白表现了良好的综合抗旱性。本文还讨论了抗旱性的复杂性以及不同性状对干旱胁迫的反应,所建立的指标对谷子全生育期抗旱鉴定具有指导意义。     

Construction of a foxtail millet linkage map and mapping of spikelet-tipped bristles 1(stb1) by using transposon display markers and simple sequence repeat markers with genome sequence information

We attempted genetic analysis and mapping of a gene responsible for the trait “spikelet-tipped bristles” (stb) in foxtail millet, Setaria italica (L.) P.Beauv., as the first step in positional cloning of the gene. This trait is important not only in grain yield such as grain number per panicle of this millet but also in the evolutionary development of the “bristle grass” clade including genera Setaria, Pennisetum and Cenchrus in subfamily Panicoideae. First of all, we confirmed that this trait is controlled by a single recessive gene, using two populations of F2 plants; one was a cross combination between two Taiwanese landraces and the other was a combination between a Taiwanese landrace and a Japanese landrace. Using the latter of the two F2 populations, with transposon display (TD) markers and simple sequence repeat (SSR) markers developed previously, we constructed a genetic map with 13 linkage groups and mapped the responsible gene (stb1) on chromosome 2. We also developed novel SSR markers by using foxtail millet genome sequence information, and we finally constructed nine linkage groups corresponding to nine chromosomes with a total length of 1287.5 cM, and mapped stb1 more precisely on chromosome 2. This work suggests that the foxtail millet genome sequences recently published are useful for developing genome-wide SSR markers for constructing linkage maps and mapping genes in this millet.     

Ribosomal DNA variation in foxtail millet, Setaria italica (L.) P. Beauv., and a survey of variation from Europe and Asia

 Restriction fragment length polymorphism (RFLP) and the structure of ribosomal RNA genes (rDNA) were investigated in 117 landraces of foxtail millet, Setaria italica (L.) P. Beauv. Five RFLP phenotypes were found when the genomic DNA was digested with BamHI; these were named types I–V. Of these types I, II and III were the most frequent. Type I was mainly distributed in the temperature zone, type II in the Taiwan-Philippines Islands and type III in South Asia. Restriction mapping of the cloned rDNA and comparison with RFLP phenotypes showed that the different types originated from a polymorphism in the length within the intergenic spacer (IGS) and BamHI site changes within the IGS. Received: 28 August 1996 / Accepted: 28 February 1997     

Genetic variability of foxtail millet (Setaria italica P. Beauv.)

Summary The genetic diversity of a world collection of foxtail millet strains (Setaria italica) and some samples of wild populations (Setaria viridis) was studied by means of electrophoresis on five enzymes (10 loci) Est, Acph, Got, Mdh, Pgd. In spite of an overall limited polymorphism, the diversity appeared to be clearly regionalized. The wild populations collected in France and China introduced new genetic variability to the cultivated forms. However, the interregional diversity within both species was greater than the between species (S. viridis/S. italica) diversity.