Oviposition and development response of perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae) to five crop seeds

The perilla seed bugs, Nysius plebeius Distant and Nysius hidakai Nakatani, are emerging pests of perilla crop in Korea. Here, we investigated the life-history variables of N. plebeius and N. hidakai on five commonly grown crop seeds: perilla [Perilla frutescens (L.) Britt.], sesame (Sesamum indicum L.), sorghum [Sorghum bicolor (L.)], proso millet (Panicum miliaceum L.) and foxtail millet (Setaria italic L.). Bug oviposition, total developmental period, adult emergence, adult longevity and adult weight of both Nysius species were determined in both choice and no-choice tests. The oviposition and development periods of N. plebeius and N. hidakai varied significantly among seed species. The most preferred seed species for oviposition were perilla seeds, followed by sesame, sorghum and foxtail millet, whereas proso millet seeds were the least preferred. The bugs development period was faster in perilla seeds, with higher adult emergence, greater adult longevity and heavier adult weight. The higher oviposition preference and faster development with longer longevity of both Nysius species on perilla seeds is probably due to the physicochemical and nutritional attributes of the seeds. This information may enable the exploration of resistant genetic materials and chemical traits associated with seeds for breeding programme. Further, the outcomes of this study are discussed in terms of bug's behavioural response to crop seeds and management strategy of Nysius species as alternative to chemical management.     

Artificial radiofrequency driven life-table parameters of perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae)

The genus Nysius (Hemiptera: Lygaeidae) are polyphagous pests of various plants that damage seeds, foliage, and flowers. Here, we studied the life-table parameters and adult performances of Nysius plebeius Distant and Nysius hidakai Nakatani after exposure to five radiofrequencies: 0 (control), 5, 10, 20, and 30 kHz in infested perilla seeds. In addition, we measured the follow on effects of treatment for four generations (Parent, F1-, F2-, and F3-generation), for both Nysius species. Radiofrequency application significantly affected the life-table parameters of both Nysius species. Radiofrequency exposures affected bug oviposition, developmental period, adult weight, and longevity. Exposure also negatively affected the fecundity of subsequent generations; total developmental period from egg to adult emergence was longer while adult longevity was shorter in the radiofrequency treatments than in the untreated control. Low radiofrequency levels had the greatest effect on the life-table parameters of Nysius species, with the lowest rate of adult emergence and the shortest adult longevity at 5 kHz. The potential of using Nysius bug susceptibilities to radiofrequency as an alternative to chemical treatment is discussed.     

Millet preference, effects of planting date on infestation, and adult and larval use of proso millet by Ostrinia nubilalis (Lepidoptera: Crambidae)

The interaction between millet and European corn borer, Ostrinia nubilalis (Hübner), was investigated to gain insight into whether millet could serve as a refuge or trap crop for O. nubilalis management. In 1995, 1996, and 1999, millet selection studies were conducted in North Dakota and New York with four millet species. Proso millet, Panicum milliaceum L., had the highest infestation and widest distribution of O. nubilalis developmental stages, indicating the presence of both univoltine and bivoltine ecotypes. Siberian foxtail millet, Setaria italica (L.) Beauvois, harbored the greatest number of adults, followed by German foxtail millet, Setaria italica (L.) Beauvois. These two millets appeared to serve as better aggregation sites than proso millet. In North Dakota in 1997, proso millet planting date studies showed later planting dates were more heavily infested than earlier dates; in 1998, this trend was reversed. The change in trends between years was probably a result of differences in the respective growing seasons and subsequent differences in O. nubilalis flights. Adult sampling showed that both old and young females aggregated in proso millet during the day; however, at night, it appeared that young females moved out of millet to oviposit, whereas old females remained in millet. Egg masses were detected in proso millet over a 7-d period in 1997 and a 4-d period in 1998. Larval sampling showed planting proso millet between late May and mid-June may maximize the presence of individuals from both O. nubilalis ecotypes. Once the optimal combination of planting date, plant density, and millet type is found, millet may serve as an effective refuge or trap crop for O. nubilalis management.     

Preferential removal of non-injured seeds by an omnivorous ant,Tetramorium tsushimae Emery,in the seed dispersal of Chamaesyce maculata (L.) small

To elucidate roles of an omnivorous ant, Tetramorium tsushimae Emery, against pre-dispersal seed consumers in the seed dispersal of Chamaesyce maculata (L.) Small, the effects of the seed injury by a stinkbug, Nysius plebeius Distat, on the seed removal by the ant and the germination rate were examined in laboratory experiments. The ants of T. tsushimae removed more frequently non-injured seeds than injured seeds. Therefore, low removal frequency of injured seeds by T. tsushimae ants might facilitate the increase in removal frequency of non-injured seeds, consequently leading to efficient seed dispersal of C. maculata. The germination rate of injured seeds that N. plebeius nymphs sucked was conspicuously lower than the non-injured seeds. The germination rate of seeds that T. tsushimae ants carried out of their nest was similar to that of the non-injured seeds. Thus, seed removal by T. tsushimae ants has hardly effects on the germination of these seeds. Therefore, the preferential removal of non-injured seeds by T. tsushimae ants might contribute to the dispersal success of C. maculata seeds. These results might show a novel interaction between myrmecochorous plants and ants in which the assessment of seed quality by ants contributes to the reproductive success of plants.     

Development and characterization of twenty-five new polymorphic microsatellite markers in proso millet (Panicum miliaceum L.)

Millets such as proso millet have excellent nutritional properties and could become a basic resource for crop breeding programs and food diversification. In this study, 25 polymorphic microsatellite markers were developed and characterized through construction of an SSR-enriched library from genomic DNA of proso millet (Panicum miliaceum L.). In total, 110 alleles were detected, with an average of 4.4 alleles per locus. Values of major allele frequency (M _AF ) and expected heterozygosity (H _E ) ranged from 0.36 to 0.98 (mean = 0.73) and from 0.04 to 0.74 (mean = 0.37), respectively. The mean genetic similarity coefficient was 0.3711, indicating that among 50 accessions of proso millet there was wide genetic variation. The newly developed microsatellite markers should be useful tools for assessing genetic diversity, understanding population structure, and breeding of proso millet.     

Characteristics and Expression Patterns of the Aldehyde Dehydrogenase (ALDH) Gene Superfamily of Foxtail Millet (Setaria italica L.)

Recent genomic sequencing of the foxtail millet, an abiotic, stress-tolerant crop, has provided a great opportunity for novel gene discovery and functional analysis of this popularly-grown grass. However, few stress-mediated gene families have been studied. Aldehyde dehydrogenases (ALDHs) comprise a gene superfamily encoding NAD (P) ⁺-dependent enzymes that play the role of “aldehyde scavengers”, which indirectly detoxify cellular ROS and reduce the effect of lipid peroxidation meditated cellular toxicity under various environmental stresses. In the current paper, we identified a total of 20 ALDH genes in the foxtail millet genome using a homology search and a phylogenetic analysis and grouped them into ten distinct families based on their amino acid sequence identity. Furthermore, evolutionary analysis of foxtail millet reveals that both tandem and segmental duplication contributed significantly to the expansion of its ALDH genes. The exon-intron structures of members of the same family in foxtail millet or the orthologous genes in rice display highly diverse distributions of their exonic and intronic regions. Also, synteny analysis shows that the majority of foxtail millet and rice ALDH gene homologs exist in the syntenic blocks between the two, implying that these ALDH genes arose before the divergence of cereals. Semi-quantitative and real-time quantitative PCR data reveals that a few SiALDH genes are expressed in an organ-specific manner and that the expression of a number of foxtail millet ALDH genes, such as, SiALDH7B1, SiALDH12A1 and SiALDH18B2 are up-regulated by osmotic stress, cold, H₂O₂, and phytohormone abscisic acid (ABA). Furthermore, the transformation of SiALDH2B2, SiALDH10A2, SiALDH5F1, SiALDH22A1, and SiALDH3E2 into Escherichia coli (E.coli) was able to improve their salt tolerance. Taken together, our results show that genome-wide identification characteristics and expression analyses provide unique opportunities for assessing the functional roles of foxtail millet ALDH genes in stress responses.     

Overexpression of millet ZIP-like gene (SiPf40) affects lateral bud outgrowth in tobacco and millet

A SiPf40 gene was identified from an immature seed cDNA library of foxtail millet (Setaria italica). This gene encodes for a 29.4 KDa protein containing eight potential transmembrane domains and a highly conserved ZIP signature motif typical of ZIPs (zinc or iron transporter proteins) family. Other SiPf40 potential homologous genes have also been identified in rice, maize, wheat and Arabidopsis by Southern analysis. Expression data showed that this gene is preferentially expressed in millet hypocotyl and bud; however, a minimal level of constitutive expression could be detected in other foxtail millet tissues.Overexpression of SiPf40 gene causes extra branches in tobacco and extra tillering in millet associated with vessel enlarging and xylary fibers increasing, whereas the tiller number decreases in SiPf40 gene silenced plants. Moreover, IAA content decreased significantly in shoot apex of the transgenic tobacco overexpressing SiPf40 gene. All together, these morphological alterations indicate that SiPf40 gene is essential for lateral shoots growth.     

Development of eSSR-Markers in Setaria italica and Their Applicability in Studying Genetic Diversity,Cross-Transferability and Comparative Mapping in Millet and Non-Millet Species

Foxtail millet ( Setaria italica L.) is a tractable experimental model crop for studying functional genomics of millets and bioenergy grasses. But the limited availability of genomic resources, particularly expressed sequence-based genic markers is significantly impeding its genetic improvement. Considering this, we attempted to develop EST-derived-SSR (eSSR) markers and utilize them in germplasm characterization, cross-genera transferability and in silico comparative mapping. From 66,027 foxtail millet EST sequences 24,828 non-redundant ESTs were deduced, representing ~16 Mb, which revealed 534 (~2%) eSSRs in 495 SSR containing ESTs at a frequency of 1/30 kb. A total of 447 pp were successfully designed, of which 327 were mapped physically onto nine chromosomes. About 106 selected primer pairs representing the foxtail millet genome showed high-level of cross-genera amplification at an average of ~88% in eight millets and four non-millet species. Broad range of genetic diversity (0.02–0.65) obtained in constructed phylogenetic tree using 40 eSSR markers demonstrated its utility in germplasm characterizations and phylogenetics. Comparative mapping of physically mapped eSSR markers showed considerable proportion of sequence-based orthology and syntenic relationship between foxtail millet chromosomes and sorghum (~68%), maize (~61%) and rice (~42%) chromosomes. Synteny analysis of eSSRs of foxtail millet, rice, maize and sorghum suggested the nested chromosome fusion frequently observed in grass genomes. Thus, for the first time we had generated large-scale eSSR markers in foxtail millet and demonstrated their utility in germplasm characterization, transferability, phylogenetics and comparative mapping studies in millets and bioenergy grass species.     

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.     

Development of 5123 Intron-Length Polymorphic Markers for Large-Scale Genotyping Applications in Foxtail Millet

Generating genomic resources in terms of molecular markers is imperative in molecular breeding for crop improvement. Though development and application of microsatellite markers in large-scale was reported in the model crop foxtail millet, no such large-scale study was conducted for intron-length polymorphic (ILP) markers. Considering this, we developed 5123 ILP markers, of which 4049 were physically mapped onto 9 chromosomes of foxtail millet. BLAST analysis of 5123 expressed sequence tags (ESTs) suggested the function for ∼71.5% ESTs and grouped them into 5 different functional categories. About 440 selected primer pairs representing the foxtail millet genome and the different functional groups showed high-level of cross-genera amplification at an average of ∼85% in eight millets and five non-millet species. The efficacy of the ILP markers for distinguishing the foxtail millet is demonstrated by observed heterozygosity (0.20) and Nei''s average gene diversity (0.22). In silico comparative mapping of physically mapped ILP markers demonstrated substantial percentage of sequence-based orthology and syntenic relationship between foxtail millet chromosomes and sorghum (∼50%), maize (∼46%), rice (∼21%) and Brachypodium (∼21%) chromosomes. Hence, for the first time, we developed large-scale ILP markers in foxtail millet and demonstrated their utility in germplasm characterization, transferability, phylogenetics and comparative mapping studies in millets and bioenergy grass species.     

Development and genetic mapping of SSR markers in foxtail millet [Setaria italica (L.) P. Beauv.]

SSR markers are desirable markers in analysis of genetic diversity, quantitative trait loci mapping and gene locating. In this study, SSR markers were developed from two genomic libraries enriched for (GA)n and (CA)n of foxtail millet [Setaria italica (L.) P. Beauv.], a crop of historical importance in China. A total of 100 SSR markers among the 193 primer pairs detected polymorphism between two mapping parents of an F₂ population, i.e. “B100” of cultivated S. italica and “A10” of wild S. viridis. Excluding 14 markers with unclear amplifications, and five markers unlinked with any linkage group, a foxtail millet SSR linkage map was constructed by integrating 81 new developed SSR markers with 20 RFLP anchored markers. The 81 SSRs covered nine chromosomes of foxtail millet. The length of the map was 1,654 cM, with an average interval distance between markers of 16.4 cM. The 81 SSR markers were not evenly distributed throughout the nine chromosomes, with Ch.8 harbouring the least (3 markers) and Ch.9 harbouring the most (18 markers). To verify the usefulness of the SSR markers developed, 37 SSR markers were randomly chosen to analyze genetic diversity of 40 foxtail millet accessions. Totally 228 alleles were detected, with an average 6.16 alleles per locus. Polymorphism information content (PIC) value for each locus ranged from 0.413 to 0.847, with an average of 0.697. A positive correlation between PIC and number of alleles and between PIC and number of repeat unit were found [0.802 and 0.429, respectively (P < 0.01)]. UPGMA analysis revealed that the 40 foxtail millet cultivars could be grouped into five clusters in which the landraces’ grouping was largely consistent with ecotypes while the breeding varieties from different provinces in China tended to be grouped together. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

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.     

增强UV-B辐射和氮对谷子叶光合色素及非酶促保护物质的影响

以谷子(Setaria italica(L)Beauv.)为对象,从拔节期开始持续给予低氮(1.875 mmol/L)和高氮(15 mmol/L)两种氮供应条件并从抽穗期开始进行26 d两种强度(4.29、7.12 kJ·m-2·d-1)的增强UV-B辐射处理,研究了谷子叶中光合色素含量、类黄酮含量和苯丙氨酸解氨酶(PAL)活性的变化.结果表明:与高氮供应条件相比,低氮供应条件明显降低了谷子叶中光合色素含量但提高了类胡萝卜素/叶绿素含量比值;在开花期中段和灌浆期中段,高氮供应条件下谷子叶中光合色素含量对增强UV-B辐射比低氮供应条件下的谷子更敏感.从灌浆期开始到处理结束,两种影响因子对谷子叶中类黄酮含量均有显著影响,增强UV-B辐射导致谷子叶中类黄酮含量逐渐升高,且相同增强UV-B辐射强度下低氮供应条件下的谷子叶中类黄酮含量明显高于高氮供应条件下的谷子.谷子叶中PAL活性对两种影响因子的响应较类黄酮含量更加敏感,低氮供应条件使谷子叶中PAL活性明显提高.结合上述指标的相关性分析结果可知,低氮供应条件加强了处于繁殖期主要阶段的谷子叶中类黄酮的积累,并使谷子叶中的类胡萝卜素/叶绿素含量比值明显提高,进而有助于维持谷子叶中光合色素含量在增强UV-B辐射条件下的相对稳定性,对植株抵抗UV-B辐射伤害有利.     

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.     

Association of an allele-specific marker with dehydration stress tolerance in foxtail millet suggests SiDREB2 to be an important QTL

Dehydration-responsive element binding (DREB) genes assist in improving stress tolerance of plants by activating the expression of several stress-responsive genes. Therefore, development of functional markers for useful alleles utilizing DREB genes is crucial for crop improvement strategies. Earlier we reported a synonymous single nucleotide polymorphism (SNP) associated with dehydration tolerance at 558^th bp (an A/G transition) in the SiDREB2 gene of foxtail millet (Setaria italica L.) and developed an allele-specific marker (ASM) for SiDREB2. In the present study, we validated this ASM using a set of 122 foxtail accessions, of which 45 were investigated in an earlier study. The QTL associated with SiDREB2 contributed to ~20 % of the total phenotypic variation (PV) for relative water content (RWC) and this signified the importance of this QTL for dehydration tolerance in foxtail millet.     

Bartonella-like bacteria carried by domestic mite species

Bacteria of the genus Bartonella are carried by haematophagous mites, ticks, fleas and flies, and attack the erythrocytes of mammals. Here we describe a Bartonella-like clade, a distinct group related to Bartonellaceae, in stored-product mites (Acari: Astigmata) and a predatory mite Cheyletus eruditus (Acari: Prostigmata) based on the analysis of cloned 16S rRNA gene sequences. By using the clade-specific primers, closely related Bartonella-like 16S rRNA sequences were amplified from both laboratory colonies and field strains of three synanthropic mite species (Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae) and a predatory mite. Altogether, sequences of Bartonella-like bacteria were found in 11 strains, but were not detected in Dermatophagoides farinae and D. pteronyssinus and two strains of L. destructor. All obtained sequences formed a separate cluster branching as a sister group to Bartonellaceae and related to other separate clusters comprising uncultured bacterial clones from human skin and hemipteran insects (Nysius plebeius and Nysius sp.). The classification of sequences into operational taxonomic units (OTUs) showed a difference between A. siro and T. putrescentiae suggesting that the Bartonella-like bacteria are different in these two mite species. However, species specific sequences in separate OTUs were observed also for C. eruditus. Possible symbiotic interactions between Bartonella-like bacteria and their mite hosts are discussed.     

Distribution of15N fertilizer in field-lysimeters sown with garlic (Allium sativum) and foxtail millet (Setaria italica)

We examined the distribution of residual¹⁵N and its uptake by a foxtail millet crop grown in field lysimeters following at previous garlic crops fertilized with either¹⁵N-urea or¹⁵N-ammonium sulphate. Garlic apprently removed more N from the lysimeters treated with urea-N than from those treated with (NH₄)₂SO₄. Fertilizer-N in the lysmeters was similar (ca. 32% of original) following millet harvest. About 16 per cent of both fertilizers in the lysimeters was removed by the millet.