Somaclonal variability as a source for creation of new varieties of finger millet Eleusine coracana (L.) Gaertn

Data on selection and characterizing of finger millet Eleusine coracana (L.) Gaertn. somaclonal variants regenerated from callus culture are presented and described. Among the tested genetically stable lines the somaclonal variant SE-7 was the most interesting due to its acquired important agricultural traits, such as a higher seed and biomass yield, rapid seed germination at lower temperatures, shortening of the main plant development stages. Data analysis shows that somaclonal variability can be a source to obtain initial material for further selection of new finger millet varieties.     

Simple and economical assay systems for evaluation of phosphinothricin resistant transgenics of sorghum, Sorghum bicolor. (L.) Moench., and pearl millet, Pennisetum glaucum (L.) R. Br

Five simple and rapid methods for evaluation of sorghum and pearl millet transgenics resistant to herbicide phosphinothricin (used as selectable marker) were studied. For rapid in vitro selection, three assays (establishment of sensitivity curves for embryogenic calli, determination of lethal doses for seed germination, and a rapid screening of cut young leaves based on the colour change of the medium) were established. For rapid screening of transgenic progeny, effects of in vivo Basta leaf spray and dip tests were studied at three different morphological stages. For all the above assays, LD50, and LD100 values were higher for pearl millet than sorghum. However, in both the crops, genotype effect was not significant. The assays standardized in the study were found to be effective for rapid, economical and mass-scale identification and characterization of transgenic plants of sorghum and pearl millet.     

Analyzing somaclonal variation in micropropagated bananas (<Emphasis Type="Italic">Musa</Emphasis> spp.)

Summary In a micropropagation program, where it is of paramount importance to produce true-to-type planting material, somaclonal variation of any kind is undesirable. Variation among plants regenerated from tissue culture is termed ‘somaclonal variation’. In banana, somaclonal variants of different type have been reported with regard to plant morphology. This article discusses various factors due to which somaclonal variations may arise. Somaclonal variation may be detected by visual screening or by using molecular markers such as randomly amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), and by cytological studies. Although somaclonal variation is undesirable in the context of micropropagation, it can be used to advantage for genetic improvement of banana, as has been described.     

Feeding behavior and development response of the perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae) on multiple crop seeds combinations

The perilla seed bugs, Nysius plebeius Distant and Nysius hidakai Nakatani, are emerging pests of several field crop species including perilla crop in Korea. Here, we investigated the oviposition, nymphal mortality, development, adult emergence, adult longevity, adult weight and female ratio of N. plebeius and N. hidakai on multiple (MC) and double (DC) combinations of five crop seed species: perilla [Perilla frutescens (L.) Britton.], sesame (Sesamum indicum L.), sorghum [Sorghum bicolor (L.)], proso millet (Panicum miliaceum L.), and foxtail millet (Setaria italic L.) in no-choice test. The life-history variables of N. plebeius and N. hidakai were significantly influenced by the crop seed combinations. The most preferred crop seed combinations for oviposition were MC (perilla + sorghum + sesame + proso millet + foxtail millet), followed by DC (perilla + foxtail millet and perilla + sorghum), whereas the least preferred seed combination was DC (proso millet + foxtail millet). Both Nysius sp. were developed faster in MC (perilla + sorghum + sesame + proso millet + foxtail millet), with minimal nymphal mortality, higher adult emergence, longer adult longevity and heavier adult weight. The positive adult bug’s performance on the MC (perilla + sorghum + sesame + proso millet + foxtail millet) may be due to the nutrient contents and physicochemical components associated with the crop seeds. Further, the findings of this study are discussed in terms of bug's behavioral response to crop seed species combinations and management strategies of Nysius sp. as an alternative to chemical management.     

Agrobacterium-mediated transformation of finger millet (Eleusine coracana (L.) Gaertn.) using shoot apex explants

A new Agrobacterium-mediated transformation system was developed for finger millet using shoot apex explants. The Agrobacterium strain LBA4404 harboring binary vector pCAMBIA1301, which contained hygromycin phosphotransferase (hptII) as selectable marker gene and β-glucuronidase (GUS) as reporter gene, was used for optimization of transformation conditions. Two finger millet genotypes, GPU 45 and CO 14, were used in this study. The optimal conditions for the Agrobacterium-mediated transformation of finger millet were found to be the co-cultivation of explants obtained on the 16th day after callus induction (DACI), exposure of explants for 30 min to agrobacterial inoculum and 3 days of co-cultivation on filter paper placed on medium supplemented with 100 μM acetosyringone (AS). Addition of 100 μM l-cysteine in the selection medium enhanced the frequency of transformation and transgenic plant recovery. Both finger millet genotypes were transformed by Agrobacterium. A frequency of 19% transient expression with 3.8% stable transformation was achieved in genotype GPU 45 using optimal conditions. Five stably transformed plants were fully characterized by Southern blot analysis. A segregation analysis was also performed in four R₁ progenies, which showed normal Mendelian pattern of transgene segregation. The inheritance of transgenes in R₁ progenies was also confirmed by Southern blot analysis. This is the first report on Agrobacterium-mediated transformation of finger millet. This study underpins the introduction of numerous agronomically important genes into the genome of finger millet in the future.     

An assessment of somaclonal variation in linseed (Linum usitatissimum)

Somaclonal lines of linseed from the parent cultivar Norlin were produced from a callus-based in oitro regeneration system (the R₀ generation). In field trials conducted over two seasons, 47 R₁ (plants produced from the R₀ generation) and 20 R₂ somaclonal lines (plants produced from the R₁ generation) were compared to the parent cultivar Norlin for quantitative characters. Irrespective of the genotype, traits in R₁'s and R₂'s were assessed on the basis of regression analysis as showing heritabilities of between 28% and 64%. Generally, the somaclonal variation assessed during these early generations revealed some detrimental traits, e.g. lower seed yield than the parent (control) cultivar and reduced 1000 seed weights, but a few lines were identified which had early or late flowering dates, improved seed yield and increased 1000 seed weights. It is concluded that somaclonal variation could be of value as an adjunct to classical breeding.     

Experiments on the effects of charring on <Emphasis Type="Italic">Setaria italica</Emphasis> (foxtail millet)

This study aims to better understand taphonomical effects relevant to Setaria italica (foxtail millet), particularly the deformation caused by charring in fully-formed grains, and the potential preservation of underdeveloped seeds. Foxtail millet is a staple grain commonly found in Neolithic and later sites across Eurasia after initial domestication in northern China. Precise control of atmospheric conditions enabled determination of ideal parameters for charring without seed destruction. These experiments were able to produce charred seeds that strongly resemble archaeological specimens, making three key findings: (1) lateral expansion found in many ancient foxtail millet seeds indicates that charring occurred with the seeds in the husks. (2) Oxidizing conditions produced far better results in terms of seed preservation and retention of identifiable characteristics. (3) Smaller and less developed or ‘filled’ seeds survived in the same conditions as larger, plump seeds. These results allow for better interpretation of depositional context of millet seeds, and point to heat treatment during the de-husking process as a common way for seeds to enter the archaeological record.     

Variation in DNA methylation patterns of grapevine somaclones (<Emphasis Type="Italic">Vitis vinifera L</Emphasis>.)

Background  

In traditional vine areas, the production should present a typicity that partly depends on the grapevine variety. Therefore, vine improvement is considered difficult because of the limited choice in the natural variability of the cultivars within the limits of their characteristics. A possibility to circumvent this problem is the use of somatic variability. In vitro somatic embryogenesis and organogenesis can lead to genotypic and phenotypic variations, described as somaclonal variation, that could be useful for the selection of improved grapevine genotypes.     

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.     

小麦体细胞无性系SSR位点的遗传变异特性分析

研究结果表明:(1)小麦体细胞无性系SSR位点变异类型有:扩增片段迁移率的变大或变小、扩增片段缺失以及新的扩增片段;(2)变异特点为:变异频率与基因型有关,不同染色体组上的SSR位点变异频率不同,而不同无性系后代的SSR位点变异频率也不同;(3)同一SSR位点的变异类型在同一基因型的无性系后代中变异表现一致,在不同基因型无性系后代中的变异表现不同,有的SSR位点在无性系后代中表现出一致的变异,而有的则不一致。     

Evolutionary history of pearl millet (Pennisetum glaucum [L.] R. Br.) and selection on flowering genes since its domestication

The plant domestication process is associated with considerable modifications of plant phenotype. The identification of the genetic basis of this adaptation is of great interest for evolutionary biology. One of the methods used to identify such genes is the detection of signatures of selection. However, domestication is generally associated with major demographic effects. It is therefore crucial to disentangle the effects of demography and selection on diversity. In this study, we investigated selection in a flowering time pathway during domestication of pearl millet. We first used a random set of 20 genes to model pearl millet domestication using approximate Bayesian computation. This analysis showed that a model with exponential growth and wild-cultivated gene flow was well supported by our data set. Under this model, the domestication date of pearl millet is estimated at around 4,800 years ago. We assessed selection in 15 pearl millet DNA sequences homologous to flowering time genes and showed that these genes underwent selection more frequently than expected. We highlighted significant signatures of selection in six pearl millet flowering time genes associated with domestication or improvement of pearl millet. Moreover, higher deviations from neutrality were found for circadian clock-associated genes. Our study provides new insights into the domestication process of pearl millet and shows that a category of genes of the flowering pathway were preferentially selected during pearl millet domestication.     

A straight-forward seed production technology system for foxtail millet (Setaria italica)

For autogamous crops, a precondition for using heterosis is to produce sufficient pure male-sterile female parents that can be used to produce hybrid seeds. To date, cytoplasmic male sterility(CMS)and environment-sensitive genic male sterility(EGMS) have been used commercially to exploit heterosis for autogamous species. However, neither CMS nor EGMS has been established for foxtail millet(Setaria italica). Here, we report on the establishment and application of a seed production technology(SPT)...     

Filter-feeding dabbling ducks (Anas spp.) can actively select particles by size

The relationship between bill morphology, function and prey use among filter-feeding dabbling ducks (Anas spp.) is poorly understood. In particular, it is not clear if interspecific differences in morphology affect the retention of prey to allow prey partitioning. The size of particles retained by ducks may be determined entirely by the distance between adjacent mandibular lamellae (interlamellar distance), possibly allowing interspecific partitioning of prey by size. Alternatively, articulation of the maxilla and mandible allows ducks to increase the distance between the maxillary and mandibular lamellae (lamellar separation) so that it exceeds their interlamellar distance, possibly allowing them to selectively expel unwanted particles larger than their interlamellar distance. In contrast, if interlamellar distance alone determines the size of particles ingested, particles larger than the interlamellar distance will always be retained because lamellar spacing is fixed. When large, preferred millet and wheat seeds were mixed with small, less preferred poppy seeds, all three ducks in this investigation ingested a greater proportion of the millet and wheat seeds than the poppy seeds, even though all three seed types were larger than the ducks' interlamellar distance. The proportion of millet and poppy seeds ingested when seeds were mixed differed from the proportion expected from foraging rates on unmixed prey, indicating the ducks actively avoided poppy seeds. These results are consistent with the lamellar separation hypothesis and clearly reject the singular role of interlamellar distance in prey retention. Because lamellar separation and water filtration rate are both determined by movement of the maxilla and mandible, there may be a trade-off between particle size selection and prey ingestion rate that allows interspecific partitioning of prey by size.     

Obtaining the transgenic lines of finger millet Eleusine coracana (L.). with dinitroaniline resistance

The current data is dedicated to the study of bioballistic and Agrobacterium-mediated transformation of finger millet with the constructs carrying the mutant α-tubulin gene (TUAml), isolated from R-biotype goosegrass (Eleusine indica L.), for the decision of problem of dinitroaniline-resistance. It was found that 10 μM of trifluralin is optimal for the selection of transgene plants of finger millet. PCR analysis of transformed lines confirmed the transgenic nature of plants. The analysis of seed of T₁ of transgenic lines confirmed heterozygous character of inheritance of trifluralin resistance.     

Ability of <Emphasis Type="Italic">Emericella rugulosa</Emphasis> to mobilize unavailable P compounds during Pearl millet [<Emphasis Type="Italic">Pennisetum glaucum</Emphasis> (L.) R. Br.] crop under arid condition

Phosphate solubilizing microorganisms are ubiquitous in soils and could play an important role in supplying P to plants where plant unavailable P content in soil was more. A phosphatase and phytase producing fungus Emericella rugulosa was isolated and tested under field condition (Pearl millet as a test crop) in a loamy sand soil. In the experimental soil 68% organic phosphorous was present as phytin; less than 1% of phosphorous was present in a plant available form. The maximum effect of inoculation on different enzyme activities (acid phosphatase, alkaline phosphatase, phytase, and dehydrogenase) was observed between 5 and 8 weeks of plant age. The depletion of organic P was much higher than mineral and phytin P. The microbial contribution was significantly higher than the plant contribution to the hydrolysis of the different P fractions. A significant improvement in plant biomass, root length, seed and straw yield and P concentration of root and shoot resulted from inoculation. The results suggest that Emericella rugulosa produces phosphatases and phytase, which mobilize P and enhance the production of pearl millet.     

Role of seed flow on the pattern and dynamics of pearl millet (<Emphasis Type="Italic">Pennisetum glaucum</Emphasis> [L.] R. Br.) genetic diversity assessed by AFLP markers: a study in south-western Niger

We studied the regional genetic diversity and seed exchange dynamics of pearl millet landraces in south-western Niger. The genetic study was based on AFLP markers. We found significant genetic differentiation between landraces in different geographical areas of south-western Niger. However, the degree of differentiation was low insofar as only 1.9% of the total molecular diversity was due to regional differentiation, suggesting a relatively high gene flow. Anthropologic studies on farming practices have suggested that seed exchanges between farmers on a large geographical scale probably make a considerable contribution to this result. In order to test this hypothesis, the effects of seed exchange on the genetic diversity of landraces was analyzed on seed samples from two distant villages in contrasting areas of south-western Niger. Seeds imported by farmers into the southern village of Sina Koara did not differ significantly from locally grown landraces. By contrast, in the northern village of Alzou, several samples were genetically different from locally grown landraces and closer to southern accessions. These data suggest that the seed flow is preferentially from south to north, i.e. from an area with more favorable rainfall conditions. The potential consequences for the genetic diversity and adaptation of northern pearl millet landraces are discussed.     

Genetic instability in calamondin (<Emphasis Type="Italic">Citrus madurensis </Emphasis>Lour.) plants derived from somatic embryogenesis induced by diphenylurea derivatives

Somatic embryos were regenerated in vitro from calamondin style–stigma explants cultured in the presence of N ⁶-benzylaminopurine (BAP) cytokinin and three synthetic phenylurea derivatives, N-(2-chloro-4-pyridyl)-N-phenylurea (4-CPPU), N-phenyl-N′-benzothiazol-6-ylurea (PBU) and N,N′-bis-(2,3-methilendioxyphenyl)urea (2,3-MDPU). The phenylurea derivative compounds tested at micromolar level (12 μM) were able to induce a percentage of responsive explants significantly higher from that obtained with BAP and hormone-free (HF) conditions. In order to verify the genetic stability of the regenerants, 27 plants coming from different embryogenic events were randomly selected from each different culture condition and evaluated for somaclonal variations using inter-simple sequence repeat and random amplified polymorphic DNA analyses. We observed that 2,3-MDPU and PBU gave 3.7% of somaclonal mutants, whereas 4-CPPU gave 7.4% of mutants. No somaclonal variability was observed when plantlets were regenerated in BAP or HF medium. Although diphenylurea derivatives show a higher embryogenic potential as compared to BAP, they induce higher levels of somaclonal variability. This finding should be taken in consideration when new protocols for clonal propagation are being developed.     

Factors influencing <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>-mediated genetic transformation of <Emphasis Type="Italic">Eleusine coracana</Emphasis> (L.) Gaertn

Agrobacterium-mediated transformation protocol has been developed for Eleusine coracana (var. PR-202) by varying several factors which influence T-DNA delivery. Green nodular regenerative calli with meristematic nodules of seed origin were used as the target tissue for Agrobacterium tumefaciens-mediated gene transfer. The highest frequency of transformation (44.4%) was observed when callus was infected, co-cultivated and incubated at 22°C. Incorporation of higher level of CuSO₄ in the regeneration medium had significantly positive effect on the recovery of transformed plants. PCR analysis of T ₀ and T ₁ generation plants with nptII-specific primers revealed the amplification of nptII gene. Southern blot analysis of six regenerated plants confirmed selectable marker gene integration in three plants. This is a first report on Agrobacterium-mediated genetic transformation of finger millet and will pave the way for further studies in this and other millet crops.