Gene banks for wild and cultivated sunflower genetic resources

Modern breeding of sunflower (Helianthus annuus L.), which started 100 years ago, increased the number and the diversity of cultivated forms. In addition, for more than 50 years, wild sunflower and other Helianthus species have been collected in North America where they all originated. Collections of both cultivated and wild forms are maintained in gene banks in many countries where sunflower is an important crop, with some specificity according to the availability of germplasm and to local research and breeding programmes. Cultivated material includes land races, open pollinated varieties, synthetics and inbred lines. The majority of wild accessions are ecotypes of wild Helianthus annuus, but also 52 other species of Helianthus and a few related genera. The activities of three gene banks, in USA, France and Serbia, are described in detail, supplemented by data from seven other countries. Past and future uses of the genetic resources for environmental adaptation and breeding are discussed in relation to genomic and improved phenotypic knowledge of the cultivated and wild accessions available in the gene banks.L’amélioration moderne du tournesol (Helianthus annuus L.) a débuté il y a un siècle, diversifiant et augmentant le nombre des formes cultivées du tournesol. De plus, des collectes de tournesols sauvages et d’espèces du genre Helianthus ont lieu depuis 50 ans en Amérique du Nord d’où ils sont tous originaires. Ainsi, des collections de tournesols cultivés et sauvages sont conservées par des centres de ressources génétiques dans de nombreux pays où le tournesol est une culture importante. Chacun d’eux présente des spécificités par rapport aux ressources génétiques maintenues, en fonction des programmes de recherche ou de sélection variétale locales. Le matériel génétique cultivé comprend des écotypes, des populations et des lignées tandis que les accessions sauvages correspondent eux écotypes d’Helianthus annuus sauvages et des 52 autres espèces apparentées du genre Helianthus. Les activités de trois centres de ressources génétiques des États-Unis, de la France et de la Serbie sont décrites en détail, complétées par des données provenant des centres de sept autres pays. L’historique de l’utilisation des ressources génétiques et les perspectives futures pour l’adaptation des variétés à l’environnement sont discutés ainsi que leur caractérisation au niveau génomique et phénotypique.The Supplementary Material is available at [https://www.ocljournal.org/10.1051/ocl/2020004/olm]

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Not AvailableSources of resistance to powdery mildew incited by Golovinomyces orontii have been identifed in wild sunfowers and few exotic lines. The present investigation has been undertaken to study the inheritance of powdery mildew resistance and to map the quantitative trait loci (QTLs) governing resistance to powdery mildew in a multiple disease resistance line, TX16R (PI 642072). The inheritance was observed as a continuous distribution in a set of 264 F2 population and 93 recombinant inbred lines (RILs) of a cross between a highly susceptible accession PS 2023 and TX16R. Screening of the two population sets was done with 484 sunfower-specifc SSR primers of which 175 primers showed polymorphism between the parents. Based on the phenotyping and genotyping data, the linkage map was constructed with 93 RILs. The map spanned 1200 cM and included 64 markers distributed along the 17 sunfower chromosomes in the haploid set. Quantitative trait loci (QTL) analysis identifed three genomic regions for resistance to powdery mildew, two of which mapped on chromosome 10 and one on chromosome 5. This is the frst report on mapping of powdery mildew resistance in sunfower and paves the way in fne mapping and introgression of resistance for powdery mildew in sunfower through marker-assisted breedingNot Availabl

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Not AvailableSources of resistance to powdery mildew incited by Golovinomyces orontii have been identified in wild sunflowers and few exotic lines. The present investigation has been undertaken to study the inheritance of powdery mildew resistance and to map the quantitative trait loci (QTLs) governing resistance to powdery mildew in a multiple disease resistance line, TX16R (PI 642072). The inheritance was observed as a continuous distribution in a set of 264 F2 population and 93 recombinant inbred lines (RILs) of a cross between a highly susceptible accession PS 2023 and TX16R. Screening of the two population sets was done with 484 sunflower-specific SSR primers of which 175 primers showed polymorphism between the parents. Based on the phenotyping and genotyping data, the linkage map was constructed with 93 RILs. The map spanned 1200 cM and included 64 markers distributed along the 17 sunflower chromosomes in the haploid set. Quantitative trait loci (QTL) analysis identified three genomic regions for resistance to powdery mildew, two of which mapped on chromosome 10 and one on chromosome 5. This is the first report on mapping of powdery mildew resistance in sunflower and paves the way in fine mapping and introgression of resistance for powdery mildew in sunflower through marker-assisted breeding.Not Availabl

Exogenous glutamine increases lipid accumulation in developing seeds of castor bean (Ricinus communis L.) cultured in vitro

This report describes biomass production and compositional changes of developing castor seeds in response to change in the nitrogen resource (glutamine) of the medium. During the early developmental period (24-36 days after pollination), oil was found to initially accumulate in the developing seeds. Carbohydrates and oil were inversely related after glutamine provision (35 mM, in the culture medium). [U-14C] sucrose labeling was used to investigate the effect of metabolic fluxes among different storage materials. Addition of glutamine led to a 7% increase of labeling in lipids and an inverse decrease of labeling in carbohydrates. It was postulated that changes in the glutamine concentration in the medium are likely to influence the partitioning of resources between the various storage products, especially carbohydrates and oil. These observations will contribute to a better understanding of assimilate partitioning in developing castor seeds and the development of molecular strategies to improve castor bean seed quality and plant breeding studies

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Not AvailableSunflower (Helianthus annuus L.) is one of the most important oilseed crops cultivated worldwide. It is one of the few crops that has been improved for several characteristics through interspecific hybridization. In the present investigation, the ploidy of 43 Helianthus species belonging to diploid, tetraploid and hexaploid status along with 2 accessions of cultivated sunflower was determined. As wide variation exists in the Helianthus species for vegetative characteristics including pigmentation, processing of the leaf samples was tried with incorporation of 1 % polyvinylpyrrolidone while chopping the leaf which gave sharp peaks with low coefficient of variation. Ploidy as determined by flow cytometry was in agreement with the reported status of the Helianthus species used in the study. The mean 1C values for diploids, tetraploids and hexaploids were 3.67, 6.73 and 10.07 pg, respectively. The technique was validated on an interspecific hybrid of cultivated sunflower (2n = 2x) with H. hirsutus (2n = 4x) which confirmed the triploid status of the hybrid.Not Availabl

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Not AvailableAcetohydroxyacid synthase (AHAS) inhibiting herbicides have played a significant role in effective weed control in the cultivation of sunflower since their discovery. The development of sunflower lines and hybrids resistant to these herbicides made their post-emergence application possible. In this study, wild Helianthus species were screened phenotypically for imidazolinone (IMI) and sulfonylurea (SU) resistance by herbicide spray and for allelic variations at Ahasl1 (Ahas1 large subunit) locus using simple sequence repeat and single nucleotide polymorphism markers. Helianthus praecox accession 1823 plants showed promising resistance to three classes of SU-based herbicides and Helianthus nuttallii accession NUT05 plants remained green for a longer time after imazethapyr spray. A total of 50 accessions belonging to 21 wild Helianthus species of different ploidy levels were analysed for allelic variation along with some parents of commercial sunflower hybrids. None of the wild species showed the resistant allele (Ahasl1-1) similar to SCG101 (IMI-resistant line), although it is present in some of the parental lines of hybrids. However, the parental lines having Ahasl1-1-type allele failed to survive the field dose of imazethapyr spray. Inter-species and interaccessional allelic variation could be observed among the species. PRA1823 and NUT05 showed repeat length variations at Ahasl1 locus. Sequencing of full length Ahasl1 gene from both these accessions did not reveal any resistance mutations in the protein sequences. The molecular basis of the phenotypes identified in this study could be explored further and utilized in breeding programmes for imparting herbicide resistance in cultivated hybrids across sunflower growing regions of the world.Not Availabl

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Not AvailableJatropha curcas L., a drought tolerant, monoecious perennial shrub, has gained attention in the tropics and sub-tropics during the past decade as a potential biodiesel crop. Adequate genetic diversity for key agronomic traits is of fundamental importance in crop improvement programmes particularly for crops such as J. curcas, which are in the early stages of domestication. In J. curcas, genetic diversity in local populations and worldwide collections has been estimated using both dominant and co-dominant molecular markers systems such as random amplified polymorphic DNA (RAPD), inter simple sequence repeats (ISSRs), sequence-characterized amplified region (SCAR), amplified fragment length polymorphism (AFLP), simple sequence repeats (SSRs) and single-nucleotide polymorphism (SNPs), etc. Assessment of genetic variation using molecular markers unequivocally established the existence of rich genetic diversity in the germplasm from Central and South American regions and narrow genetic base in populations from Asia and Africa. Establishment of phylogenetic relationships among Jatropha species using molecular markers has been limited to species naturalized and distributed in India. Research expansion over the past decade has indicated the availability of considerable genetic variation in the genus Jatropha for vegetative and floral traits linked to productivity, seed oil content, fatty acid profiles, toxicity (phorbol esters, curcin), etc. The diverse genetic sources identified in J. curcas germplasm and the compatible wild species need to be exploited for genetic improvement of the crop through conventional breeding and interspecific gene transfer, which could be further accelerated through marker-aided selection.Not Availabl

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Not AvailableJatropha curcas has been intensively investigated recently as a biodiesel feedstock producer because of its adaptability to adverse soil and climatic conditions. It has been seen that increasing value from byproducts of oil production is important for the viability of the crop for the farmers. The seed kernel meal left after oil extraction is potentially of high market value as an animal feed ingredient. Every kilogram of oil produced from jatropha seeds generates about 0.75 kg of high quality seed kernel meal. It has a high protein content (65% on a dry matter basis) with a favourable amino acid composition, but is toxic because of the presence of compounds called phorbol esters. We introduce a non-toxic jatropha variety where phorbol esters are absent in the seeds and hence, the kernel meal can be included in animal feeds after conventional heat treatment similar to that done for soybean meal. Preliminary observations in a field trial indicates that there are non-toxic jatropha provenances that are similar to or better than the conventional toxic jatropha varieties in seed yield per plant and seed oil content. Non-toxic jatropha has potential as a viable bio-oil crop if high quality seeds are used for developing the plantation.Not Availabl

Methods in Molecular Biology

Not AvailableParticle bombardment/biolistic delivery is a very popular method of genetic transformation of diverse targets including cells and intact tissues. Delivery of DNA through particle bombardment is genotype and species independent, nevertheless, an ef fi cient protocol for large-scale generation of transgenic plants through embryogenic tissues with a high ( ³ 80%) shoot regeneration ef fi ciency is a prerequisite. Young embryogenic tissues or multiple shoot buds in early stages of induction are the most suited target tissues for recovery of transgenic plants. We describe the protocol for delivery of foreign genes using particle delivery system (Biorad gene gun, PDS-1000/He) in to the meristematic tissues of embryonic axes derived from mature seeds of castor. With the optimized physical and biological parameters, putative transformants were obtained at a frequency of 1.4% through particle gun bombardment of castor embryo axes. Also, transformation of embryogenic calli of sorghum using particle in fl ow gun (PIG) is described.Not Availabl