No abstract

Transgenic sorghum plants have been obtained after microprojectile bombardment of immature zygotic embryos of a drought-resistant sorghum cultivar, P898012. DNA delivery parameters were optimized based on transient expression of R and Cl maize anthocyanin regulatory elements in scuteflar cells. The protocol for obtaining transgenic plants consists of the delivery of the bar gene to immature zygotic embryos and the imposition of bialaphos selection pressure at various stages during culture, from induction of somatic embryogenesis to rooting of regenerated plantlets. One in about every 350 embryos produced embryogenic tissues that survived bialaphos treatment; six transformed callus lines were obtained from three of the eight sorghum cultivars used in this research.Transgenic (To) plants were obtained from cultivar P898012(two independent transformation events). (1). It is a primary staple in the semiarid tropics of Africa and Asia for over 300 million people. These are evidentiary statistics of the significance of this crop in these regions, which are predominated by subsistence agriculture. In the western hemisphere sorghum is used primarily as livestock feed (2). The development of hybrid varieties of sorghum in the 1950s contributed substantially to the increase in production in the United States. Presently, sorghum is third amongst cereals in U.S. production and is the preferred crop in areas oflow water availability because of its yield stability under drought conditions. Advances in biotechnology are now beginning to be used to augment traditional approaches for crop improvement. Restriction fragment length polymorphism (RFLP) linkage maps are being constructed that should greatly facilitate plant breeding efforts for marker-assisted backcross programs (3,4) and, in the near future, may be used to clone agriculturally important genes through the use of map-based cloning strategies (5). To this date, however, there are no programs in sorghum to access the pool of genes that are available as the result of genetic engineering research, because of the lack of a transformation system. Transformation of protoplasts byThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. electroporation (6) or cell suspensions by microprojectile bombardment (7) has resulted in stable expression of transferred genes; however, transgenic plants were not obtained.Microprojectile bombardment as a method to introduce DNA into cells circumvents two major constraints of cereal transformation. These are the lack of an available natural vector such as Agrobacterium tumefaciens and the difficulty to regenerate plants when protoplasts are used for transformation. Particle bombardment can target cells within tissues or organs that have high morphogenic potential. Immature or mature zygotic embryos (8-10), immature inflorescences (11,12), and shoot tips (13) of sorghum exhibit emb...

19The BARLEYMAP pipeline was designed to map both genomic sequences and

No abstract

The pan-genome of a species is defined as the union of all the genes and non-coding sequences found in all its individuals. However, constructing a pan-genome for plants with large genomes is daunting both in sequencing cost and the scale of the required computational analysis. A more affordable alternative is to focus on the genic repertoire by using transcriptomic data. Here, the software GET_HOMOLOGUES-EST was benchmarked with genomic and RNA-seq data of 19 Arabidopsis thaliana ecotypes and then applied to the analysis of transcripts from 16 Hordeum vulgare genotypes. The goal was to sample their pan-genomes and classify sequences as core, if detected in all accessions, or accessory, when absent in some of them. The resulting sequence clusters were used to simulate pan-genome growth, and to compile Average Nucleotide Identity matrices that summarize intra-species variation. Although transcripts were found to under-estimate pan-genome size by at least 10%, we concluded that clusters of expressed sequences can recapitulate phylogeny and reproduce two properties observed in A. thaliana gene models: accessory loci show lower expression and higher non-synonymous substitution rates than core genes. Finally, accessory sequences were observed to preferentially encode transposon components in both species, plus disease resistance genes in cultivated barleys, and a variety of protein domains from other families that appear frequently associated with presence/absence variation in the literature. These results demonstrate that pan-genome analyses are useful to explore germplasm diversity.