Novel sulI binary vectors enable an inexpensive foliar selection method in Arabidopsis

<p>Abstract</p> <p>Background</p> <p>Sulfonamide resistance is conferred by the <it>sul</it>I gene found on many <it>Enterobacteriaceae </it>R plasmids and Tn21 type transposons. The <it>sul</it>I gene encodes a sulfonamide insensitive dihydropteroate synthase enzyme required for folate biosynthesis. Transformation of tobacco, potato or <it>Arabidopsis </it>using <it>sul</it>I as a selectable marker generates sulfadiazine-resistant plants. Typically <it>sul</it>I-based selection of transgenic plants is performed on tissue culture media under sterile conditions.</p> <p>Findings</p> <p>A set of novel binary vectors containing a <it>sul</it>I selectable marker expression cassette were constructed and used to generate transgenic <it>Arabidopsis</it>. We demonstrate that the <it>sul</it>I selectable marker can be utilized for direct selection of plants grown in soil with a simple foliar spray application procedure. A highly effective and inexpensive high throughput screening strategy to identify transgenic <it>Arabidopsis </it>without use of tissue culture was developed.</p> <p>Conclusion</p> <p>Novel <it>sul</it>I-containing <it>Agrobacterium </it>binary vectors designed to over-express a gene of interest or to characterize a test promoter in transgenic plants have been constructed. These new vector tools combined with the various beneficial attributes of sulfonamide selection and the simple foliar screening strategy provide an advantageous alternative for plant biotechnology researchers. The set of binary vectors is freely available upon request.</p

SEED COATS: STRUCTURE, DEVELOPMENT, COMPOSITION, AND BIOTECHNOLOGY

Although seeds have been the subject of extensive studies for many years, their seed coats are just beginning to be examined from the perspective of molecular genetics and control of development. The seed coat plays a vital role in the life cycle of plants by controlling the development of the embryo and determining seed dormancy and germination. Within the seed coat are a number of unique tissues that undergo differentiation to serve specific functions in the seed. A large number of genes are known to be specifically expressed within the seed coat tissues; however, very few of them are understood functionally. The seed coat synthesizes a wide range of novel compounds that may serve the plant in diverse ways, including defense and control of development. Many of the compounds are sources of industrial products and are components of food and feeds. The use of seed coat biotechnology to enhance seed quality and yield, or to generate novel components has not been exploited, largely because of lack of knowledge of the genetic systems that govern seed coat development and composition. In this review, we will examine the recent advances in seed coat biology from the perspective of structure, composition and molecular genetics. We will consider the diverse avenues that are possible for seed coat biotechnology in the future. This review will focus principally on the seed coats of the Brassicaceae and Fabaceae as they allow us to merge the areas of molecular biology, physiology and structure to gain a perspective on the possibilities for seed coat modifications in the future. Key words: biotechnology; Brassica; genes; legume; seed coat

Adaptation and Acclimation of Photosynthetic Microorganisms to Permanently Cold Environments

Persistently cold environments constitute one of our world's largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages

Valorization of corn stover and molasses for enzyme synthesis, lignocellulosic hydrolysis and bioethanol production by Hymenobacter sp. CKS3

During the last few decades, energy demand is increasing rapidly. Concerning this, the use of renewables - lignocellulose biomass, for bioethanol production, as an efficient alternative to replacing fossil fuels, is highly recommended. In this study, valorization of two agricultural wastes was used for various hydrolytic enzyme production by Hymenobacter sp. CKS3, lignocellulosic hydrolysis, and bioethanol production. Conditions for obtaining maximum enzyme production, using agro-industrial waste - molasses and corn stover, were statistically optimized. Under the optimal conditions, in a medium containing 5.0% corn stover, 2.5% molasses, and during 94.55 h (similar to 4 days) of fermentation, the maximum enzymatic activity was achieved - CMCase 1.11 IU/ml, Avicelase 0.92 IU/ml, and pectinase 3.69 IU/ml. The obtained crude enzyme mixture was further used for enzymatic hydrolysis of non-treated corn stover and bioethanol production. The reducing sugar yield of 3.85 g/l was obtained under optimal conditions (corn stover 6.6% and time of hydrolysis 78.8 h (similar to 3 days and 7 h)). Scanning electron microscopy revealed structural changes in corn stover samples after enzymatic hydrolysis. Under non-optimized conditions, 0.37% of ethanol was produced by waste brewer's yeast. The obtained results show that bacteria belonging to the genus Hymenobacter have a still unexplored enzymatic potential that could be used for sustainable production of biotechnologically value-added products including biofuels. Specifically, for the first time, a soil bacterium, classified within the genus Hymenobacter, was used for cellulases (CMCase and Avicelase) and pectinase production