Draft Genome Sequence of Mentha Iongifolia and Development of Resources for Mint Cultivar Improvement

The genus Mentha encompasses mint species cultivated for their essential oils, which are formulated into a vast array of consumer products. Desirable oil characteristics and resistance to the fungal disease Verti- cillium wilt are top priorities for the mint industry. However, cultivated mints have complex polyploid ge- homes and are sterile. Breeding efforts, therefore, require the development of genomic resources for fertile mint species. Here, we present draft de novo genome and plastome assemblies for a wilt-resistant South African accession of Mentha Iongifolia （L.） Huds., a diploid species ancestral to cultivated peppermint and spearmint. The 353 Mb genome contains 35 597 predicted protein-coding genes, including 292 disease resistance gene homologs, and nine genes determining essential oil characteristics. A genetic linkage map ordered 1397 genome scaffolds on 12 pseudochromosomes. More than two million simple sequence repeats were identified, which will facilitate molecular marker development. The M. Iongifolia genome is a valuable resource for both metabolic engineering and molecular breeding. This is exemplified by employing the genome sequence to clone and functionally characterize the promoters in a peppermint cultivar, and demonstrating the utility of a glandular trichome-specific promoter to increase expression of a biosynthetic gene, thereby modulating essential oil composition.

Fabrication,characterization and optimization of high conductivity and high quality nanocrystalline molybdenum thin films

The present study investigated the influence of substrate temperature(Ts)and working pressure(P(Ar))on tailoring the properties of nanocrystalline(nc)molybdenum(Mo)films fabricated by radio-frequency magnetron sputtering.The structural,morphological,electrical and optical properties of nc-Mo films were evaluated in detail.The Mo films exhibited(110)orientation with average crystallite size varying from 9 to 22(±1)nm on increasing Ts.Corroborating with structural data,the electrical resistivity decreased from 55μΩcm to 10μΩcm,which is the lowest among all the Mo films.For Mo films deposited under variable P(Ar).the(110)peak intensity decrement coupled with peak broadening on increasing P(Ar).Lower deposition pressure yielded densely packed thin films with superior structural properties along with low resistivity of 15μΩcm.Optimum conditions to produce high quality Mo films with excellent structural,morphological,electrical and optical characteristics for utilization in solar cells as back contact layers were identified.

A Dual-Promoter Gene Orchestrates the Sucrose-Coordinated Synthesis of Starch and Fructan in Barley

Sequential carbohydrate synthesis is important for plant survival because it guarantees energy supplies for growth and development during plant ontogeny and reproduction. Starch and fructan are two important carbohydrates in many flowering plants and in human diets. Understanding this coordinated starch and fructan synthesis and unraveling how plants allocate photosynthates and prioritize different carbohydrate synthesis for survival could lead to improvements to cereals in agriculture for the purposes of greater food security and production quality. Here, we report a system from a single gene in barley employing two alternative promoters, one intronic/exonic, to generate two sequence-overlapping but functionally opposing transcription factors, in sensing sucrose, potentially via sucrose/gluco lose 6-phosphate signaling. The system employs an autoregulatory mechanism in perceiving a sucrose- controlled trans activity on one promoter and orchestrating the coordinated starch and fructan synthesis by competitive transcription factor binding on the other promoter. As a case in point for the physiological roles of the system, we have demonstrated that this multitasking system can be exploited in breeding barley with tailored amounts of fructan to produce healthy food ingredients. The identification of an intron/exon-spanning promoter in a hosting gene, resulting in proteins with distinct functions, adds to the complexity of plant genomes.