Improvement of xylanase production by Cochliobolus sativus in solid state fermentation / Melhoramento da produção de xilanase por Cochliobolus sativus por fermentação em estado sólido

The xylanase production by Cochliobolus sativus strain Cs6 was improved under solid state fermentation (SSF). High xylanase activity (1079 U/g) was obtained when wheat straw was used after 8 days of incubation. Combinations of sodium nitrate with peptone or yeast extract resulted in an increased xylanase production (1543 and 1483 U/g, respectively). The Cs6 strain grown in SSF in a simple medium, proved to be a promising microorganism for xylanase production.

A produção de xilanase por Cochliobolus sativus cepa Cs6 SATIVUS por fermentação em estado sólido (SSF) foi melhorada. Com o emprego de palha de trigo, obteve-se elevada atividade de xilanase (1079 U/g) após 8 dias de incubação. Combinações de nitrato de sódio com peptona ou extrato de levedura aumentaram a produção de xilanase (1543 e 1483 U/g, respectivamente). Comprovou-se que a cepa Cs6, cultivada em SSF em meio simples, é um microrganismo promissor para produção de xilanase.

Inheritance and identification of molecular markers associated with spot blotch (Cochliobolus sativus L) resistance through microsatellites analysis in barley

Spot blotch resistant (IBON 18) and susceptible (RD 2508) lines were crossed to investigate inheritance of resistance and to identify simple sequence repeats (SSRs) associated with resistance. F1 resistance was intermediate and suggested additive nature of inheritance. Three additive genes was noted in the distribution of F3, F4 and F5 generations. In F6 and F6-7, the quantitative and qualitative approaches also suggested the control of three resistance genes. The parents and the RILs (F6/F6-7) were grown in four environments and spot blotch severity recorded. Forty five SSR primers, specific for chromosomes 1 (7H) and 5 (1H), were applied. Of these, 12 were polymorphic between the parents, and between the resistant and susceptible bulks. Three markers BMS 32, BMS 90 and HVCMA showed association with resistance, which was further confirmed through selective genotyping. The co-segregation data on the molecular markers (BMS 32, BMS 90 and HVCMA) and spot blotch severity on 173 RILs was analyzed by single marker linear regression approach. Significant regression suggested linkage among BMS 32, BMS 90 and HVCMA and the three resistant genes (designated as Rcs-qtl-5H-1, Rcs-qtl-5H-2 and Rcs-qtl-1H-1.) respectively. These markers explained 28 percent, 19 percent and 12 percent of variation respectively, for spot blotch resistance among the RILs.