Enhancement of Trichoderma harzianum CFAM-422 for cellulase and hemicellulase production by deletion of the carbon catabolite repressor gene cre1.

Carbon catabolite repression (CCR) is a mechanism by which microorganisms can utilize preferably highly energetic compounds over those of difficult degradation. For Trichoderma reesei, the protein that acts as repressor in the presence of glucose is CRE1. In this project, we aim to delete cre1 gene in Trichoderma harzianum CFAM-422 and obtain mutants with enhanced production of biomass degrading enzymes. Disruption of cre1 in T. harzianum CFAM-422 was performed by gene replacement of cre1 for hph (hygromycin B phosphotransferase) via homologous recombination. Hygromycin resistant mutants and parental strains enzyme production was evaluated in both inductive and repressive conditions in four different carbon sources. Enzymatic indexes (EI) were determined and compared. All genetically stable transformants showed increased enzymatic index under inductive conditions and modest inhibition under repressive conditions for most carbon sources, indicating that the deletion of cre1 in T. harzianum can be beneficial to cellulase and hemicellulase production with reduced product inhibition.SINAFERM; SHEB. 3 a 6 de setembro. Seção Trabalhos. Ref. 59019

Development of RAPD-AFLP map of eggplant and improvement of tolerance to Verticillium wilt

Verticillium wilt is one of the most serious diseases in eggplant and one of the main goals of eggplant breeding is the achievement of Verticillium wilt tolerant hybrids. Solanum sodomeum L. has shown a mechanism of partial resistance against Verticillium wilt. Interspecific hybrids were obtained by using an accession of S. sodomeum from Sicily and the eggplant variety Buia. The results of the screenings for eggplant genotypes tolerant/resistant to Verticillium wilt by using backcrosses are reported. In a naturally infected field, from 1998 to 2001, the resistance to V dahliae of backcrossed progenies was increased by about 60%. The interspecific hybrids were both selfed and backcrossed using different types of eggplant. An integrated linkage map of eggplant (Solanum melongena L.) has been obtained by using 48 plants of an F-2 population. Starting from a genetic RAPDs map with similar to 100 markers mapped on 13 linkage groups, 4 AFLPs primer combinations were screened in order to improve the genetic map with the aim to achieve markers linked to Verticillium tolerance. Mendelian segregation of loci was verified by chi-square tests of the expected 3:1 and 1:1 ratios. Marker order was determined and all the data were combined to construct the most likely map. The integrated analysis of markers resulted in the construction of a map consisting of 273 loci and 12/13 linkage groups spanning 736 cM in a total. Linkage between different AFLP markers and the tolerance to Verticillium is discussed