No abstract

Mapping population of recombinant inbred lines (RILs) representing 541 × Ot1-3 cross exhibited wide variations of benzoxazinoid (BX) content in leaves and roots, brown rust resistance, α-amylase activity in the grain, and resistance to preharvest sprouting. QTL mapping of major BX species using a DArT-based map revealed a complex genetic architecture underlying the production of these main secondary metabolites engaged in stress and allelopathy responses. The synthesis of BX in leaves and roots was found to be regulated by different QTL. The QTL for the BX content, rust resistance, α-amylase activity, and preharvest sprouting partially overlapped; this points to their common genetic regulation by a definite subset of genes. Only one QTL for BX located on chromosome 7R coincided with the loci of the ScBx genes, which were mapped as two clusters on chromosomes 5RS (Bx3-Bx5) and 7R (Bx1-Bx2). The QTL common for several BX species, rust resistance, preharvest sprouting, and α-amylase activity are interesting objects for further exploration aimed at developing common markers for these important agronomic traits.

By screening for bacteriocin-producing lactic acid bacteria of 1,428 strains isolated from authentic Bulgarian dairy products, Lb. bulgaricus BB18 strain obtained from kefir grain was selected. Out of 11 yogurt starters containing Lb. bulgaricus BB18 and S. thermophilus strains resistant to bacteriocin secreted by Lb. bulgaricus BB18 a yogurt culture (S. thermophilus 11A+Lb. bulgaricus BB18) with high growth and bacteriocinogenic activity in milk was selected. Continuous (pH-stat 5.7) prefermentation processes were carried out in milk at 37 degrees C in a 2l MBR bioreactor (MBR AG, Zurich, Switzerland) with an IMCS controller for agitation speed, temperature, dissolved oxygen, CO2 and pH. Prefermented milk with pH 5.7 coagulated in a thermostat at 37 degrees C until pH 4.8-4.9. S. thermophilus 11A and Lb. bulgaricus BB18 grew independently in a continuous mode at similar and sufficiently high-dilution rates (D=1.83 h(-1)-S. thermophilus 11A; D=1.80 h(-1)-Lb. bulgaricus BB18). The yogurt cultures developed in a stream at a high-dilution rate (D=2.03-2.28 h(-1)). The progress of both processes (growth and bacteriocin production) depended on the initial ratio between the two microorganisms. The continuous prefermentation process promoted conditions for efficient fermentation and bacteriocinogenesis of the starter culture during the batch process: strong reduction of the times for bacteriocin production and coagulation of milk (to 4.5-5.0 h); high cell productivity (lactobacilli-4x10(12) CFU ml(-1), streptococci-6x10(12) CFU ml(-1)); high productivity of bacteriocins (4,500 BU ml(-1))-1.7 times higher than the bacteriocinogenic activity of the batch starter culture.

Abiotic stresses, which at the molecular level leads to oxidative damage, are major determinants of crop yield loss worldwide. Therefore, considerable efforts are directed towards developing strategies for their limitation and mitigation. Here the superoxide-inducing agent paraquat (PQ) was used to generate oxidative stress in the model species Arabidopsis thaliana and the crops tomato and pepper. Pre-treatment with the biostimulant SuperFifty (SF) effectively and universally suppressed PQ-induced leaf lesions, H2O2 build up, cell destruction and photosynthesis inhibition. To further investigate the stress responses and SF-induced protection at the molecular level, we investigated the metabolites by GC-MS metabolomics. PQ induced specific metabolic changes such as accumulation of free amino acids (AA) and stress metabolites. These changes were fully prevented by the SF pre-treatment. Moreover, the metabolic changes of the specific groups were tightly correlating with their phenotypic characteristics. Overall, this study presents physiological and metabolomics data which shows that SF protects against oxidative stress in all three plant species.

No abstract