ABSTRACT
The present study revealed that all characters showed in variable crosses depicted heterosis in both positive and negative directions indicating that genes with negative as well as positive effects were dominant. The cross JCS-596 x Swetha showed highest positive heterosis for number of branches per plant over mid parent. The range of heterosis for number of capsules per plant was 74.27 to 50.74 over better parent. Maximum positive heterosis for number of capsules per plant was exhibited by NIC 8283x KMR-74 over mid parent and better parent. The magnitude of heterosis was 103.62 % and 98.53 % over mid parent and better parent for yield per plant respectively. The hybrids Rajeswari x Swetha, Chandana x Swetha, JCS-596 x KMR-74, JCS-596 x Swetha and NIC 8283x KMR-74 recorded highly significant positive standard heterosis for plant height. Maximum significant standard heterosis for number of capsules per plant was found in the crosses NIC 8283 x KMR-74, Chandana x Swetha and NIC-8392 x Swetha. The crosses Chandana x Swetha (36.63%) and NIC 8283 x KMR-74 (18.26%) were exhibited highest standard heterosis for seed yield per plant.The crosses JCS-596 x Swetha, NIC 8283 x KMR-74 and Chandana x Swetha can be utilized in heterosis breeding.
ABSTRACT
The effect of sub-lethal concentrations of isoniazid, ethambutol, rifampicin and pyrazinamide on the growth in vitro and the production of both exochelins and mycobactins by the high virulent and the South Indian low virulent strains of M. tuberculosis was examined under iron-deficient and iron-rich conditions. There was a marked decrease in the growth of both strains in the presence of increasing concentrations of all four drugs, the inhibition being total in the presence of minimal inhibitory concentrations of the drugs. It was also observed that the growth-inhibitory effect of all four drugs was slightly reversed in the presence of high concentration of iron in the medium. A significant increase was observed in the concentrations of both siderophores in the presence of all four drugs, under both iron-deficient (or) iron-rich conditions.
Subject(s)
Antitubercular Agents/pharmacology , Iron/metabolism , Iron Chelating Agents/metabolism , Mycobacterium tuberculosis/drug effects , Oxazoles/metabolism , Peptides, Cyclic/biosynthesisABSTRACT
Hemoglobin is known to support the growth of several bacterial species. The growth and the production of siderophores by 4 strains of mycobacteria in the presence of hemoglobin was studied in vitro. The findings were compared with those obtained in the presence of equivalent concentrations of iron in the medium. Increase in the concentrations of hemoglobin caused an appreciable increase in the growth of all 4 strains. This was however, accompanied by a significant decrease in the production of both exochelins and mycobactins. It was also observed that hemoglobin supported the growth of all strains as well as that with free iron and the concentrations of both siderophores was significantly higher in the presence of hemoglobin than in that of free iron.