Genetic regulation of carotene biosynthesis in selected tomato strains: aspects of beta-carotene biosynthesis and B gene specificity.
A comparative qualitative and quantitative study of the carotene compositions of a high beta-carotene type mutant Priya Darshini-1 (PD-1), high lycopene type, Pusa Ruby (PR) and the F1 hybrid of these two strains was carried out. Increased amounts of beta-zeacarotene and gamma-carotene were realized in the PD-1 parent and in the F1 hybrid. This correlates the increased beta-zeacarotene and gamma-carotene synthesis with increased beta-carotene synthesis. Introduction of gene B (the gene that regulates beta-carotene biosynthesis) to a system lacking it induces considerable amount of beta-carotene synthesis at the expense of lycopene in the hybrid. Based on these observations a 'three point control' for the beta-carotene biosynthesis in tomato fruits is suggested with the gene B capable of promoting two different pathways in the high beta-carotene types. The probable sites of action of the modifier mOB (the gene that regulates expression of B gene) are indicated. Beta-carotene and xanthophyll contents of different parts of tomato plants of a PD-1 type and the PR type F2 segregates of the F1 hybrid (PR X PD-1)F1 have been studied. Results indicate that the action of gene B is highly specific and exclusively oriented towards the fruit and not expressed in any other parts of the tomato plant.
B R
BR
Premachandra
D002338:Carotenoids / Q000096:biosynthesis* / Q000235:genetics; D005796:Genes; D014975:Lutein / Q000302:isolation & purification; D009154:Mutation; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D014675:Vegetables; D019207:beta Carotene
D019207:beta Carotene; D002338:Carotenoids; D014975:Lutein