Origin of new Brassica types from a single intergeneric hybrid between B. rapa and Orychophragmus violaceus by rapid chromosome evolution and introgression.

Many novel lines were established from an intergeneric mixoploid between Brassica rapa (2n = 20) and Orychophragmus violaceus (2n = 24) through successive selections for fertility and viability. Pedigrees of individual F(2) plants were advanced to the 10th generation by selfing. Their breeding habit was self-compatible and different from the self-incompatibility of their female parent B. rapa, and these lines were reproductively isolated to different degrees from B. rapa and B. napus. The lines with high productivity showed not only a wide spectrum of phenotypes but also obvious variations in fatty acid profiles of seed oil and glucosinolate contents in seed meal. These lines had 2n = 36, 37, 38, 39 and 40, with 2n = 38 being most frequent (64.56%), and no intact O. violaceus chromosomes were detected by genomic in situ hybridization (GISH) analysis. Amplified fragment length polymorphism (AFLP) analyses revealed a high extent of variation in genomic compositions across all the lines. O. violaceus-specific bands, deleted bands in B. rapa and novel bands for two parents were detected in these lines, with novel bands being the most frequent. The morphological and genetic divergence of these novel types derived from a single hybrid is probably due to rapid chromosomal evolution and introgression, and provides new genetic resources for rapeseed breeding.

Goitrogenic content of Indian cyanogenic plant foods & their in vitro anti-thyroidal activity.

BACKGROUND & OBJECTIVES: Consumption of cyanogenic foods has been considered as one of the etiological factors in certain instances for the persistence of endemic goitre. The present study was undertaken to study the cyanogenic glucosides, glucosinolates and thiocyanate content in edible portion of certain selected plant foods of Indian origin. Further in vitro anti-thyroidal activity using raw, boiled and cooked extracts of these plants with and without excess iodide was also studied. METHODS: Cyanogenic plant foods generally vegetables were collected from different areas of West Bengal and Tripura. Cassava was obtained from Meghalaya and Kerala and their cyanogenic glucosides, glucosinolates and thiocyanate were estimated. Thyroid peroxidase activity (TPO) of human thyroid was assayed from microsomal fraction following I3- from iodide. The anti-TPO activities of the plants were assayed after adding raw, boiled and cooked extracts in the assay medium with and without extra iodide. Relative antithyroidal potency of the plant extracts was also evaluated in terms of the concentration (IC50) necessary to produce 50 per cent inhibition of TPO activity. PTU equivalence of the plant foods was also determined. RESULTS: Cabbage and cauliflower were rich in glucosinolates, bamboo shoot and cassava were rich in cyanogenic glucosides, mustard, turnip and radish were relatively rich in thiocyanate however all the constituents were present in each plant. Boiled extracts showed maximum inhibition of TPO activity followed by cooked and raw extracts. Excess iodide was found relatively effective for raw extract but less effective for boiled and cooked extracts in reversing anti-TPO activity. Inhibition constant (IC50) was found highest with bamboo shoot and least with cabbage. INTERPRETATION & CONCLUSION: Raw, boiled and cooked extracts of the plants showed anti-thyroidal activity in vitro. Excess iodide reversed the anti-TPO activity to same extent but could not neutralise it.