| Rapeseed is one of the main oil crops in the world, and the countries and scientific researchers of rapeseed are attaching much importance to the production and scientific research of rapeseed. Nowadays, genie engineering is advancing rapidly, but in generally, the transformation efficiency of rapeseed is not very high, which is related with the low regeneration frequency of rapeseed. So one of the central parts of transformation study on rapeseed is the establishment of a regeneration system with a high and steady regeneration frequency. In the researches of building regeneration system, hypocoryl and cotyledon are always used of all explants.Up to now, all experimental materials used in study on the regeneration system of hypocoryl and cotyledon in Brassica napus L. are black- or brown-seeded rapeseed. There were no reports about regeneration system study of hypocoryl and cotyledon in yellow-seeded rapeseed. Compared to black- or brown-seeded rapeseed (Brassica napus L.) line, yellow-seeded rapeseed line has thinner seed coat, lower hull percentage, higher oil and protein and lower crude fiber. Thus, the breeding of yellow-seeded rapeseed becomes one of the main objectives in rapeseed breeding. The research of hypocotyl regeneration system in yellow-seeded rapeseed (Brassica napus L.) can widen the material range of regeneration study in rapeseed and establish, on the other hand, the technique foundation for genetic transformation study in yellow-seeded rapeseed.In this present study, some yellow- and black-seeded rapeseed (Brassica napus L.) lines, such as GH01 and PI respectively, were used as experimental materials and the regenerations of hypocotyl and cotyledon were analyzed. The contents of this study included: the comparison of shoot regeneration frequency (SRF) of hypocotyl among 9 yellow-seeded rapeseed lines; the key factors which affected the SRF of hypocotyl in yellow-seeded rapeseed using orthogonal design; as well as the SRF differences of hypocotyl between yellow- and black-seeded lines and those between hypocotyl and cotyledon of yellow-seeded lines. The effect of adding 6-BA and NAA in germination medium was also investigated.The results gained from this study were as follows:The SRF differences of hypocotyl among different yellow-seeded rapeseed lines were significant on the same treatment condition. In generally, some lines were easy to regenerate, of which the SRFs were high, the others were hardly regenerated and their SRFs were low. The interaction of line × treatment condition was also obvious. So, there was a special treatment condition on which the SRF of a given line would reach the highest.Among the 4 yellow-seeded rapeseed lines, the SRF of line GH03 was very low and steady, and it was not sensitive to treatments. However, for the other three lines GH01, GH06 and GH19, the concentrations of 2,4-D and 6-BA in pre-culture medium were the main factors which affected theregeneration ability; The day number of pre-culrure and the concentration of AgNO3 showed no obvious effect on the SRF of hypocotyl; The effects of the concentration of NAA, 6-BA and AgNO3 in differentiation medium varied between different lines. The best treatments were founded for each of the four lines in this study. For GH01, GH03, GH06 and GH19, the concentrations of 2,4-D in pre-culture medium were 4.0, 2.0, 1.0, 1.0 mg/L respectively; The concentrations of 6-BA in pre-culture medium were 0.2,1.0,1.0, 0.2 mg/L respectively; The day number of pre-culrure was all 4d; The combinations of NAA and 6-BA in differentiation medium were NAA 0.1 + 6-BA 2.0. NAA 0.1 + 6-BA 2.0, NAA 0.2 + 6-BA 3.0, NAA 0.2 + 6-BA 3.0 mg/L respectively; The concentrations of AgNO3 were 5.0, 10.0, 5.0, 10.0 mg/L respectively.By comparing the SRFs of hypocotyl between yellow- and black-seeded rapeseed lines, it was found that the difference was not obvious. In generally, the SRFs of hypocotyl in yellow-seeded rapeseed lines were relatively low; the differences among lines were significant. But there were some Hnes having...
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