Studies On Endogenous Hormones Of Resynthesised Rapeseed Lines With Special Long Pods

The objective of this study was to investigate the correlation between endogenous hormones and the pod-length in rapeseed (Brassica napus L). Enzyme-linked immunosorbent assays (ELISA) and exogenous hormone treatment were applied with six rapeseed lines, including a super-long pod line "H218"and short pod line "MSP334". The major results are the following:1 In contrast to the pod development of each line in different stages, The key factors to determine the final pod-lengths were the difference rate of development stage between the 10th-20th after flowering.2 From the variance analysis, it is showed endogenous hormone concentrations were obviously diverse in the different lines, but each line's hormone change rule were discard. The correlation analysis showed that the correlation coefficients between hormones content and pod-length (either at the stage of examination or the final pod-length)-were not significant. This suggested that the endogenous hormones contents were not directly related to the final pod-lengths.3 Similarity was found in variations of the relative contents of endogenous Correlation analysis showed that hormones in the various lines, the relative content of IAA on the 1st and 5th day after flowering, the relative content of GA3 on the 5th day after flowering were significantly correlated to the final pod lengths. It was indicated that the lower relative content of IAA and higher relative content of GA3, the longer final pod length would be.4 The ratios between hormones also showed similar variations When the dynamic charts of GA3/IAA, IAA/GA3 were compared to the chart of relative content of GA3, IAA, the rules could be conclude as the same as for the ratio between IAA and GA3. Correlation analysis showed that GA3/IAA on the 1st and 5th day after flowering were significantly correlated to the final pod lengths. This indicated that the higher ratio of GA3/IAA at the initial pod development stage, the longer final pod length would be.5 The exogenous hormones treatments showed, IB A, PP333 shortened the podlengths in both the long pod line and the short pod line. With hormone concentrations raised, the effect of restraint became more significant. This proved that, at initial stage, the lower IAA concentration and higher GA3 concentration were favorable of the longer pod-length formation.6 A comprehensive analysis showed that the major factor resulting in the super long pod was its higher GA3/IAA ratio at the initial pod stage. IAA and GA3 could alter the speed of cell's division, the activities of expansins, cellulose enzyme, Xyloglucanen dotransglycosylase, and orientation of the microtubules to promote cell division and elongation.7 The change in the rules of absolute contents of hormones in each line were not similar, and the correlation to pod length were also not significant. This indicated the relationship between the hormones and pod length, were more dependent on the hormonal environment, instead of the simple hormone concentrations.8 From the analysis of correlation, it was seem that all absolute content, relative content or ratio between hormones were not significantly correlated to pod length, at the corresponding stages. On the other hand, the relative content of IAA, GA3 and the ratio of GA3/IAA at the initial stage were strongly correlated to the final pod length. This indicated that the actions of the hormone were not synchronistic to the pod lengths.