Internode length in Pisum. I. The effect of the Le/le gene difference on endogenous gibberellin‐like substances

Tall peas ( Pisum sativum L.) contain a relatively large amount of a polar gibberellinlike substance(s) which is either absent or present in only small amounts in dwarf peas. This biochemical difference can be attributed to a genetic difference at the le locus. Preliminary results using unrelated pure breeding tall ( Le ) and dwarf ( le ) lines were confirmed by the use of an F 2 progeny segregating for the Le/le pair of alleles. The polar gibberellin‐like substance(s) in tall peas is located mainly in the actively growing and elongating apical region of the shoot. The level of this substance(s) is much reduced in mature stem and leaf tissue. The gibberellin‐like substance(s) in question remains unidentified although it can be characterised by activity in both the lettuce hypocotyl bioassay and the rice seedling bioassay. The dwarf rice cultivars ‘Tan‐ginbozu’ and ‘Waito C’ are both sensitive. The magnitude of the other major zone of gibberellin‐like activity (the GA 20 ‐like zone) did not vary greatly between tall and dwarf segregates but the apical regions of the shoots again contained significantly more activity than the mature regions.