Relationship Between Heterosis and Endogenous Plant Hormones in Liriodendron

摘要

To investigate the possible involvement of endogenous plant hormones in heterosis of Liriodendron interspecific hybrid, growth traits and contents of endogenous GA_(1/3) (gibberellin A_1, A_3), IAA (indole-3-acetic acid) and iPA (isopentenyl adenine) of tulip tree (L. chinense (Hemsl.) Sarg.), yellow poplar (L. tulipifera L.) and their interspecific hybrid (L. chinense x L. tulipifera) were examined. Results showed that: (1) the heterosis in height growth trait of the interspecific hybrid was mainly caused by the reletively greater elongation of internodes. Although the uppermost three internodes had the potential of elongation, the first one, which had the greatest elongation amount, contributed to the heterosis of the height growth trait; (2) the contents of endogenous GA_(1/3), IAA and iPA were greatly different among tulip tree, yellow poplar and their interspecific hybrid. All of the three interspecific hybrid families studied significantly contained higher amount of endogenous GA_(1/3) and iPA in the uppermost first internode than their parental species. And thus, a correlation between the contents of endogenous GA_(1/3) and iPA, and hybrid vigor for height growth trait in Liriodendron was observed; (3) the rankings of endogenous GA_(1/3) and iPA contents in the uppermost first internode of three hybrid families studied were not similar to the ranking for height of 3-year-old trees. Therefore, the contents of endogenous GA_(1/3) and iPA in the uppermost first internode could not be used in predicting hybrid vigor among hybrid families.