Analysis of gibberellins in growing fruits ofLycopersicon esculentumafter pollination or treatment with 4-chlorophenoxyacetic acid

Abstract

SummaryIdentification and quantification of gibberellins (GAs) were conducted in tomato pistils (Lycopersicon esculentum Miller) two days before anthesis as well as in pollinated fruits and parthenocarpic fruits induced by 4-chlorophenoxyacetic acid (4-CPA) treatment at 1, 3,6,10 and 14 d after anthesis. GA1, GAg, GA17, GA19, GA20, GA29 and GA44 were identified by combined gas chromatography-mass spectrometry (GC-MS) in pollinated fruits and parthenocarpic fruits; pollinated fruits in addition contained GA9, GA15, GA24 and GA25. 2 β-OH-GA53 was also tentatively identified in both types of fruits. Activity of GAs could not be detected in emasculated pistils. In the early stage of growth of pollinated fruits between 1 and 6 d after anthesis, the biosynthetic pathway to the C20-GA precursor of GA1, GA19, was much more accelerated than in parthenocarpic fruits, indicating that pollination may stimulate the pathway more strongly than 4-CPA. Parthenocarpic fruit tissues had a much higher concentration of GA1 than those from pollinated fruits at 10-14 d after anthesis, indicating that higher levels of GA1 may correlate with the size of fruit, because larger fruit was associated with parthenogenesis in the early stage of fruit growth. In pollinated fruits, the concentration of G A20 was much higher than that of GA1, indicating that 3 β-hydroxylation of GA20 may be a limiting step in GA1 biosynthesis for pollinated fruit growth.