No abstract

In addition to the previously-reported gibberellins: GA1; GA8, GA20 and GA29 (García-Martínez et al., 1987, Planta 170, 130-137), GA3 and GA19 were identified by combined gas chromatography-mass spectrometry in pods and ovules of 4-d-old pollinated pea (Pisum sativum cv. Alaska) ovaries. Pods contained additionally GA17, GA81 (2α-hydroxy GA20) and GA29-catabolite. The concentrations of GA1, GA3, GA8, GA19, GA20 and GA29 were higher in the ovules than in the pod, although, with the exception of GA3, the total content of these GAs in the pod exceeded that in the seeds. About 80% of the GA3 content of the ovary was present in the seeds. The concentrations of GA19 and GA20 in pollinated ovaries remained fairly constant for the first 12 ds after an thesis, after which they increased sharply. In contrast, GA1 and GA3 concentrations were maximal at 7 d and 4-6 d, respectively, after anthesis, at about the time of maximum pod growth rate, and declined thereafter. Emasculated ovaries at anthesis contained GA8, GA19 and GA20 at concentrations comparable with pollinated fruit, but they decreased rapidly. Gibberellins a1 and A3 were present in only trace amounts in emasculated ovaries at any stage. Parthenocarpic fruit, produced by decapitating plants immediately above an emasculated flower, or by treating such flowers with 2,4-dichlorophenoxyacetic acid or GA7, contained GA19 and GA20 at similar concentrations to seeded fruit, but very low amounts of GA1 and GA3 Thus, it appears that the presence of fertilised ovules is necessary for the synthesis of these last two GAs. Mature leaves and leaf diffusates contained GA1, GA8, GA19 and GA20 as determined by combined gas chromatography-mass spectrometry using selected ion monitoring. This provides further evidence that vegetative tissues are a possible alternative source of GAs for fruit-set, particularly in decapitated plants.

No abstract

l h e effect of the /e mutation on the growth and gibberellin (CA) content of developing fruits was investigated using the near-isogenic lines of fisum sativum L. 205+ (LeLe) and 205-(/ele). Although stem elongation is known to be reduced in 205-plants by approximately 65%, the growth of pods and seeds was unaffected by the /e mutation. CAI, CA,, and CAZo stimulated parthenocarpic development of unpollinated ovaries on both 205+ and 205-plants. GA2, was less active on 205-ovaries than on 205+, whereas CAI had similar, high activity i n both lines. The activity of CA, was even higher than that of CAI in both lines. Decapitation of 205+ plants induced parthenocarpic development of unpollinated ovaries, but this treatment was much less effective on 205-plants. l h e contents of CAI and GA, in entire ovaries 6 d after anthesis, as well as in the pod and fertilized ovules, were substantially lower in 205-than in 205' plants, whereas the reverse was true for the levels of CAzO and CAz9. lhese results suggest that 30-hydroxylation of CAzo to CAI is reduced i n ovaries as well as in vegetative tissues. Thus, the /e mutation appears to be expressed in young reproductive organs of the 205-line, even though it does not affect the fruit phenotype. Because the content of CAI i n the ovary was similar in the two lines, one explanation for the normal fruit size i n the 205-line is that CA, is the native regulator of pod growth. Alternatively, sufficient CAI may still be produced in 205-fruits to maintain normal pod growth.There is considerable evidence that fruit-set and pod development in Pisum sativum L. (garden pea) are regulated by GAs, which are probably supplied by the fertilized ovules (Eeuwens and Schwabe, 1975; Garcia-Martinez and Carbonell, 1980; Sponsel, 1982; Garcia-Martinez et al., 1987, 1991a. GAI, GA3, GAs, GA19, GAzo, and GAZ9 have been identified in ovules and pods of 4-d-old pollinated ovaries of pea cv Alaska, and GAI7, GAsl, and GA29 catabolite were identified additionally in the pods (Garcia-Marthez et al., 1987, 1991b). GAl, GA3, and GA20 induced parthenocarpic ovary growth in cv Alaska, with the order of activity GA3 > GA1 > GAZo (Sponsel, 1982; Garcia-Martínez et al., 1987).The contents of GAl and GA3 in pea ovaries are maximal during the time of rapid pod elongation (Garcia-Marthez et al., 1991b), suggesting that these GAs are involved in the regulation of fruit-set and development.Work with GA biosynthesis mutants indicates that GAI controls shoot elongation in maize, pea, and rice (Phinney, 1984), and a linear relationship was found between intemode length in pea and the logarithm of GA1 concentration in the shoot (Ross et al., 1989). The Le gene was shown to control the 3P-hydroxylation of GAZ0 to GAl in pea shoots on the basis of the following evidence: (a) Extracts from shoots of dwarf le mutants contain 10-to 18-fold less GA1 than those from the wild types (Ross et al., 1992;Smith et al., 1992); (b) the le mutation reduces the conversion of [3H]GA20 and [17-13C,3Hz]GAz0 to labeled GAl and GAs, ...