GIBBERELLINS ARE REQUIRED FOR EMBRYO GROWTH AND SEED DEVELOPMENT IN PEA

Citation
Sm. Swain et al., GIBBERELLINS ARE REQUIRED FOR EMBRYO GROWTH AND SEED DEVELOPMENT IN PEA, Plant journal, 12(6), 1997, pp. 1329-1338
Citations number
33
Language
INGLESE
art.tipo
Article
Journal title
ISSN journal
0960-7412
Volume
12
Issue
6
Year of publication
1997
Pages
1329 - 1338
Database
ISI
SICI code
0960-7412(1997)12:6<1329:GARFEG>2.0.ZU;2-Y
Abstract
The gibberellin (GA) biosynthesis mutants Ih-1 and Ih-2 have been used to examine the physiological role of GAs in pea seed development. The LH protein is required for the three-step oxidation of ent-kaurene to ent-kaurenoic acid early in the GA biosynthesis pathway. The allele-s pecific interaction of Ih-1 and Ih-2 with chemical inhibitors of these three steps suggests that LH encodes the multifunctional GA biosynthe sis enzyme ent-kaurene oxidase. Unlike the Ih-2 mutation which reduces seed weight and decreases seed survival by similar to 50% compared wi th wild-type plants, the Ih-1 allele has a transient effect on embryo and seed growth and only slightly increases seed abortion. These seed phenotypes parallel the effects of the two mutant alleles on GA levels in young seeds. Detailed examination of the growth of Ih-1 seeds reve als homeostatic regulation of GA-promoted embryo and seed growth. Alth ough GA-deficient seeds grow more slowly than WT seeds, decreased assi milate availability to the developing seeds is not the primary reason for the altered seed development. Instead, GAs act to promote some pro cess(es) required for embryo and seed growth and only indirectly influ ence the distribution of assimilates. How GA deficiency causes seed ab ortion is not known but it may simply be a consequence of reduced seed or embryo growth rate. These results demonstrate that even relatively small changes in the levels of GAs in young seeds can alter seed deve lopment and suggest that the available GA-related mutants may represen t only a subset of all possible mutants with reduced GA levels or GA s ignalling.