R. Keller et al., Reduced inositol content and altered morphology in transgenic potato plants inhibited for 1D-myo-inositol 3-phosphate synthase, PLANT J, 16(4), 1998, pp. 403-410
Myo-inositol is a precursor of many plant metabolites, including polyols, c
ell wall components and phosphoinositides. The first committed step in the
de novo myo-inositol synthetic pathway is catalysed by the enzyme 1D-myo-in
ositol 3-phosphate synthase (MIPS; EC 5.5.1.4), which converts D-glucose 6-
phosphate to 1D-myo-inositol 3-phosphate. Suppression of MIPS activity by a
n antisense RNA approach in transgenic potato (Solanum tuberosum L.) plants
to below 20% of the wild-type level in leaves resulted in strongly reduced
levels of inositol, galactinol and raffinose (approximately 7%, 5% and 12%
, respectively, of wild-type values). In contrast, increases were observed
for concentrations of hexose phosphates (up to 1.7-fold), sucrose (twofold)
and starch (two- to fourfold). Transgenic plants exhibited reduced apical
dominance, altered leaf morphology, precocious leaf senescence and a decrea
se in overall tuber yield. These observations indicate a crucial role for m
yo-inositol in plant physiology and development.