SUGAR AND METABOLIC-REGULATION OF GENES FOR SUCROSE METABOLISM - POTENTIAL INFLUENCE OF MAIZE SUCROSE SYNTHASE AND SOLUBLE INVERTASE RESPONSES ON CARBON PARTITIONING AND SUGAR SENSING
Ke. Koch et al., SUGAR AND METABOLIC-REGULATION OF GENES FOR SUCROSE METABOLISM - POTENTIAL INFLUENCE OF MAIZE SUCROSE SYNTHASE AND SOLUBLE INVERTASE RESPONSES ON CARBON PARTITIONING AND SUGAR SENSING, Journal of Experimental Botany, 47, 1996, pp. 1179-1185
Sugar responsiveness of genes for both paths of sucrose metabolism cou
ld provide a mechanism not only for transcriptional regulation of the
first step in the use of imported carbon, but also for altering signal
s to the sugar-sensing system. This hypothesis was examined by compari
son of (1) sugar regulation among maize genes for sucrose synthase and
invertase, (2) their contrasting patterns of tissue expression, and (
3) their influence on production of effecters for other sugar-responsi
ve genes. Cloning and characterization of the lvr1 and lvr2 invertase
genes of maize indicated that these genes belong to distinct subfamili
es of the maize soluble invertase gene family. In addition, maize inve
rtases can be grouped with the sucrose synthases (Sh1 and Sus1) on the
basis of shared patterns of differential sugar-responsiveness and tis
sue-specific expression. Extension of this comparison to include genes
for sucrose metabolism from other species revealed a more widespread
association between starvation-tolerant expression and restricted patt
erns of tissue distribution. Consideration of current models for plant
sugar-sensing systems and transport pathways suggested that the site
and mechanism of sucrose cleavage in the cell could affect the magnitu
de and type of signal generated.