New Insights into Desiccation-Associated Gene Regulation by Lilium longiflorum ASR during Pollen Maturation and in Transgenic Arabidopsis - International Review of Cell and Molecular Biology - page 72

SlASR1 overexpression increases salt tolerance in tobacco and influences
glucose metabolism in potato ( Frankel et al., 2007 ; Kalifa et al., 2004b ).
The overexpression of tomato ASR1 in Arabidopsis produces an abscisic acid-
insensitive 4 (abi4) phenotype, wherein seed germination is not sensitive to
inhibition by ABA, glucose, and NaCl ( Shkolnik and Bar-Zvi, 2008 ).
4.4. Response to Glucose Stress
Glucose, one of the hydrolytic products of sucrose, is a key metabolic signal
that controls the expression of many genes via diverse mechanisms, such as
transcription, translation, and modification of mRNA and protein stability
( Li et al., 2006 ; Matiolli et al., 2011 ; Price et al., 2004 ; Rolland et al., 2006 ).
Despite extensive studies on the involvement of ABA in glucose sensing
and signaling, information regarding the interactions between glucose and
ABA signaling pathways and their integration with developmental pro-
grams is still far less complete. Thus far, only a number of regulators, such
as MYBs, SUSIBA2, and MBF1c, which are required for a sugar have been
identified ( Abe et al., 2003 ; Lu et al., 2002 ; Matiolli et al., 2011 ; Sun et al.,
2005 ). Additional regulators and signaling components are expected to be
found to unravel the regulatory networks that transmit sugar signals. ASR, a
newly identified regulator, is reportedly involved in sugar and ABA signal-
ing ( Cakir et al., 2003 ; Saumonneau et al., 2012 ). Considering ABA/sugar
interactions have been reported for a multitude of processes, a thorough
understanding of the underlying molecular mechanisms of sugar and ABA
interactions is important.
Wild-type Arabidopsis (Col) plants under 3% glucose stress for 12 h
or under drought stress conditions were analyzed using a microarray
in parallel with unstressed wild-type Arabidopsis (Col) plants. Only the
genes with high significance ( P < 0.05) and at least twofold changes
in expression were selected. Thus, 1126 and 819 genes with expression
ratios (3% glucose/unstressed; drought/unstressed) greater than twofold
induction were identified as glucose- and drought-inducible, respectively.
Similarly, 757 and 709 genes with expression ratios greater than twofold
repression were identified as glucose- and drought-repressive, respec-
tively. Our analysis is consistent with other microarray analysis showing
that glucose treatment regulates a broad range of gene functions ( Price
et al., 2004 ; Thimm et al., 2004 ). In this study, 293 glucose-upregulated,
166 drought-upregulated, 144 glucose-downregulated, and 116 drought-
downregulated genes with induction or repression greater than sixfold
were used for comparison.