Zea mays, a water use efficient crop with sugar-rich tissues,
has a very good potential as an alternative feedstock for
ethanol production. Sucrose represents one of the major
carbohydrate transport forms of photosynthetically assimilated
carbon in plants. Hence, it is crucial to understand the
molecular mechanism of sucrose transportation in Z. mays.
In this study, we identified four sucrose transporter genes
(ZmSUT1, ZmSUT2, ZmSUT4 and ZmSUT5) through extensive
search at maize genome database and NCBI database
with rice OsSUTs as query sequence. Spatial expression studies
using reverse transcription polymerase chain reaction
(PCR) showed that ZmSUT1 and ZmSUT2 are abundant in
leaves than in roots while ZmSUT4 did not show any alteration
in expression level. ZmSUT5 transcript level was higher
in roots. Phosphate starvation had led to an increase in the
level of ZmSUT1 and ZmSUT2 transcripts without affecting
the expression of ZmSUT4. Increase in sucrose level has
been observed as an early response to phosphate starvation in
many plants. Thus, this study demonstrates that ZmSUT1 and
ZmSUT2 being upregulated in response to Pi stress, may be
involved in the transport of sucrose in maize while ZmSUT4
remains a house-keeping gene.

http://link.springer.com/article/10.1007%2Fs12041-015-0491-3