Reference "Analysis of transcripts that are differentially expressed in three sectors of the rice root system under water deficit"

Reference ID

26313

Title

Analysis of transcripts that are differentially expressed in three sectors of the rice root system under water deficit

Source

Mol Genet Genomics, 2004, vol. 272, pp. 433-442

Authors (6)

Yang-L	Zheng-B
Mao-C	Qi-X
Liu-F	Wu-P

Abstract

Short periods of water deprivation can stimulate the growth of seminal and
lateral roots in rice, and inhibit the emergence of adventitious roots.
Identification of genes in the different tissues that respond to a water deficit
may help us to understand the mechanism underlying root growth under conditions
when water is scarce. cDNA-amplified fragment length polymorphism (AFLP)
analysis was used to profile gene expression upon imposition of water deficit in
three types of root tissue from the upland rice variety Azucena: seminal root
tips, lateral root zones and adventitious root primordial zones. In all, 121
unique transcript-derived fragments (TDFs) were cloned, and Northern analysis
was carried out for 30 TDFs to confirm their expression patterns. Sixty-six TDFs
were differentially expressed in all three root samples. Four (AC2, D6, L22 and
T23) were up-regulated by water deficit in seminal root tips and lateral root
zones, and down-regulated in adventitious root primordial zones, an expression
pattern which reflects the phenotypic changes observed in the different root
sectors. In contrast, T17 and T37 showed the opposite expression pattern in
Azucena: up-regulation in adventitious roots and repression in the other two
zones. Functions could be assigned to five of these six TDFs on the basis of
homology: they encode an expansin (T37), a fruit-ripening protein similar to ASR
(T23), submergence-induced protein 2A (T17), a dehydrin (D6) and a 9- cis -
epoxycarotenoid dioxygenase1 (L22), respectively. AC2 did not show a significant
match to any known gene. Northern analysis showed that these six clones
exhibited expression patterns that differed between the two cultivars tested
(Azucena and the lowland variety IR1552) with respect to regulation by water
limitation. Furthermore, T17, T37, D6 and T23 mapped within intervals known to
contain QTLs (quantitative trait loci) for root growth in rice under water
deficit. These genes may regulate or co-regulate the growth and development of
the three root zones in a tissue-specific manner, and may play a role in the
processes that underlie the early changes in root architecture under conditions
of water deprivation.