College Papers

Discussion; This study provides a broad sense of


This study provides a
broad sense of vision  to explain that in
rice, root hair elongation by regulating auxin transport and biosynthesis in
specific zones of the roots is promoted by ABA. First, exogenous ABA treatment increases
root hairlength  in rice root tip and stops
ABA synthesis also inhibit  the root hair
elongation. Studies shows at low concentration (0.1 µM) of exogenous ABA can accelerate
root length , but high concentrations (>0.5 µM) of ABA inhibits root
elongation (Ghassemian et al.,2000;Rowe et al.,2016). 0.1 µM  of ABA stops root hair elongation, while 0.5
µM and 2 µM ABA promote rice root hair important function
reported is the role of ABA in phytohormones signaling . so  variable concentrations of  ABA shows the different levels and feedback.
Second,expression of transgenic lines overexpressed OsABIL2 or SAPK10,a main
factor in ABA signaling In rice  showed
that ABA-promoted root hair elongation depend on the PYR/PP2C/SnRK signals. The
insensitive ABA OsABIL2-OE line exhibits less root hair elongation, and the
ABA-enriched line SAPK10-OE showed prominent root hair elongation. Third, our
observation shows that auxin acts much 
alongwith of ABA signaling to promote root hair elongation, depending on
the ABA-regulated r auxin movement and local auxin biosynthesis. Previous
studies also assist our findings that ABA and auxin interact in roots (Rock and
Sun,2005;Xu et al.,2013). For example, ABA insulation encourage auxin transport
tips of roots  and increase  secretion  of proton for root growth mantainance under mild
water stress (Xu et al.,2013). Fourth, RNA-seq analysis and RHE screening
identified 35 genes that respond strongly to ABA and auxin and may also be
specifically expressed in root hair cells in the rice LRH zone. These genes may
have play vital  functions in root hair
growth in rice. The last few years research have revolutionized in root hair
enlonation in rice, but some research gaps still found, especially compared
with Arabidopsis, in which root hair development gene 138 have been detected.
While 8 genes that are involved in root hair development (Marzec et al.,2015).
provide Our recent  data and previous findings
suggested a model for the root hair elongation regulated by ABA in rice (Figure 7). ABA signaling promotes
auxin biosynthesis in the Tip and LRH regions, and further promote  the distribution of auxin via auxin transport
to assimilate auxin in the LRH region.

The high concentration
of IAA assisted downstream gene expression to enhance root hair elongation. In
the future, we plan to find the ABA signaling speific component which directly
regulate gene expression play role  in
auxin transport and biosynthesis. further, the zone-specific genes found in
this study provide a new platform and resource to further understand how ABA
regulates root hair elongation.More, the root hair region seems moving down
during ABA treatment.I analysed this might caused by local auxin biosynthesis .
According to our outcomes, ABA promotes auxin acropetal and basipetal transport
in rice root  tips and resulted  in local auxin accumulation. When ABA
concentration increased, auxin may accrue in the piece much close to rice root
tip, which lead to the move down of long root hair section.furthurmore, the repressed
root elongation by high concentration ABA may also play role in the long root
tips growth.