Agriculture Reference
In-Depth Information
Fig. 6.1 Schematic diagram of boron transport from soil to xylem via root tissue. In sufficient B
condition NIP5;1 imports B from the soil to epidermal, cortex and endodermal cells, and BOR
1 exports B from stelar cell (xylem loading)
After loading in the xylem, B is transported to the shoot through the transpiration
stream (Wimmer and Eichert
2013
; Bogiani et al.
2014
). Transport of B through
phloem was also reported, and such transport differs between species (Brown and
Hu
1996
; Brown and Shelp
1997
; Ganie et al.
2013
). In certain plants, B is
transported and translocated to reproductive and vegetative tissue via the phloem
(Matoh and Ochiai
2005
). It is also suggested that there is a formation of a boron-
diol complex involving a sugar alcohol, which acts as the transport molecule
(Brown and Hu
1996
; Hu et al.
1997
). Transgenic tobacco and rice with enhanced
sorbitol production had a higher ability to transport B through the phloem towards
the plant shoot (Brown et al.
1999
; Bellaloui et al.
2003
). Plants that produce sugar
alcohols like sorbitol and trehalose, have the ability of B transport via the phloem,
whereas plants without any production of sugar alcohols have no such transport
system (Stangoulis et al.
2001
; Takano et al.
2001
; Matoh and Ochiai
2005
).
Role of Boron in Plant Functioning
Since the beginning of twentieth century, B has been considered to be an important
micronutrient for plant growth, but there are very few records regarding its actual
biochemical role. Deficiency of B is common all over the world, which has an
