Agriculture Reference
In-Depth Information
Fig. 16.2
Strategies to develop crops with reduced arsenic contents:
1
Overall reduction in arse-
nic load can be promoted through lowering arsenite uptake at the root-soil boundary and/or by
extrusion of arsenite through carriers and pumps by using genes from bacterial sources. Lowering
arsenate influx is more problematic because it negatively affects phosphate uptake
2
Localizing
arsenic concentrations in root tissues by root-specific upregulation of arsenate reductase, PC bio-
synthesis and vacuolar sequestration would safeguard cytoplasmic metabolism but might create
increased sulphur demand for the synthesis of thiol compounds. Thus, sulphur assimilation path-
ways will also need to be enhanced
3
Exclusion from shoot tissue and above ground edible parts
could be achieved by reducing the root-to-shoot translocation of arsenite by suppression of the
arsenite transporters
4
Volatilization of arsenic as trimethylarsine from leaf cells using bacterial
genes would reduce shoot arsenic levels. Target processes that need to be increased in capacity
are depicted using bold lines, those that need repression are shown using dotted lines. (Source:
Tripathi et al. TRENDS in Biotechnology-(65))
uptake keeping in view phytoremediation. In addition to agronomic practices that
deal with soil, water management and fertilization to minimize arsenic stress, crop
improvement practices can be grouped into classical/molecular breeding and ge-
netic engineering approaches (see Fig.
16.2
).
