4.3.3 C. japonica seem to have a greater capacity for
oxidative stress
We detected the remarkable expansion or positive selection of HSPgenes (including HSP70 and HSP90 ), which probably encode
prototypical chaperonin to prevent the accumulation of unfolding
proteins and/or assist in the refolding or degradation of denatured
proteins (Haslbeck et al., 2005; Beck et al., 2009). The ZNF gene
family was also enriched in the C. japonica genome. Zinc finger
proteins are the most abundant protein in eukaryotes and have a wide
range of structures and functions (Laity et al., 2011). Interestingly,
the positive selection or expansion of RING-type zinc finger proteins
occurred in C. japonica . As a zinc finger protein widely found in
plants and animals, RING-type zinc finger protein confers a strong
drought tolerance in Arabidopsis thaliana (Moon et al., 2010),
because RING-type zinc finger protein can regulate the
ubiquitin–proteasome system to degrade misfolded proteins and thus
improve the defense of an organism against external environmental stress
(Ryota et al., 2002).
In conclusion, C. japonica ’s metabolism, oxygen supply, and
antioxidative stress abilities may help this species to survive longer
in drought environments. Due to the high desiccation-tolerance
capability of C. japonica , this information will be valuable in
the transportation and farming strategies.