Agriculture Reference
In-Depth Information
function of detoxifying ROS, including singlet oxygen. We know that drought
resistance was reported to be controlled by histidine kinase (Nongpiur et al.,
2012; Xoconostle-Cazares et al., 2011). Histidine kinase activities showed
circadian rhythm in cyanobacteria (Iwasaki et al., 2000) and rates of
photosynthesis showed circadian rhythm (Hennessey and Field, 1991), which
are greatly affected by ROS including singlet oxygen.
We demonstrated that the major component of circadian rhythm was ROS,
including singlet oxygen by use of
Neurospora crassa
(Yoshida et al., 2008;
Yoshida et al., 2011). Small histidine kinases, NDPK1, (transit peptide-
)NDPK2 and (pre-sequence-)NDPK3 were demonstrated directly to concern to
the detoxification processes of singlet oxygen and H
2
O
2
in
Arabidopsis
thaliana
,
N. crassa
and
P. sativum
cv. „Alaska‟ (Fukamatsu et al., 2003;
Yoshida et al., 2006; Wang et al., 2007; Haque et al., 2010). The
R3-1
mutant
showed retardation of flower bud formation of 35 days, and also showed 2-
fold higher phosphorylation and enzymatic activities in small histidine kinase
of transit peptide-NDPK2 Ile12Leu Lys205Glu than those of the wild-type.
These high activities of phosphorylation of transit peptide-NDPK2 Ile12Leu
Lys205Glu will result in the retardation of effective concentration of ROS,
including sinlet oxygen, conferring the change of condition to initiate flower
bud formation.
The
R3-1
mutant showed a high temperature-resistant phenotype. At high
temperatures such as 35˚C the rate of respiration will increase. In the case of
wild-type, the increase in temperature under light will cause rising up of
singlet oxygen emission and increase in pore formation in plasma membrane
and vacuolar and microsomal membranes at the unsaturated fatty acids
permitting the rising up of [Ca
2+
]cyt. The condition will result in a higher
respiration in mitochondria and results in the death of seedlings. However, in
the case of the
R3-1
mutant, a high activity of transit peptide-NDPK2 Ile12Leu
Lys205Glu, which functions in the detoxyfication of singlet oxygen, will
contribute to the reduction in the reactions with unsaturated fatty acids in the
membranes triggered by the singlet oxygen (Haque et al., 2010), thus,
maintaining higher survival rates at high temperatures than that of the wild-
type.
A
CKNOWLEDGMENT
We are grateful to Winslow R. Briggs for his continuous encouragement
throughout this study. We thank Nissan Motor, Co., Ltd. for assisting in the
