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Triticeae Genomics and Genetics 2012, Vol.3, No.1, 1
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5
Figure 4 Secondary structure of DHN6 proteins in the samples
and hull-less barley
Note: Horizontal axis indicates amino acid sites, Blue indicates
alpha helix; Six-rowed barley (BZ-12), Four-rowed barley (BZ-16),
Two-rowed barley (BZ-26), Hull-less barley (AF043091)
2 Discussion
In general, the conserved amino acid mutations were
usually determined by the conserved nucleotides.
Namely, the slower evolutionary speed was frequently
observed in the higher bias base of the species
(Tamura, 1992; Sun et al., 2008). In this study,
analysis of amino acid mutations of DHN6 indicated
that sequence similarity was consistent to the conserved
nucleotide sites in barley (Table 1). Moreover, we
found that higher conserved nucleotide sites appeared
in the first site of genetic sites of
Dhn
6 gene. In fact,
due to the environmental choice pressure, changeable
replacement sites were determined by bias base of
genetic codes. The characteristics of conserved sites
and bias base of genetic codes showed that higher
ratio of replacement/transversion could take place in
Dhn
6 gene. It was accordingly deduced that DHNs
would be played an important role in evolutionary
process of plants suffered from water deficit.
DHNs might act as water attractants in cells with low
water potential, having a role in osmotic potential
regulation based on the characters of amino acid
sequences (Compbell and Close 1997; Porcel et al.,
2005). In our tests, none of contents of Gly, molecular
weight, instability index (Table 2), and secondary
Figure 5 Phylogenetic tree analysis of amino acid sequences in
DHN6
Note:
Cornus sericea
(AAL83427),
Hippophae rhamnoides
ssp.
sinensis
(AAP94627),
Brassica napus
(AAQ74768),
Coffea
canephora
(ABC55671),
Panax ginseng
(ABF48479),
Picea
abies
(ABU89751),
Zea mays
(ACG48456),
Hordeum vulgare
ssp.
vulgare
(AF043091),
Aegilops umbellulata
(AM180925),
Nicotiana tabacum
(BAD13498),
Daucus carota
(BAD86644) ,
Six-rowed barley (BZ-12), Four-rowed barley (BZ-16),
Two-rowed barley (BZ-26),
Prunus persica
(CAC00637),
Helianthus annuus
(CAC20238),
Tithonia rotundifolia
(CAC80717),
Pinus sylvestris
(CAD54622),
Betula pubescens
(CAD87733),
Fagus sylvatica
(CAE54590),
Cleistogenes
songorica
(FJ972827),
Hordeum vulgare
ssp.
spontaneum
(GU216698),
Oryza sativa
(NM001074374),
Triticum turgidum
ssp.
Durum
(X78431)
structure (Table 3) was associated with hydropathicity
index in the deduced protein of DHN6. It was a
possible conclusion that hydropathicity capacity of
DHNs was attributed to the advanced structures of
protein. Reports indicated DHNs could counteract the
irreversible damaging effects of increasing ionic
strength in the cytosol during desiccation by
sequestration of ions in plants under water stress
(Close, 1997; Danyluk et al., 1998). In recent