Molecular Plant Breeding 2015, Vol.6, No.18, 1
-
8
1
Research Report
Open
Access
DNA Sequence Variation of Aquaporins Candidate Genes (
TIP
and
PIP2
) for
Drought Stress Response in Tunisian olive Cultivars (
Olea Europaea
L.).
Abdelhamid S.
1
, Yoon I.S.
2
, Byun M.O.k
2
1.Olive Tree Institute, Laboratory of Molecular Biology, Rue de l’Aéroport, B.P 1087, 3000-Sfax, Tunisia;
2.National Academy of Agricultural Science, Molecular Breeding Division, RDA, Jeonju, 560-500, Republic of Korea.
Corresponding
authors
email:
Molecular
Plant
Breeding,
2015,
Vol.6,
No.18
doi:
10.5376/mpb.2015.06.0018
Received:
22
Jun.,
2015
Accepted:
11
Aug.,
2015
Published:
10
Sep.,
2015
Koohdar © 2015
Abdelhamid et al.,
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License,
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Preferred
citation
for
this
article:
Abdelhamid S., Yoon I.S.,and Byun M.O.k., 2015,
DNA Sequence Variation of Aquaporins Candidate Genes (
TIP
and
PIP2
) For Drought Stress Response in
Tunisian olive Cultivars (
Olea Europaea
L.)., Interaction,
Molecular
Plant
Breeding,
6(18):
1
-
8 (doi:
Abstract
Aquaporins (AQPs) have been shown to be involved in drought stress response. It is widely known that drought may be
considered one of the most frequent environmental constraints in Tunisia. In particular, the arid and semi-arid areas are subjected to
high solar radiation and a high rate of evapo-transpiration. We describe the genetic diversity in
TIP
and
PIP2
genes in 15 Tunisian
olive cultivars.
Targeted-PCR amplification yielded polymorphisms giving in total 119 SNPs. Genetic variation at the nucleotide level was estimated
from nucleotide diversity and from the number of segregating sites (πTIP = 0.0024; πPIP 2= 0.0017; ϴTIP = 0.0020 and ϴPIP2 =
0.0013 respectively). The studied cultivars showed higher values of nucleotide diversity in synonymous sites as well as in
non-synonymous sites. Higher expected heterozygosity and higher observed homozygosity were found in
TIP
fragment gene than in
PIP2 gene. Each gene based-marker classified the cultivars under investigation into clear separated clusters but not according to their
environment range. Although, partial agreement was achieved with respect to cultivars relationships with
PIP2
gene data.
The results indicate that the SNP represents an efficient molecular marker system for the assessment of Tunisian olive genetic
diversity at studied aquaporin genes and, hence, the knowledge of genetic diversity of olive cultivars exposed to variable
environmental conditions to preserve this valuable tree species.
.
Keywords
Olea europaea
L; nucleotide diversity; Aquaporine; TIP, PIP2; SNP
1 Background
Olive (
Olea europaea
L.) is one of the most important
cultivated tree crop species in Mediterranean regions
(Rugini and Baldoni 2004). Tunisia is the most
important olive-growing country of the southern
Mediterranean region. Tunisian olive resources are
estimated over 70 million olive trees, grown on 1 680
000 ha. Olives are found in all the regions of Tunisia,
from North to South. Close to 90% of cultivated olive
acreage is located in the central and southern regions.
Tunisian areas are arid and semi-arid regions which
indicate remarkable differences in the rates of
precipitation which cause water stress. This region is
characterized by a high rate of evapo-transpiration,
high solar radiation and an irregular rainfall that does
not surpass 200 mm per year. Periods with water
restrictions as a result of climatic changes are frequent
and problems of drought (due to non-irrigation) can
appear. As olive cultivars may exhibit a different level
of drought tolerance, the knowledge and the selection
of the most drought-tolerant cultivars acquires
relevance. The molecular basis of dehydration
tolerance in plant is extremely complex and a wide
variety of expressional candidate genes and metabolic
pathways has been suggested during drought stress
(Umezawa et al. 2006; Syed Sarfraz et al. 2011).
Consequently, much effort has been directed towards a
better understanding of the genetic basis of the
adaptive response of plants to drought, and how best
to apply this knowledge to molecular plant breeding.
The physiological mechanisms and the genetic basis
of drought stress tolerance in olive tree are scarce. For
these reasons, advancement in the current understanding of
the responses of olive trees undergo severe stress
through seasonal drought has become a major target
for research in Tunisia. In this respect, the selection of
cultivars with enhanced water use efficiencies and
drought tolerance is one of the most effective
