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© 2016 The Japan Mendel Society Cytologia 81(1): 103–110
The Effects of Aloe vera L. Leaf Extract on Some
Physiological and Cytogenetical Parameters in
Allium cepa L. Seeds Germinated under Salt Stress
Dilek Çavuşoğlu*, Selma Tabur and Kürşat Çavuşoğlu
Department of Biology, Faculty of Arts and Science,
Süleyman Demirel University, Isparta 32260, Turkey
Received May 10, 2015; accepted December 19, 2015
Summary The present study was performed to evaluate the role of Aloe vera L. leaf extract (AvLE) on some
physiological and cytogenetical parameters of Allium cepa L. seeds exposed to salinity. The radicle length of the
seeds germinated in the medium with AvLE alone increased as compared with ones of the control seeds germi-
nated in distilled water medium, while their radicle number and fresh weight reduced according to the control.
In addition, the germination percentage of the mentioned seeds statistically was the same as the control seeds.
Furthermore, the seeds germinated in the media containing 0.1 mg/L AvLE alone showed a significant increase
of mitotic index, although they exhibited a higher number of chromosomal aberrations and micronucleus (MN)
formation as compared with the seeds germinated in control conditions. On the other hand, salt stress consider-
ably inhibited the seed germination and seedling growth of A. cepa. Moreover, salinity markedly decreased the
mitotic index in root tip meristems of the seeds and increased the number of chromosomal aberrations. The nega-
tive effect of salt on the seed germination, seedling growth, mitotic activity and MN formation was alleviated in
dramatically varying degrees by AvLE application. In contrast, the detrimental effects of salt on the chromosomal
aberrations greatly increased with this treatment. Consequently, we reported that the application of AvLE alone
induced chromosomal aberrations and MN formation, which are an indicator of genotoxicity, and had cytotoxic
activity in normal conditions. However, the frequency of MN is greatly reduced in root tip cells of the seeds ger-
minated in the medium containing 0.1 mg/L AvLE +0.15 M NaCl.
Key words Aloe vera L., Chromosomal aberration, Mitotic activity, Salinity, Seed germination, Seedling
growth.
Soil salinization is a global issue that affects plant
growth and limits agricultural production. Approximate-
ly 20% of the worlds cultivated land, which accounts for
over 6% of the worlds total area, is threatened by salin-
ity. In Turkey, 500000 hectares of irrigation areas are
affected by salinization (FAO 2015). Salt-affected soil in
Turkey is primarily located in the Central South, Central
North and Mediterranean regions (Haktanır et al. 2012).
The salt-affected soils contain excess salts, which affect
plants by decreasing the osmotic potential of the soil so-
lution (osmotic stress), interfering with normal nutrient
uptake, inducing ionic toxicity, and associating nutrient
imbalances (Dudley 1992, An et al. 2003). Processes
such as seed germination, seedling growth and vigour,
vegetative growth, flowering and fruit set are adversely
affected by high salt concentrations, ultimately causing
diminished economic yield and also quality of produc-
tion (Sairam and Tyagi 2004).
Salt adversely affects plant growth and development,
hindering seed germination (Al-Karaki 2001), seedling
growth (Ashraf et al. 2002, Çavuşoğlu et al. 2013),
enzyme activity (Dash and Panda 2001), DNA, RNA
and protein synthesis (Tal 1977) and mitosis (Tabur
and Demir 2009, 2010a, b). The most efficient way to
minimize the detrimental effects of salinity on plant
breeding is the development of varieties with high salin-
ity tolerance. Hence, researchers have used various plant
growth regulators and vitamins to reduce or eradicate
negative effects of salinity on seed germination (Duan
et al. 2008, Emam and Helal 2008), seedling growth
(Çavuşoğlu et al. 2013, 2014) and mitotic activity (Tabur
and Demir 2009, 2010a, b). In addition, most researchers
agree that the best way to proceed with breeding would
be via pyramiding different useful physiological traits.
However, in spite of substantial efforts, the outcome
is still disappointingly poor due to the physiological
and genetic complexity of this trait, the lack of reliable
screening tools, and most importantly, the lack of a
comprehensive understanding of the mechanisms behind
salinity tolerance (Zhu et al. 2015).
Aloe vera L. (Av) is a perennial member of the Lili-
aceae family with over 300 species (Ni et al. 2004). The
plant has triangular, fleshy leaves with serrated edges,
* Corresponding author, e-mail: cavusoglu.dilek@gmail.com
DOI: 10.1508/cytologia.81.103
104 D. Çavuşoğlu et al. Cytologia 81(1)
yellow tubular flowers and fruits that contain numer-
ous seeds (Surjushe et al. 2008). The leaves have a
thick epidermis covered with a cuticle surrounding the
mesophyll, which can be differentiated into chloren-
chyma cells and thinner walled cells that form the pa-
renchyma. The parenchyma cells contain a transparent
mucilaginous jelly which is referred to as Aloe vera gel
(Ramachandra and Srinivasa 2008). The flowers prefer
light, and the plant requires well-drained soil and can
grow in nutritionally poor soil conditions (Mukherjee
and Roychowdhury 2008). It is highly appreciated due to
its short growth period and high economic value among
all the Aloe species and is used in pharmaceuticals, folk
medicine, healthcare, cosmetic and food products (Ab-
dollahi et al. 2011).
A. vera leaf extract (AvLE) is a very excellent source
of plant nutrients, such as calcium, iron, magnesium,
potassium, phosphorous and zinc (Dagne et al. 2000);
enzymes, such as amylase, catalase, lipase, oxidase and
superoxide dismutase (Vazquez et al. 1996); amino ac-
ids, such as alanine, glycine, leucine and proline (Reyn-
olds and Dweck 1999); vitamins. such as B-complex,
C,β-carotene and α-tocopherol (Vinson et al. 2005);
and other organic compounds, such as triglicerides, tri-
terpenoid, gibberellin, potassium sorbate and salicylic
acid (Hamman 2008). AvLE possesses various biologi-
cal and physiological attributes: healing ability of skin
burns and cutaneous injuries, prophylactic effect against
radiation leucopenia, anti-ulcer, inhibitory action against
some bacteria and fungi, inflammation-inhibiting effect,
inhabitation of the prostaglandin synthesis by anthraqui-
none-type compounds and inhabitation of the AIDS vi-
rus by acemannan (Hernandez-Cruz et al. 2002, Ni and
Tizard 2004, Talmadge et al. 2004).
Allium L. is the largest genus of petaloid monocotyle-
dons, containing hundreds of species naturally distrib-
uted in temperate climates of the northern hemisphere
(Koçyiğit and Özhatay 2010). The Allium test has im-
portant advantages (Rank 2003, Kuras et al. 2006) and
has been used for many years in investigating physical
and chemical mutagenesis, pollutant agents, plant ex-
tracts, and similar active materials cytogenetic effects in
mitotic cell division. It is stated that the Allium test ex-
hibits similar results with mammalian test systems (El-
Shabbaby et al. 2003, Teixera et al. 2003). The present
study was designed to examine the influences of AvLE
in the reducing of detrimental effects of salt stress on
the seed germination, seedling growth, mitotic activity,
micronucleus formation and chromosomal aberrations of
Allium cepa L., commonly known as onion.
Materials and methods
Seed, salt and AvLE concentrations
In this study, Allium cepa L. seeds were used. The salt
(NaCl) concentration used was 0.15 M. The AvLE con-
centration used in the experiments was 0.1 mg/L. AvLE
(60 capsules of 3000 mg) was obtained from Herbal
Farma Medical Natural Products, Bursa, Turkey. AvLE
and NaCl concentrations were determined in a prelimi-
nary investigation conducted by us.
Germination of the seeds
Germination experiments were carried out at a con-
stant temperature (20C) in the dark in an incubator.
Healthy and approximately equal-sized A. cepa seeds
were selected. The seeds were sterilized with 2.5% sodi-
um hypochloride solution for 10 min and washed for 24 h
in ultra-distilled water (Türkmen et al. 2009). Twenty
seeds from each treatment group were placed into plastic
containers. The seeds were divided into four groups:
- Group I (control) was treated with distilled water for
seven consecutive days.
- Group II was treated with 0.15 M NaCl alone for
seven consecutive days.
- Group III was treated with a 0.1 mg/L dose of AvLE
for seven consecutive days.
- Group IV was treated with a 0.1 mg/L dose of AvLE
+0.15 M NaCl for seven consecutive days.
The plastic containers were placed into an incubator
for germination. It was assumed that the radicle should
be 10 mm long for germination to take place. At the end
of the seventh day, after determination of the final ger-
mination percentages, radicle numbers were also record-
ed, and radicle lengths of the seedlings were measured
in mm, and in addition, the fresh weights in g/seedling
were determined. All experiments were repeated three
times.
Cytogenetical and statistical analysis
Root tips of A. cepa seeds germinated in the treatment
groups mentioned above were excised for cytogenetic
analysis when they reached 1–1.5 cm in length. Next,
they were pretreated with saturated para-dichloroben-
zene for 4 h, fixed with Carnoy (ethanol : acetic acid,
3 : 1) overnight at room temperature and stored at 4C
in 70% ethanol until required. Then, the root tips were
hydrolysed in 1 N HCl at 60C for 15 min, stained with
Feulgen for 1–1.5 h, smashed in a drop of 45% acetic
acid and squashed (Sharma and Gupta 1982). After 24 h,
microscopic slides were made permanent by mounting
in balsame. The mitotic phases and mitotic aberra-
tions were photographed (1000) with a digital camera
(Olympus C-5060) mounted on an Olympus CX41 mi-
croscope.
Mitotic index, i.e., percentage of dividing cells scored,
was evaluated by analysing at least 30000 cells per treat-
ment (approx. 10000 per slide). Chromosomal abnor-
malities were calculated for each treatment groups as
the percentage of 2000 dividing cells counted. Statistical
evaluation concerning all parameters was realized by
using the SPSS program according to Duncans mul-
2016 Physiological and Cytogenetical Effects of AvLE on Salinity 105
tiple range test at a level of significance p≤0.05 (Duncan
1955).
Micronucleus (MN) analysis
Slides were examined at 1000 magnification using a
binocular light microscope (Olympus CX41). Micronu-
clei were evaluated in those cells that complete nuclear
division following exposure to the test groups. At least
2000 micronucleated cells per slides were scored to
assess the frequency of micronuclei and a score was
obtained for slides from each treatment groups. For the
scoring of MN, the following criteria were adopted from
Fenech (2000): (i) the number of MN in at least 1000
cells should be scored, (ii) the diameter of MN should
be at most 1/3rd of the main nucleus, (iii) MN sould be
non-refractile and they must therefore be readily dis-
tinguished from artifacts such as staining particles, (iv)
MN should not be linked or connected to the main nu-
cleus, (v) MN may touch but should not overlap the main
nucleus and the micronuclear boundary should be dis-
tinguishable from the nuclear boundary, (vi) MN should
be the same staining intensity as the main nucleus, but
occasionally, staining may be more intense.
Results
Effects of AvLE on seed germination and seedling
growth
As shown in Table 1, the radicle length of group III
seeds treated with AvLE significantly increased in com-
parison with ones of group I (control) seeds germinated
in distilled water medium. However, their radicle num-
ber and fresh weight partly reduced according to group
I seeds. In addition, the germination percentage of group
III seeds statistically showed the same value as group I
seeds (Table 1).
Salt exhibited an inhibitive effect on all examinated
growth parameters. For example, group I (control) seeds
germinated in distilled water medium displayed 100%
germination on the seventh day, while this value became
10% in group II seeds germinated in 0.15 M salinity. In
other words, salt prevented 90% the germination of A.
cepa seeds. AvLE application markedly alleviated the
inhibitive effect of salt stress on the seed germination.
Group IV seeds treated with AvLE demonstrated 100%
germination in the mentioned salt level. Finally, A. cepa
seeds showed a performance such as germinated under
normal conditions, not in saline conditions. AvLE also
continued its success on seedling growth parameters
such as the radicle length, radicle number and fresh
weight. The radicle length, radicle number and fresh
weight of group II seedlings grown in 0.15 M salinity
were 10.3 mm, 11.5 and 1.1 g, respectively, while these
values became 27.8 mm, 17.5 and 9.0 g in group IV
seedlings treated with AvLE (Table 1).
Effects of AvLE on mitotic index, micronucleus forma-
tion and chromosomal aberrations
The mitotic index in root tip meristems of A. cepa
germinated in the media containing 0.15 M NaCl de-
creased 66% as compared with group I seeds (in
distilled water, control), and the frequency of mitotic
aberrations more than doubled. For instance, while the
mitotic index and chromosomal aberrations were 5.6 and
11.9 at control (group I) respectively, they were 3.7 and
25.5 at 0.15 M NaCl concentration. The mitotic index
of group III seeds germinated in the media with AvLE
alone remarkably increased according to group I sam-
Table 1. Effect of AvLE on some growth parameters of Allium cepa L.
Groups
Growth parameters
Germination percentage (%) Radicle length (mm) Radicle number Fresh weight (g/seedling)
Group I *1000.0b73.71.5c40.70.6d11.41.1c
Group II 100.0a10.30.2a11.5 1.8a1.10.2a
Group III 1000.0b81.21.1d36.00.6c10.00.5b
Group IV 1000.0b27.8 2.5b17.5 1.2b9.00.3b
* The difference between values with the same letter in each column is not significant at the level 0.05 (SD). Group I (control) was treated
with distilled water; Group II was treated with 0.15 M NaCl alone; Group III was treated with a 0.1 mg/L dose of AvLE; Group IV was treated
with a 0.1 mg/L dose of AvLE +0.15 M NaCl.
Table 2. Effect of AvLE on some cytogenetic parameters of Allium cepa L.
Groups Mitotic index (%) Micronucleus frequency (%) Chromosome aberration (%)
Group I *5.61.2a0.00.0a11.91.6a
Group II 3.7 0.6a0.05 0.0a25.5 0.6b
Group III 16.50.5b2.560.4c57.61.7c
Group IV 24.61.4c1.03 0.1b68.81.5d
* The difference between values with the same letter in each column is not significant at the level 0.05 (SD). Group I (control) was treated
with distilled water; Group II was treated with 0.15 M NaCl alone; Group III was treated with a 0.1 mg/L dose of AvLE; Group IV was treated
with a 0.1 mg/L dose of AvLE +0.15 M NaCl.
106 D. Çavuşoğlu et al. Cytologia 81(1)
ples, whereas this treatment caused an approximately
five-fold increase of chromosomal aberrations. However,
although not successful in alleviating the detrimental
effect of salinity on the chromosomal aberrations,
AvLE+NaCl application (Group IV) showed a perfectly
good performance in ameliorating the negative effects
of salinity on the mitotic activity. Statistically, all values
mentioned here are substantially significant (Table 2).
Fig. 1. Chromosomal aberrations encountered in mitotic phases of Allium cepa root tip cells. (a, b) micronuclei, (c) disorderly
prophase, (d, e) uncoiling chromosomes, (f) chromosomes encircled, (g, h) sticky chromosomes, (i) disorderly anaphase,
(j–l) bridges in anaphase, (m, n) alignment anaphase, (o) vagrant chromosomes in anaphase, (p) fault polarization in ana-
phase, (r) bridges in telophase, (s) fault polarization in telophase. Scale bar =10 µm.
2016 Physiological and Cytogenetical Effects of AvLE on Salinity 107
In addition, during microscopic examination of A.
cepa root tip meristem cells, it was observed that MN
formation was not in control samples, but significantly
increased in groups II, III and IV samples. The fre-
quency of MN was the highest in meristem cells of seeds
treated with AvLE alone. The mitotic index, micro-
nucleus frequency and aberration scores obtained from
the control and treated seeds are summarized in Table 2.
Also, many chromosomal aberrations were observed,
such as micronucleus (Fig. 1a, b), disrderly prophase
(Fig. 1c), uncoiling chromosomes (Fig. 1d, e), chromo-
somes encircled (Fig. 1f), sticky chromosomes (Fig. 1g,
h), disorderly anaphase (Fig. 1i), anaphase bridges (Fig.
1j–l), alignment anaphase (Fig. 1m, n), vagrant chromo-
some in anaphase (Fig. 1o), fault polarizations in ana-
phase (Fig. 1p), bridges in telophase (Fig. 1r) and fault
polarizations in telophase (Fig. 1s). The most prominent
aberrations observed in all applications were the bridges
in anaphase and fault polarizations in telophase (Fig.
1j–l, s). The minimal common aberrations were vagrant
chromosomes in anaphase (Fig. 1o) and bridges in telo-
phase (Fig. 1r).
Discussion
Physiological and cytogenetical effects of exogenous
AvLE in normal conditions
Unless there are general stress conditions, there is no
need to exogenously add any plant growth regulators in
the germination process. Exogenous growth regulator
application may cause a positive or negative effect on the
seed germination and seedling growth under non-stress
conditions (Çavuşoğlu et al. 2007, 2013). However,
there are few studies on the effects of AvLE on the seed
germination and seedling growth under normal condi-
tions. Thus, we also wanted to test the effects of AvLE
application on the seed germination and seedling growth
in non-stress conditions. Our results showed that the
radicle length of the seeds germinated in the medium
with AvLE alone significantly increased in comparison
with ones of the control seeds germinated in distilled
water medium, while their radicle number and fresh
weight partly reduced according to the control. In addi-
tion, the germination percentage of the mentioned seeds
statistically exhibited the same value as the control seeds
(Table 1). Imran et al. (2014) reported that the final ger-
mination percentage, radicle length and fresh weight of
lentil (Lens culinaris Medik) seeds germinated in differ-
ent concentrations (from 1 up to 5%) of AvLE increased
according to ones of the control seeds germinated in
distilled water medium. Furthermore, İlbaş et al. (2012)
reported that all tested concentrations (2, 5, 10, 20 and
40%) of AvLE caused a significant inhibition on the
radicle length of A. cepa seeds germinated under normal
conditions. Although some of these results were consis-
tent with our findings, some were not consistent with
our findings. It can be said that AvLE showed different
effects on the seed germination and seedling growth
depending on the plant species and the concentrations
used.
Whats more, some growth regulators may particu-
larly cause mitotic irregularities, cell distortions and
chromosomal aberrations even without stress conditions
(Ünal et al. 2002, Tabur and Demir 2009, 2010a, b).
Although numerous researchers in recent years declared
that some commonly used plant extracts have significant
mutagenic action (Palanikumar et al. 2011, Fatemeh
and Khosro 2012, Eren and Özata 2014, Kalpana et al.
2014, Karaismailoğlu 2014, Siddiqui 2014), there are
limited studies relating to the effects of AvLE on the mi-
totic activity and chromosomal aberrations under normal
conditions (İlbaş et al. 2012, Alege and Ojomah 2014).
Therefore, we have investigated firstly whether AvLE is
affecting these parameters in normal conditions or not.
The results from data obtained in the present work indi-
cated that the mitotic index in root meristems of A. cepa
seeds exposed to AvLE application in normal conditions
(group III) was more than approximately three times
higher than those in group I (control) seeds germinated
in distilled water. That is, 0.1 mg/L AvLE application
showed a perfectly successful effect on the mitotic activ-
ity by accelerating cell division. However, the frequency
of chromosomal aberrations increased up to five-fold
with this dose of AvLE application. In this case, we can
say that some aberrations may result from this stimula-
tor (Table 2). Also, the high numbers of micronucleus
frequency in root meristems of seeds treated with alone
AvLE supports our opinion. As is known, the MN test
is commonly used to determine the genotoxic effects of
toxic agents on somatic cells, and an increase of MN fre-
quency indicates genomic instability. According to our
results, AvLE had cytotoxic activity and induced MN
formation in the root tip of A. cepa. as reported by many
researchers. MN formation results from different types
of chromosomal aberrations such as their inhibition or
delay in the formation of the chromosome-spindle com-
plex (İnceer et al. 2003, Türkmen et al. 2009, Arya and
Mukherjee 2014).
The most striking abnormalities in the present study
were the bridges in anaphase and fault polarizations in
telophase. Mitotic irregularities, such as fault polar-
ization and bridge in anaphase and telophase, may be
mainly the result of spindle dysfunction and constitute
a significant portion of chromosomal aberrations. Spin-
dle dysfunction may lead to abnormal segregation of
chromosomes due to defective microtubule–kinetochore
interaction, and abnormal mitotic segregation of chro-
mosomes triggers bridge formations (Tabur and Demir
2010b).
108 D. Çavuşoğlu et al. Cytologia 81(1)
Physiological and cytogenetical effects of exogenous
AvLE in saline conditions
It was reported previously that saline conditions nega-
tively affect growth and development events in general,
even in halophytes. Howewer, the effect mechanism of
salinity has not been completely clarified so far (Al-
Karaki 2001, Ghoulam and Fores 2001). It is well known
that salinity prevents seed germination (Chartzoulakis
and Loupanak 1997, Hosseini et al. 2002, Demir et
al. 2003) and seedling growth (Dash and Panda 2001,
El-Mashad and Kamel 2001, Ashraf et al. 2002). The
seedling growth and germination of A. cepa seeds, as
expected, were inhibited under saline conditions (Table
1). Salt stress can perform preventive effects in many
ways. It may interfere with seed germination by chang-
ing the water status of the seed so that water uptake is
inhibited (Ali 2000). Our results showing the decrease in
fresh weight and water content of the seedlings in saline
medium may be explained by the failure of the roots to
receive sufficient water due to the high osmotic pressure
of medium (Al-Karaki 2001). The inhibitive effect of
salt on the radicle length and radicle number may result
from reducing cell division (Mccue and Hanson 1990),
nucleic acid and protein synthesis (Prakash et al. 1988).
On the other hand, AvLE treatment markedly removed
the inhibitor effect of salt stress on the seed germina-
tion and seedling growth parameters such as the radicle
length, radicle number and fresh weight (Table 1). Un-
fortunately, we have not encountered any studies con-
cerning the effects of AvLE on the seed germination and
seedling growth under saline conditions until now. That
AvLE alleviates salt stress on the seed germination and
seedling growth can be understood from the decrease in
the salts osmotic effects. For example, in 0.15 M NaCl
medium, AvLE application significantly increasing the
fresh weights of the seedlings as compared to the control
indicates this probability (Table 1). Moreover, it reduced
the preventive effect of salt on the seed germination and
seedling growth by stimulating mitotic activity of the
embryo (Table 2). It could have made a counter-attack
against the ABA being a germination inhibitor whose
amount probably increases due to the salt existence. In
addition to all these, AvLE might have been successful
in decreasing the inhibitive effect of salt stress on the
seed germination and seedling growth by increasing nu-
cleic acid and protein synthesis, by providing stabiliza-
tion of cell membranes or by raising antioxidant enzyme
activities.
The inhibitory effects of salt stress on mitotic activ-
ity have been known for a long time (Katsuhara and
Kawasaki 1996, Lutsenko et al. 2005, Radic et al. 2005,
Tabur and Demir 2009, 2010a, b). On the other hand,
the detrimental effects of salt stress on chromosomal
abnormalities have recently begun to be studied (Radic
et al. 2005, Tabur and Demir 2009, 2010a, b). According
to some researchers, high salt concentration causes total
inhibition of mitotic activity and chromosomal abnor-
malities in root-tip cells (Radic et al. 2005, Tajbakhsh et
al. 2006). With the present work, it is worth mentioning
again that salinity adversely affected the mitotic activity
and chromosome behaviors in root meristem cells of A.
cepa. Our data indicated that salinity according to con-
trol decreased the mitotic index by 66% and resulted in a
higher number of chromosomal abnormalities.
The frequency of aberrations by salinity increased
twice as compared to control group. For example, the
frequency of chromosomal aberrations in the root tip
meristems of the seeds germinated in distilled water
was 11.9 while it was 25.5 at 0.15 M salinity (Table 2).
However, 0.1 mg/L AvLE application exhibited a perfect
performance by alleviating approximately seven times
the inhibitive effect of salinity on the mitotic index. Sta-
tistically, this performance was substantially significant.
In contrast, AvLE application could not be successful
in decreasing the detrimental effect of salinity on the
chromosomal aberrations. The frequency of aberrations
in root tip cells of the seeds germinated in AvLE appli-
cation together with salinity (group IV) was more than
approximately six times higher than in the control (Table
2). The cause of these high abnormalities may be due
to salt and AvLE interaction as mentioned above. The
chromosomal aberrations in root tip meristems of the
seeds germinated at 0.15 M NaCl were lower than those
which were treated with AvLE alone. The most strik-
ing aberrations observed in group IV (0.1 mg/L AvLE
+0.15 M NaCl) were bridge formation and fault polariza-
tion in telophase, whereas vagrant chromosomes and
bridges in telophase were small in number. However,
the MN formations, which are strong indicators of geno-
toxicity, were observed in higher number at group III as
compared to group IV (Table 2). This also demonstrated
that AvLE application in saline conditions caused a sig-
nificant decrease in the genotoxic effect, as all growth
regulators. Hence, the result proves that if AvLE used at
convenient concentrations, it might help to alleviate the
genotoxic effects of salt stress.
In general, accurate chromosome segregation in mi-
tosis requires that sister kinetochores attach to microtu-
bules emanating from opposite spindle poles. Because
kinetochore attachment is a stochastic process, it is er-
ror prone and can result in chromosome malorientation
(Rieder and Salmon 1998). Mitotic irregularities such
as disorderly prophase and anaphase, fault polarization,
alignment anaphase and bridges may be mainly the re-
sult of the abovementioned reasons or spindle dysfunc-
tion, and constitute a significant portion of chromosomal
aberrations. The formations of micronuclei are likely the
consequence of vagrant chromosomes and fragments
(Briand and Kapoor 1989). Sticky chromosomes may
result from improper folding of the chromatin fibres
(Klasterska et al. 1976). Some researchers reported that
the stickiness reflects a highly toxic effect on chromatin
2016 Physiological and Cytogenetical Effects of AvLE on Salinity 109
(Fiskesjö and Levan 1993). The prophase and metaphase
cells with uncoiled chromosomes may be the result of
disorderly chromosome contractions. Also, anaphase
and telophase bridges could be the result of inversions
(Tabur and Demir 2010b). Shortly, AvLE might function
as a stimulator triggering the synthesis of proteins nec-
essary for normal cell division and accelerate the mitotic
cycle.
There is no present literature data related to the ef-
fects of AvLE application in salinity conditions on
physiological and cytogenetical parameters studied here.
Therefore, our results in the present work are the first
report, particularly for effects in stress conditions. In
conclusion, our study indicates that AvLE, either alone
or in salty conditions, may improve the activations such
as seed germination, seedling growth and mitotic index
correlated with mitotic processes. However, the mecha-
nisms by which salinity inhibits growth are complex and
controversial. Moreover, these mechanisms may vary ac-
cording to species and cultivar. A universal mechanism
has not been established yet. Although the causes of
salinity have been characterized, our understanding of
the mechanisms by which salinity prevents plant growth
is still rather poor. Therefore, further studies should be
carried out in order to gain more knowledge about the
effect of AvLE on the molecular metabolism of germina-
tion, cell division and cell cycle. This work suggested
that application of AvLE at convenient doses might help
to alleviate all these negative effects on plant develop-
ment in stress conditions. Moreover, our work may serve
to provide new conceptual tools for designing salt toler-
ance hypotheses in plants.
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