Genetic diversity and selection in tomato genotypes under water stress induced by mannitol

Abstract

The tomato crop adapts to different climatic conditions. However, the water stress, which is a relevant factor in the tomato cropping, can affect the productivity. This experiment aimed to estimate the genetic variability, after two backcrosses, and select tomato genotypes that are tolerant to water stress induced by mannitol. The advance of the generations was done on the field and the water stress test was done in laboratory atmosphere, in a completely randomized design with four replications. 17 genotypes, in the generation F2BC2, which were obtained from an interespecific cross between Solanum pennellii and Solanum lycopersicum L. and three check treatments, one resistant [wild access LA-716 (Solanum pennellii)] and two susceptible (cv. Santa Clara and UFU-650), were evaluated. After subjected to the osmotic potential of -0.3 Mpa, the seeds were evaluated for: germination percentage, standard germination percentage, first counting percentage, germination velocity index, average time of germination and initial and final length of radicle. As expected, the wild access, S. pennellii, was better than the susceptible check treatments. The genotype UFU102/F2BC2#71115 highlighted, compared to the others F2BC2 genotypes and in relation to the three check treatments, susceptible (cv. Santa Clara and UFU-650) and resistant (S. pennellii). Analyzing the genetic diversity, 8 different groups were obtained, being an indicative of genetic variability between the evaluated genotypes. The variable %G contributed with 33.9% in the diversification of the genotypes, presenting as the most important criterion, to be evaluated in genetic diversity studies, in the tomato crop under water stress, induced by mannitol. © 2017, Universidade Federal de Uberlandia. All rights reserved.

Full text

592
Original Article
Biosci. J., Uberlândia, v. 33, n. 3, p. 592-600, May/June. 2017
GENETIC DIVERSITY AND SELECTION IN TOMATO GENOTYPES
UNDER WATER STRESS INDUCED BY MANNITOL
DIVERSIDADE GENÉTICA E SELEÇÃO EM GENÓTIPOS DE TOMATEIRO SOB
ESTRESSE HÍDRICO INDUZIDO POR MANITOL
Monique Ellis Aguilar BORBA
1
; Gabriel Mascarenhas MACIEL
2
;
Guilherme Repeza MARQUEZ
3
; Eusímio Felisbino FRAGA JÚNIOR
4
;
Gregory Gustavo Silva NOGUEIRA
5
1. Mestre em Fitotecnia pela Universidade Federal de Uberlândia, Uberlândia, MG, Brasil. monick1212@hotmail.com; 2. Professor e
Pesquisador da Universidade Federal de Uberlândia, Instituto de Ciências Agrárias, Monte Carmelo, MG, Brasil, gabrielmaciel@ufu.br;
3. Mestrando em Produção Vegetal pela Universidade Federal de Uberlândia, MG, Brasil; 4. Professor e Pesquisador da Universidade
Federal de Uberlândia, Instituto de Ciências Agrárias, Monte Carmelo, MG, Brasil; 5. Graduando em Agronomia pela Universidade
Federal de Uberlândia, Monte Carmelo, MG, Brasil.
ABSTRACT:
The tomato crop adapts to different climatic conditions. However, the water stress, which is a
relevant factor in the tomato cropping, can affect the productivity. This experiment aimed to estimate the genetic
variability, after two backcrosses, and select tomato genotypes that are tolerant to water stress induced by mannitol. The
advance of the generations was done on the field and the water stress test was done in laboratory atmosphere, in a
completely randomized design with four replications. 17 genotypes, in the generation F
2
BC
2
, which were obtained from an
interespecific cross between Solanum pennellii and Solanum lycopersicum L. and three check treatments, one resistant
[wild access LA-716 (Solanum pennellii)] and two susceptible (cv. Santa Clara and UFU-650), were evaluated. After
subjected to the osmotic potential of -0.3 Mpa, the seeds were evaluated for: germination percentage, standard germination
percentage, first counting percentage, germination velocity index, average time of germination and initial and final length
of radicle. As expected, the wild access, S. pennellii, was better than the susceptible check treatments. The genotype
UFU102/F
2
BC
2
#71115 highlighted, compared to the others F
2
BC
2
genotypes and in relation to the three check treatments,
susceptible (cv. Santa Clara and UFU-650) and resistant (S. pennellii). Analyzing the genetic diversity, 8 different groups
were obtained, being an indicative of genetic variability between the evaluated genotypes. The variable %G contributed
with 33.9% in the diversification of the genotypes, presenting as the most important criterion, to be evaluated in genetic
diversity studies, in the tomato crop under water stress, induced by mannitol.
KEYWORDS:
Solanum pennellii. Solanum lycopersicum. Abiotic stress. Seeds. Seedlings.
INTRODUCTION
The tomato (Solanum lycopersicum L.) is a
vegetable crop with high social and economic
importance all over the world (HEINE et al. 2015).
The crop adapts to different climatic conditions
(ALVARENGA 2013), but the water stress, which
is the moment when the absorption rate of water is
lower than the loss rate (COSTA et al. 2008), is one
of the major problems that affect the tomato yield.
During the cropping, this vegetable needs, approach,
700 mm of water (de MELO et al. 2014) and, the
inadequate supply of it might interfere on the
development and productivity of the plants (Bray
2004).
In the last years, the conflicts about the use
and water restrictions became a limiting factor, not
only in arid and semi-arid regions, but also in places
with high water content, but incapable to supply the
high demand (TELLES; COSTA 2010). Because of
that, the development of genotypes that are tolerant
to water stress present as a good strategy of low cost
and high efficiency in regions with drought
(GIROTO et al. 2012).
Commercially, does not exist a genotype
that has excellent agronomic characteristics and is
also tolerant to water stress. This fact can be
explained for the lack of efficient methodologies
that are used to select the genotypes (BERENGUER
2015). The wild access LA-716, S. pennellii, is
originating from a dry and hot region and because of
the evolution over time, the specie is efficiency on
the water use, compared to the common cultivars
(ROCHA et al. 2016). Therefore, it is possible the
introgression of genes, from S. pennellii, in
advanced generations of tomato plants, aiming the
development of genotypes that are tolerant to water
stress.
The seed’s germination in soils with low
water potential depends on the characteristics of
each species. In a laboratory atmosphere, it is
possible to simulate the water stress through
germination studies that use aqueous solutions of
sucrose, salts, mannitol and polyethylene glycol.
Received: 07/10/16
Accepted: 20/12/16

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Biosci. J., Uberlândia, v. 33, n. 3, p. 592-600, May/June. 2017
These solutes reduce the water potential when added
to it and, allow the selection of tolerant genotypes
(SANTOS et al. 1992).
The use of direct methods, in the selection
for water stress, is expensive and demand long time,
making the indirect methods more advantageous.
The indirect method using mannitol, an inert
chemical product and non-toxic (ECHER et al.
2010), has been widely used in different species,
aiming simulate the water stress on laboratory
atmosphere (COELHO et al. 2010, PELEGRINI et
al. 2013, SOARES et al. 2015). According
Berenguer (2015), the adequate osmotic potential,
used for evaluate the water stress in tomato seeds
and seedlings, is -0.3 Mpa. However, the low
genetic variability, combined with the high
susceptibility that the current genotypes show, has
made difficult to obtain advances on the tomato
breeding programs.
This study aimed to estimate the genetic
variability, after two backcrosses, and select tomato
genotypes that are tolerant to water stress, induced
by mannitol.
MATERIAL AND METHODS
The experiments were conducted on the
laboratory of seeds analyze and genetic resources
(LAGEN) and in the vegetable’s experimental
station of the Federal University of Uberlândia
(UFU), both located on Monte Carmelo city
(18
o
42’43”S; 47
o
29’55”; 873 m of altitude), in the
period from January, 2013, to July, 2016.
In order to create a genetic variability, were
realized an interespecific cross, in May 2013,
between Solanum pennellii (wild access LA-716)
versus Solanum lycopersicum L. (pre-commercial
line UFU-650). The pre-commercial line belongs to
the germplasm bank of the UFU and it has
determinate growth habit, large fruits (180 g) of
Santa Cruz type and is susceptible to water stress.
The wild access, LA-716, has indeterminate growth
habit, small fruits (12 g) and is tolerant to water
stress (ROUSSEAUX et al. 2005, ROCHA et al.
2016). After the F1 generation (hybrids) were
obtained, the first and second backcrosses were
made, in 2014 and 2015, respectively. In January,
2016, a selfing of the F
1
BC
2
was made, obtaining 17
genotypes F
2
BC
2
.
Aiming checking the germination, the seeds
were submitted to a pre-test, named standard
germination (SG), which did not has osmotic
solution. The pre-test was design in a completely
randomized system, with four replications of 25
seeds and 20 treatments, which were 17 genotypes
F
2
BC
2
: UFU102/F
2
BC
2
#71115;
UFU102/F
2
BC
2
#71114; UFU102/F
2
BC
2
#7118;
UFU102/F
2
BC
2
#7117; UFU102/F
2
BC
2
#7122;
UFU102/F
2
BC
2
#7912; UFU102/F
2
BC
2
#7139;
UFU102/F
2
BC
2
#7917; UFU102/F
2
BC
2
#7714;
UFU102/F
2
BC
2
#71813; UFU102/F
2
BC
2
#71111;
UFU102/F
2
BC
2
#7189; UFU102/F
2
BC
2
#71013;
UFU102/F
2
BC
2
#791; UFU102/F
2
BC
2
#7812;
UFU102/F
2
BC
2
#7185; UFU102/F
2
BC
2
#7153 and
three check treatments: a recurrent parent, UFU-
650; a donor parent, LA-716 and the cv. Santa
Clara, totalizing 80 experimental plots, represented
by plastic and transparent boxes (Gerbox).
After checking the SG, in each genotype, a
new sowing was realized, aiming an indirect
selection of the F
2
BC
2
family, and a solution of
mannitol (-0.3 Mpa), which is an inert chemical
product and non-toxic (Echer et al. 2010) used for
simulate the water stress on laboratory atmosphere,
was applied. The sowing of the treatments was
realized in plastic and transparent boxes of 11 x 11 x
3.0 cm and, the seeds were placed on two papers of
“Germitest” type, in a completely randomized
design, with four replications of 50 seeds in each
box. The substrate was previously moistened with
mannitol solution (-0.3 Mpa). The boxes were
sealed with Parafilm
®
, in order to reduce the water
loss, and were put on a germination chamber, BOD
type, with temperature of 25
0
C and 12 hours of
photoperiod.
Seven variables were evaluated:
germination percentage (%G), under the presence of
osmotic solution of mannitol (-0.3 Mpa), on the
eleventh day after sowing. The seeds that produced
a primary root were considered germinated. The
results were expressed in average percentage,
according to the number of normal plants. The
second variable analyzed was the standard
germination percentage (%SG), which had not
osmotic solution (check treatment), accounting the
germination percentage. The third one was the first
counting percentage (%FC), which was done
together with the germination test. This analyze
consisted in evaluate the percentage of normal
plants that were checked in the first counting of the
germination test and it was done on the fifth day
after sowing (BRASIL 2009). The fourth variable
analyzed were the germination velocity index
(GVI), calculated by the sum of the germinated
seeds in each day, divided by the number of days
elapsed between sowing and germination. The fifth
variable was the average time of germination
(ATG), obtained by counting, every day, the
germinated seeds, until the eleventh day after
sowing. It was calculated using the equation:

594
Genetic diversity… BORBA, M. E. A. et al
Biosci. J., Uberlândia, v. 33, n. 3, p. 592-600, May/June. 2017
(
)
∑
∑
=
iii
n/ tnATG
, where n
i
is the number of
germinated seeds in each count interval; t
i
is the
elapsed time between the beginning of the
germination and the last counting. The sixth variable
analyzed was the initial length of radicle (IL, mm),
measured with an aid of a millimeter ruler, on the
fourth day after sowing, in the fifty plants
considered normal on the boxes. The values were
added and the average of each plot was obtained.
The seventh and final variable analyzed was the
final length of radicle (FL, mm), that was also
measured with an aid of a millimeter ruler, on the
seventh day after sowing, in the fifty plants
considered normal on the boxes. The values were
also added and the average of each plot was
obtained.
After checking the analyze of variance
(ANOVA) assumptions, examining the normality
distribution of the residuals (Kolmogorov-
Smirnov’s test) and homogeneity of variances
(Levene’s test), it was done an analyze of variance
(F test, p < 0.01) and, in case of a significant effect,
the following tests were done: Scott-Knott test (p <
0.05); orthogonal contrasts of interest (Scheffé’s test
p < 0.05 and 0.01); relative contribution of the
characters (SINGH 1981) and optimization
grouping of Tocher. The statistic analyze was done
with an aid of the computational program, GENES
(CRUZ 2013).
RESULTS AND DISCUSSION
In the standard germination (SG), it was
checked that the percentage of average germination,
for all genotypes, were above 64% (Table 1). It was
checked an decreased in the germination percentage
(%G), when the seeds were submitted to a water
stress and, this was due to a reduction in water
availability, required for activation and maintenance
of the seeds metabolism (BEWLEY et al. 2013).
After the tomato seeds were inducted to a
water stress’s test, it was possible to verify a
significant difference between the genotypes, when
the variables (germination, first counting,
germination velocity index, average time of
germination, initial and final length of radicle) were
analyzed (Table 1).
The wild access, S. pennellii, which is
tolerant to water stress, significantly differed from
the susceptible check treatment, UFU-650, for
almost all analyzed variables, except for initial and
final length of radicle. The wild specie also
presented higher tolerance to water stress than the
cv. Santa Clara and differed, significantly, for
almost all variables, except for initial length of
radicle. Considering the variables %G and %FC
(Table 2), the wild access LA-716 (S. pennellii)
showed superiority of 146.3% and 900%,
respectively, in relation to the cv. Santa Clara. When
compared to the genotype UFU-650, the S. pennellii
also showed superiority of 58.3% and 260% for the
variables %G and %FC, respectively. These results
demonstrate that the water stress, induced by
mannitol on the osmotic potential level of -0.3 Mpa,
is efficient on the selection of tomato genotypes
with tolerance to water stress. Custódio et al.
(2009) verified in their worked that the potentials, 0,
-0.3, -0.6 and -0.9 Mpa of the solution, did not
promote differences in the germination of bean
seeds. On the other hand, Ávila et al. (2007),
working with canola seeds, observed that the seeds
showed satisfactory germination when submitted to
osmotic potential of -0.25 Mpa and, after this
potential level, the germination rate had reduced.
The fact of the cv. Santa Clara showed one of the
worst performance among the genotypes, confirms
its susceptibility to a water stress. This fact can be
confirmed analyzing the relative superiority (Table
2).
The genotypes UFU102/F
2
BC
2
#71115 and
UFU102/F
2
BC
2
#71114 highlighted, showing higher
tolerance to water stress than the others. They
presented 238.9% and 237.0% of relative
superiority, respectively, for %G and 1533.1% and
1611.1%, respectively, for %FC, compared to the
cv. Santa Clara (Table 2). When compared to the
access UFU-650, these genotypes also showed
relative superiority of 117.9% and 116.7%, for %G
and 488.0% and 516% for %FC, respectively. The
genotypes UFU102/F
2
BC
2
#71115 and
UFU102/F
2
BC
2
#71114 highlighted not only in
relation to the two susceptible check treatments,
they showed relative superiority of 37.6% and
36.8% for %G and 63.3% and 71.1% for %FC,
respectively, in relation to the donor parent, S.
pennellii. It is worth mentioning that other
genotypes also showed relative superiority in
relation to the wild access, having the possibility to
be used in a tomato breeding program.
After the contrasts were analyzed, it was
observed that the C1 and C3 were not significantly.
It demonstrates that the F
2
BC
2
genotypes were
similar to the wild access LA-716 (S. pennellii).
Analyzing the C2, it was possible to verify that the
average of the genotypes were mostly higher than
the averages of the susceptible check treatments, cv.
Santa Clara and UFU-650. After the C4 was
evaluated, it was possible to verify that, for all
variables analyzed, the average of the F
2
BC
2

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Biosci. J., Uberlândia, v. 33, n. 3, p. 592-600, May/June. 2017
treatments was higher than the average of the
genotypes UFU-650 and LA-716. The results
obtained by the contrasts reinforce the efficiency in
the use of mannitol, for selection tomato genotypes
tolerant to water stress and indicate that the
genotypes UFU102/F
2
BC
2
#71115 e
UFU102/F
2
BC
2
#71114 were superior than others in
relation to water stress.
Table 1. Germination percentage (%G), first counting percentage (%FC), germination velocity index (GVI),
average time of germination (ATG), initial length (IL) and final length (FL), in tomato genotypes
under osmotic potential of -0.3 Mpa, induced by mannitol and standard germination percentage
(%SG) without osmotic solution. Monte Carmelo city, Federal University of Uberlândia, 2016.
Genotype (x)
% G %SG %FC GVI ATG
(Days) IL (mm) FL
(mm)
T1 UFU102/F
2
BC
2
#71115 91.5 a 90.0 a 73.5 a 11.7 a 4.4 c 5.2 a 25.0 a
T2 UFU102/F
2
BC
2
#71114 91.0 a 92.0 a 77.0 a 11.3 a 4.6 c 4.2 a 21.5 a
T3 UFU102/F
2
BC
2
#7118 85.5 a 94.0 a 73.0 a 11.2 a 4.3 c 3.5 b 19.2 a
T4 UFU102/F
2
BC
2
#7117 77.0 b 83.0 b 61.5 a 9.4 a 4.8 c 4.4 a 15.5 b
T5 UFU102/F
2
BC
2
#7122 76.0 b 84.0 b 39.5 b 10.1 a 5.1 c 2.1 c 13.3 b
T6 UFU102/F
2
BC
2
#7912 74.5 b 91.0 a 44.0 b 7.7 b 5.7 b 1.6 c 14.2 b
T7 UFU102/F
2
BC
2
#7139 70.5 b 88.0 a 50.0 b 7.5 b 5.2 c 2.5 b 14.4 b
T8 UFU102/F
2
BC
2
#7917 70.0 b 85.0 b 47.5 b 8.0 b 4.9 c 2.4 b 16.9 b
T9 LA-716 66.5 b 98.0 a 45.0 b 7.6 b 5.2 c 1.0 d 9.3 c
T10 UFU102/F
2
BC
2
#7714 65.0 b 73.0 b 50.0 b 7.6 b 4.9 c 3.3 b 10.1 c
T11 UFU102/F
2
BC
2
#71813 53.5 c 77.0 b 40.0 b 8.1 b 4.8 c 2.6 b 7.8 c
T12 UFU102/F
2
BC
2
#71111 53.0 c 81.0 b 27.5 c 4.9 c 5.9 b 0.3 d 8.5 c
T13 UFU102/F
2
BC
2
#7189 49.0 c 71.0 b 26.5 c 5.4 c 5.7 b 2.0 c 6.8 c
T14 UFU102/F
2
BC
2
#71013 49.0 c 67.0 c 19.5 c 5.3 c 6.1 b 0.5 d 4.3 d
T15 UFU-650 42.0 c 88.0 a 12.5 d 3.5 d 6.4 b 0.3 d 6.0 c
T16 UFU102/F
2
BC
2
#791 38.5 d 65.0 c 17.5 c 4.7 c 5.7 b 0.8 d 5.8 c
T17 UFU102/F
2
BC
2
#7812 36.5 d 81.0 b 17.5 c 3.3 d 6.3 b 0.3 d 1.7 d
T18 UFU102/F
2
BC
2
#7185 29.5 d 64.0 c 20.0 c 4.1 c 5.4 c 1.2 c 2.5 d
T19 UFU102/F
2
BC
2
#7153 29.0 d 93.0 a 5.0 d 2.2 d 7.4 a 0.1 d 2.6 d
T20 cv. SantaClara 27.0 d 83.0 b 4.5 d 2.1 d 7.2 a 0.2 d 3.2 d
Contrasts of Interest (y) Estimating Contrasts
C1=
[(T1+T2+T3+T4+T5+T6
+T7+T8+T10+T11+T12
+T13+T14+T16+T17+T
18+T19)/17)]-(T9)
5.4
ns
16.9
ns
4.4
ns
0.4
ns
0.2
ns
1.2
ns
1.9
ns
C2=
[(T1+T2+T3+T4+T5+T6
+T7+T8+T10+T11+T12
+T13+T14+T16+T17+T
18+T19/17)]-
(T15+T20/2)
26.6
**
4.4
ns
32.1
**
4.4
**
1.5
**
1.9
ns
6.6
ns
C3= [(T1+T2/2)]-(T9) 24.8
ns
7.0
ns
30.3
ns
3.9
ns
0.7
ns
3.7
*
14.0
**
C4= [(T1+T2/2)]-
(T15+T20/2) 56.8
**
5.5
ns
66.8
**
8.7
**
2.3
**
4.4
**
18.6
**
(x) Means followed by the same letter in the column did not differ, significantly, from each other, by Scott-Knott test, p < 0.05 and
(y)
**, * and
ns
= significant α=0.01, α=0.05 and not significantly, respectively, by the Scheffé test.

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Table 2. Relative superiority of the 17 F
2
BC
2
genotypes, in relation to the check treatments, wild access LA-
716 (S. pennellii), cv. Santa Clara and UFU-650. Monte Carmelo city, Federal University of
Uberlândia, 2016.
Genotype
RS (G%)
LA-716
RS (FC%)
LA-716
RS (G%) cv.
Santa Clara
RS (FC%) cv.
Santa Clara
RS(G%)
UFU-650
RS (FC%)
UFU-650
T1 UFU102/F
2
BC
2
#71115 37.6 63.3 238.9 1533.3 117.9 488.0
T2 UFU102/F
2
BC
2
#71114 36.8 71.1 237.0 1611.1 116.7 516.0
T3 UFU102/F
2
BC
2
#7118 28.6 62.2 216.7 1522.2 103.6 484.0
T4 UFU102/F
2
BC
2
#7117 15.8 36.7 185.2 1266.7 83.3 392.0
T5 UFU102/F
2
BC
2
#7122 14.3 -12.2 181.5 777.8 81.0 216.0
T6 UFU102/F
2
BC
2
#7912 12.0 -2.2 175.9 877.8 77.4 252.0
T7 UFU102/F
2
BC
2
#7139 6.0 11.1 161.1 1011.1 67.9 300.0
T8 UFU102/F
2
BC
2
#7917 5.3 5.6 159.3 955.6 66.7 280.0
T9 LA-716 0.0 0.0 146.3 900.0 58.3 260.0
T10 UFU102/F
2
BC
2
#7714 -2.3 11.1 140.7 1011.1 54.8 300.0
T11 UFU102/F
2
BC
2
#71813 -19.5 -11.1 98.1 788.9 27.4 220.0
T12 UFU102/F
2
BC
2
#71111 -20.3 -38.9 96.3 511.1 26.2 120.0
T13 UFU102/F
2
BC
2
#7189 -26.3 -41.1 81.5 488.9 16.7 112.0
T14 UFU102/F
2
BC
2
#71013 -26.3 -56.7 81.5 333.3 16.7 56.0
T15 UFU-650 -36.8 -72.2 55.6 177.8 0.0 0.0
T16 UFU102/F
2
BC
2
#791 -42.1 -61.1 42.6 288.9 -8.3 40.0
T17 UFU102/F
2
BC
2
#7812 -45.1 -61.1 35.2 288.9 -13.1 40.0
T18 UFU102/F
2
BC
2
#7185 -55.6 -55.6 9.3 344.4 -29.8 60.0
T19 UFU102/F
2
BC
2
#7153 -56.4 -88.9 7.4 11.1 -31.0 -60.0
T20 cv. SantaClara -59.4 -90.0 0.0 0.0 -35.7 -64.0
Based on the cluster analyze of the
optimization method of Tocher (Table 3), the
genotypes were separated in five different groups,
indicating variability between the evaluated
materials. Nine genotypes were putted on the group
I, with both susceptible check treatments, cv. Santa
Clara and UFU-650, indicating that these genotypes
are, potentially, susceptible to water stress.
The group II was composed by eight genotypes and
inside of it, was the resistant check treatment, LA-
716 (S. pennellii), responsible for donate the genes
that confer tolerance to water stress. Facing that, it
is possible to state that the genotypes
UFU102/F
2
BC
2
#7139, UFU102/F
2
BC
2
#7917,
UFU102/F
2
BC
2
#7912, UFU102/F
2
BC
2
#7117,
UFU102/F
2
BC
2
#7714, UFU102/F
2
BC
2
#7118 and
UFU102/F
2
BC
2
#71114 showed satisfactory levels
of tolerance to water stress induced by mannitol.
However, it does not indicate that these genotypes
were better. Observing the average tests (Table 1),
it is possible to verify that the genotype
UFU102/F
2
BC
2
#71115 highlighted, presenting the
best results for all variables analyzed and because of
that, stayed in an isolated group (III), which showed
better characteristics than the group that had the
donor parent, S. pennellii. Therefore, it is possible to
say that the genotype UFU102-F
2
BC
2
-71115 is the
most indicate in a future breeding program that aims
obtaining tomato genotypes with satisfactory levels
of tolerance to water stress. The agglomerated
average of the groups (Table 4) revealed that the
genotype UFU102/F
2
BC
2
#71115, which was the
only component of the group III, had the higher
average for %G (91.5), %FC (73.5), GVI (11.7), IL

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Biosci. J., Uberlândia, v. 33, n. 3, p. 592-600, May/June. 2017
(5.2 mm) and FL (25.0 mm) and also presented the
lowest average time of germination (4.4 days).
Table 3. Grouping standard of 20 tomato genotypes, based on genetic diversity. Monte Carmelo city, Federal
University of Uberlândia, 2016.
Group Number of genotypes
Genotypes
I 9
UFU102/F
2
BC
2
#7153, cv. Santa Clara, UFU 650,
UFU102/F
2
BC
2
#7812, UFU102/F
2
BC
2
#791, UFU102/F
2
BC
2
#7189,
UFU102/F
2
BC
2
#71013, UFU102/F
2
BC
2
#71111 and
UFU102/F
2
BC
2
#7185
II 8
UFU102/F
2
BC
2
#7139, UFU102/F
2
BC
2
#7917,
UFU102/F
2
BC
2
#7912, UFU102/F
2
BC
2
#7117,
UFU102/F
2
BC
2
#7714, LA-716, UFU102/F
2
BC
2
#7118 and
UFU102/F
2
BC
2
#71114
III 1 UFU102/F
2
BC
2
#71115
IV 1 UFU102/F
2
BC
2
#71813
V 1 UFU102/F
2
BC
2
#7122
Table 4. Agglomerated average of the groups, in function of six variables. Monte Carmelo city, Federal University of
Uberlândia, 2016.
Variables
I II III IV V
% G
39.3 75.0 91.5 53.5 76.0
%FC
16.7 56.0 73.5 40.0 39.5
GVI
3.9 8.8 11.7 8.1 10.1
ATG (days)
6.2 4.9 4.4 4.8 5.1
IL (mm)
0.6 2.8 5.2 2.6 2.1
FL (mm)
4.6 15.1 25.0 7.8 13.3
The group II, which was consisted of
genotypes that are similar to the wild access S.
pennellii, showed the second highest average for
%FC (56.0), IL (2.8 mm) and FL (15.1 mm). The
group V presented the second highest average for
%G (76.0%), similar to the group II (75%). The
group I, which had as component the susceptible
check treatments, showed the lowest averages for
%G, %FC, GVI, IL and FL, but it presented the
highest average for ATG (days), which is an
important variable for detecting how fast the seeds
can germinate and, consequently, settle in a place
(FERREIRA et al. 2001, BORGHETTI;
FERREIRA 2004). According Kramer (1974), a
decrease in the seedlings growth, under water stress,
is due to a reduction on the expansion of existing
cells. By lowering the pressure of turgor, the water
stress affects the cellular growth and interferes on
the metabolism, growth and establishment of the
seedlings (JALEEL et al. 2009).
The variables with most relative
contributions on the evaluation diversity of the
genotypes (Table 5) were, according to the method
of Singh (1981), % germination, germination
velocity index and final length.
The variable %G contributed with 33.9% in
the diversification of the genotypes, presenting as
the most important criterion. Analyzing the average
of the groups (Table 4) for %G, it is possible to
verify that the genotypes were expressive distinct,
having 39.3% on group I and 91.5% on group III of
variability, making the variable an important factor
in the selection of tomato genotypes with tolerance
to water stress.

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Biosci. J., Uberlândia, v. 33, n. 3, p. 592-600, May/June. 2017
Table 5. Relative contribution of the variables %G, GVI, FL (mm), %FC, ATG and IL (mm) for diversity
analyze - SINGH(1981). Monte Carmelo city, Federal University of Uberlândia.
Variable
S.J %
%G
1.387.8 33.9
GVI
771.5 18.9
FL (mm)
697.0 17.0
%FC
518.3 12.7
ATG (days)
445.7 10.9
IL (mm)
270.3 6.6
Suggestion of variable for discard : IL
The characteristics that provided the minor
contributions, with the lowest values of relative
importance, were the percentage of first counting
(%FC), average time of germination (ATG) and
initial length (IL, mm). The variable IL had the
lowest relative contribution, with only 6.6%,
making it a possible discard.
CONCLUSIONS
There was genetic variability between the
evaluated genotypes.
The variable %G was the most important
criterion in the differentiation of the genotypes, after
they were submitted to a water stress induced by
mannitol.
The genotype UFU102/F
2
BC
2
#71115 was
the most tolerant to water stress, suggesting a future
use of it in a tomato breeding program that aim
obtaining genotypes with satisfactory levels of
tolerance to water stress.
ACKNOULEDGMENTS
The authors would like to thank the Federal
University of Uberlândia, CNPq and FAPEMIG, for
the financial support on this research project.
RESUMO
: O tomateiro é uma planta que se adapta a diferentes condições climáticas. No entanto, o estresse
hídrico, considerado um importante fator no cultivo de tomate, pode afetar a produção. O objetivo do experimento foi
estimar a variabilidade genética, após dois retrocruzamentos, e selecionar genótipos de tomateiro tolerantes ao estresse
hídrico induzido por manitol. O avanço das gerações foi realizado no campo e o teste de estresse hídrico, feito no
laboratório, em delineamento inteiramente casualizado com quatro repetições. Foram avaliados 17 genótipos, em geração
F
2
BC
2
, oriundos de um cruzamento interespecífico entre o Solanum lycopersicum e o Solanum pennellii e três
testemunhas, sendo uma resistente [acesso selvagem LA-716 (Solanum pennellii)] e duas suscetíveis (cv. Santa Clara e
UFU-650). Após serem submetidas ao potencial osmótico de -0.3 Mpa, as sementes foram avaliadas para: porcentagem de
germinação, porcentagem de germinação padrão, porcentagem de primeira contagem, índice de velocidade de germinação,
tempo médio de germinação e comprimento inicial e final de radícula. Como esperado, o acesso selvagem, S. pennellii,
mostrou-se superior às testemunhas suscetíveis. O genótipo UFU102/F
2
BC
2
#71115, destacou-se quando comparado aos
outros genótipos F
2
BC
2
e em relação às três testemunhas, tanto as suscetíveis (cv. Santa Clara e UFU-650) quanto a
resistente (S. pennellii). Analisando a diversidade genética, foi possível a obtenção de oito grupos diferentes, sendo um
indicativo de variabilidade genética entre os genótipos avaliados. A variável %G contribuiu com 33.9% na diferenciação
dos genótipos, apresentando-se como o critério mais importante a ser avaliado, em estudos de divergência genética, na
cultura do tomateiro, sob estresse hídrico induzido por manitol.
PALAVRAS-CHAVE
: Solanum pennellii. Solanum lycopersicum. Estresse abiótico. Sementes. Plântulas.
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