|
Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 9, Num. 3, 2006, pp. 286-290
|
Electronic Journal of Biotechnology, Vol. 9, No. 3, Special
Issue, 2006, pg. 286-290
RESEARCH ARTICLE
NaCl
effects in Zea mays L. x Tripsacum dactyloides (L.) L.
hybrid calli
and plants
Julieta Pesqueira*1, Maria Dina García2,
Sebastian Staltari3, Maria del Carmen Molina4
1Facultad de
Ciencias Agrarias,
Universidad Nacional de Lomas de Zamora,
Ruta 4 Km. 2,
CC 95, 1832 Lomas de Zamora,
Buenos Aires, Argentina,
Tel/fax: 54 11 4282-6263/7860/7896 E-mail: julietapesqueira@yahoo.com
2Facultad de
Ciencias Agrarias,
Universidad Nacional de Lomas de Zamora,
Ruta 4 Km. 2,
CC 95, 1832 Lomas de Zamora,
Buenos Aires, Argentina, Tel/fax: 54 11 4282-6263/7860/7896 E-mail: mdinaga@hotmail.com
3Facultad de
Ciencias Agrarias,
Universidad Nacional de Lomas de Zamora,
Ruta 4 Km. 2,
CC 95, 1832 Lomas de Zamora,
Buenos Aires, Argentina,
Tel/fax: 54 11 4282-6263/7860/7896 E-mail: sstaltari@hotmail.com
4Instituto
Fitotécnico
de Santa Catalina,
Facultad de Ciencias Agrarias y Forestales,
Universidad Nacional de la Plata,
CIGen (UNLP-CONICET-CIC),
Garibaldi 3400, CC4, 1836, Llavallol,
Buenos Aires, Argentina,
Tel/fax: 54 11 4282-0233
E-mail: mcmgen@yahoo.com
*Corresponding author
Financial support: FCAyF-UNLP
(grant A129), FCA-UNLZ and CONICET (grant 4650).
Code Number: ej06042
Abstract
High salt concentrations in
soils negatively affect maize growth. Techniques such as remote hybridization
and in vitro selection have been extensively used to accelerate
breeding processes. In order to determine the usefulness of Tripsacum to
improve salt tolerance in maize, the effects of NaCl, in vitro and in
vivo, were evaluated in an intergeneric hybrid (MT) obtained from crossing Zea
mays with Tripsacum dactyloides. Organogenic calli, induced
from immature MT hybrid embryos, were exposed to different NaCl concentrations
and the survival and regeneration percentages were calculated. Plants of
the MT hybrid, obtained from the organogenic calli, were exposed to NaCl
concentrations considered harmful for maize. The shoot dry weights of plants
exposed to 250 mM NaCl did not show significant
differences respect to the control ones. Although sodium content in shoots
was incremented 2,5 fold, it was not toxic for this material. The MT hybrid
showed better behavior, in vitro and in vivo, that maize
genotypes exposed to similar conditions.
Keywords: intergeneric hybrid, plant regeneration, organogenesis, salinity
tolerance.
Abbreviations:
|
2,4-D: 2,4-dichlorophenoxyacetic acid
MT: Zea mays L. (2n = 40) and Tripsacum dactyloides (2n
= 72) hybrid
|
Article
High salt
concentrations in soils negatively affect maize growth and, consequently,
produce a large drop in yield (Pasternak et al. 1995).
In many countries of the world soil salinity is a serious problem for agriculture
and, consequently, the development of salinity tolerant genotypes is considered
an important research subject for genetic improvement (Flowers
et al. 1997).
Salinity
causes both, hyperionic and hyperosmotic stress effects, and the consequence
of these can be plant demise. Most common stress is caused by high Na+ and
Cl- concentrations in soil solution (Hasegawa et
al. 2000). Maize soil salinity effects have been widely studied. On one
hand, NaCl presence in soil solution affects crop water relations, which
becomes in an osmotic stress for maize plants (Cramer et al.
1994; Hasegawa et al. 2000). And on the other hand,
shoot Na+ concentration in maize increases with NaCl increments
in soil solution, which involves ionic balance alterations (Shabala
et al. 1998).
Resistance
to abiotic stresses in general, and to salt stress in particular is under
polygenic control, which have hindered the improvement in this aspect (Flowers
and Yeo, 1995; Winicov, 1996). Techniques such as remote
hybridization and in vitro selection have been greatly used to accelerate
the breeding process. Hybridization of two phylogenetically distant species
offers a great potential to increase the genetic variability, whether by
introgression of desirable characters in the cultivated species (introduction
of simple genes or addition/substitution/translocation of chromosomes or
chromosome segments), or by the generation of new allopolyploids with one
or more genomes and several useful characteristics of both parental species
(Matzk, 1997).
Tripsacum
dactyloides is a highly palatable and productive perennial grass (Faix
et al. 1980), which shows tolerance to different environmental stresses
(Foy, 1997; Clark et al. 1998; Ray
et al. 1999). Long-term organogenic calli have been obtained from tetraploid
maize (2n = 40) x Tripsacum dactyloides (2n = 72) hybrid embryos.
Regenerated hybrid plants showed a somatic chromosome number 2n = 56 (García
et al. 2000) and high tolerance to salinity (Pesqueira
et al. 2003) and low temperatures (Jatimliansky et al.
2004). Even though maize x T. dactyloides F1 hybrid plants exhibit
very low fertility, a few viable seeds have been obtained (Leblanc
et al. 1995; Sokolov et al. 2000; Molina
et al. 2005). Fertility and seed production increased in subsequent
generations by reducing the number of Tripsacum chromosomes (Khatypova
et al. 2002; Molina et al. 2005). Further, meiotic
cells of these hybrids showed maize and Tripsacum chromosomes pairing,
which suggest the possibility of genetic recombination between parental
species (Molina et al. 2005). In this context, maize
x T. dactyloides F1 hybrids could be a source of salinity tolerance
to use in a maize improvement program.
Although
methods such as remote hybridization and in vitro selection have been
widely used to accelerate plant breeding process, some frequent limitations
observed have been the difficulty to regenerate plants from the selected
material (Lutts et al. 1999) or the lack of correlation
between in vitro and in vivo tolerance (McCoy,
1987).
The aims
of the present study were to evaluate the effects of different NaCl concentrations
on the following parameters of the MT hybrid: i) regeneration capacity and
survival of organogenic calli; ii) growth of the regenerated plants exposed
to a NaCl concentration considered to be harmful to cultivated maize; iii)
plant shoot concentrations of sodium, potassium and calcium.
Materials
and Methods
Plant
Material
MT hybrid
organogenic calli, obtained from crossing the maize line N107B (2n = 40)
and Tripsacum dactyloides (2n = 72); and MT hybrid plants, obtained
from regenerated shoots.
In
vitro culture and plant regeneration
MT hybrid
calli growth and shoot regeneration, were carried out in a basic medium (García
et al. 1992) with 1 mg L-1 2,4-D. The regenerated shoots were
separated and individually transferred to the basic medium to induce root
production. After 45 days, the plantlets were transplanted into 200 ml pots
with a mixture of equal parts of earthworm compost and sterile soil, and
covered with plastic bags. After 50 days rusticated plants were transferred
to bigger pots (1700 ml) and watered with tap water.
NaCl
treatments in vitro
MT hybrid
calli were exposed to the following NaCl concentrations: 0; 70; 140 and 210 mM. After 35 days in vitro,
in a growth room with 13/11 h photoperiod and 30/25ºC and a photon flux density
of 31 µmol m-2 s-1, percentages of living (green callus)
and regenerating callus (those showing at least one shoot) were determined.
In
vivo methodology
Sixty
plants with an average height of 45
cm, were randomly selected. Half of the plants were
watered during 21 days with 250 mM NaCl, and the other ones with
tap water (control). The experiment was carried out in the greenhouse. When
the experiment was finished, fresh and dry weights of the shoot, as well
as the root were registered. Dried and milled shoots were digested with nitric
and percloric acids. Na+, Ca2+ and K+ contents
were determined by atomic absorption spectrophotometry (Isaac
and Kerber, 1971).
Results
and Discussion
NaCl
effects on MT hybrid organogenic calli
MT hybrid
calli survival and regeneration decreased as NaCl concentration increased
in the culture medium (Figure 1). After 35 days in
culture, 40% of the calli exposed to 140
mM NaCl survive and 30% of these showed shoot regeneration
(Table 1). Regenerated and rusticated plants were phenotypically
normal and homogeneous, contrary to what have been observed in rice, for
example, a total inhibition of shoot regeneration in presence of 100
mM NaCl (Lutts et al. 1999).
NaCl
effects on MT hybrid plants
MT hybrid
plants watered with 250 mM NaCl
did not show significant differences, neither in the fresh nor in the dry
shoot weights, compared to control plants. However, root dry weight was significantly
higher in NaCl treated plants than in the control ones (Table 2). This increment in root dry weight, determined a shoot/root rate 2.7
fold less than control plants. A drought tolerant maize hybrid, under drought
conditions, produced a similar effect, suggesting an osmotic response (Grzesiak
et al.1999). Nevertheless, it has been shown that NaCl ionic effect was
responsible for the root growth rate increment observed in tomato transformed
roots (Talano et al. 2002).
Sodium
content in the MT hybrid plants significantly increased respect to the control,
when they were watered with 170 mM NaCl
(2.7 g.kg-1 vs. 6.8
g.kg-1, control and stress, respectively)
(Pesqueira et al. 2002) as well as with 250
mM NaCl (2.94
g.kg-1 vs. 7.65 g.kg-1 control and stress,
respectively) (Figure 2). Meanwhile calcium and potassium
concentrations did not result statistically different (Table 3). Cramer et al. (1994) observed sodium accumulation
in maize salinity tolerant cultivars exposed to NaCl, which suggests that
the principal cause in salt sensitivity is the osmotic effect.
In conclusion,
our results and those previously reported, suggest that MT hybrid salt tolerance
is based, firstly on the strategy to accumulate sodium, and consequently
to lower leaves water potential, maintaining the turgor pressure required
for vegetative growth; and secondly, on the capacity to lower shoot/root
rate, which is a favourable aspect for plant water balance. Compared to the
controls, MT hybrid plants watered with 250 mM NaCl, did not show significant
differences neither in the dry weights nor in the calcium and potassium concentrations.
In addition, although sodium content in shoots increased 2.5 fold, when watered
with NaCl solution, it was not toxic for this genotype. Therefore, the MT
hybrid showed better behavior, in vitro as well as in vivo,
that maize genotypes exposed to similar conditions. It deserves further research
to determine the presence of any biochemical marker of salt stress tolerance,
which may be participating in the observed response.
Acknowledgments
Wed like
to thank Dr. Ma. Elena Dallorso for her contributions in spectrophotometry.
References
-
CLARK,
R.B.; ALBERTS, E.E.; ZOBEL, R.W.; SINCLAIR, T .R.; MILLER, M.S.;
KEMPER, W.D. and FOY, C.D. Eastern gamagrass ( Tripsacum dactyloides)
root penetration into and chemical properties of claypan soils. Plant
and Soil, 1998, vol. 200, no. 1, p. 33-45. [CrossRef]
-
CRAMER,
G.R.; ALBERICO, G.J. and SCHMIDT, C. Salt tolerance is not associated with
the sodium accumulation of two maize hybrids. Australian Journal of
Plant Physiology, May 1994, vol. 21, no. 3, p. 675-692. [CrossRef]
-
FAIX,
J.J.; KAISEER, C.J. and HINDS, F.C. Quality, yield, and survival of Asiatic
bluestems and an eastern gamagrass in southern Illinois. Journal
of Range Management, 1980, vol. 33, no. 5, p. 338-390.
-
FLOWERS,
T.J. and YEO, A.R. Breeding for salinity resistance in crop plants: where
next? Australian Journal of Plant Physiology, 1995, vol. 22, no.
6, p. 875-884.
-
FLOWERS,
T.J.; GARCÍA, A.; KOYAMA, M. and YEO, A.R. Breeding for salt tolerance
in crop plants - the role of molecular biology. Acta Physiologiae Plantarum,
1997, vol. 19, no. 4, p. 427-433.
-
FOY,
C.D. Tolerance of eastern gamagrass to excess aluminum in acid soil and
nutrient solution. Journal of Plant Nutrition, 1997, vol. 20, no.
9, p. 1119-1136.
-
GARCÍA,
M.D.; MOLINA, M.C. and CASO, O.H. El cultivo de callos organogénicos como
fuente de variabilidad genética para el mejoramiento del maíz. In: Revista
del V Congreso Nacional del Maíz - II Reunión Suramericana de Maiceros. (11 th -
13 th November, 1992, Pergamino, Buenos Aires, Argentina). Cap.
I, p. 61-69.
-
GARCÍA,
M.D.; MOLINA, M.C. and PESQUEIRA, J. Genotype and embryo age affect
plant regeneration from maize/ Tripsacum hybrids. Maize Newsletter,
2000, vol. 74, no. 1, p. 41-42.
-
GRZESIAK,
S.; HURA, T.; GRZESIAK, M.T. and PIENKOWSKI, S. The impact of limited soil
moisture and waterlogging stress conditions on morphological and anatomical
root traits in maize hybrids of different drought tolerance. Acta Physiologiae
Plantarum, 1999, vol. 21, no. 3, p. 305-315.
-
HASEGAWA,
P.M.; BRESSAN, R.A.; ZHU, J. and BOHNERT, H.J. Plant cellular and molecular
responses to high salinity. Annual Review of Plant Physiology and Plant
Molecular Biology, 2000, vol. 51, no. 1, p. 463-499. [CrossRef]
-
ISAAC,
R. and KERBER, J. Techniques and uses in soil, plant and water analysis.
In: Atomic Absorption and Photometry. Madison, Wisconsin,
1971, p. 17-37.
-
JATIMLIANSKY,
J.R.; GARCÍA, M.D. and MOLINA, M.C. Response to chilling of Zea mays, Tripsacum
dactyloides and their hybrid. Biologia Plantarum, 2004, vol.
48, no. 4, p. 561-567. [CrossRef]
-
KHATYPOVA,
I.V.; NAUMOVA, T.N.; KRAVTCHENKO, A.Y. and SOKOLOV, V.A. Cytoembryological
study of maize- Tripsacum hybrids. Maize Genetics Cooperation
Newsletter, 2002, vol. 76, no. 1, p. 50-52.
-
LEBLANC,
O.; GRIMANELLI, D.; GONZÁLEZ-DE-LEÓN, D. and SAVIDAN, Y. Detection
of the apomictic mode of reproduction in maize- Tripsacum hybrids using
maize RFLP markers. Theoretical and Applied Genetics, 1995, vol.
90, no. 7, p. 1198-1203. [CrossRef]
-
LUTTS,
S.; KINET, J.M. and BOUHARMONT, J. Improvement of rice callus regeneration
in the presence of NaCl. Plant, Cell, Tissue and Organ Culture,
July 1999, vol. 57, no. 1, p. 3-11. [CrossRef]
-
MATZK,
F.; OERTEL, C.; ALTENHOFER, P.; SCHUBERT, I. Manipulation of reproductive
systems in Poaceae to increase the efficiency in crop breeding and production. Trends
in Agronomy, 1997, vol. 1, no. 1, p. 19-34.
-
MC
COY, T. Tissue culture evaluation of ClNa tolerance in Medicago species:
cellular and whole plant response. Plant and Cell Reproduction,
December 1987, vol. 6, no. 1, p. 31-34. [CrossRef]
-
MOLINA,
M.C.; GARCIA, M.D. and CHORZEMPA, S.E. Estudio de la meiosis en los
híbridos
de Zea mays ssp mays (2n = 40) x T. dactyloides (2n = 72) y su progenie.
In: BairesBiotec2005, VI Simposio Nacional de Biotecnología. (7 th -
10 th June 2005, Buenos Aires, Argentina). Abstracts, 2005, p.
275.
-
PASTERNAK,
D.; SAGIH, N.; DEMALACH, Y.; KEREN, Y. and SHAFFER, A. Irrigation with
brackish water under desert conditions XI. Salt tolerance in sweet-corn
cultivars. Agricultural Water Management, 1995, vol. 28, no. 4,
p. 325-334. [CrossRef]
-
PESQUEIRA,
J.; GARCÍA, M.D. and MOLINA, M.C. NaCl tolerance in maize ( Zea mays ssp. mays L.)
x Tripsacum dactyloides L. hybrid calli and regenerated plants. Spanish
Journal of Agricultural Research, June 2003, vol. 1, no. 2, p. 59-63.
-
PESQUEIRA,
J.; GARCÍA, M.D.; DALLORSO, M.E. and MOLINA, M.C. Nivel de tolerancia a
salinidaddel híbrido intergenérico entre Zea mays y Tripsacum
dactyloides en los primeros estadios de crecimiento . In: XXIV
Reunión Argentina de Fisiología Vegetal, I Congreso Uruguayo de Fisiología
Vegetal. XI Reunión Latinoamericana de Fisiología Vegetal (22 nd 25 th October
2002, Punta del Este, Uruguay). Abstracts, 2002, p. 141.
-
RAY,
J.D.; KINDIGER, B. and SINCLAIR, T.R. Introgressing root aerenchyma into
maize. Maydica, 1999, vol. 44, no. 2, p.113-117.
-
SHABALA,
S.N.; SHABALA, S.I.; MARTYNENKO, A.I.; BABOURINA, O. and NEWMAN, I.A. Salinity
effect on bioelectric activity, growth, Na + accumulation and
chlorophyll fluorescence of maize leaves: a comparative survey and prospects
for screening. Australian Journal of Plant Physiology, 1998, vol.
25, no. 5, p. 609-616.
-
SOKOLOV,
V.A.; DEWALD, C.L. and KHATYPOVA, I.V. The genetic programs of nonreduction
and parthenogenesis in corn-gamagrass hybrids are inherited and expressed
in an independent manner. Maize Newsletter, 2000, vol. 74, no. 1,
p. 55-57.
-
TALANO,
M.A.; AGOSTINI, E.; MEDINA, M.I.; MILRAD, S.R. and TIGIER, H.A. Efecto
de estrés osmótico y salino sobre crecimiento y actividad peroxidasa de
cultivos de raíces transformadas de tomate. In: XXIV Reunión Argentina
de Fisiología Vegetal, I Congreso Uruguayo de Fisiología Vegetal. XI Reunión
Latinoamericana de Fisiología Vegetal. (22 nd - 25 th October
2002, Punta del Este, Uruguay). Abstracts, 2002. p. 161.
-
WINICOV,
I. Characterization of rice ( Oryza sativa L.) plants regenerated
from salt-tolerant cell lines. Plant Science, 1996, vol. 113, no.
1, p. 105-111. [CrossRef]
Note: Electronic Journal of Biotechnology
is not responsible if on-line references cited on manuscripts are not available
any more after the date of publication.
© 2006 by Pontificia Universidad Católica de Valparaíso
-- Chile
The following images related to this document are available:
Photo images
[ej06042t1.jpg]
[ej06042t2.jpg]
[ej06042f2.jpg]
[ej06042t3.jpg]
[ej06042f1.jpg]
|