Inheritance of resistance to Aphis gossypii G. in TGR-1551
(Cucumis melo L.) and its relation with resistance to virus transmission
Sarria, E., Yuste-Lisbona, F. J., Palomares-Rius, F. J., López-Sesé, A.I. and Gómez-Guillamón, M.L.
Experimental Station ‘La Mayora’, CSIC. 29760-Algarrobo, Malaga (Spain).
Introduction
The introduction of genetic resistance in
commercial varieties is the most efficient strategy
to decrease the harmful effects of A. gossypii in
melon crops.
together with virus transmission resistance are
controlled by Vat gene in both, PI 161375 and PI
14723 melon lines (3, 4, 5, 6).
Based on genetic studies, antixenosis and
antibiosis mechanisms against A. gossypii
kkkkkkk
Garzo et al. (2002) described aphid resistance
in TGR-1551 but genetic control was unknown till
date. In this paper, the inheritance mode of this
mmmmmmmm
The aphid resistant lines TGR-1551 and PI
414723 and the aphid susceptible Spanish
cultivar ‘Bola de Oro’ were used to obtain the
necessary populations for genetic analyses.
Aphis gossypii colonies were maintained on
plants of the aphid susceptible melon cultivar
‘ANC-57’ and only apterous adults were used in
the experiments.
‘Bola de Oro’
resistance as well as cosegregations of tolerance
/ antixenosis and tolerance / virus transmission
resistance have been analyzed in populations
coming from the cross between TGR-1551 and
‘Bola de Oro’. In addition, an allelism test
involving PI 414723 has also been done.
Material and methods
Melon plants with clear symptoms of the CMVM730 (‘Song’ pathotype) were used as inoculum
source in virus transmission tests.
X TGR-1551
TGR-1551
X PI 414723
Segregation data were analyzed by Chisquare test, while the cosegregation analyses
were made using the kappa test.
F1, F2, BCs
F1, F2
Tolerance
Antixenosis
Virus transmission resistance
Tolerance was evaluated through massive
infestation of seedlings (2). Five days after aphids
were released, plants with curled leaves were
considered susceptible and plants with normal
leaves were considered tolerant. These plants
were also evaluated for antixenosis once the
aphids used for tolerance test were eliminated.
Ten aphids were placed on the adaxial surface
of the second leaf from the plant apex. After 72 h.,
remaining adult aphids on infested leaves were
recorded. Plants with 4 or less aphids were
considered resistant.
Virus transmission resistance and aphid
tolerance were tested in the same plants using
viruliferous aphids. Five days after infestation,
aphids were eliminated and tolerance data were
recorded. Virus presence in plants was evaluated
15 days after infection, based on both, symptomatology and ELISA test.
3 days after
infestation
≤ 4 aphids
10 aphids
5 days after
infestation
Infestation
Infestation
Tolerant
&
15 days after
infectation
> 4 aphids
Resistant
Resistant Susceptible
Susceptible
ELISA
Symptoms
Susceptible
Results and discussion
Tolerance and antixenosis tests
Regarding the segregations obtained, it could be concluded that
antixenosis and tolerance to A. gossypii in TGR-1551 have the same
dominant monogenic control (Tables 1 and 2). Cosegregation of both
characters was highly significant (Table 2) but tolerance evaluation resulted
to be and easier evaluation method.
Table 1.
Tolerance to A. gossypii
χ2
Antixenosis to A. gossypii
Genotype
Expected
segregation
Observed
segregation
TGR-1551
1/0a
11/0a
11/0a
‘Bola de Oro’
0/1
0/15
1/14
Value
P
Observed
segregation
χ2
Value
Tolerance and virus transmission resistance
The segregations obtained in this experiment confirmed that aphid
tolerance in TGR-1551 is controlled by a single dominant gene while the
virus transmission resistance was not expressed as a reliable monogenic
character (Table 3). Ten to 15 % virus transmission occurred in TGR-1551,
in the F1 and in the BCR (Table 3). Cosegregation of both characters
suggested that they have the same genetic control (Table 4), but additional
factors (genetic or environmental) should be involved in virus transmission
resistance in aphid resistant genotypes.
P
Table 3.
Tolerance to A. gossypii
Genotype
Observed
segregation
χ2
Observed
segregation
F1
1/0
11/0
F2
3/1
76/24
0.05
0.82
79/21
0.85
0.35
TGR-1551
1/0a
10/0a
9/1a
BCS
1/1
28/22
0.72
0.39
29/21
1.28
0.26
‘Bola de Oro’
0/1
0/10
0/10
BCr
1/0
47/0
F1
1/0
10/0
9/1
F2
3/1
66/16
1.31
0.25
BCS
1/1
31/28
0.15
0.69
BCR
1/0
48/0
F2
BCS
47/0
Tolerance vs. antixenosis
Table 2.
Genotype
10/1
Expected
segregation
Virus transmission resistance
Response against
A. gossypii
Antixenosis
No antixenosis
Tolerance
75
1
Susceptibility
3
21
Tolerance
27
1
Susceptibility
1
21
P
< 0.001
Genotype
The authors thank the collaboration
of R. Tobar, R. Camero and J. M.
Alba. This work has been financed
by the CICYT Research Project:
AGL2005-03850-C02-01.
Literature cited
1.
2.
3.
4.
5.
6.
7.
Garzo et al., (2002) Phytoparasitica 30: 129-140
Ivanoff (1945). J Hered 36: 357-361
Klinger et al., (2001) J Am Soc Hortic Sci 126(1): 56-63
Kishaba et al., (1976). J Am Soc Hortic Sci 101(5): 557-561
Pitrat M, Lecoq H (1980) Phtytopathology 70: 958-961
Pitrat M, Lecoq H (1982) Agronomie 2(6): 503-508
Soria et al., (2003). Euphytica 133: 313-318
Value
P
53/29
4.67
0.03
32/27
0.42
0.51
41/7
Response against
A. gossypii
Virus
symptoms
No virus
symptoms
Tolerance
14
52
Susceptibility
16
0
Tolerance
4
27
Susceptibility
28
0
F2
BCS
Neither the infested plants of TGR-1551 nor PI 414723 melon lines were
curled by A. gossypii five days after infestation; no curled leaves were
observed in the evaluated progenies [F1,(10); F2 (152)], revealing that aphid
tolerance in both accessions might be controlled by the same gene.
P
Tolerance vs. virus transmission resistance
< 0.001
Allelism test
Acknowledgments
Table 4.
Value
χ2
P
< 0.001
< 0.001
Conclusions
1. Aphid resistance in TGR-1551 is controlled by one
dominant gene.
2. According to allelism test, Vat gene seems to be
responsible of the aphid resistance in TGR-1551.
3. Tolerance to A. gossypii, measured as absence of leaf
curling after massive aphid infestation, is an easy and
accurate method to evaluate aphid resistance.