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Cucurbit Genetics Cooperative Report 12:70-71 (article 30) 1989

Inheritance of Mottled Leaf in Cucurbita moschata

A. Ribeiro and C.P. da Costa

Department of Genetics, ESALQ/USP, CP 83, CEP13400, Piracicaba, SP, Brazil

The mottled leaf trait in the genus Cucurbita has been described as silver gray areas in axils of leaf veins controlled by a single dominant gene, M, in C. maxima, C. moschata and C. pepo (1, 2, 3). Modifier genes have been reported as extending and/or intensifying the character expression, and at least five phenotypes were described (2, 5). According to Shifriss (6) cell position and environment also contribute to variation in mottling.

Shifriss (4, 5, 6, 7) reported an association between mottled leaf trait and an escape mechanism against aphid-transmitted virus diseases. Mottled leaf plants either repelled aphids similarly to aluminum mulch or slowed speed of virus multiplication.

In the cv. Pira-Moita (C. moschata), we observed a great range of expression for the trait, from non-mottled to highly mottled plants. Contrasting lines were isolated after three selfing cycles, and six generations (P1, P2, F1, F2, BC1, and BC2) were compared from the cross, highly mottled leaf (P1) x non-mottled leaf (P2). Plants were evaluated for degree of mottling at first leaf stage, and data analyzed by chi-square (Table 1).

Table 1. Inheritance of mottled-leaf character in different generations from the cross between two lines, highly mottled leaf (P1) and non-mottled leaf (P2), derived from cv. Pira-Moita (Cucurbita moschata).

 

Number of plants

 

 

 

Generation

Mottled leaf

Non-mottled leaf

Tested ratio

X2

P

P1

all

-

1:0

-

-

P2

-

all

0:1

-

-

F1

all

-

1:0

-

-

F2

627

214

3:1

0.09

0.75-0.90

BC1

819

2

1:0

-

-

BC2

549

581

1:1

0.91

0.25-0.50

All of the F1 plants showed intermediate phenotypes, moderately mottled leaves, indicating partial dominance. The chi-square test indicated good fit to a 3:1 ratio for F2 generation and to a 1:1 ratio for BC2 generation, corroborating earlier published studies. A single, partially dominant gene confers mottled leaf, but there are modifier genes affecting the character as indicated by the continuous variation in mottled expression in F2.

Besides, the possible partial protection of Cucurbita plants against aphid-transmitted virus diseases, the trait may be useful as a seedling genetic marker.

Literature Cited

  1. Coyne, D.P. 1970. Inheritance of mottled-leaf in Cucurbita moschata poir. Hortscience 5:226-227.
  2. Scarchuk, J. 1954. Fruit and leaf characters in summer squash. J. Heredity 45:295-297.
  3. Scott, D.H. and E. Riner. 1946. A mottled-leaf character in winter squash. J. Heredity 37:27-28.
  4. Shifriss, O. 1981. Do Cucurbita plants with silvery leaves escape virus infection? Origin and characteristics of NJ 260. Cucurbit Genetics Coop. Rpt. 4:42:43.
  5. Shifriss, O. 1982. On the silvery-leaf trait in Cucurbita pepo. Cucurbit Genetics Coop. Rpt. 5:48-50.
  6. Shifriss , O. 1982. Reflected light spectra from silvery and non-silvery leaves of Cucurbita pepo. Cucurbit Genetics Coop. Rpt. 6:89-90.
  7. Shifriss, O. 1984. Further notes on the silvery-leaf trait in Cucurbita. Cucurbit Genetics Coop. Rpt. 7:81-83.
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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 23 October, 2009