A geminivirus vectored by the sweetpotato whitefly (Bemisia tabaci) has become a problem to Florida tomato production since the fall 1989 season. Symptoms resemble TMV as leaves turn light green and are mottled. Sometimes there is a an adaxial leaf curl, reduced leaf size and epinasty. Plant growth is slow and partially stunted. The earlier the infection the greater the stunting and other symptoms. On the wild species L. peruvianum, L. chilense, L. pennellii, and L. hirsutum, the leaves have a bright yellow mosaic appearance.
In fall 1990, 97 accessions were screened in the field to find a source of resistance. The germplasm tested consisted of breeding lines thought to have some tolerance from 1989 observations, accessions with reported resistance or tolerance to other geminiviruses [tomato yellow leaf curl (TYLCV) and Chino del Tomate (CdTV)], accessions with other reported virus resistance [cucumber mozaic virus (CMV), potato virus Y (PVY) and Beet Curly Top], and the entire collection of L. chilense from the Tomato Genetics Stock Center.
Disease pressure was high with no escapes in susceptible control lines The most tolerant of the accessions other than L. chilense are in Table 1. These include almost all of the accessions tested with tolerance to TYLCV, CdTV and CMV. Some, but not nearly all accessions with reported PVY resistance also had some tolerance to the Florida tomato geminivirus. Beet Curly Top resistant accessions were very susceptible as were the 1989 breeding line selections, although the latter generally set a lot of fruit despite the virus. Many of the most tolerant accessions were of the L. pimpinellifolium species. In general, indeterminate tomatoes exhibited less symptoms than determinate ones. It might be hard to transfer tolerance from indeterminate accessions to determinate tomato lines.
Of the 61 L. chilense accessions, plants were obtained from only 36 and many of these had a low number of plants tested (Table 2). Nevertheless, of the 36 L. chilense's tested, 25 had no symptoms (Table 2). Several of these accessions have deeply serrated and/or narrow leaves which might not be attractive to the whitefly. This coupled with the small number of plants underscores the preliminary nature of these data. However, L. chilense may prove a valuable source of geminivirus resistance. L. chilense accession LA 1969 has recently been reported to have resistance to TYLCV (Zakay et al. 1991). Of the accessions tested, LA 1932, 1938, 1959, 1960, 1961, 1963, 1968, 1969, 2747, 2762, 2774, and 2779 were selected for crossing with tomato since plant and leaf sizes were relatively large and attractive to the whitefly.
These results indicate some homology in resistance to geminiviruses.
Literature cited:
Zakay, Y., N. Navot, M. Zeidan, N. Kedar, H. Rabinowitch, H. Czosnek, and D. Zamir. 1991. Plant Disease 75(3):279-280.
Table 1. Florida geminivirus disease rating for accessions with reported resistance (tolerance) to other viruses.
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Reported Mean Disease
Accession Species Resistance* Rating**
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PI 211840 L. pimpinellifolium TYLC 1.18 a***
LA 386 L. hirsutum TYLC 1.26 ab
INRA 1986 L. peruvianum CMV 1.33 abc
L 10/3 L. pimpinellifolium CdTV 1.41 abc
PI 212408 L. pimpinellifolium TYLC 1.50 abcd
LA 373 L. pimpinellifolium TYLC 1.55 abcd
LA 1582 L. pimpinellifolium TYLC 1.85 abcd
LA 1478 L. pimpinellifolium TYLC 2.00 abcde
Hirsute L. pimpinellifolium TYLC 2.05 abcde
PI 127821 L. esculentum PVY 2.10 abcde
TY-20 L. esculentum TYLC 2.20 bcde
LA 121 L. esculentum TYLC, CdTV 2.20 bcde
PI 195006 L. esculentum PVY 2.20 bcde
EC 104395 L. esculentum TYLC 2.25 bcde
PI 131880 L. esculentum PVY 2.25 bcde
PI 117897 L. esculentum PVY 2.30 cde
PI 126410 L. esculentum PVY 2.48 de
LA 1401 L. cheesmanii TYLC 2.50 de
Sunny L. esculentum -- 3.00 e
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*Resistance often partial; TYLC = Tomato Yellow Leaf Curl, CMV = Cucumber
Mozaic Virus, CdTV = Chino del Tomate Virus, PVY = Potato Virus Y.**On a scale of 0 to 4 where 0 = no symptoms, 1 = slight symptoms visible only after a careful search, 2 = slight symptoms but more readily seen, 3 = moderate symptoms over most of plant and 4 = severe symptoms over entire plant.
***Mean separation by DMRT, 5% level, based on a larger number of accessions.
Table 2. Number of plants and disease rating for L. chilense accessions field tested for the Florida geminivirus
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Disease Rating*
Accession Plant (no.) Mean Range
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LA 2749 1 3.00 -
LA 2930 2 3.00 3-3
LA 2404 1 3.00 -
LA 2757 2 1.50 0-3
LA 1972 2 1.00 0-2
LA 2932 2 1.00 0-2
LA 2780 7 0.58 0-2
LA 1782 3 0.50 0-2
LA 2750 2 0.50 0-1
LA 1929 4 0.25 0-1
LA 1970 7 0.15 0-1
LA 1938 14 0.03 0-0.5
LA 456 2 0.00 -
LA 460 1 0.00 -
LA 470 1 0.00 -
LA 1930 11 0.00 -
LA 1932 16 0.00 -
LA 1958 5 0.00 -
LA 1959 7 0.00 -
LA 1960 11 0.00 -
LA 1961 14 0.00 -
LA 1963 2 0.00 -
LA 1965 1 0.00 -
LA 1967 1 0.00 -
LA 1968 4 0.00 -
LA 1969 3 0.00 -
LA 2406 1 0.00 -
LA 2737 1 0.00 -
LA 2747 2 0.00 -
LA 2751 1 0.00 -
LA 2762 6 0.00 -
LA 2765 1 0.00 -
LA 2771 1 0.00 -
LA 2774 5 0.00 -
LA 2778 3 0.00 -
LA 2779 11 0.00 -
LA 2891 1 0.00 -
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*On a scale of 0 to 4 where 0 = no symptoms, 1 = slight symptoms visible only
after a careful search, 2 = slight symptoms but more readily seen, 3 =
moderate symptoms over most of plant and 4 = severe symptoms over entire
plant.