Young, F. A.
Unusually wide tomato leaflets are due to two recessive alleles, c and e. They are difficult to distinguish sometimes because the expression of e is indistinct in certain phenotypes. Usually the leaflets of ee broad-leaf tomato plants are wider than normal and the end leaflets are nearly entire with a few sharp pointed basal lobes. Young plants 3 to 6 inches tall generally show this character, but when there is doubt large plants should be raised. If identification is still uncertain, then crosses with gene testers are necessary, as in the case with G1668.
The cc potato-leaf tomato plants have almost entire terminal leaflets with mostly, smooth margins. However, some end leaflets have halberd shape or 1 to 4 lobes. Plants with cc and ee have compound leaves. The Cc gene occurs in Chromosome 6, Linkage Group IV while the Ee gens occurs in Chromosome 4, Linkage Group XI.
G1668 tomato from C. F. Andrus (his No. 2795A-3-1-B-2) is a high bush determinate type with vide very dark green leaflets. In tests at Jacksonville. G1668 tomato leaves resisted sand Storms that severely damaged the many other kinds of tomatoes in the fields. G1668 bore good crops of large red fruits with moderate resistance to fruit cracking. It has the following geneology chart:
|Stokesdals X (Devon Surprise
[(Victor X Dobbies Champion) X Pan America] |X Marglobe) X (Stokesdale)
X Rutgars -- with normal leaves. | X (Pan America).
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| |
T2752 -- selected a wide-leaf mutant. STEP 68 with normal leaves.
\_______________ ____________/
\ /
STEP 68 X T2752
|
G1668 -- selection with wide leaflets, F5.
_______________/ \__________
/ \
G1668 X G2038 Barham's Gene Tester NC1006 | G1668 X G1077 MacArthur's gene tester.
? cc potato leaf. | cc++ ++ee
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F1 = 124 plants all with potato leaflets. | F1 = 151 plants all with normal
| leaflets; +c+e.
|
F2 = 60 plants of which 58 plants had the | F2 = 65 plants showed the following
potato-leaf character and 2 plants | phenotypes:
had normal leaflets. | 47 plants with normal leaflets
| 14 plants with potato leaflets (cc)
| 4 plants with broad leaflets (ee)
________________*These 2 normal-appearing plants may be explained as natural crosses in the field with normal +-pollen from other plants.
Evidently, G1668 has the c-allele.
This ratio of 47:14:4 deviates from the expected ratio of 37 normal : 12 broad leaf : 16 potato-leaf. The difference may be due to testing too small a number of plants. However apparently G1668 does not have the e-allele for broad leaflets.