Mathan, D.
Lanceolate (La), a new dominant leaf-shape gene appeared in the heterozygous condition in a line obtained from Dr. Casseres of the Turrialba Station, Costa Rica. The lanceolate heterozygote has simple, entire, elongated leaf which is much smaller than eitner normal, potato (cc) or broad (ee), and is easily distinguished from the latter three in the early seedling stage. Associated with the lanceolate leaf shape is an early appearance of axillary shoots leafy inflorescenes and a reduced flower-size.
When lanceolate plants of the parent line were selfed, they gave a good fit to the ratio of 1 normal : 2 lanceolate, which indicated that homozygous lanceolate was lethal. On the other hand, when the F1 (broad x lanceolate) plants that exhibited the lanceolate features were backcrossed to the lanceolate parent, a new phenotype, narrow, appeared in the progeny, which segregated, 1 normal : 2 lanceolate : 1 narrow. In comparison with lanceolate, narrow plants had even smaller leaves, more axillary shoots early in the life of the plant and much smaller flowers. From a total of 9 narrow plants only one small fruit was obtained but it did not produce viable seeds. On the basis of its frequency of appearance and its morphology, narrow has been assigned the genotype La La, the homozygous lanceolate. The appearance of narrow in the hybrids with broad is assumed to be conditioned by a modifier or modifiers provided by the broad parent.
There was no evidence of close linkage between lanceolate (La) and broad (e) or lanceolate (La) and potato (c).