Dosage Effects of the Lanceolate Gene in Tomato

Abstract

In contrast to the odd‐pinnately compound leaf of the normal (+/+) tomato plant (Lycopersicon esculentum), the single‐gene mutant lanceolate (La/+) generally has a simple leaf. Lanceolate plants, also, have small fruits and flowers, weak apical dominance, and exhibit variation in the position and fusion of cotyledons. Homozygous mutants (La/La) appear in 3 different phenotypes, 1 of which, narrow, has narrow simple leaves, sterile inflorescences, and extremely weak apical dominance. The other 2, modified, and reduced, lack an organized shoot. After selfing La/ + plants for 9 generations, autotetraploids were produced with the aid of colchicine. In addition, several triploid plants arose spontaneously. The study of diploid, triploid, and tetraploid material with various proportions of the La allele revealed in many characters a graded series as a function of the La dosage. With increasing La dose, there was a gradual reduction in: (1) total leaf length; (2) the number and size of primary and secondary lateral leaflets; (3) the number and size of marginal lobes of the terminal leaflet, associated with an increase in the proportional length of the terminal leaflet. Many leaves were found with the basal lobes of the terminal leaflet resembling incompletely separated lateral leaflets. The differences in leaf shape between different genotypes came about before the leaf primordium was 3 mm long. There was a progressive delay in the initiation of lateral primordia with increasing La dosage. It is proposed that the gradual changes from compound to simple leaves with increasing La dosage are produced by successively greater restrictions of meristematic activity after the terminal leaflet is formed. With increasing proportion of La alleles, the reproductive structures showed: (1) a decrease in the number of flowers per inflorescence; (2) a decrease in the length of the sepals; (3) an increase in the proportion of flowers with dialytic anthers. Dialytic anthers had narrow adaxial lobes and were frequently twisted along their main axes. The common denominator for most trends affected by the La allele seems to be a general reduction of growth, but more so in lateral than in longitudinal growth. Histological data suggest that the reduction in lateral growth is mainly brought about by a reduction of cell division in lateral meristems.

TCP Transcription Factors Regulate the Activities of ASYMMETRIC LEAVES1 and miR164, as Well as the Auxin Response, during Differentiation of Leaves inArabidopsis

“…In addition, the stamens of these Pro35S:mTCP3 plants were occasionally fused ( Figures 1Q and 1R). These results were largely consistent with the previous report that the homozygous mutants of LA in tomato had fused cotyledons and lacked a functional SAM, whereas the heterozygous mutants had leaves with simple and lanceolate shapes (Mathan and Jenkins, 1962;Settler, 1964;Ori et al, 2007). (T) Expression of CUC2 in leaves at the eighth, ninth, and tenth positions from the wild type and those from the Pro35S:mTCP3 plants with a mild phenotype.…”

Tomato Telotrisomics: Origin, Identification, and Use in Linkage Mapping

“…The phenotype of these telotrisomics closely approximated that for La/+/+ described by Stettler (1964 Tables 2 and 3 do not correspond with eath other . These discrepancies probably owe to the fact that the progenies reported in Table 2 were in heterozygous background while those in Table 3 were in the uniform background of a highly inbred line of cv VF36, to which the telotrisomics have been made isogenic by a program of repeated backcrossing.…”

Roles of miR319 and TCP Transcription Factors in Leaf Development

“…Compared with the leaf serrations, the cotyledon boundary is likely to be tolerant against the genetic mutations in the miR319-mediated regulatory pathway. Consistently, a tomato homozygous lanceolate mutation impairs its cotyledons and shoot meristem, while a heterozygous mutation is sufficient for conversion of the originally complex leaf form into a simple form (Mathan and Jenkins, 1962;Settler, 1964;Ori et al, 2007).…”