Studies on the origin of the lemon

Abstract

The legend for figure 10 on page 373 does not agree with the orientation of the photograph. To read correctly, the photo should be turned 90 degrees clockwise with the rule at the bottom.Hybrids of 'Eureka' and 'Lisbon' lemons were studied along with their parents and possible ancestral types to investigate the phylogeny of Citrus Zintort (L.) Burm. f. Data on leaf, flower, and fruit characters were collected and analyzed for inheritance of specific characters and for the amount of variability. Leaf and rind-oil components were analyzed by gas chromatography. Those hybrids producing suscient microspores were studied for meiotic abnormalities. Segregation of all characters studied demonstrates the heterozygosity of C. limo*. Color (anthocyanin) development in flower buds and young leaves is most likely controlled by a single dominant gene. Color on the young stems may be controlled by two dominant genes, one of which also controls color in flower buds and young leaves. Preformed root initials are most likely controlled by one, and leaf articulation by at least two genes.Characters specific to C. medica were present in the lemon progeny, indicating definite involvement of the citron in the lemon ancestry. Some characters indicate a possible common gene source with C. amadfolk and C. jambhiri. The deviation of some hybrids from their parents or proposed ancestors indicates a contributing gene source that has not yet been identified.The presence of much sterility and wide segregation of characters argues against the specific standing of C. & m m . It has a common gene source with the citron-lime group, and it may be a derived hybrid involving some unidentified taxa. The overlapping geographical distribution of various Citrus taxa at the assumed place of origin of C. 1imo.n further suggests the possibility of intercrowing or common origin of various Citrus species.

The relationships among lemons, limes and citron: a chromosomal comparison

“…Biochemical and molecular data suggest that all lemons are hybrids, with low genotypic variability and high heterozygosity (Malik et al, 1974;Herrero et al, 1996;Roose et al, 1998;Nicolosi et al, 2000). These data also indicate C. medica as one of the ancestral species of limes and lemons.…”

“…They are certainly hybrids, as indicated by the heterozygosity in chromosome markers B, C, D, F L , and G, as well as in 5S and 45S rDNA sites. This pronounced chromosomal heterozygosity can explain the genetic heterozygosity revealed by morphological markers, isoenzyme patterns, essential oils and molecular markers (Malik et al, 1974;Barrett and Rhodes, 1976;Moore and Castle, 1988;Herrero et al, 1996;Nicolosi et al, 2000). It can also explain the meiotic abnormalities reported for C. limon (Longley, 1925;Raghuvanshi, 1962).…”

Phylogenetic study of Fraction I protein in the genus Citrus and its close related genera.

“…These results suggest that the species in the two groups including Fortunella species, C. hystrix, C. latipes, C. grandis and C. reticulata, might have been the next ones to have differentiated in an early period. C. limon is, however, included in group 3, since other studies have shown that this species is a hybrid origin (Malik et al 1974;Scora 1975). We also consider that C. limon may be a hybrid derived from species included in group 1, 3 or 6 that contain SS c. C. ichangensis included in group 4 contains SS b which is very close to SS c. It is most likely that this species has been derived from group 3 that has SS c. Since group 1 contains SS c and d, we propose that C. aurantifolia, C. jambhiri, C. paradisi, C. aurantium, C. sinensis, C. tachibana, C. junos, C, limonia, C. nobilis and some cultivars of C. reticulata have hybrid origins.…”

Metabolic Fingerprinting of Citrus Cultivars and Related Genera Using HPLC and Multivariate Analysis

“…Based on morphological characteristics, lemon was supposed to be a hybrid of citron (C. medica) and lime (C. aurantifolia) (Swingle, 1943;Malik et al, 1974;Scora, 1975). Barrett and Rhodes (1976) reported that lemon is a trihybrid of citron, pummelo and Microcitrus and had a higher proportion of citron genes.…”