Species Of Tagetes Research Articles

New records of the carpopodium in Compositae and its taxonomic use

The carpopodium has been recorded for the first time in 40 Compositae, species of Tolpis, Hieracium, Catananche, Microseris, Stephanomeria, Hypochoeris, Lactuca, Crepis, Vernonia, Cirsium, Centaurea, Aster, Calendula, Inula, Cosmos, Helianthus, Zinnia, and Tagetes. The evolution of the carpopodium, its functions, and possible use in taxonomy, are discussed.

Change in the solubility of crystalline Fraction I proteins correlated with change in the composition of the small subunit

Fraction I protein crystals were obtained by a simple method from four additional species in addition to seven species of Nicotiana previously reported and from Solanum melongena. Crystals were obtained neither from several other genera of the Solanaceal nor from N. debneyi, but 14C protein from the latter co-crystallized with N. tabacum Fraction I protein. Co-crystallization did not occur with 14C proteins from species of Tagetes, Allium, Beta, Brassica and Hyocyamus whose Fraction I proteins were evidently too different in their quaternary structures to occupy the same crystal lattice with N. tabacum protein. Fraction I proteins from N. gossei and N. excelsior differed in solubility as a function of the NaCl concentration. The two proteins were alike in the isoelectric point of the three primary peptides composing the large subunit, but differed in the isoelectric point of one out of four primary peptides of the small subunit; this difference was also consistent with a difference in tryptic peptide fingerprints. Proteins from N. tabacum and N. glauca differed both in the composition of their large and small subunits but did not differ in solubility. However, by changing the composition of the small subunit without changing the large subunit, the solubility of each protein was changed. The change in small subunit composition could be achieved by isolating proteins from the reciprocal F1 hybrids of N. tabacum × N. glauca where the maternal inheritance regulates the composition of the large subunit, whereas both maternal and paternal genes regulate the composition of the small subunit.

CYTOGENETIC STUDIES ON THE ORIGIN OF TAGETES PATULA. I. MEIOSIS AND MORPHOLOGY OF DIPLOID AND ALLOTETRAPLOID T. ERECTA × T. TENUIFOLIA

Towner, Joseph W. (U. California, Los Angeles.) Cytogenetic studies on the origin of Tagetes patula. I. Meiosis and morphology of diploid and allotetraploid T. erecta × T. tenuifolia. Amer. Jour. Bot. 48 (9): 743–751. Illus. 1961.—Cytological and morphological evidence is presented to show that Tagetes patula L. is an allotetraploid species (2n = 48) which probably originated by hybridization between the diploids T. erecta L. and T. tenuifolia Cav., or species closely related to them. The putative parent species are separated by strong reproductive isolation barriers, and controlled crosses between them yielded very few good seed. Most of the hybrid seedlings died before reproductive age, and the few survivors were sterile and extremely weak. At meiosis in the diploid hybrid, bivalent frequency per cell was 0–11 and averaged 4.4. Although 43.6% of the quartet stage consisted of restitution dyads, pollen was essentially all non‐viable and seed set was less than 1%. A true‐breeding, fertile, allotetraploid T. erecta‐tenuifolia was synthesized by colchicine‐doubling of the chromosome number of the F1 hybrid. In the synthetic allotetraploid, average chromosomal association was 23.97 bivalents plus 0.05 univalents, and 97.4% of MI cells had 24 bivalents; there were no multivalents, bridges, or fragments. Tagetes erecta‐tenuifolia showed a striking morphological similarity to T. patula. Both the natural and synthetic allotetraploids were intermediate between T. erecta and T. tenuifolia for nearly every character. Of 10 species of Tagetes whose chromosome numbers are known, 5 are tetraploid (2n = 48).