Leucaena Cytogenetics in Relation to the Breeding of Low Mimosine Lines1
- Ventura Gonzalez,
- James L. Brewbaker and
- D. Elizabeth Hamill2
Cytological and biochemical studies were conducted in the genus Leucaena in relation to the breeding of low mimosine, high yielding forage types of L. leucocephala (Lam.) de Wit. Meiotic and mitotic chromosomes were studied in the following species; L. leucocephala and L. pulverulenta (Schlecht) Benth. (2n = 56); L. trichodes Benth., L. lanceolata (S. Wats.), L. stenocarpa (Urban), and accessions designated “L. buitenzorg” (2n = 52) and “L. esculenta” (2n = 104).
All species of Leucaena hybridized freely, insofar as they were tested. The 80-chromosome hybrids of L. pulverulenta ✕ L. leucocephala were grown and studied in detail. Seed recovery and yields of these hybrids were high, despite meiotic chromosome pairing of 26 bivalents and 28 univalents. F2 plants ranged widely in chromosome numbers.
Assays for the toxic alkaloid, mimosine, were conducted on F1, F2, and backcross progenies from a cross of high ✕ low mimosine strains of L. leucocephala. Despite the apparent polyploidy of the species, wide variations were observed in mimosine contents of the segregating generations, enabling the selection of plants with less than 30% of the normal mimosine values (ca. 4% dry weight) of tropical forage strains. The correlation between mimosine and protein contents for related F2 segregants from high ✕ low mimosine crosses was not significant (r = .60).Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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