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Somatic Analysis of a Mutable Trait for Anthocyanin Pigmentation in Alfalfa 1
Author(s) -
Talbert L. E.,
Bingham E. T.
Publication year - 1986
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1986.0011183x002600040041x
Subject(s) - biology , petal , anthocyanin , botany , variegation (histology) , shoot , white (mutation) , cutting , genetics , gene
Mutable anthocyanin pigmentation in alfalfa ( Medicago sativa L., 2 n =4 x =32) is characterized by streaks and sectors of pigment in flower petals and seeds that are otherwise white. Similarly, hypocotyls and stems of mutable plants have streaks and sectors of pigment. The mutable condition was discovered in a plant in the F 2 generation of a cross between ‘Ranger’ and a white‐flowered stock. In the present study, 21 mutable plants descending from the original mutable plant were examined over several cycles of regrowth in the field and greenhouse for 2 yr. All 21 mutable plants eventually produced a branch or a shoot with entirely purple flowers. Two of the 21 mutable plants produced shoots with fewer streaks per petal than the main plant, and one of the 21 plants produced a shoot with white flowers. Clonal lines of shoots with changes in the mutable condition were propagated by shoot cuttings. In one case all variations in mutable frequency as well as white flowers were propagated by cuttings from one plant. Self‐progeny of purple‐, mutable‐, and white‐flowered propagules of this plant segregated for similar frequencies of purple‐, mutable‐, and white‐flowered plants. This result indicated that the germline was the same among propagules and that changes in flower pigmentation were periclinal chimeras. Histological examination revealed that pigmentation is in the epidermal cell layer of the flower petals and in the outermost subepidermal layer of hypocotyls and stems. Mutation to the dominant state commonly occurs relatively late in development of petals, seed coats, and stem tissue, and results in streaks of pigment. Mutation to the dominant state earlier in development occurs at a much lower frequency and results in purple flowered shoots that usually are periclinal chimeras. Mutation to the dominant state in the germline results in purple‐flowered progeny that segregate along with mutable‐ and white‐flowered progeny in self and testcross families. Allelism tests indicated that the mutable trait is attributable to a mutable allele at the C 2 locus. The allele frequently mutates from the recessive to the dominant state of C 2 . Mutable‐flowered progeny inherit the allele in its mutable state. The mutable state may be caused by the interaction of a transposable element with a dominant allele at the C 2 locus.