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Backcrossing Tetraploidy into Diploid Medicago Falcata L. Using 2n Eggs
Author(s) -
Bingham E. T.
Publication year - 1990
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/cropsci1990.0011183x003000060038x
Subject(s) - biology , backcrossing , germplasm , ploidy , hybrid , pollen , medicago sativa , botany , stamen , chromosome number , pollination , chromosome , karyotype , gene , genetics
Chromosome manipulation may be useful in germplasm enhancement where wild and cultivated forms are at different ploidy levels. In this study, tetraploidy was backcrossed into a diploid Medicago falcata L. synthetic (2 x WISFAL‐1) in a series of five 2 x ‐4 x backcrosses using 2 x WISFAL‐1 as the recurrent parent and the 4 x M. sativa L. as the nonrecurrent parent. Since nearly all 2 x M. falcata plants produced a low background frequency of 2 n eggs, it was necessary to pollinate only =500 2 x flowers with 4 x pollen to obtain one to five tetraploid hybrids per 2 x plant. The new tetraploid form of M. falcata , designated 4 x WISFAL‐1, contains 98% M. falcata germplasm and 2% M. sativa . The broad‐based synthetic 4 x WISFAL‐1 has all the characteristics of 2 x WISFAL‐1 except that it has larger vegetative and reproductive organs, and crosses directly with cultivated alfalfa. The 4 x WISFAL‐1 can be used for gene transfer from M. falcata to cultivated alfalfa. The yellow flower color of 4 x WISFAL‐1 also can be used as a codominant flower‐color marker at the tetraploid level. Two narrow‐based tetraploid populations were developed by backcrossing to PI 231731 and PI 258754, respectively, using 4 x WISFAL‐1 as the nonrecurrent parent. Thus, 4 x WISFAL‐1 is also useful in germplasm enhancement of individual diploid Pis by elevating them to the tetraploid level for direct crossing with cultivated M. sativa .