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Unreduced gametes in diploid Medicago and their importance in alfalfa breeding

Unreduced gametes in diploid Medicago and their importance in alfalfa breeding 122 72 72 1 1 F. Veronesi A. Mariani E. T. Bingham Istituto di Miglioramento Genetico Vegetale Università degli Studi di Perugia Perugia Italy Centro di Studio per il Miglioramento Genetico delle Piante Foraggere C.N.R. Perugia Italy Department of Agronomy University of Wisconsin Madison Wis USA Summary In the genus Medicago , it is known that 2n gametes have been important in the evolution and breeding of cultivated alfalfa, which is a natural polysomic polyploid (2n=4x=32), however little is known on the frequency of male and female 2n gametes in diploid relatives of alfalfa. To obtain data on the frequency of 2n gametes, more than 12,000 2x–4x and 4x–2x crosses were made in 1982 at Madison (USA). Diploid parents in crosses were from four populations of M. coerulea , two of M. falcata and one diploid population of cultivated M. sativa which was derived by haploidy. The tetraploid seed parent in the crosses was a male-sterile M. sativa clone and vigorous tetraploid M. sativa plants were used as pollen parents. Each of 274 diploid plants was utilized both as male and as female. Of the 548 cross combinations, 266 crosses produced variable quantities of seeds which were sown in 1983 in a greenhouse at Perugia (Italy); the plants were subsequently space transplanted in the field in 1984. The identification of ploidy level of these genotypes was made on the basis of morphological characters, plant fertility, pollen stainability and chromosome counts. Of the 515 plants analyzed, the majority behaved as normal tetraploids indicating that many diploid plants produced 2n gametes. Diplogynous and diplandrous gamete production was not correlated with each other, which indicated a different genetic control of 2n sporogenesis in the 2 sexes. Only 4 F 1 triploid plants confirmed the presence of a very effective triploid block in alfalfa. In consequence, bilateral sexual polyploidization is a more likely alternative for the origin of tetraploid alfalfa than triploid bridges. The present study showed that it is possible to efficiently identify genotypes able to produce high frequencies of 2n gametes within natural populations of diploids Medicago that are useful in alfalfa breeding. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png TAG Theoretical and Applied Genetics Springer Journals

Unreduced gametes in diploid Medicago and their importance in alfalfa breeding

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References (20)

Publisher
Springer Journals
Copyright
Copyright © 1986 by Springer-Verlag
Subject
Life Sciences; Biotechnology; Agriculture; Biochemistry, general; Plant Biochemistry; Plant Sciences; Plant Genetics & Genomics
ISSN
0040-5752
eISSN
1432-2242
DOI
10.1007/BF00261451
pmid
24247768
Publisher site
See Article on Publisher Site

Abstract

122 72 72 1 1 F. Veronesi A. Mariani E. T. Bingham Istituto di Miglioramento Genetico Vegetale Università degli Studi di Perugia Perugia Italy Centro di Studio per il Miglioramento Genetico delle Piante Foraggere C.N.R. Perugia Italy Department of Agronomy University of Wisconsin Madison Wis USA Summary In the genus Medicago , it is known that 2n gametes have been important in the evolution and breeding of cultivated alfalfa, which is a natural polysomic polyploid (2n=4x=32), however little is known on the frequency of male and female 2n gametes in diploid relatives of alfalfa. To obtain data on the frequency of 2n gametes, more than 12,000 2x–4x and 4x–2x crosses were made in 1982 at Madison (USA). Diploid parents in crosses were from four populations of M. coerulea , two of M. falcata and one diploid population of cultivated M. sativa which was derived by haploidy. The tetraploid seed parent in the crosses was a male-sterile M. sativa clone and vigorous tetraploid M. sativa plants were used as pollen parents. Each of 274 diploid plants was utilized both as male and as female. Of the 548 cross combinations, 266 crosses produced variable quantities of seeds which were sown in 1983 in a greenhouse at Perugia (Italy); the plants were subsequently space transplanted in the field in 1984. The identification of ploidy level of these genotypes was made on the basis of morphological characters, plant fertility, pollen stainability and chromosome counts. Of the 515 plants analyzed, the majority behaved as normal tetraploids indicating that many diploid plants produced 2n gametes. Diplogynous and diplandrous gamete production was not correlated with each other, which indicated a different genetic control of 2n sporogenesis in the 2 sexes. Only 4 F 1 triploid plants confirmed the presence of a very effective triploid block in alfalfa. In consequence, bilateral sexual polyploidization is a more likely alternative for the origin of tetraploid alfalfa than triploid bridges. The present study showed that it is possible to efficiently identify genotypes able to produce high frequencies of 2n gametes within natural populations of diploids Medicago that are useful in alfalfa breeding.

Journal

TAG Theoretical and Applied Genetics – Springer Journals

Published: Apr 1, 1986

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