Genetics, cytology, and crossing behavior of an alfalfa (Medicago sativa) mutant resulting in failure of the postmeiotic cytokinesis

1983 ◽  
Vol 25 (4) ◽  
pp. 390-397 ◽  
Author(s):  
T. J. McCoy ◽  
L. Y. Smith
Keyword(s):  
Medicago Sativa ◽  
Low Frequency ◽  
Recessive Gene ◽  
Microspore Mother Cell ◽  
Developmental Sequence ◽  
Single Recessive Gene ◽  
Single Nucleus ◽  
Medicago Sativa L ◽  
Jumbo Pollen ◽  
Is Failure

During pollen investigations on diploid alfalfa (Medicago sativa L.) several plants were identified which produced "jumbo" pollen. The cause of the jumbo pollen is failure of the postmeiotic cytokinesis. These plants produce a single, four-nucleate microspore from one microspore mother cell (MMC) rather than the normal four, single-nucleate microspores from one MMC. Subsequent gametophyte development is characterized by fusion of the four nuclei into a single nucleus in most cases (range of 80 to 100%), followed by a developmental sequence comparable to normal alfalfa. Mature 4n male gametophytes are thus formed from 2n sporophytes. Genetic control of the postmeiotic cytokinesis failure is by a single recessive gene, designated jp. Although a low frequency of jumbo pollen does germinate (range of 3.1 to 37.8%), crossing studies demonstrate jumbo pollen is incapable of effecting fertilization. The use of the jp mutant in breeding studies, and interspecific hybridization research, is discussed.

THE NATURE AND INHERITANCE OF A YELLOW-LEAF CHARACTER IN MEDICAGO SATIVA L.

1962 ◽  
Vol 40 (1) ◽  
pp. 89-93 ◽  
Author(s):  
W. R. Childers
Keyword(s):  
Medicago Sativa ◽  
Leaf Morphology ◽  
Histological Study ◽  
Recessive Gene ◽  
Yellow Leaf ◽  
Single Recessive Gene ◽  
Green Leaves ◽  
Normal Green ◽  
Leaf Character ◽  
Medicago Sativa L

An alfalfa mutant with yellow cotyledons and yellow leaves is described. The few seedlings that live to maturity are dwarfs. The character is determined by a single recessive gene (Xantha-1 or X1) inherited tetrasomically. A histological study of the leaf morphology indicated that the tissues of the mutant have similar structure to those of green leaves. The plastids are well formed but take up stain weakly in comparison with the plastids in normal green leaves.

THE INHERITANCE AND HISTOLOGY OF A CHLOROPHYLL-DEFICIENT CHARACTER IN MEDICAGO SATIVA L.

1961 ◽  
Vol 39 (4) ◽  
pp. 847-853 ◽  
Author(s):  
W. R. Childers ◽  
H. A. McLennan
Keyword(s):  
Recessive Gene ◽  
Single Recessive Gene ◽  
Mesophyll Cells ◽  
Genetic Studies ◽  
Continuous Layer ◽  
Mesophyll Tissue ◽  
Plant Stage ◽  
Chlorophyll Production ◽  
Medicago Sativa L ◽  
Palisade Cells

Further support for tetrasomic inheritance in alfalfa was shown from genetic studies of a chlorophyll-deficient seedling character. The character was determined by a single recessive gene for which the symbol Viridis-1 or v1 is proposed. At the mature-plant stage, low and intermediate classes for chlorophyll production were observed. Histological examination and chlorophyll analyses confirmed this classification. The low-chlorophyll-producing class was characterized by a lack of plastids in the leaf blades although some plastids occurred in mesophyll tissue around the midrib. The intermediate chlorophyll-deficient class was characterized by yellowish-green leaf blades, associated with colorless palisade cells that overlay a single continuous layer of mesophyll cells in which the plastids were well developed.

THE STAGES AT WHICH FROST INJURY OCCURS IN ALFALFA

1966 ◽  
Vol 44 (11) ◽  
pp. 1471-1483 ◽  
Author(s):  
C. G. Greenham
Keyword(s):  
Medicago Sativa ◽  
Cell Membranes ◽  
Low Frequency ◽  
Maximum Resistance ◽  
Frost Injury ◽  
Medicago Sativa L ◽  
Frozen State ◽  
Minimum Resistance

This investigation deals with the injury caused to four varieties of alfalfa (Medicago sativa L.), under freezing–thawing conditions comparable with those of Australian tableland regions.Evidence is presented to show that the intactness of cell membranes influences the magnitude of the low-frequency resistance attained in frozen tissues.Measurements of the maximum resistance attained during freezing, the proportionate drop in resistance after freezing, and the minimum resistance attained after freezing, are considered in relation to two subsequently determined criteria of injury. The results are interpreted as showing that injury occurs in tissue during freezing, in the frozen state, and during thawing.Brief comments follow concerning causes of injury at the various stages, factors responsible for hardiness, and the procedure necessary for selecting the most hardy genotype.

HEXAPLOID ALFALFA, MEDICAGO SATIVA L.: ORIGIN, FERTILITY AND CYTOLOGY

1969 ◽  
Vol 11 (2) ◽  
pp. 359-366 ◽  
Author(s):  
E. T. Bingham ◽  
A. Binek
Keyword(s):  
Medicago Sativa ◽  
Low Frequency ◽  
Field Testing ◽  
Pollen Stainability ◽  
Ovule Number ◽  
Medicago Sativa L ◽  
Seed Increase ◽  
Genetic Bases

Two spontaneously occurring hexaploids, 6-1 and 6-2, 2n = 6x = 48, were discovered among tetraploid plants of the variety 'Saranac'. They were selfed, crossed with each other and with diploid (2x), triploid (3x), and tetraploid (4x) alfalfa. Self and cross progeny of 6-1 and 6-2 were all hexaploid; 2x-6x crosses produced a plant with 32 chromosomes; 3x-6x crosses produced hexaploids probably due to unreduced triploid gametes; and 4x-6x crosses produced plants with 32, 34, 35, 36, 37, 38, 40, and 56 chromosomes. Thus many additional hexaploids, two pentaploids, 2n = 40, and a septaploid, 2n = 56, were obtained.Chromosome associations were mostly bivalents, with a low frequency of univalents and quadrivalents in hexaploids with six sativa genomes or five sativa and one falcata genome. Pollen stainability was in excess of 95%, ovule number averaged 12 per carpel, and several grams of hexaploid seed were produced from hand crosses. Five different hexaploid synthetics with narrow and wide genetic bases were produced for future seed increase and field testing. The value of hexaploids in breeding and cytogenetic research was discussed.

Further studies on the determination of cold hardiness in Trifolium repens L. and Medicago sativa L.

1960 ◽  
Vol 11 (1) ◽  
pp. 1 ◽  
Author(s):  
CG Greenham ◽  
H Daday
Keyword(s):  
Medicago Sativa ◽  
Trifolium Repens ◽  
Cold Hardiness ◽  
Cold Treatment ◽  
Low Frequency ◽  
Resistance Index ◽  
Medicago Sativa L ◽  
Trifolium Repens L ◽  
Probe Measurements

This paper deals with probe measurements of low frequency resistance (RLF), high frequency resistance (RHF), and resistance index (= 100 x RLF/RHF), for the determination of cold hardiness or the injury caused by cold treatments. Populations of white clover (Trifolium repens L.) were subjected to different periods of freezing. Discrimination between treatments could be made in terms of RLF, RHF, and resistance index, though discrimination in terms of RHF is poor. The rest of the paper deals with lucerne (Medicago sativa L.). Measurements were made after a cold treatment on field plants consisting of four commercial strains and their F1 crosses, and also on F2 seedlings. RLF and the resistance index appear to be equally good predictors for the recovery of strains or of individual plants from such populations. The Appendix deals with measurements on commercial (tetraploid) plants, diploids, and colchicine-produced tetraploids.

Cytogenetic analysis of interspecific hybrids between alfalfa (Medicago sativa L.) and M. rhodopea Velen.

Genome ◽  
1987 ◽  
Vol 29 (6) ◽  
pp. 853-858 ◽  
Author(s):  
C. R. Denton ◽  
T. J. McCoy
Keyword(s):  
Medicago Sativa ◽  
Embryo Culture ◽  
Pollen Germination ◽  
Interspecific Hybrids ◽  
Backcross Progeny ◽  
Microspore Mother Cell ◽  
Triploid Hybrid ◽  
Pollen Stainability ◽  
Medicago Sativa L ◽  
High Level

Interspecific hybrids between diploid (2n = 2x = 16) Medicago sativa L. and diploid (2n = 2x = 16) M. rhodopea Velen., were recovered using an ovule–embryo culture methodology. Most hybrids were vigorous, and morphological comparisons demonstrated that F1 hybrids were generally intermediate between that of the parents. Peroxidase isozyme phenotypes of the F1 hybrids confirmed hybridity. The chromosome number of most of the hybrids was diploid (2n = 2x = 16), with the exceptions of two triploids (2n = 3x = 24) and two tetraploid (2n = 4x = 32) plants. Chromosome pairing configurations in diploids were almost exclusively eight bivalents or seven bivalents and two univalents, indicating a high level of homology between the M. sativa and M. rhodopea genomes. However, the one triploid hybrid analyzed had only 0.4 trivalents per microspore mother cell indicating preferential pairing of parental genomes. Pollen stainability, pollen germination, and fertility of the diploid F1 hybrid plants were very low; however, it was possible to obtain backcross progeny (BC1) from seed. Pollen stainability, pollen germination, and fertility of the BC1 plants were also very low; however, most BC1 plants had workable levels of male and female fertility. The utilization of M. rhodopea in studies of the evolution of hexaploid Medicago species is discussed. Key words: interspecific hybrids, ovule–embryo culture, isozymes, Medicago.

Meiotic mutants of Medicago sativa show altered levels of α- and β-tubulin

Genome ◽  
2000 ◽  
Vol 43 (1) ◽  
pp. 166-171 ◽  
Author(s):  
Anna Mariani ◽  
Prisca Campanoni ◽  
Silvia Gianì ◽  
Diego Breviario
Keyword(s):  
Medicago Sativa ◽  
Recurrent Selection ◽  
2N Gametes ◽  
Spindle Orientation ◽  
Meiotic Mutants ◽  
Plant Microtubules ◽  
2N Gamete ◽  
Medicago Sativa L ◽  
Jumbo Pollen ◽  
Β Tubulin

We have analysed the level of accumulation of α- and β-tubulin polypeptides in flowers collected from different meiotic mutants of alfalfa (Medicago sativa L.). The H33 mutant previously identified as a producer of male and female gametes with the somatic chromosome number (2n gametes) as a result of defective spindle orientation or, more rarely, abnormal cytokinesis, showed a higher level of α- and β-tubulin compared to control diploid plants and approximately the same level as control tetraploid plants. A higher level of tubulin was likewise observed in diploid plants displaying abnormalities in spindle orientation and cytokinesis, which had gone through 3-4 cycles of phenotypic recurrent selection to increase 2n gamete production. A similar analysis was performed on another class of Medicago meiotic mutants characterized by production of 4n pollen (jumbo pollen, due to the absence of cytokinesis at the end of meiosis) and 2n eggs. Again, the level of α- and β-tubulin was found to be higher in the mutants than in diploid controls. We conclude that meiotic defects, such as abnormal spindle orientation or cytokinesis leading to the formation of 2n gametes, determine an increased level of tubulin, the main constituent of plant microtubules (MTs). Key words: meiotic mutants, 2n gametes, cytoskeleton, α- and β-tubulin.

Organisation de la variabilité enzymatique des populations marocaines de luzerne (Medicago sativa L.): structures géniques et génotypiques

Genome ◽  
1989 ◽  
Vol 32 (1) ◽  
pp. 120-128 ◽  
Author(s):  
A. Birouk ◽  
Y. Dattée
Keyword(s):  
Medicago Sativa ◽  
Significant Role ◽  
Allelic Diversity ◽  
Low Frequency ◽  
The Other ◽  
Good Discrimination ◽  
Mountainous Regions ◽  
Hardy Weinberg Equilibrium ◽  
Medicago Sativa L ◽  
Fixation Indices

Five enzymatic loci have been analyzed electrophoretically to study the genic and genotypic structures of 20 populations of alfalfa (Medicago sativa L.) from Morocco. Five different geographical origins were considered: Ziz, Drâa and Dadès (three oases in the Sahara), Demnate, and oases from mountainous regions. For comparison, three cultivars (African, Moapa, Europe) and four populations (one from Sudan, two from Spain, and one from Provence) of foreign origin were included in the study. The genic structures of the above 27 populations or cultivars allowed a good discrimination among populations and origins. The alleles with low frequency played a significant role in the discrimination and the discrimination was better when established on the basis of allelic diversity than on genotypic structures. The Flemish cultivar Europe differed from all other mediterranean material (African, Moapa, Provence, Morocco populations) but closely resembled two Spanish ecotypes from Mielga. The cultivars African and Moapa proved to be different from the Morocco populations. The latter could be divided into two different genic pools: one consisted of the Demnate populations, the other grouped populations of the Sahara and mountainous oases with no clear distinction between geographical origins. Genotypic structures based on the analyses of 30 plants from each population or cultivar did not allow to discriminate among populations. To study fixation indices and verify the panmictic equilibrium hypothesis, the number of specimen per population or cultivar had to be increased for a few populations. All the populations or cultivars analyzed showed a lack of heterozygous plants and the hypothesis of a Hardy–Weinberg equilibrium could not be accepted. Frequencies of monogenic individuals and digenic duplexes were high, but tetragenic individuals were infrequent.Key words: alfalfa, isozymes, genic structures, genotypic structures, infrequent alleles.[Journal translation]

Cone clusters in jack pine

1986 ◽  
Vol 16 (6) ◽  
pp. 1180-1184 ◽  
Author(s):  
Thomas D. Rudolph ◽  
Nicholas C. Wheeler ◽  
Narinder K. Dhir
Keyword(s):  
Low Frequency ◽  
Recessive Gene ◽  
Jack Pine ◽  
The Other ◽  
Single Recessive Gene ◽  
Seed Cone

Regularly repeated seed cone clustering on two jack pine (Pinusbanksiana Lamb.) trees, one in Alberta, Canada, and the other in Wisconsin, U.S.A., is described. The clusters on the Alberta tree apparently result from the replacement of dwarf shoots by ovulate cones; those on the Wisconsin tree apparently result from replacement of staminate cones by ovulate cones. The low frequency of cone clustering in open-pollinated progenies of the two trees suggests that the clustering trait may be controlled by a single recessive gene.

Estimación de biomasa aérea de forrajes de invierno bajo riego a través de un dron

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
Francisco Gavi Reyes ◽  
César Botello-Aguillón ◽  
Leonardo Tijerina-Chávez ◽  
Arturo Galvis-Spíndola ◽  
Rodrigo Roblero-Hidalgo
Keyword(s):  
Medicago Sativa ◽  
Avena Sativa ◽  
Medicago Sativa L

E Objetivo: Desarrollar un procedimiento para estimar biomasa con imágenes digitales captadas desde un dron y modelación 3D (ID-Dron-3D) aplicable en alfalfa (Medicago sativa L.) y avena forrajera (Avena sativa L.). Diseño/metodología/aproximación: Con una cámara digital acoplada al dron se obtuvieron imágenes antes de la cosecha de los cultivos, que fueron procesadas con software para luego estimar volumen de biomasa. En cada cultivo se midió altura de la planta y área cosechada, volumen aparente y real de biomasa, y peso de biomasa fresca y seca. Resultados: Con base en el análisis de regresión se obtuvieron modelos lineales a una p<0.05 para predecir: biomasa fresca en avena (R2=0.70) y alfalfa (R2 =0.47); y biomasa seca en avena (R2=0.78) y en alfalfa (R2=0.31) mediante ID-Dron-3D. Limitaciones del estudio/implicaciones: Considerando las R2 de los modelos obtenidos, los resultados en la avena forrajera fueron mejores, respecto a los detectados en alfalfa, lo cual se puede deber a la mayor variabilidad de la cobertura vegetal, ya que, en algunas unidades de muestreo, las plantas de alfalfa no cubrían completamente el suelo. Hallazgos/conclusiones: El rendimiento de biomasa fresca y seca de ambos cultivos se correlacionó significativamente con su respectivo volumen aparente estimado con imágenes digitales tomadas desde un dron y su procesamiento 3D (ID-Dron-3D).

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