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.

CYTOLOGY OF 2n POLLEN FORMATION IN DIPLOID ALFALFA, MEDICAGO SATIVA

1979 ◽  
Vol 21 (4) ◽  
pp. 525-530 ◽  
Author(s):  
Nicholi Vorsa ◽  
E. T. Bingham
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Pollen Grains ◽  
Genetic Constitution ◽  
2N Pollen ◽  
Diploid Parent ◽  
2N Gamete ◽  
Medicago Sativa L ◽  
Pollen Formation ◽  
Mother Cells

Four diploid (2x) clones of alfalfa, Medicago sativa L., which produced good seed set when used as male parents in 4x-2x crosses were selected for study. The 2x clones descended from 2x haploids of cultivated 4x alfalfa. Fertility in the 4x-2x cross was due to the production of pollen with the unreduced chromosome number (2n pollen) from the 2x parent. The cytological mechanism of 2n pollen formation was found to be disorientation of spindles at metaphase II in up to 38% of the pollen mother cells. Thus, both n and 2n pollen were produced by all four diploids examined. Normal spindles at metaphase II were oriented such that they defined the poles of a tetrahedron and resulted in normal tetrads in a tetrahedral arrangement. Disoriented spindles were basically parallel to each other and resulted in formation of dyads and occasionally a triad. Dyads developed into two 2n pollen grains; triads developed into one 2n and two n pollen grains. Since both n and 2n pollen grains are produced by the diploids, they can be maintained as diploids or they can be used as male parents in crosses to tetraploids. The genetic constitution of 2n pollen resulting from parallel spindles is similar to that expected after first division restitution of meiosis and much of the heterozygosity of the diploid parent is conserved in the gametes. The 2n gamete mechanism has potential application in germplasm transfer and in maximizing heterozygosity in tetraploid hybrids.

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.

Identification and selection for salt tolerance in lucerne (Medicago sativa L.)

1984 ◽  
Vol 35 (2) ◽  
pp. 239 ◽  
Author(s):  
CL Noble ◽  
GM Halloran ◽  
DW West
Keyword(s):  
Salt Tolerance ◽  
Medicago Sativa ◽  
Recurrent Selection ◽  
Leaf Damage ◽  
Shoot Number ◽  
Two Generations ◽  
Medicago Sativa L ◽  
Selection For ◽  
Efficiency Of Selection ◽  
Chloride Concentrations

Variation existed between plants of the lucerne (Medicago sativa L.) cultivar CUF 101 for dry matter production, shoot number and length, and leaf damage when grown for 70 days under 250 mM NaCl (15 h photoperiod, 20�C day, 10�C night). Salt tolerance evaluation using the criteria percentage leaf damage (percentage of total number of leaves with complete or partial necrosis) and length of the main shoot, isolated plants which showed salt tolerance of reasonably high heritability (h2=0.41). Two generations of recurrent selection for tolerance significantly increased the mean population tolerance without decreasing production under non-saline conditions. While both sodium and chloride concentrations of the shoot were lower in the tolerant than in less tolerant plants, chloride was more closely associated with salt tolerance than sodium. Sodium and chloride concentrations in the roots did not vary with the level of salt tolerance. No association of shoot and root potassium concentration with tolerance was evident. Selection for salt tolerance in lucerne plants using percentage leaf damage of less than 10% as the main criterion should give a rapid response to selection. The efficiency of selection may be increased if selection is based on the efficiency of chloride exclusion from the shoots and/or the level of chloride tolerated by the shoots prior to leaf damage becoming evident.

Effect of phenotypic recurrent selection on genetic diversity of non-dormant multifoliolate lucerne (Medicago sativa L.) populations

2015 ◽  
Vol 66 (11) ◽  
pp. 1190 ◽  
Author(s):  
A. Odorizzi ◽  
E. M. C. Mamani ◽  
P. Sipowicz ◽  
B. Julier ◽  
J. Gieco ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Medicago Sativa ◽  
Recurrent Selection ◽  
Selection Process ◽  
Phenotypic Recurrent Selection ◽  
Total Genetic Diversity ◽  
Significant Difference ◽  
Medicago Sativa L ◽  
Two Populations

The nutritional quality of lucerne (alfalfa, Medicago sativa L.) plants correlates positively with the presence of multifoliolate (MF) leaves. Using phenotypic recurrent selection, we developed populations with an increased percentage of MF expression from 6.7% in the original population (C0) to 77.7% in the fourth cycle (C4). The effect of selection on genetic diversity within and among populations was evaluated. The populations C0 and C4 were represented by 40 plants genotyped by using 25 simple sequence repeats (SSR). The number of alleles per locus was large in both C0 and C4, averaging 6.28. The within-population genetic diversity (HE) overall estimation was 0.723 for C0 and 0.726 for C4, the absence of significant difference between the two populations indicating that the genetic diversity was as large in C4 as in C0. The Nei’s population differentiation (GST) overall estimation was 0.013, meaning that only 1.3% of the total genetic diversity was between populations and 98.7% was within populations. An efficient selection process was conducted without any increase in inbreeding or genetic drift.

Quantitative genetic analysis of in vitro callus proliferation in alfalfa

1997 ◽  
Vol 77 (2) ◽  
pp. 225-229 ◽  
Author(s):  
G. A. Kielly ◽  
S. R. Bowley
Keyword(s):  
Medicago Sativa ◽  
Combining Ability ◽  
Variance Components ◽  
Recurrent Selection ◽  
Experimental Population ◽  
Reciprocal Effects ◽  
Callus Production ◽  
Callus Proliferation ◽  
Medicago Sativa L

Genetic variability exists for in vitro callus growth within plant species, including alfalfa (Medicago sativa L.). The objective of this study was to investigate, using diallel crosses, the genetic variance components of in vitro callus production in tetraploid alfalfa. Nine genotypes were randomly chosen from among 60 plants from the cultivar Saranac and the experimental population OAC81-120R, which were previously characterized as being able to initiate callus. The group of nine plants was divided and crossed to generate two, six-plant diallel sets (A and B) with reciprocals; and the progeny were evaluated for callus production. Significant (P < 0.01) differences were found among crosses and for general combining ability (GCA) effects in both diallels. Specific combining ability (SCA) and reciprocal effects were found to be nonsignificant (P < 0.05). Estimates of heritability (h2) for callus production on a plot mean basis were 73% and 61% for diallel A and B, respectively. Since the heritabilities were high, and no reciprocal effects were detected, breeding strategies employing recurrent selection should result in the development of high in vitro callus producing populations. Key words: Medicago sativa L., callus proliferation, tissue culture, quantitative genetics, heritability, alfalfa

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).

ALFALFA (Medicago sativa L.) CULTIVADA EN CAMPECHE, MÉXICO Y SU INTEGRACIÓN LOCAL EN LA ALIMENTACIÓN DE CORDEROS EN CONFINAMIENTO

2018 ◽  
Vol 11 (9) ◽  
Author(s):  
CC. Castillo-Águilar
Keyword(s):  
Medicago Sativa ◽  
Pennisetum Purpureum ◽  
Medicago Sativa L

Se comparó el uso de diferentes dietas con base en heno de alfalfa cultivada (Medicago sativa L.) en Campeche y su relación con un concentrado comercial y pasto Taiwán (Pennisetum purpureum), T1=concentrado comercial, T2=T1+heno de alfalfa, T3=T1+pasto Taiwán, T4=heno de alfalfa. Se evaluó el comportamiento productivo y metabólico de corderos en sistema intensivo utilizando 20 corderos machos con encaste de Pelibuey, Dorper y Black Belly de 12.5±1 kg de peso vivo (PV). Se midió el consumo de materia seca total (CMS), la ganancia diaria de peso (GDP), la conversión alimenticia (CA), y la digestibilidad in situ de la materia seca (DISMS). También fueron evaluados el pH, nitrógeno amoniacal (NH3) y la concentración de ácidos grasos volátiles (AGV) en líquido ruminal. La mejor GDP en gramos por día, de 234 g (p?0.05) se obtuvo en el T2; en contraste, el T3 mostró la menor GDP. La dieta que incluyó la mezcla de heno de alfalfa y concentrado mejoró significativamente las condiciones de las variables pH, NH3 y AGV (p?0.05).

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