Male Sterility Trait Research Articles

Identification of AFLP markers linked to one recessive genic male sterility gene in oilseed rape, Brassica napus

The commercial utilization of heterosis in seed yield by means of hybrid varieties is of great importance for increasing oilseed rape production in China. This requires a functional system for the production of hybrid seed. The Brassica napus oilseed rape line 9012AB is a recessive epistatic genic male sterility (GMS) two-type line, in which the sterility is controlled by two pairs of recessive duplicate sterile genes (ms1 and ms2) interacting with one pair of a recessive epistatic inhibitor gene (rf). Homozygosity at the rf locus (rfrf) inhibits the expression of the recessive male sterility trait in homozygous ms1ms1ms2ms2 plants. This study was conducted to identify molecular markers for one of the male fertility/sterility loci in the B. napus male sterility line 9012AB. Sterile bulk (BS) and fertile bulk (BF) DNA samples prepared from male sterile and male fertile plants of the homozygous two-type line 9012AB were subjected to amplified fragment length polymorphic (AFLP) analysis. A total of 256 primer combinations were used and seven markers tightly linked to one recessive genic male sterile gene (ms) were identified. Among them, six fragments co-segregated with the target gene in the tested population, and the other one had a genetic distance of 4.3 cM. The markers identified in this study will greatly enhance the utilization of recessive GMS for the production of hybrid seed in B. napus oilseed rape in China.

The mouse t complex distorter/sterility candidate, Dnahc8, expresses a γ-type axonemal dynein heavy chain isoform confined to the principal piece of the sperm tail

Heterozygosity for a t haplotype ( t) in male mice results in distorted transmission (TRD) of the t-bearing chromosome 17 homolog to their offspring. However, homozygosity for t causes male sterility, thus limiting the spread of t through the population at large. The Ca 2+-dependent sperm tail curvature phenotypes, “fishhook”, where abnormally high levels of sperm exhibit sharp bends in the midpiece, and “curlicue”, where motile sperm exhibit a chronic negative curving of the entire tail, have been tightly linked to t-associated male TRD and sterility traits, respectively. Genetic studies have indicated that homozygosity for the t allele of Dnahc8, an axonemal γ-type dynein heavy chain (γDHC) gene, is partially responsible for expression of “curlicue”; however, its involvement in “fishhook”/TRD, if any, is unknown. Here we report that the major isoform of DNAHC8 is copiously expressed, carries an extended N-terminus and full-length C-terminus, and is stable and equally abundant in both testis and sperm from +/+ and t/t animals. By in silico analysis we also demonstrate that at least three of the seventeen DNAHC8 t mutations at highly conserved positions in wild-type DHCs may be capable of substantially altering normal DNAHC8 function. Interestingly, DNAHC8 is confined to the principal piece of the sperm tail. The combined results of this study suggest possible mechanisms of DNAHC8 t dysfunction and involvement in “curlicue”, and support the hypothesis that “curlicue” is a multigenic phenomenon. They also demonstrate that the accelerated “fishhook” phenotype of sperm from +/t males is not directly linked to DNAHC8 t dysfunction.

An Arabidopsis aspartic protease functions as an anti‐cell‐death component in reproduction and embryogenesis

The components and pathways that regulate and execute developmental cell death programmes in plants remain largely unknown. We have found that the PROMOTION OF CELL SURVIVAL 1 (PCS1) gene in Arabidopsis, which encodes an aspartic protease, has an important role in determining the fate of cells in embryonic development and in reproduction processes. The loss-of-function mutation of PCS1 causes degeneration of both male and female gametophytes and excessive cell death of developing embryos. Conversely, ectopic expression of PCS1 causes the septum and stomium cells that normally die in the anther wall to survive instead, leading to a failure in anther dehiscence and male sterility. PCS1 provides a new avenue for understanding the mechanisms of the programmed cell death processes that are associated with developmental pathways in plants and makes available a useful tool for engineering the male sterility trait for hybrid seed production.

Cytogenetic Analysis of Thermosensitive Genic Male Sterility (TGMS) Recovered from a Pennisetum glaucum (L.) R. Br.×P. violaceum (Lam.) L. Rich Cross

One male-sterile plant was recovered from a cross between pearl millet (Pennisetum glaucum) and its wild progenitor P. violaceum. The behavior of male sterility was temperature dependent, as the development of pollen mother cells to pollen grains was found to be dependent on temperature. The plant showed sterility at lower temperatures while it was fertile at higher temperatures during seasonal variations. This thermosensitive male sterility trait was found to be genetically controlled based on the segregation data of backcross generation. Segregation was observed for ca. 50% of the population expressing this trait. These TGMS plants exhibited transition from fertility to sterility when mean daily temperature reduced to ca. 20°C or below, and fertility was restored above this temperature. The period of 4 to 5 d prior to anthesis was found to be most sensitive to temperature variations. Chromosomal studies on the parent plant as well as segregants showed 2n=14 with regular meiosis during non-sensitive phase (period exhibiting male-fertility) ruling out aneuploidy and/or gross chromosomal structural aberrations as a cause of male sterility. Fertility characters were also studied for TGMS and non-TGMS plants during sensitive and non-sensitive phases. Pollen grains shed from the TGMS plants were much more vulnerable than from normal plants during sensitive phase indicating poor development of the membrane and walls of the pollen grains during sterility inducing conditions. Transition characteristics from male sterility to male fertility during sensitive and non-sensitive phases for TGMS and non-TGMS plants are discussed.

Genetic Studies of a Male-Sterile, Female-Fertile Soybean Mutant

Studies on a new spontaneous male-sterile / female-fertile soybean mutant identified by the Embrapa Soybean breeding program were carried out in Londrina, PR. The mutant showing segregation for male-sterility (BR93-12879) was selected within F 4 progeny lines derived from the IAS-5 (3) X OCEPAR 9-SS1 cross performed in 1993. The F 1 , F 2 and F 3 generations of cross among heterozygous plants of the BR93-12879 line and recessive homozygous plants (male-sterile) of the T 266H (ms 1 ms 1 ), T 259H (ms 2 ms 2 ), T 273H (ms 3 ms 3 ), T 274H (ms 4 ms 4 ), T 277H (ms 5 ms 5 ) and T 295H (ms 6 ms 6 ) lines were studied to identify whether the new mutation is conditioned by a new allele or by a mutation in one of the six loci already described in the literature. The F 1 , F 2 and F 3 plants from the crosses were visually classified as male-sterile or male-fertile. Results from the allele test and inheritance study among the mutant genotype and the recessive homozygous male-sterile lines (ms 1 , ms 2 , ms 3 , ms 4 , ms 5 and ms 6 ) showed that a single recessive gene controls the male-sterile trait of BR93-12879. This gene is allele to the already described ms 1 -gene and resulted from a genetic mutation in the ms-loci.

Inheritance of male sterility in apricot

Progenies (total of 1,114 seedlings) from crosses representing all possible genotypic combinations between 4 male-fertile and 1 male-sterile apricot parents were scored for the male sterility trait. Crosses between putative heterozygous normal cultivars yielded 25% of male-sterile seedlings, which supports a previous hypothesis that male sterility is controlled by a recessive allele of one nuclear locus. Crosses between those parents and putative homozygous normal cultivars did not produce any male-sterile tree. Finally, the proportion of male-sterile progeny in crosses between a male-sterile and two male-fertile cultivars depended on the genotype of the male parent. When it was heterozygous approximately 50% of the progeny was sterile, whereas when a homozygous fertile parent was used, no male-sterile progeny was obtained. These results confirm a previously proposed model, in which the male sterility trait in apricot is controlled by a single recessive gene.

Genetics of a new male-sterility locus in pigeonpea (Cajanus cajan [L.] Millsp.).

A natural male-sterile mutant was found in the population of a short-duration pigeonpea (Cajanus cajan[L.] Millsp.) cultivar ICPL 85010. This mutant is characterized by light yellow anthers of reduced size that are devoid of pollen grains. This mutant was crossed with two pigeonpea cultivars to study its inheritance. The F1, F2, and test cross data of the two crosses suggested that this male sterility trait is genetic in origin and is controlled by a single recessivegene. The F1 (mutant x ICPL 85010) plants were crossed with translucent (ms1) and arrowhead type (ms2) genetic male steriles reported earlier to study their allelic relationships. Segregation in the three-way cross F1 and F2 populations revealed that the mutant male-sterile gene was nonallelic to ms1 and ms2 loci and it is designated ms3. The new male sterility sources in pigeonpea will help in producing high-yielding hybrids and populations in diverse phenological groups.

Cytoplasmic male sterility in the olive (Olea europaea L.)

The olive tree is usually hermaphrodite but self-incompatible. In the Western Mediterranean some cultivars are totally male-sterile. Three different male-sterile phenotypes have been recognised. To infer the genetic basis of male sterility we studied its inheritance and cytoplasmic diversity in wild (oleaster) and cultivated Mediterranean olive. In the cross Oliviere×Arbequina, the male-sterile trait was maternally inherited and affected all progenies. We also checked that both chloroplast and mitochondrial DNAs are maternally inherited. RFLP studies on chloroplast and mitochondrial DNAs revealed several cytotypes: two chlorotypes and four mitotypes in cultivars and oleaster (wild or feral Mediterranean olive). Furthermore, a total linkage desequilibrium between the CCK chlorotype and the MCK mitotype in cultivars and oleaster from different regions supports the fact that paternal leakage of organelles was not observed. The male sterility (ms 2) displayed by Oliviere, plus six other cultivars and three oleaster was strictly associated with the CCK chlorotype and the MCK mitotype. These facts suggest that Oliviere carries cytoplasmic male sterility. Male-fertile and male-sterile oleasters carrying this cytotype showed the presence of restorer alleles. This CMS might be due to a distant cross between olive taxa. The two other male-sterile phenotypes displayed by Lucques (ms 1) and Tanche (ms 3) were associated with the ME1 mitotype but we have not demonstrated CMS.

Inheritance of the Trait of Male Sterility in Cryptomeria japonica

Matings of male-sterile C. japonica and fertile elite C. japonica, as well as backcross seedlings of male-sterile trees, were carried out to clarify the genetic trait of male sterility of the C. japonica. The seeds from male-sterile C. japonica were germinated in an incubator and grown them in the greenhouse between 1994 and 1997. The seedlings were treated with 100 ppm gibberellin at early July 1994 and early July 1995 to promote the formation of male flowers. In the middle of January 1995, the male flowers of all seedlings were examined under the microscope to confirm the production of pollen. In January 1996, pollen did not developed in to the male flowers from the seedlings between the fertiled elite and backcross C. japonica. In January 1997, all seedlings of elite C. japonica produced pollen in their male flowers; however, pollen did not developed in 55 out of 120 backcrossed seedlings. This evidence suggests that the heredity pattern of male sterility in C. japonica is nuclear male sterility controlled by a pair of recessive genes.

Inheritance of an induced male-sterile trait in transgenic plants expressing an engineered unedited atp9 mitochondrial gene

Flowers of tobacco transformed with the genomic (unedited) coding sequence of the mitochondrial atp9 gene (u-atp9), fused to the yeast coxIV mitochondrial targeting pre-sequence, exhibited either semi-fertile or male-sterile phenotypes. The inheritance of the induced male-sterile trait, was first investigated on a population of 25 plants of the R0 generation and then on R1, F1 and R2 progeny of the lines H2.11 and H2.16. The analyses showed that the male-sterile character was generally inherited as a Mendelian trait for one or two loci, and that u-atp9 is involved in the male-sterile phenotype and is stably inherited in the progeny of the original transformants. Molecular investigations performed on the plants of the R0, R1 and R2 generations confirmed the genetic analyses. The final proof of the involvement of u-atp9 in the emergence of the male-sterile trait was provided from experiments dealing with the restoration of male fertility. By using antisense RNA technology, we showed that crossing male-sterile plants containing the u-atp9 transgene with transgenic plants containing the same gene in antisense orientation (as-atp9) produces F1 progeny restored to male fertility. The high expression of as-atp9 causes a dramatic reduction of u-atp9 transcript levels and suppresses their deleterious effects, resulting in normal flower development and seed production.

Nucleotide sequence, genetic organization and expression strategy of the double-stranded RNA associated with the '447' cytoplasmic male sterility trait in Vicia faba.

The entire nucleotide sequence of the double-stranded (ds) RNA associated with the unconventional '447' cytoplasmic male sterility (CMS) trait in Vicia faba was determined from overlapping cDNA clones and by RT-PCR. Confirming previous observations, it was found that the negative-strand was continuous and 17,635 nt long, while the positive-strand featured an interruption, probably a nick, that could potentially define two subgenomic RNAs of 2735 nt and 14,900 nt, with the smaller RNA being located on the 5' side. The entire positive-strand could encode a single in-frame ORF starting at the first AUG at position 42-44 and ending with a TGA at 17,517-17,519. This long potential polypeptide with a predicted molecular mass of 654,109 is the largest described to date in the plant kingdom and contains conserved amino acid sequence motifs typical of viral helicases and RNA-dependent RNA polymerases (RDRP). Only limited sequence homology was detected with the ORF B encoded by the hypovirulence-associated dsRNA of chestnut blight fungus, a dsRNA replicon similarly contained in host-derived membranous vesicles and considered to share a common ancestry with potyviruses. By contrast, the helicase and RDRP domains were in the same respective arrangement and shared extensive sequence homologies with those identified in the polyprotein encoded by the dsRNA isolated from Japonica rice, another dsRNA replicon featuring a specific nick in the positive-strand. Although no proteolytic self-cleavage activity has yet been demonstrated, it appears likely that this long ORF is a polyprotein that undergoes proteolytic maturation, with one of the polypeptides derived by self-cleavage being the determinant of the CMS trait.

Development of a Thermosensitive Genetic Male Sterile Line for Hybrid Breeding through Ovary Culture in Rice (Oryza sativa L.)

Unpollinated young ovaries from the F1 plants of the cross between UPRI 95-140, a TGMS donor, and UPRI 95-117, a good plant type line of indica rice were pretreated at 8°C for 14 days and cultured onN6 medium supplemented with lactoprotein hydrolysate 500 mg l-1 2,4-D 4.0 mg l-1 NAA 2.0 mg l-1 and BA 1.0 mg l-1. Five calli with 0.5% of callus induction were obtained. Four of these calli gave complete green plantlets possible of spontaneous dihaploids while the remaining one gave partially green plantlets onMS plant regeneration medium supplemented with casein acid hydrolysate 500 mg l-1, NAA 0.5 mg l-1 and BA 1-5 mg l-1. One of the regenerated green plantlets was identified with thermosensitive genetic male sterility (TGMS) trait. The spikelet fertility transformation of this plant was closely related to mean minimum daily and mean average daily temperatures of the 15-d thermosensltive stage prior to 5 days of heading. It presented complete spikelet sterility between May 1 and Sept 5 and 0.5 to 12.3% and 0.5 to 41.5% of seed set between Sept 18 and Nov 1, 1995 and March 10 to april 27, 1996, respectively at Pantnagar in the northern India. And the line in H2 present homogenous performance with optimum spikelet fertility transformation in Wet season, 1996. This line is being used to develop two-line heterotic hybrids.

The dynamics of gynodioecy in Plantago lanceolata L. I. Frequencies of male-steriles and their cytoplasmic male sterility types

The maintenance of a gynodioecious breeding system (hermaphrodites and male-steriles) was studied in Plantago lanceolata. Cytoplasmic-nuclear inheritance is important in the maintenance of male-steriles. The male-sterile trait is cytoplasmically based (CMS), and male fertility can be restored by nuclear genes. Male-sterile frequencies differ among populations. Several hypotheses can be considered. (1) In each population a different equilibrium could be optimal because of environmentally dependent fitnesses. (2) None of the populations has reached an equilibrium (yet). (3) The populations are in different phases of a dynamic equilibrium, i.e. limit cycles. The last two explanations both predict a dynamic process, a continuous change within populations. Sex phenotype frequencies and their underlying gene frequencies were assessed. Sex phenotype frequencies changed over years within populations. We showed that these changes resulted from changes in genotype composition, which favours the two hypotheses (2 and 3) that predict a dynamic process. CMS-type frequencies were estimated using mtDNA markers. Among populations, CMS types differed in frequencies. CMSI and CMSIII seemed to exclude each other, and CMSII types occurred in all populations. In all populations, CMSI appeared to be less restored than the other CMS types. This was not expected on the basis of either of the two theoretical models that included dynamics (hypotheses 2 and 3).

The dynamics of gynodioecy in Plantago lanceolata L. I. Frequencies of male-steriles and their cytoplasmic male sterility types

The maintenance of a gynodioecious breeding system (hermaphrodites and male-steriles) was studied in Plantago lanceolata. Cytoplasmic-nuclear inheritance is important in the maintenance of male-steriles. The male-sterile trait is cytoplasmically based (CMS), and male fertility can be restored by nuclear genes. Male-sterile frequencies differ among populations. Several hypotheses can be considered. (1) In each population a different equilibrium could be optimal because of environmentally dependent fitnesses. (2) None of the populations has reached an equilibrium (yet). (3) The populations are in different phases of a dynamic equilibrium, i.e. limit cycles. The last two explanations both predict a dynamic process, a continuous change within populations. Sex phenotype frequencies and their underlying gene frequencies were assessed. Sex phenotype frequencies changed over years within populations. We showed that these changes resulted from changes in genotype composition, which favours the two hypotheses (2 and 3) that predict a dynamic process. CMS-type frequencies were estimated using mtDNA markers. Among populations, CMS types differed in frequencies. CMSI and CMSIII seemed to exclude each other, and CMSII types occurred in all populations. In all populations, CMSI appeared to be less restored than the other CMS types. This was not expected on the basis of either of the two theoretical models that included dynamics (hypotheses 2 and 3).

Effects of CMS types and restorer alleles on plant performance in Plantago lanceolata L.: an indication for cost of restoration

AbstractIn gynodioecious species, male steriles co‐occur with hermaphrodites. Usually, the male sterile trait is maternally inherited, hence it is called Cytoplasmic Male Sterility (CMS). Nuclear loci restore male fertility in combination with their ‘own’ specific cytoplasmic types. In theory, two fitness components are important for the maintenance of this breeding system: a fitness advantage of the male steriles, and costs of restoration. The costs of restoration are alleged negative pleiotropic effects of restorer alleles.In this study the effects of different CMS types on plant performance and the cost of restoration were assessed in two experiments with Plantago lanceolata L. Biomass production differed significantly between the CMS types studied. In order to assess the costs of restoration, hermaphrodites with or without restorer alleles for a CMS type other than its own were compared. The studied restorer alleles caused a reduction in weight per seed, but the number of seeds produced was unaffected. The estimated cost of restoration measured as reduction of seed biomass was 13% for restorer alleles for CMSI. However, in the second experiment no pleiotropic effects of restorer alleles were detected, either because the assumptions for the experimental set‐up were not valid or the costs of restoration may not always be expressed.

Inheritance of Male Sterility in Lesquerella fendleri

Lesquerella fendleri (Gray) Wats., Brassicaceae, is a potential oilseed crop native to the southwestern U.S. The seed oil contains hydroxy fatty acids, similar to castor. Unique properties of the oil, along with coproducts, allow additional applications that would not be in competition with castor. Plants with vestigial anthers were discovered in a bulk population growing in the greenhouse in 1993. The inheritance of the trait was investigated the following three crop seasons. Crosses were made among sterile and fertile plants and reciprocals among fertile plants. Chi-square results indicate the male sterility trait is expressed by a recessive nuclear gene with cytoplasmic influence restoring fertility. Cytoplasmic male sterile lines can be utilized for development of hybrids. Development of lines without male sterility should lead to higher yields than current bulk populations of lesquerella. Hybrid plants and higher yields will enhance the commercialization potential of this new, alternative crop.

Transgenic male-sterile plant induced by an unedited atp9 gene is restored to fertility by inhibiting its expression with antisense RNA.

We have previously shown that the expression of an unedited atp9 chimeric gene correlated with male-sterile phenotype in transgenic tobacco plant. To study the relationship between the expression of chimeric gene and the male-sterile trait, hemizygous and homozygous transgenic tobacco lines expressing the antisense atp9 RNA were constructed. The antisense producing plants were crossed with a homozygous male-sterile line, and the F1 progeny was analyzed. The offspring from crosses between homozygous lines produced only male-fertile plants, suggesting that the expression antisense atp9 RNA abolishes the effect of the unedited chimeric gene. In fact, the plants restored to male fertility showed a dramatic reduction of the unedited atp9 transcript levels, resulting in normal flower development and seed production. These results support our previous observation that the expression of unedited atp9 gene can induce male sterility.

RAPD MARKERS ASSOCIATED WITH SINGLE GENE TRAITS IN IPOMOEA TRIFIDA

Ipomoea trifida (2X = 30) is purported to be the wild Ipomoea species most closely related to the commercially grown Ipomoea batatas (sweetpotato, 6X = 90). The two species can be crossed with much difficulty, but seed occur rarely. Ipomoea trifida has been shown to possess some agronomically desirable traits that are missing in sweetpotato (e.g., sweetpotato-weevil resistance). Attempts to locate morphological markers in the diploid trifida that would serve as indicators of successful crosses with sweetpotato resulted in the identification of two traits controlled by single genes: nectary color and male sterility. Both traits require flowering to identify, and flowering is often difficult to induce in Ipomoea species. An analysis of I. trifida accessions using RAPD molecular markers was undertaken. Using a segregant population resulting from crossing a green nectary, fertile plant with a yellow nectary, male, sterile plant, RAPD analysis resulted in clear markers for both the nectary color trait and the male sterility trait. These traits now can be identified in the absence of flowering plants.

Observations on Inheritance of Male Sterility in Apricot

Male sterility is defined as the deviant condition in normally bisexual plants when no viable pollen is formed (Frankel and Galun, 1977). Male sterility has been exploited as an effective tool to aid hybrid seed production in many crops. Using this trait, seed producers can transform one inbred from a planned hybridization into a “female” line, thereby ensuring seed of hybrid origin on the male-sterile parent (Janick, 1972). However, male sterility is an undesirable characteristic in scion cultivars of Prunus to be used for fruit production because this trait would restrict yield in large monocultural production blocks. From the viewpoint of an apricot breeding program, male sterility is a characteristic to be avoided (Scott and Weinberger, 1944). A review of apricot (Prunus armeniaca L.) pollen fertility (Burgos, 1991) indicated that only two cases of male-sterile apricot cultivars (‘Arrogance’ and ‘Colorao’) have been described (Garcia et al., 1988). In this paper we show where several male-sterile trees were observed in progenies from controlled hybridizations in P. armeniaca, and we propose a preliminary inheritance model of the trait. Nine different crosses with a total of 378 trees were scored for the male sterility trait. Male-sterile anthers can be distinguished visually from normal fertile anthers during the bloom period. Shrunken, discolored anthers are indicative of male-sterile pollen and provide a sharp contrast to the swollen, yellow appearance of normal pollen-fertile anthers (Connors, 1927). Several samples of shrunken, discolored anthers were chosen randomly to

Chloroplast ultrastructure and fluorescence response of oilseed rape containing male-sterile radish cytoplasm

The production of hybrid seed is facilitated if one parent possesses a male-sterile cytoplasm. Introduction of the cytoplasm of male-sterile radish (Raphanus sativus L.) into rapeseed (Brassica napus L.) results not only in transfer of the desirable male-sterile trait but induces a chlorophyll defect in the backcrossed male-sterile plants. In this study we show that the defect manifests itself in two different ways in the alloplasmic plants: a) smaller and fewer chloroplasts with an impaired ultrastructure and b) an increase in chlorophyll fluorescence. Defective chloroplasts were characterized by a reduction in both the number and size of grana, the latter due to poor stacking of thylakoids and with frequent discontinuity in the intergranal thylakoid systems. The changed chloroplast morphology and the increase in chlorophyll fluorescence are probably the cause of the lowered photosynthetic efficiency associated with the alloplasmic plants. We propose that the deficiency is the result of incompatibility between the genomes of the radish chloroplast and the rapeseed nucleus. Supporting this hypothesis are studies of male-sterile rapeseed plants in which, by protoplast fusion, the radish chloroplasts were substituted by those of normal male-fertile rapeseed. Such plants showed complete restoration of their photosynthetic potential and displayed both normal chloroplast ultrastructure and normal levels of chlorophyll fluorescence.