In vitro production of male sterile Zinnia elegans

Summary Axillary bud proliferation of Zinnia elegans Jacq. was accomplished from vegetative bud explants of greenhouse-grown plants. Photoperiod extension via metalarc lamps in the greenhouse stock plant environment significantly increased both the quantity and quality of explants. Shoot cultures initiated from axillary buds of identified male sterile plants proliferated best on a medium with 1M BAP. Microshoots exhibited 80% rooting on media without growth regulators, and 100% acclimatization of rooted plantlets was accomplished in a lighted, high humidity chamber. In vitro- produced male sterile plants were more compact, more heavily branched, and demonstrated earlier flowering than seed-propagated plants. These male steriles were cross pollinated to male fertile lines to verify their ability to serve as a uniform female parent.     

Cytoplasmic-genetic male sterility in radish (Raphanus sativus L.). Identification of maintainers,inheritance of male sterility and effect of environmental factors

Summary Research has been carried out on identification of maintainers for cytoplasmic-genetic male sterile lines in Japanese and European radish, on the mode of inheritance of male sterility and on the effect of environmental factors on the expression of this character.In a Japanese radish population and in most early European radish populations maintainers were found in high frequency. Segregations for male sterility in full-sib families, obtained by crossing male sterile and male fertile plants, and in backcross generations, indicated that male sterility is probably determined by one dominant and two recessive independently acting genes, but also minor genes may be involved.The expression of male sterility was not affected by seasonal influences. In some populations a reversible temperature effect was found, most ms plants occurred at 10, 14 and 26°C and most mf plants at 17 and 20°C.     

Cytoplasmic male sterility in quinoa

Summary The quinoa cultivar Apelawa carries both normal and male sterile cytoplasms. Plants with male sterile cytoplasm produce flowers characterized by the complete absence of anthers and prominent exsertion of stigmas. Intraspecific crosses between male sterile quinoa plants and normal male fertile pollen donors consistently produced male sterile offspring under greenhouse conditions. Interspecific hybridization between male sterile quinoa plants and the related weed species Chenopodium berlandieri resulted in offspring with partial restoration of male fertility. The male sterile cytoplasm found in Apelawa has potential for use in the production of quinoa hybrids, although a more complete restorer system than that identified in C. berlandieri would be desirable.     

Natural male sterile mutant in hot chilli (Capsicum annuum L.)

Summary A natural male sterile mutant was recovered from the normal population of chilli cv. CA 452-1. The male sterility in the mutant was governed by a single recessive gene ms. The excessive vegetative growth provided easy identification of male sterile plants in the seedling stage. The plant was found to be promising for hybrid seed production.     

Analysis of genic male sterility in Brassica oleracea

Summary The male sterility system MS-1 of Brassica oleracea was studied in order to elucidate if nucleo-cytoplasmic interactions determine this system. Crosses of male sterile MS-1 genotypes with heterozygous MS-5 genotypes gave fully fertile F₁ progenies. Selfing of seven F₁ plants resulted in five F₂ populations showing a 9:7 segregation ratio and two a 3:1 ratio for fertile and male sterile plants. Two F₂ progenies deviated from the expected 9:7 or 3:1 segregation ratios for fertile and male sterile plants. Thermosensitivity and distortion of the meiosis are suggested as the causal factors underlying the deviation of the segregation ratios. It was concluded that nuclear factors determine the male sterility in the MS-1 system, because the presence of a nucleocytoplasmic interaction in this system should have given only a 3:1 segregation ratio for fertile and male sterile plants in the F₂ generation.     

The effect of gibberellic acid on male fertility in bread wheat

Summary The effect of gibberellic acid (GA₃) on male fertility was investigated in wheat. Greenhouse and field experiments were carried out. GA₃ induced high levels of male sterility both in gibberellin (GA)-sensitive and GA-insensitive genotypes. The optimum concentration was 2000 ppm of GA₃ when applied at successive sprays. The critical period for GA₃ treatment, in the general sense, extended from glume differentiation to premeiotic interphase in the oldest florets of the spike, though differences were found between GA-sensitive and GA-insensitive genotypes in the extension of this period. The effect of GA₃ on plant height was also studied. The potential use of GA₃ as a chemical hybridizing agent in wheat breeding is discussed.Abbreviations GA gibberellin - GA₃ gibberellic acid - ms male sterility Scientific Paper GEN-810 of the Instituto de Gen]'etica, CICA, INTA, Castelar, Argentina     

Genetic relationship between some cytoplasmic male sterility systems in sorghum

Summary Genetic analysis of cytoplasmic male sterility systems in sorghum was undertaken by evaluating a set of 25 A×B crosses and another set of 171 A×R crosses. Male steriles included diverse sources reported from U.S.A. and India. Fertility restoration in crosses was assessed by studying pollen sterility under microscope and seed setting under selfed earheads. Male fertility restorers are identified for diverse cytoplasms. Accordingly the diverse cytoplasms are grouped and listed in the increasing order of their sterility as A₁ & CK 60A A₂ A₄ M31-2A & M35-1A (A₄ tentative) A₃ & VZM2A G₁A (A₅ tentative) and consequently fertility restoration also becomes difficult in the same order for utilization in the breeding programmes. Among the non-milo cytoplasms, A₂ among exotics and maldandi (M31-2A and M35-1A) among Indian sources, can be utilised for practical exploitation in breeding programmes.     

Cytoplasmic differentiation using near-isonuclear polycytoplasmic male sterile lines in pearl millet

Summary Five near-isonuclear polycytoplasmic versions of 81A₁ and two of Pb 402A₃ male sterile lines of pearl millet (Pennisetum typhoides), along with their corresponding maintainer lines (81B and Pb 402B) were studied for 14 agronomic and two disease traits, and for isozymes of peroxidase in anthers and leaves for assessing cytoplasmic differences. Significant differences among isonuclear polycytoplasmic lines of both 81A₁ and Pb 402A₃, having the same genome and variable cytoplasms, were observed for several agronomic traits. Banding pattern of peroxidase isozymes revealed clear cut differences among cytoplasms. The results provide evidence for the influence of cytoplasmic factors on the phenotypic expression of nuclear genes.     

Cytological and genetical studies of a male sterile celery

Summary The inheritance and nature fo male sterility of a cerley (Apium graveolens L.) strain (MS1) is reported. Male sterility in MS1 is determined by a a recessive genotype for a single locus. Tests for linkage with the isozyme chromosome markers SDH-1 and PGM-1 were negative. MS1 male sterility was associated with a defective tapetum characterized by prominent vacuoles and premature degeneration. The stamens in the male sterile strain persisted in the flowers up to stigma receptivity, while in the male fertile plants they dropped before style expansion. The male sterile flowers produced normal amounts of nectar, resulting in cross pollination by various species of pollinators. It was estimated that the sterile strain produced 30% less seed than normal male fertile. Its possible use for hybrid celery seed production is discussed.Research supported by grants from the California Celery Research Board and BARD I-483-82.     

A new source of cytoplasmic male sterility in sunflower

Summary Interspecific substitutions of the nucleus of Helianthus annuus (2n=34) cv. Saturn into the cytoplasm of H. petiolaris (2n=34) by successive backcrossing, resulted in progenies with indehiscent anthers containing white, rather than normal yellow, pollen. Further backcrossing by cv. Saturn failed to restore pollen shed, suggesting that the male sterility was cytoplasmic. In vivo germination tests of pollen from 23 such plants from eight BC₅ lines, indicated complete pollen sterility for 14 plants, but normal seed set, suggesting that female fertility was not affected. Meiosis in all plants examined was normal.Crosses between seven sources of pollen-fertility restorer, one collection of wild H. annuus, and an existing source of cytoplasmic male sterility, resulted in a high frequency of plants with normal pollen shed in all F₁ progenies. However, no normal pollen shed was evident in F₁ progenies for similar crosses between BC₅ male-steriles and three of the seven restorer sources, nor for the single wild H. annuus evaluated. The foregoing suggests that the backcross substitution lines are a new source of cytoplasmic male sterility. The inheritance of restoration of pollen shed was complex and not fully elucidated. Some data suggested that two independent, complementary, dominant genes were required, but others indicated two to three independent, dominant genes.     

A new cytoplasmic male sterility source from wild Helianthus annuus

Summary A new cms source, ANN-5, was found in wild Helianthus annuus. This source showed high stability under different conditions in 1991 and 1992. All progenies from crosses of this source with several stable B-lines and restorer lines, which are homozygous for the gene which restores Leclercq's source of male sterility, were completely male sterile. Flower contained pistils and atrophied stamens. The cytological analysis showed that pollen mother cell degeneration took place in a premeiotic stage.     

Identification and inheritance of male sterility in groundnut (Arachis hypogaea L.)

Summary Some plants without pods but with gynophores were observed in two F₄ progenies of two crosses of goundnut (Arachis hypogaea L.). The flowers on these plants had translucent white anthers with no or a few sterile pollen grains. Three such plants in the succeeding generation were hand pollinated with pollen from a short-duration Indian cv. JL 24. The resulting F₁ hybrid plants (male sterile x JL 24) were normal. Chi-square tests for segregation for male fertile and male sterile plants in F₂ and F₃ generations indicated that the male sterility in these crosses of groundnut is governed by two recessive genes. We designate these genes as ms₁ and ms₂ with ms₁ms₁ms₂ms₂ being a male sterile genotype.Submitted as ICRISAT J. A. No. 1812.     

Digenic nature of male sterility in pepper (Capsicum annuum L.)

Summary A cross was made between two nearly isogenic lines differing for male sterility genes, viz. ms₁ms₁Ms₂Ms₂ s Ms₁Ms₁Ms₂ms₂. F₁ plants yielded F₂ populations which segregated either in 3:1 or 9:7 ratios of fertile vs male sterile individuals. Test crosses between male sterile and male fertile sibs in the 9:7 segregating populations provided a few lines in which most of the progenies were male sterile. A 3:1 ratio model of male steriles vs fertiles is suggested and the value of the system is discussed.Contribution A.R.O. Agricultural Research Organization, The Volcani Center, Bet Dagan 50 250, Israel No. 3703-E, 1992 series.     

Genetics of thermosensitive genic male sterility in rice

Summary Inheritance of thermosensitive genic male sterility (TGMS) in Norin PL12 and IR32364TGMS and their allelic relationship were studied from F₁, F₂ testcross (TC) and F₃ generations of the crosses made with the two mutants and several fertile tester parents. F₂, TC and F₃ segregation behavior for pollen and spikelet fertility indicated that the TGMS trait in the two mutants was controlled by a single recessive gene. Allelic relationship studies indicated that TGMS genes of the two mutants were different. Since TGMS gene in Norin PL12 has been designated as tms ₂ , the TGMS gene present in IR32364TGMS is tentatively designated as tms ₃ (t) until allelic test is done with another TGMS gene (tms ₁ ) reported from China in a line 5460S seeds of which were not available.     

Induction of cytoplasmic male sterility in the seed progeny derived from artificially-synthesized interspecific chimera in Brassica

We produced artificial interspecific chimeras by in vitro grafting, and obtained cytoplasmic male sterile (CMS) variants in the seed progenies derived from backcrossing the chimera with one of the mother plants, B. campestris cv. Komatsuna. The induced CMS has been stably inherited by crossing it with `Komatsuna', not with `Ruby Ball' cabbage. The nuclear component of CMS is complete `Komatsuna' type in morphology, chromosome number (2n = 20) and Southern blot using ribosomal 17S RNA gene as a probe. PCR analysis by using mitochondrial atpA primer showed the complete `Ruby Ball' type, suggesting nuclear-cytoplasmic exchange. However, Southern blot patterns were different among those of the CMS and both parents by using atpA. Recombination or some unknown change is supposed in the mitochondrial genome via the processes of synthesis and propagation of the chimeras.     

Photoperiod-sensitive cytoplasmic male sterility in wheat with Aegilops crassa cytoplasm

Summary Triticum aestivum cv. Norin 26 with Aegilops crassa, Ae. juvenalis or Ae. vavilovii cytoplasm (all D² type) has been studied relative to its photoperiodic response of male sterility and fertility restoration patterns. Alloplasmic lines of Norin 26 with a D² type cytoplasm showed almost complete male sterility under long-day conditions (15 h), but high male fertility under short-day conditions (14.5 h). No significant influence of temperature on reduction in male fertility was observed. Thus, this type of male sterility is called photoperiod-sensitive cytoplasmic male sterility (PCMS). The PCMS is expressed in the form of pistillody of stamens. Histological studies revealed that there were incomplete ovule-like structures instead of tapetal cells and pollen grains in the pistillate stamens. The floret differentiation stage of the plant is the stage that is sensitive to photoperiod. The PCMS can be used as a new means for hybrid wheat production, named two-line system. The PCMS line is maintained and multiplied by self-fertilization under short-day conditions, and hybrid seed can be produced by crossing the PCMS line with a pollinator line under long-day conditions. In contrast to the system of hybrid wheat production using the T. timopheevi cytoplasm, the present system requires only PCMS and pollinator lines.Abbreviation CS Chinese Spring - N26 Norin 26 - PCMS photoperiod-sensitive cytoplasmic male sterility     

Genetic analysis of male sterility in rice mutants with environmentally influenced levels of fertility

Summary Twenty-six male sterile plants grown in the field were recovered in the M7 generation from ethyl methane sulfonate-treated material of the rice cultivar M-201. Fertility increased five-fold when ratooned plants from the field were grown in a growth chamber with a 12 hour daylength. Crosses between mutant and normal fertile cultivars produced fertile F₁ plants. Female fertility was normal as judged by percent seed set from unbagged panicles of parental and recombinant lines. Transgressive segregation for fertility was observed for all crosses in the F₂ and F₃ generations. Five of 37 F₃ male sterile plants showed moderate levels of seed fertility under winter greenhouse conditions and reduced seed set when transplanted to summer field plots. Fertility data from reciprocal crosses suggested cytoplasmic factors had little or no effect on levels of male sterility in the mutant lines. Chi-squared analyses of F₂ and F₃ generation results indicated male sterility of the mutants is conditioned by two nuclear genes with epistatic effects.     

Development of photoperiod-sensitive cytoplasmic male sterile (PCMS) wheat lines showing high male sterility under long-day conditions and high seed fertility under short-day conditions

A “two-line system” using photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm under long-day photoperiods (≧15 h) has been proposed as a means of producing hybrid varieties in common wheat (Triticum aestivum). The PCMS line is maintained by self-pollination under short-day conditions, and hybrid seeds can be produced through outcrossing of the PCMS line with a pollinator line under long-day conditions. Our previous studies revealed that PCMS lines showing complete male sterility under long-day conditions are necessary for practical hybrid wheat breeding, especially to obtain high hybrid purity in F₁ seeds. Furthermore, practical PCMS lines should have high seed fertility under short-day conditions, which is associated with female fertility. Wheat cv. Norin 26 with Ae. crassa cytoplasm exhibits high seed fertility under short-day conditions, and cv. Fujimikomugi with Ae. crassa cytoplasm shows high male sterility under long-day conditions. Here we developed practical PCMS lines derived from the F₁ generation of Norin 26 and Fujimikomugi (with Ae. crassa cytoplasm) that were then backcrossed to elite wheat lines.     

Interaction between the eui gene and thermo-sensitive genic male sterility in rice

Panicle enclosure is a typical phenotype of almost all male-sterile rice lines. An elongated uppermost internode (eui) mutant exhibited notably rapid elongation of the uppermost internode at the heading stage; this is considered as a potential mechanism to eliminate panicle enclosure. We developed thermo-sensitive genic male-sterile (TGMS) eui mutants that were characterized by notably elongated uppermost internodes. The elongation of the uppermost internode in the TGMS eui mutant Changxuan 3S (CX) is mainly attributed to an increase in cell number and cell elongation, the latter being the more significant process. Temperature treatments revealed that the effects of temperature on panicle exsertion were similar to those on fertility and that the most temperature-sensitive stage coincides with the period from the formation of the pollen mother cell to meiosis during panicle initiation. These results indicate that elongation increases as temperature decreases and that the expression of the eui gene is more efficient at low temperatures than at high temperatures. In hybrid rice seed production using the TGMS eui mutant, the temperature range should be optimized at 24–28°C in order to preserve the development of completely male-sterile pollen and to eliminate panicle enclosure. Consequently, by using TGMS eui rice lines, gibberellin application can be avoided, thereby reducing the cost of hybrid seed production. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Inheritance of male fertility restoration of the cytoplasmic-nuclear male-sterile line NJCMS1A of soybean [Glycine max (L) Merr.]

At present, no report on inheritance of male fertility restoration has been released, yet more than 10 cytoplasmic-nuclear male-sterile soybean lines as well as their maintainers and restorers have been developed. Based on our previous work, 25 restorers for the male-sterile line NJCMS1A were identified and the inheritance of male fertility restoration for these restorers was studied. The results showed that F₁s between NJCMS1A and its restorers were completely male-fertile. The numbers of fertile and sterile plants in the F₂ population of Cross I (NJCMS1A × N23601) and Cross II (NJCMS1A × N23683) corresponded to a segregation ratio of 15:1, and the numbers of non-segregation lines, 3:1 segregation lines and 15:1 segregation lines in F_2:3 of the same two crosses fitted a 7:4:4 genotypic segregation ratio. The testcross BC₁F₁s between the F₁s of the above two crosses and NJCMS1A, NJCMS1B showed a 3:1 segregation ratio. Accordingly, it was inferred that two pairs of duplicate dominant genes controlled the male fertility restoration of NJCMS1A in both crosses. Meanwhile, F₂ of other 23 crosses between NJCMS1A and its 23 restorers showed a fertility segregation ratio of 3:1 or 15:1. The F₁s of the five testcrosses between NJCMS1A and the F₁s of five crosses selected from the above 23 crosses showed that fertility segregation was 3:1 in BC₁F₁s between NJCMS1A and F₁s of the crosses of which fertility segregation fitted 15:1 in F₂ population, while fertility segregation in BC₁F₁s was 1:1 for those fertility segregation fitted 3:1 in F₂ population. Allelism tests showed that restore genes of all restorers in the experiment were allelic to two pairs of dominant genes. All results showed that some restorers bore one pair of dominant restore gene and the others bore two pairs of duplicate dominant gene. The mechanism of F₁ male sterility of the cross N8855 × N2899 was discussed.