Andromonoecious Plants Research Articles

Identification of molecular markers for selection of supermale (YY) asparagus plants

The research was aimed to elaborate a method for selection of male plants (XY, YY) and female ones (XX) as well as for identification of supermale genotypes (YY) among male phenotypes. The population obtained by self-pollination of andromonoecious plants was analysed. In order to identify the bands differentiating the male from the female genotypes, Bulk Segregant Analysis (BSA) was carried out. Primers identified by BSA analysis were used for RAPD amplification on the template of the male and female individuals. Among the products obtained by the use of primer OPB-20, some bands were linked with sex. A band of about 700 bp was found in all female plants, and in 4 phenotypically male specimens. In the male plants, the band showed a much lower intensity, compared with the female specimens. It seems that this fragment can be linked to the X chromosome in the investigated specimens. In the female specimens with XX karyotype, template duplication occurs and hence the band intensity is twice as high as in the XY karyotype. Three male plants did not include the OPB-20-700 fragment so they could potentially have the supermale (YY) karyotype. If the obtained marker proved its usefulness for identification of supermale plants, it could become a valuable tool facilitating breeding work.

Plasticity in Sex Expression of Spinach (Spinacia oleracea) Regenerated from Root Tissues

The sex expression of spinach (Spinacia oleracea L.) was modified by a procedure where plants were regenerated from root callus of spinach over three successive generations. Somatic embryos obtained from the root callus of female or male plants were grown in vitro under long day conditions until flowering. Although the regenerants derived from somatic embryos derived from female plants were all female at the first generation, few progenies produced male flower organs and expressed gynomonoecy in subsequent generations. Once the female plants regenerated into gynomonoecy, they never expressed complete femaleness at post generation. However, the male plants easily altered into andromonoecy at subsequent generations, and several andromonoecious plants showed the sex reversion at post generation, although this phenomenon did not occur in the female progenies. No absolute sex conversion was found in both female and male progenies. The plasticity of the sex expressions of spinach indicates that female and male individuals might essentially be capable of generating both flower organs.

Functions of staminate flowers in andromonoecious Pseudocymopterus montanus (Apiaceae, Apioideae)

AbstractThe pollen donor and pollinator attractor hypotheses are non‐exclusive alternative explanations for the functions of the staminate flowers of andromonoecious plants. We tested assumptions and predictions of both hypotheses using the andromonoecious perennial Pseudocymopterus montanus (Apiaceae, Apioideae), in which staminate flowers are approximately one‐third as massive as perfect ones and sequentially blooming umbels bear varying proportions of staminate flowers. We confirmed that larger umbels receive more visits than smaller ones. We demonstrated that fluorescent dye is a suitable analog of P. montanus pollen and that larger umbels donate more dye to nearby recipient umbels than do smaller ones. We showed that experimental removal of staminate flowers lowers fruit set only in primary umbels. We used stepwise multiple regressions to examine the effects of staminate flowers on xenogamous pollination, overall (xenogamous and geitonogamous) pollination and fruit set. The regressions revealed significant effects of staminate flowers only for cross pollination of primary umbels. We concluded that in P. montanus, staminate flowers function primarily as pollen donors.

Sexual modification of female spinach seeds (Spinacia oleracea L.) by irradiation with ion particles.

The female seeds of a spinach plant (Spinacia orelacea L.) were exposed to He (12.5 MeV/n) and C (18.3 MeV/n) ions in order to investigate the effects of ion particles on sex expression. He ions did not affect germination rates or flowering at doses up to 50 Gy. C ions did not affect germination rates or flowering at doses up to 15 Gy, but a dose of 25 Gy resulted in many plants with morphological aberrations. When unexposed female plants were grown without cross-fertilization for 10 weeks after sowing, 5.6-14.3% of the plants produced anthers from female flowers. These sex-modified plants could self-pollinate and form seeds, which expressed only female organs. Conversely, gynomonoecious plants were induced from these female seeds by exposure to He ions (5-50 Gy) and C ions (5-25 Gy) without any difference in the rates of flowered progeny. Moreover, andromonoecious plants were induced from female seeds by exposure to He ions at 50 Gy. These results suggest that the sex of a spinach plant is expressed as a flexible phenotype, converging from female to gyno- and andromonoecy after exposure to ion particles.

Differentiation of the timing of flower abortion in Tilia japonica

AbstractThe sex expression of Tilia japonica is functional andromonoecy (an andromonoecious system with abortion of perfect flowers). Some of protandrous flowers are aborted after shedding pollen grains and thus are functionally male flowers (FMF). When both male and female organs are retained in a flower, the plants can more flexibly regulate sex allocation, or resource allocation to male and female functions than true andromonoecious plants, which is considered as an adaptive significance of functional andromonoecy. However, the plants have to pay some costs of female organ in FMF. For functional andromonoecious plants, there is a conflict between flexibility and cost in determining the timing of flower abortion, or arrest investing in female functions in a flower. We clarified that (i) differentiation of the timing of flower abortion caused two types of FMF: short‐style (SS) and normal‐style (NS) flowers; (ii) SS can be produced at a lower cost than NS, and (iii) plants having NS can flexibly regulate sex allocation following a sudden change in conditions. Hence, we concluded that differentiation of the timing of flower abortion makes a compromise of the conflict. We also found that NS is more frequent than SS, and we discuss the adaptive significance of keeping potential fertility.

Inheritance, distribution and biology of andromonoecy in the agamic complex of the Maximae (Panicoideae)

Panicum maximum belongs to the agamic complex of the Maximae Panicoideae) which includes two other species, P. infestum Anders., P. trichocladum K. Schum., and several morphologically intermediate types. Andromonoecy and hermaphroditism have been recorded in this complex, but their distribution depends on the species, the level of ploidy, the mode of reproduction and the geographical origin. In particular, hermaphroditism appears to exist only in polyploid apomicts of the species P. maximum and was more frequent in maritime regions. Andromonoecy showed a monogenic and recessive inheritance. In andromonoecious plants, flowering of the male flower occurred later than that of the hermaphrodite flower within the spikelet. This flowering discrepancy varied between clones in respect of both mean and variance. All results are discussed in terms of the evolutionary process involved.

Sex allocation and reproductive success in the andromonoecious perennial Solanum carolinense (Solanaceae). I. Female success

Relative allocation of resources to growth vs. reproduction has long been known to be an important determinant of reproductive success. The importance of variation in allocation to different structures within reproductive allocation is somewhat less clear. This study was designed to elucidate the importance of allocation to vegetative vs. reproductive functions, and allocation within reproductive functions (sex allocation), to realized female success in an andromonoecious plant, Solanum carolinense. Allocation measurements were taken on plants in experimental arrays exposed to natural pollination conditions. These measurements included total flower number, the proportion of flowers that were male, flower size, and vegetative size. Flower number explained the majority of the variation among individuals in their success-that is, there was strong selection for increased flower production. There was also selection to decrease the proportion of flowers that were male, but neither flower size nor vegetative size (a measure of overall resource availability) were direct determinants of female success. After Bonferroni corrections for multiple comparisons, most phenotypic correlations among the traits measured were nonsignificant. Thus, in this andromonoecious species there is not a strong relationship between resource availability (vegetative size) and female success, and female success is instead determined by the relative production of the two different flower types.

The quantitative genetics of sex allocation in the andromonoecious perennial, Solanum carolinense (L.)

The quantitative genetics of allocation to sexual functions was examined in the andromonoecious plant, Solanum carolinense. A restricted maximum likelihood (REML) analysis was employed to determine heritabilities and genetic and environmental correlations for flower number, the proportion of those flowers that were male, and the size of flower parts (corolla diameter, pistil length, and anther length and width) in each of three populations used in a diallel crossing design. All floral characters were highly heritable. The sizes of flower parts were positively genetically correlated with one another, which will restrict the independent evolution of these parts. Negative genetic and environmental correlations exist between flower size and proportion male flowers, indicating the potential for the evolution of individuals with either many, small male flowers or few, large, cosexual flowers. The high heritabilities of the traits examined as well as the genetic correlations among them indicate the potential for the evolution of gender specialization in this species, because flower size and number have the potential to affect sex-specific reproductive success.

The quantitative genetics of sex allocation in the andromonoecious perennial, Solanum carolinense (L.)

The quantitative genetics of allocation to sexual functions was examined in the andromonoecious plant, Solanum carolinense. A restricted maximum likelihood (REML) analysis was employed to determine heritabilities and genetic and environmental correlations for flower number, the proportion of those flowers that were male, and the size of flower parts (corolla diameter, pistil length, and anther length and width) in each of three populations used in a diallel crossing design. All floral characters were highly heritable. The sizes of flower parts were positively genetically correlated with one another, which will restrict the independent evolution of these parts. Negative genetic and environmental correlations exist between flower size and proportion male flowers, indicating the potential for the evolution of individuals with either many, small male flowers or few, large, cosexual flowers. The high heritabilities of the traits examined as well as the genetic correlations among them indicate the potential for the evolution of gender specialization in this species, because flower size and number have the potential to affect sex-specific reproductive success.

AFLP markers tightly linked to the sex locus in Asparagus officinalis L.

Nine AFLP markers linked to the sex locus in Asparagus officinalis L. have been identified by non-radioactive AFLP technique and bulked segregant analysis. A composite map of one F2 and two F1 populations identified three very tightly linked markers. These markers did not give recombinants in the three different populations and mapped 0.5, 0.7 and 1 cM to the sex locus. Codominant scoring of the markers in the F2 population from a selfed andromonoecious plant could distinguish the XX, XY and YY asparagus plants. The AFLP markers were isolated from the gel and cloned into plasmid vectors. The marker E41M50, which is a low-copy sequence and did not give any recombinants in the screened populations, detected polymorphism between female and male plants when used as RFLP probe. The AFLP markers we obtained are important to plant breeding, particularly in the development of sex specific PCR primers that could be used in the screening of different asparagus plants at the seedling stage. They are likewise important in the elucidation of the mechanisms underlying sex determination and differentiation in this species.

Applicazione dell'androgenesiin vitroal miglioramento genetico dell'asparago

Abstract The sex genetic determinants of the dioecious species Asparagus offcinalis are codified on the chromosome pair n. 5 and inherited as a monomendelian trait; since the dominant alleal controls the development of androecium, the males are heterozygous and the female homozygous. The male plants of asparagus are know to be superiour respect to the female ones for important yield components, therefore one objectiv of the breeding is the synthesis of all-male hybrids. That is possible by crossing female plants (m/m) with male plaits (M/M) homozygous for sex pair chromosome. The synthes of such kind of males by selfing the rare andromonoecious plants, involves several problems which can be overcome by using the in vitro anther culture technique. At our Institute this technique has been sistematically applied during the last twenty years and allowed to regenerate doubled haploid clones which were evaluated in the field for a minimum period of four years. The best male and female clones were then utilized as parents of all-male F1 hybrids. Following omparative varietal trials in different location for several years, the best F1 all-mal hybrids were identified and released to private seed companies for the production of commercial seed.

Different kinds of male flowers in the dioecious plant Asparagus of officinalis L.

In the dioecious plant Asparagus officinalis L. the female plants bear flowers that are all strictly of the same type, with well-developed pistils and collapsed and consistently sterile rudiments of anthers, while male plants, on the contrary, show a great variety of vestigial female organs, from small, rudimentary ovaries with no style and stigma, up to pistils provided with a rather long style that is often enlarged in a stigma. In our investigations, we used homozygous male and female doubled haploid plants obtained from in vitro anther culture, the all-male F1 progeny and male individuals from subsequent backcrosses. The results showed that: (1) the character “length of the style” is genetically inherited and involves at least two genes, the influence of the environment being quite negligible; (2) in male pistils provided with style and stigmatic papillae, the pollination and growth of the pollen tubes up to the ovules do actually occur as a rule, the only barrier to fertilization being the absence of normal embryo sacs inside the ovules; (3) the character “length of the style” is a very reliable marker of the trend towards hermaphroditism in Asparagus, since a correlation always exist between length of the style, size of the ovary, tendency to self-pollination, vascularization and rate of development of the ovules inside the male ovaries. On the whole, most of our observations, together with the high inbreeding depression observed when occasional andromonoecious plants are selfed, are consistent with the hypothesis of the origin of dioecy in Asparagus from hermaphroditism via the gynodioecy pathway.

Environmentally Influenced Changes in Sex Expression in an Andromonoecious Plant

Sexual expression and maternal investment were investigated in the herbaceous perennial Solanum carolinense (Solanaceae). Field censuses, pollen germination studies, and the results of hand—pollination experiments in a greenhouse revealed that there are three flower types. Morphological males (M) are found near the tip of the inflorescence and have short styles; these flowers did not set fruit when pollinated. All other flowers have long styles and are morphological hermaphrodites (H); among these, those near the base of an inflorescence set fruit when pollinated (fruiting hermaphrodites, FH) while those in intermediate positions did not (functional males, FM). No morphological differences were apparent between FH and FM flowers. Male function of M and H flowers was indistinguishable in terms of pollen germination and quantity and quality of seed produced. The proportions of FM flowers decreased with later inflorescences, but the proportion of FM flowers increased correspondingly. Thus, the morphological sex ratio, M/(M + H), decreased with plant size, while the functional sex ratio, (M + FM)/(M + FM + FH) did not vary. These data do not support evolutionary theories that predict increased allocation to female versus male function with increasing plant size. In addition, experimental manipulations were performed on greenhouse plants. Morphological sex ratio changed in response to various plant hormones, which suggests hormone involvement. Sex ratio increased in response to increased shade and water stress, which supports those evolutionary theories that predict a shift to maleness in response to stress. However, increasing levels of fertilizer also increased the morphological sex ratio Pollination did not influence the morphological sex of subsequent flowers; rather, regulation of fruit—set after pollination occurred via changes in the proportion of H flowers that did (FH) or did not (FM) set fruit. The results are discussed in terms of three stages at which maternal investment can be regulated: flower initiation, flower maturation, and fruit maturation.

Comparative fecundity of morphs in a mixed monoclinous-andromonoecious population ofWurmbea dioica subsp.alba (Liliaceae) in Western Australia

A population ofWurmbea dioica subsp.alba in Western Australia contained monoclinous and andromonoecious individuals in roughly equal proportions. The average number of flowers per inflorescence for the former was 2.6 and for the latter 2.9, with its terminal flower staminate. Ovule number and seed production per perfect flower of both morphs decreased progressively from lower to upper flowers in the inflorescence. Two-flowered monoclinous individuals had a greater percentage of ovules maturing to seed than did threeflowered ones, but seed production of the latter exceeded that of the former. No differences in percent seed set or in seed production were noted for similar individuals of andromonoecious individuals. Although monoclinous and andromonoecious plants apparently contributed equally to the pollen pool, seed production of the former exceeded that of the latter. Thus, the energetic costs of monocliny exceed those of andromonoecy in this population.

Behavior of bumble bee pollinators of Aralia hispida Vent. (Araliaceae).

The andromonoecious plant Aralia hispida has a complicated blooming schedule involving alternations between male and female phases.Nectar and pollen are released gradually through the day. Plants vary considerably in number of flowers per umbel and number of umbels per plant. The major pollinators, bumble bees, show several characteristic behaviors in response to the plant's presentation. 1. Foraging bees preferentially visit umbels that bear large numbers of open, male-phase flowers. They also prefer shoots with large numbers of umbels. 2. If bees have received high nectar rewards at one umbel, they are more likely to visit a neighboring umbel rather than leaving the area. On drained umbels, bees probe more empty flowers before rejecting the umbel if they have been rewarded just previously. 3. Individual bees restrict their foraging to limited areas. Within these areas, they concentrate their visits on certain shoots which they tend to visit in repeatable sequences, or "traplines". It is inappropriate to consider these bees as "searching". 4. We discuss some of the implications of these data for two areas of current theoretical interest: plant reproductive strategies and optimal foraging.

Vegetative and floral bud abortion in cucumber plants: Hormonal and environmental effects

The acropetal, zonal pattern of axillary buds along the main shoot of the cucumber plant, which includes bare nodes (no appreciable development), staminate, mixed and, lastly, pistillate (or hermaphrodite) ones, is described in monoecious, gynoecious, andromonoecious and hermaphrodite genotypic lines grown at various seasons and treated with gibberellin (GA 4 + 7) or with an ethylene-releasing compound (CEPA, 2-chloroethyl phosphonic acid). Under optimal growing-conditions, GA given to gynoecious and hermaphrodite plants mimicked summer conditions by increasing the number of basal bare nodes and the proportion of abortive female buds and staminate buds. CEPA given to monoecious and andromonoecious plants generally imitated winter conditions by decreasing the proportion of bare and abortive nodes, and increasing female tendency. Bud abortion was also noticed under sub-optimal growing-conditions (low light intensities and relatively low temperatures) during the winter. This seems to be physiologically unrelated to the above mentioned phenomena.

Studies on the sex expression of flowers in Cucumis Melo L. (I)

Experiments have been continued to investigate the sex expression in Cucumis Melo L. In the present paper, the structure of flower and the inheritance of andromonoeciousness versus monoeciousness are described, and the result of comparison as regards function of pollen from either hermaphroditic or staminate flower is presented. The andromonoe-cious plant used in the experiment was commercial variety Earl's Favourite which represents C. Melo L, var. reticulatus, and for the monoecious plant No. 111 and No. 981, collected in Afghanistan and Pakistan by the Japanese expedition in 1955 were used, of which No. 111 is believed to belong to the snake melon, C. Melo L. var. fLexuosus (Fig. 1). The results obtained are summarized as followes. 1. The hermaphroditic flower on andromoneci-ous plant bore the pistil and the stamens filled with pollen, while the pistillate flower on monoe-cious plant bore the pistil and the rudimentary stamens (Fig. 3, 4). 2. Though there was a fare occurrence of the andromonoecious plant bearing pistillate flower and of the monoecious plant bearing hermaphroditic flower, it was confirmed that the monoeciousness differed from the andromonoeciousness in a single dominant allele (Table 1. 2). 3. Pollen grains of the hermaphroditic flower as well as those of the staminate flower within the same vine germinated on the artificial media (1 agar, 5% sucrose and pH 6. 5) in different degree. The difference of germination percentage of the pollen of hermaphroditic and staminate flower was significant at 5 per cent level, i.e. 75.8 per cent and 66. 2 per cent respectively after one hour of culture. No significant difference was shown in the elongation of pollen tubes, and moreover, the rate of normal pollen was as high as 95 per cent or more in either hermaphroditic or staminate flower (Table 3). 4. Either through the intra self pollination or through the neighbour pollination with pollen of staminate flower within the same vine, the yield and the market value of the mature fruit from hermaphroditic flower were the same. Comparing the character of hermaphroditic flower with those of staminate flower, no significant difference was found with regards the function of pollen, i.e. the rate of fruit setting, the number of germinable seed, and the weight of fruit or seed. From the results, it is suggested that the intra self pollination on hermaphroditic flower facilitates practical procedure of pollination, with an advantage of securing the strict inbred seed.