Male Strobili Research Articles

Variation in Clone Fertility and its Effect on the Gene Diversity of Seeds From a Seed Orchard of Chamaecyparis obtusa in Korea

Abstract Male and female strobilus production was assessed annually over a four-year period for a clonal seed orchard of hinoki (Chamaecyparis obtusa Endl.) in Korea. Clonal fertility and fertility variation, expressed by both sibling coefficient and coefficient of variation in strobilus production among 50 orchard clones, were reported. Fertility varied among clones and among years producing four-year averages per ramet of 510.2 and 1050.6 for female and male strobili, respectively. The correlation between female and male strobilus production was positive in each of the four years studied and, with the exception of one year, statistically significant. The clonal status number (Ns), a measure of gene diversity, was calculated based on the observed clonal fertility variation and varied from 28.0 (N = 50) in the poorest flowering year (2002) to 46.7 in the best year (2005). On average (pooled), the relative status number was 95% of the census number (N). Variation in female fertility was generally higher than that for male fertility, and this variation was reflected in the status numbers of female and male parents. The pooled Ns estimated from all four years was higher than that for any single year, implying that gene diversity would increase when seeds collected from different years are pooled. Sexual asymmetry calculations showed that clonal contributions would be balanced between genders.

Graft survival and promotion of female and male strobili by topgrafting in a third-cycle slash pine (Pinus elliottiivar.elliottii) breeding program

A total of 2561 slash pine ( Pinus elliottii Engelm. var. elliottii) grafts were topgrafted in the winter of 2003 and evaluated in January of 2004. The objectives of this study were to understand the effect of the genetic material and crown position on survival and flowering response of topgrafts. Also, the effects of geographic direction, branch order, and scion age on topgraft response were assessed. Topgrafting was an effective tool for promoting both female and male strobili. The genetic material (scion and interstock clones) and the crown position had large effects on the promotion of female flowering and topgraft survival. More than 23% of the total variation in female flowering and 16.3% of the total variation in topgraft survival were due to differences among scion clones and among interstock clones, respectively. The highest survival rate was reached by grafting in the mid-top followed by the top crown position. Grafting in the top of the crown was highly superior in promoting female strobili followed by the mid-top position. First-order branches showed a significantly superior production of female strobili. Chronologically older scions, from selections made in the first and second generations of the tree improvement program, produced more female and male strobili than third-cycle forward selections.

Growth characters and number of strobili in clonal seed orchards of Pinus sylvestris

Observations were made on six grafts for each of 25 clones in three Scots pine (Pinus sylvestris) seed orchards in Turkey. The characters studied were number of female and male strobili, height below and above the longest branch, total height; diameter at base and breast height, crown diameter, and number of branches. Variation, broad-sense heritability (H2) and correlations between characters were estimated.

Study of male sterility in Taiwania cryptomerioides Hayata (Taxodiaceae)

A study of male sterility over a period of three consecutive years on a conifer species endemic to Taiwan, Taiwania cryptomerioides Hayata (Taxodiaceae), was done for this article. With the aids of fluorescence and electron microscopic observations, the ontogenic processes in the fertile and sterile microsporangia are compared, using samples collected from Chitou Experimental Forest and Yeou-Shoei-Keng Clonal Orchard of the National Taiwan University, Nantou, Taiwan. The development of male strobili occurred from August to the end of March. Microsporogenesis starts with the formation of the archesporium and ends with the maturation of 2-celled pollen grains within the dehiscing microsporangium. Before meiosis, there was no significant difference in ultrastructure between the fertile and sterile microsporangia. Asynchronous pollen development with various tetrad forms may occur in the same microsporangium of either fertile or sterile strobili. However, a callose wall was observable in the fertile dyad and tetrad, but not in the sterile one. After dissolution of the callose wall, the fertile microspores were released into the locule, while some sterile microspores still retained as tetrads or dyads with intertwining of exine walls in the proximal faces. As a result, there was no well developed lamellated endexine and no granulate ectexine or intine in the sterile microspores. Eventually, the intracellular structures in sterile microspores were dramatically collapsed before anthesis. The present study shows that the abortion in pollen development is possibly attributed to the absence of the callose wall. The importance of this structure to the male sterility of T. cryptomerioides is discussed.

Quantification of pollen grains borne in male strobili of Abies firma

Quantification of pollen grains borne in male strobili of Abies firma

Fertility Variation and Genetic Diversity in a Clonal Seed Orchard of Cryptomeria japonica

AbstractClonal differences in fertility (expressed as the number of female and male strobili) were determined for three consecutive years (2002-2004) in a clonal seed orchard of sugi (Cryptomeria japonica D. Don) in Korea. Fertility varied among clones and among years producing three-year averages of 196 and 652 for female and male strobili per ramet, respectively. Correlation between female and male strobilus production was positive over the three years and statistically significant in 2003, a good flowering year. Based on the observed fertility variation, the status numbers (Ns, measure of genetic diversity) were calculated and varied from 25.6 to 31.7 among the three studied years. On average (pooled), relative status number was 86% of the census number (N). Variation in female fertility was higher than that in male fertility, and this variation was reflected on female and male parents’ status numbers. Pooled Ns estimated from the three years was higher than that for any single year, implying that genetic diversity would increase when seeds collected from different years are pooled.

Interspecific Separation Of <I>Gnetum</I> L. (Gnetaceae) Based On Macro And Micro Morphological Features

The study confirmed the occurrence and distribution of two species of Gnetum (G. africanum and G. buchholzianum) in southeastern Nigeria. A new collection, Gnetum species, which is clearly distinguishable from the other two by the peculiar structure of its male strobili is reported. Macro morphological variation was observed in characters like leaf form, leaf margin, inflorescence type, fruit shape and colour. Entire and lanceolate leaves are peculiar to G. buchholzianum while bead-like inflorescence of the new collection distinguishes it from the other species. Morphometric features like length of leaf, length of internode and length of spike varied among the species. However, analysis of variance on these features showed no significant difference (P < 0.05) in their mean values. The species are hypostomatic with amphibrachy-paracytic type of stomata. Pollens are generally spherical and acolpate. Pollen fertility values were high in the three species with the new collection having the highest value of 96%. Though difference was observed in pollen diameter, the generality of micro morphological characters suggest close affinity of the species. These results are discussed with a view to providing good description and taxonomic separation of the species. KEY WORDS: Gnetum, male-strobili, pollen, stomata, vegetative-character Global Journal of Pure and Applied Sciences Vol.11(1) 2005: 23-29

Fertility variation in six populations of Brutian pine (Pinus brutia Ten.) over altitudinal ranges

Fertility (number of strobili) was investigated in six natural populations over three ranges of altitudes (215–960 m) in Brutian pine (Pinus brutia Ten.) for two consecutive years. The fertility and fertility variation varied among populations and years. The average of strobilus production varied between 173 and 269 in female, and between 533 and 1,060 in male, respectively. The fertility variation did not seem closely related to the altitude, and it was not consistently dependent on the richness of strobilus production. Positive significant correlations were found between female and male strobilus production for all populations and years. Coefficient of variation in strobilus production among individual trees varied between 0.638 and 0.838 for female; and between 0.603 and 0.809 for male when flowering assessments were combined. The clone fertility variations among trees were slightly different among all six stands (sibling coefficient ranged from 1.354 to 1.525) and it is unlikely that trees in typical stands vary extremely in reproductive success.

Sexual Asymmetry based on Flowering Assessment in a Clonal Seed Orchard of Pinus densiflora

Abstract Two equations were formulated in order to estimate the degree of sexual asymmetry for monoecious species. The concepts of the equations were formulated on the basis of the effective population numbers of female and male parents [i.e, As (v)], and the differences of relative frequency between genders [i.e., As (x)]. These equations were applied to estimate the degree of sexual asymmetry based on the empirical data of flowering assessment in a clonal seed orchard of Pinus densiflora. The yearly variation in the production of female and male strobili was found. The effective population numbers at gamete levels (vf and vm) and clone level (vb) varied among 8 observation years. Both As (x) and As (v) were negatively correlated with effective numbers at gamete and clone levels. Averages of female and male strobilus production and estimates of sexual asymmetry were negatively correlated but the correlation was not significant. The correlations among effective number of clone (vb), arithmetic mean of female and male effective numbers (va) and estimate of sexual asymmetry [As (x)] were strong and significant. Relatively larger difference between vb and va were found when higher level of sexual asymmetry were observed.

Fertility Variation and Status Number Between a Base Population and a Seed Orchard of Pinus brutia

Abstract Female, male and total fertility variations were estimated in a base population and a seed orchard derived from the base population in Pinus brutia. Relative status number for gametes (female and male contribution) and zygotes (average of female and male contribution) were estimated based on the fertility variation. Average female and male strobilus production were 229.1 and 1003.3 in the base population, and 98.9 and 244.9 in the seed orchard for combined years, respectively. Positive and significant correlations were found between female and male strobilus production in both base population and seed orchard. The male fertility variation was higher than female fertility variation in the seed orchard, while female fertility variation was higher than male fertility variation in the base population. Coefficients of variations in female and male strobilus production were 0.721 and 0.696 in the base population, and 0.403 and 1.110 in the seed orchard for combined years, respectively. Total fertility variation was 1.41 in the base population and 1.40 in the seed orchard for combined years. The relative status numbers estimated based on the total fertility were 70% of census number in the base population, and 71% in the seed orchard for combined years.

Analysis of the parental reproductive balance in a Pinus pinaster Ait. seed orchard

The number of female and male strobili were assessed for 22 clones in a Pinus pinaster Ait. seed orchard along four consecutive years. The data showed that differences for the production of both female and male strobili among clones were very large and statistically significant for all years examined. Differences in female strobili production among clones were more variable than in male strobili. Pearson’ s correlations between years were highly significant. Both correlations between female and male flowers were moderate and positive for all 4 years. Broad-sense heritabilities for flower production on an individual ramet basis varied from 0.14 to 0.50, while those on a clone-mean basis were much higher, from 0.39 to 0.82. Maleness index indicated high sexual symmetry (Mi= 0.47-0.49). The results are useful for planning further activities in the seed orchard such as pruning, roguing or selective cone harvest.

Promotion of Female Strobili Flowering and Seed Production in two Japanese Pine Species by 6-Benzylaminopurine (BAP) Paste Application in a Field Seed Orchard

Treatment with 6-benzylaminopurine (BAP) to promote the flowering of female strobili and to increase seed production in a seed orchard was examined at different times of conebud differentiation for Japanese red pine (Pinus densiflora) and Japanese black pine (P. thunbergii), from late August to mid-September 1998. BAP was mixed with lanolin and Vaseline to prepare a paste (BAP, 2000 mg/L), which was used for a “terminal bud treatment” and also applied in a “girdling treatment.” The BAP treatment in early September transformed lateral buds on lower branches that would have normally differentiated as male strobili into female strobili. The highest percentages of female flowering branches were 21.1% (red) and 40.5% (black) produced by the terminal bud treatment, while control branch percentages were 5.0% and 7.1%, respectively. Girdling combined with BAP treatment further promoted female flowering branches to 32.3% (red) and 64.3% (black), while those of controls were 8.3% and 9.9%, respectively. Moreover, the numbers of female strobili per female flowering branch were 6 to 11-fold greater than controls. Mature seed cones were harvested in October two years later from which full seeds with a high germination ratio were recovered. Use of BAP treatment is thus highly effective for enhancing seed production in seed orchards of these two pine species.

Changes in growth conditions alter the male strobilus gene expression pattern in Cryptomeria japonica.

Two-year old saplings grown from cuttings of Cryptomeria japonica D. Don initiate strobilus development following treatment with gibberellic acid under long-day photoperiods. At 25 degrees C with a 14-h photoperiod in a phytotron, male strobili initiated normally; however, they remained green and fell from the saplings prematurely. To examine the change in male strobilus development at the molecular level, three genes expressed specifically in male strobili were analyzed. Two were MADS box genes homologous to the B-function genes in angiosperms, CjMADS1 and CjMADS2, and the third was Cry j I, which encodes an allergen protein, and this gene is expressed mainly in microspores. Under phytotron growing conditions, the homeotic genes were expressed constantly, which reflected the extended early developmental stage of male strobili. On the other hand, Cry j I expression was detected after a long delay just before strobilus development ceased. These results indicate that the expression of the genes related to male reproductive development in C. japonica is regulated by a factor(s) that is sensitive to environmental signals.

Expression of the viviparous 1 (Pavp1) and p34cdc2 protein kinase (cdc2Pa) genes during somatic embryogenesis in Norway spruce (Picea abies [L.] Karst).

Detailed expression analysis of the Norway spruce (Picea abies [L.] Karst) Viviparous 1 (Pavp1) and p34cdc2 (cdc2Pa) genes was carried out during somatic embryogenesis. Pavp1, a gene associated with embryo development, was expressed in proliferating embryogenic suspension cultures in the absence of exogenous ABA. When somatic embryo formation was promoting by blocking proliferation, Pavp1 expression was reduced. During maturation, exogenous ABA induced increased Pavp1 expression, which peaked at the early cotyledonary stage of somatic embryogenesis. Following partial desiccation of mature somatic embryos at high relative humidity, Pavp1 expression persisted under germination conditions. Pavp1 expression was also detected in non-dormant immature male strobili and dormant terminal buds. These data confirm the functional conservation of Pavp1 during the evolution of seed plants and extend its function beyond the embryo. Cdc2Pa, a gene associated with the cell cycle, was up-regulated when the proliferation of embryogenic cells was blocked. Expression was again up-regulated in early embryogeny and again during germination. The implications of this up-regulation of cdc2Pa are discussed.

Flowering and Airborne Pollen Occurrence in a Pinus sylvestris Seed Orchard Consisting of Northern Clones

To explain the high background pollination rate detected in earlier studies, this study investigated the flowering phenology of a Scots pine seed orchard with respect to airborne pollen occurrence during 1992 and 1993. The receptive period of the female strobili and the shedding period of the male strobili were observed visually. Airborne pollen was monitored with Rotorod traps located inside and outside the seed orchard. There was no time gap in the onset of flowering between the earliest female and male strobili in 1992. Female flowering began 3 days earlier than male flowering in 1993, and the earliest strobili were probably pollinated by pollen transported long distance from more southerly areas. The almost simultaneous peak in pollen occurrence inside the seed orchard and in surrounding pine stands indicates that the seed orchard clones are not temporally isolated from sources of contamination. However, pollen concentrations inside the seed orchard were higher than those in the surrounding stands. Therefore, flowering phenology cannot sufficiently explain the observed pollen contamination rates in this seed orchard.

Considerations of correlated fertility between genders on genetic diversity: the Pinus densiflora seed orchard as a model.

The correlation between 99 clone female and male fertilities in a first generation seed orchard of Pinus densiflora was studied over 6 years. The effective number of the parent ( N(p)) and the variance effective population number [ N(e)((v))] were used to assess the impact of total (Psi(T)), female (psi(f)) and male (psi(m)) fertility variation. A theoretical framework was developed to account for female and male fertility correlations as well as the impact of possible pollen contamination. Total fertility variation was described by the sibling coefficient (Psi(T): the probability that two genes randomly chosen from the gamete gene pool originate from the same parent), which was further subdivided into psi(f) and psi(m). These parameters were compared under various conditions including the total seed harvest, imposing on equal seed harvest among the orchard's clones and two contamination scenarios ( M = 0 and 20%). Fertility variations among females, males and clones were observed within and among years. Sibling coefficients (Psi(T)) were lower, but the effective number of parent ( N(p)) and variance effective population number ( N(e)((v))) were higher in years with moderate female and good male strobilus production. N(p) for female and male reproductive outputs varied from 49 to 82 and from 57 to 93, respectively. N(p) was higher for males than females. When the crop of the 6 years was pooled, N(p) for female, male and the clone were 73, 87 and 85, respectively. The impact of female-male fertility correlation for conditions with no-, positive- and negative-correlations were assessed and their impact on Psi(T), N(p) and N(e)((v)) was also evaluated. It was demonstrated that the practice of equal seed harvesting from every clone, or the mixing of seeds from several years, would substantially improve the genetic diversity and the genetic representation of the seed orchard population when a positive correlation between gender fertilities was observed. The relevance of these results to supplemental-mass-pollination was discussed under two cases where equal- and un-equal amounts of pollen from clones were included in the pollen mixes.

Pollen viability of Scots pine ( Pinus sylvestris) in different temperature conditions: high levels of variation among and within latitudes

We examined the viability of pollen in a widely distributed anemophilous species, Scots pine ( Pinus sylvestris L.), along a south–north gradient from 60 up to 69°N in Finland. It was hypothesised that problems in the reproduction cycle of Scots pine in northern marginal areas are partly due to the poor adaptedness of pollen at low temperatures. The pollen was collected directly from the male strobili and germinated in vitro at different temperatures. The results revealed marked variation in pollen viability both among and within latitudes and also among different temperature treatments. A contrast between southern and northern pollen was found in each year: in 1997–1999, southern pollen performed better, but an opposite contrast was observed in 1998. Pollen germination at the smaller temperatures was low across all the study areas, but very good at the highest temperature which was 20 °C. Variation in pollen viability among stands may lead to differential success of pollen of different origin. Variation among years was also high; thus different pollen might be favoured in different years. Finally, the possibility of gene flow from south to north was assessed.

Eastern White Pine Flowering in Response to Spray Application of Gibberellin A4/7 or Procone™

Abstract Eastern white pine (Pinus strobus L.) is an important forestry species in the northeastern and midwestern United States and in eastern Canada. Induction of early and reliable flowering and cone production will shorten the breeding cycle and aid in the development of genetically improved white pine. The objective of this study was to determine if a foliar spray application of gibberellin A4/7 (GA4/7) or ProCone™ would induce both male and female strobili on young grafted eastern white pine selected for white pine blister rust resistance. Trees were sprayed (500 mg L-1) weekly in 1998 during the period of rapid shoot elongation (mid-May through July), for a total of 11 applications. Flowering data were collected June 15, 1999. Twenty-five out of 53 genotypes produced male strobili. For all genotypes studied, the total number of male strobili clusters per tree (and the mean number ± SE of pollen-cones per cluster) produced with GA4/7, ProCone™, or untreated controls were: 643 (7.1 ± 0.3); 574 (7.9 ± 0.3); and 79 (8.3 ± 0.8), respectively. Twenty out of 53 genotypes produced female strobili. For all genotypes studied, the total number of female strobili per tree (and the mean number ± SE of female strobili per shoot) produced with GA4/7, ProCone™, or untreated controls were: 87 (1.1 ± 0.1); 130 (1.3 ± 0.1); and 33 (0.6 ± 0.1), respectively. Eleven genotypes produced both male and female strobili. Control trees that flowered may have been the result of spray drift. The results indicate that a foliar spray application of GA4/7 or ProCone™ at 500 mg L-1 will induce both male and female strobili, but not on all selected genotypes of eastern white pine.

Isolation and characterization of cDNAs that encode homologs of a pathogenesis-related protein allergen from Cryptomeria japonica.

Many plant pathogenesis-related (PR) proteins are allergenic. We isolated three cDNAs, Cry j 3.1, Cry j 3.2, and Cry j 3.3, that encoded homologs of Jun a 3, a PR protein allergen in Juniperus ashei, from a cDNA library derived from the pollen of Cryptomeria japonica. The predicted amino acid sequences encoded by the three cDNAs were more than 85% identical to each other and about 57% identical to the sequence of Jun a 3. The Cry j 3 genes seemed to form a small multigene family in the genome of C. japonica. Expression of Cry j 3 was strong in roots and in female and male strobili; expression was weaker in cotyledons, leaves, stems, and pollen grains.

Penetration and Infection Processes in Japanese Cedar Twig Blight Caused by Stromatinia cryptomeriae

The diversity of host invasion mechanisms of the causal pathogen of Japanese cedar twig blight (Stromatinia cryptomeriae) was elucidated through detailed investigations of the disease cycle. Scanning electron microscopy (SEM) showed that ascospores began to germinate, and invade male strobilus tissue, within 24 h after arriving on the strobili. This involved direct penetration of the cuticle, and examination by SEM showed that cuticle degeneration had occurred around the point of penetration. A mucilage-like-substance was also observed around the tips of the germ tubes. Meanwhile field studies showed that incipient mycelial mat emerged from the bases of male strobilus in early June, and ceased growing onto the surface of the twig at the beginning of July. Macroscopically, the mycelial mat began to shed in mid-July, and disappeared completely during the summer season by the end of August. Immediately after the mat disappeared the first necrotic symptoms became evident on the twigs. This suggested strongly that these mats were involved in lesion formation. Observations of the mat's behavior on the surface of twigs with light and differential interference microscopy, and SEM, showed that S. cryptomeriae had two modes of invasion, i.e. stomatal and cuticular invasion. Hyphae from the mat were able to enter twig tissues through the stomata. Additionally, mycelial mat infected host tissue directly by hyphal penetration of the cuticle at the axes of cedar twigs. The mat was able to grow along the twig surface, then hyphae forming mat entered the host tissue and caused necrotic lesions. This paper describes the mechanisms of infection on both a strobilus and twig utilized by the pathogen of Japanese cedar twig blight.