Early Reproductive Ontogeny in Interspecific Crosses of Arachis hypogaea and Section Arachis Species

Wild Arachis species have been recognized as sources of resistanceto pests and pathogens that infect A. hypogaea L. and causesubstantial yield losses. However, utilization of these geneticresources for crop improvement has been difficult. This studywas conducted to (a) understand the processes of early embryogrowth and development in four Arachis species, two A. hypogaeacultivars and their hybrids and (b) identify parental compatibilitiesin reciprocal crosses of A. hypogaea. The results indicatedthat delayed fertilization beyond 24 h, coupled with slow proembryogrowth, leads to embryo abortion in many interspecific crosses.For example, in female A. cardenasii crosses, lack of or delayedfertilization leads to failure to obtain hybrids. When A. batizocoiwas used as a female parent, delayed fertilization and the inabilityof quiescent proembryos to resume growth after soil penetrationcaused abortion. Embryos of A. hypogaea x A. glandulifera crossesdeveloped normally during the first 21 d after fertilization,but then aborted at a later time. In this study, A. hypogaeawas always a better female parent than the wild Arachis species.Increasing the number of pollinations per cross, using the cultivatedspecies as the female parent, utilizing different A. hypogaeavarieties, and embryo rescue techniques are suggested to improvethe probability of obtaining interspecific hybrids in Arachis.Copyright1995, 1999 Academic Press Peanut, interspecific hybrids, Arachis, wild species, incompatibilities     

Intergeneric hybridization between Diplotaxis siifolia,a wild species and crop brassicas

Summary Attempts were made to obtain intergeneric hybrids between Diplotaxis siifolia, a wild species, and cultivars of Brassica (B. campestris, B. juncea, and B. napus). The crosses showed unilateral incompatibility. When the wild species was used as female parent, pollen germination and pollen tube growth were normal, but hybrid seeds aborted due to post-fertilization barriers. Reciprocal crosses (cultivars as female parent) showed strong pre-fertilization barriers; although pollen grains showed germination, pollen tubes failed to enter the stigma. Hybrids were realized in two of the crosses, D. siifolia x B. juncea and D. siifolia x B. napus, through ovary culture. The hybrids were multiplied in vitro by multiplication of axillary shoots, or somatic embryogenesis. Detailed studies were carried out on the hybrid D. siifolia x B. juncea. F₁ hybrids had shrivelled anthers and were pollen sterile. Amphiploids of this hybrid showed 60% pollen fertility and produced seeds upon self-pollination as well as backcross pollination with the pollen of B. juncea.     

Microsatellite and flow cytometry analysis to help understand the origin of Dioscorea alata polyploids

Background and Aims Dioscorea alata

is a polyploid species with a ploidy level ranging from diploid (2n = 2x = 40) to tetraploid (2n = 4x = 80). Ploidy increase is correlated with better agronomic performance. The lack of knowledge about the origin of D. alata spontaneous polyploids (triploids and tetraploids) limits the efficiency of polyploid breeding. The objective of the present study was to use flow cytometry and microsatellite markers to understand the origin of D. alata polyploids.

Methods

Different progeny generated by intracytotype crosses (2x × 2x) and intercytotype crosses (2x × 4x and 3x × 2x) were analysed in order to understand endosperm incompatibility phenomena and gamete origins via the heterozygosity rate transmitted to progeny.

Results

This work shows that in a 2x × 2x cross, triploids with viable seeds are obtained only via a phenomenon of diploid female non-gametic reduction. The study of the transmission of heterozygosity made it possible to exclude polyspermy and polyembryony as the mechanisms at the origin of triploids. The fact that no seedlings were obtained by a 3x × 2x cross made it possible to confirm the sterility of triploid females. Flow cytometry analyses carried out on the endosperm of seeds resulting from 2x × 4x crosses revealed endosperm incompatibility phenomena.

Conclusions

The major conclusion is that the polyploids of D. alata would have appeared through the formation of unreduced gametes. The triploid pool would have been built and diversified through the formation of 2n gametes in diploid females as the result of the non-viability of seeds resulting from the formation of 2n sperm and of the non-viability of intercytotype crosses. The tetraploids would have appeared through bilateral sexual polyploidization via the union of two unreduced gametes due to the sterility of triploids.     

A genetic linkage map of water yam ( Dioscorea alata L.) based on AFLP markers and QTL analysis for anthracnose resistance

A genetic linkage map of the tetraploid water yam (Dioscorea alata L.) genome was constructed based on 469 co-dominantly scored amplified fragment length polymorphism (AFLP) markers segregating in an intraspecific F₁ cross. The F₁ was obtained by crossing two improved breeding lines, TDa 95/00328 as female parent and TDa 87/01091 as male parent. Since the mapping population was an F₁ cross between presumed heterozygous parents, marker segregation data from both parents were initially split into maternal and paternal data sets, and separate genetic linkage maps were constructed. Later, data analysis showed that this was not necessary and thus the combined markers from both parents were used to construct a genetic linkage map. The 469 markers were mapped on 20 linkage groups with a total map length of 1,233 cM and a mean marker spacing of 2.62 cM. The markers segregated like a diploid cross-pollinator population suggesting that the water yam genome is allo-tetraploid (2n = 4x = 40). QTL mapping revealed one AFLP marker E-14/M52-307 located on linkage group 2 that was associated with anthracnose resistance, explaining 10% of the total phenotypic variance. This map covers 65% of the yam genome and is the first linkage map reported for D. alata. The map provides a tool for further genetic analysis of traits of agronomic importance and for using marker-assisted selection in D. alata breeding programmes. QTL mapping opens new avenues for accumulating anthracnose resistance genes in preferred D. alata cultivars.     

Sexual reproduction in the cork oak (Quercus suber L). II. Crossing intra- and interspecific barriers

Intraspecific barriers promote outcrossing while interspecific mechanisms may contribute to the isolation of species; both control the exchange of genes between plants. In this paper we establish that post-pollination mechanisms promote outcross and act at different temporal and spatial levels to control seed set and quality in Quercus species. Controlled pollinations were performed to investigate intraspecific crossing barriers in Q. suber and pollen-pistil interactions following interspecific pollinations with some simpatric Quercus species. Cytological data of intraspecific crosses in Q. suber and Q. ilex have shown different kinetics on pollen tube growth after self and outcross pollination, but pollen tubes were able to reach the base of the styles in both species and seed set was successful. Although some pre-zygotic interaction is occurring at the style, the most important interaction takes place at ovary. The cross between Q. ilex and Q. suber is possible only in one direction, revealing a case of unilateral incongruity. We show that the lack of seed set observed in the cross Q. suber×Q. ilex is due to the inability of pollen tubes to penetrate the transmitting tissue after germination. With Q. suber mainly as female parent, pollinations with other simpatric Quercus species have shown different levels of constraint on pollen tube progression at stigma and style levels. Eventual hybridisation between Quercus species will depend on the compatibility of pollen-pistil interactions, on the competitive ability of pollen genotypes, and, most important, on the overlapping of geographical, phenological and ecological factors. Differences in seed set and seed allocation was evident in all crosses, and was particularly outstanding in interspecific and in self intraspecific crosses, determining the ultimate level of seed production and quality in Quercus species. Received: 4 April 2001 / Accepted: 8 May 2001     

Intergeneric Hybridisation between Litchi (Litchi chinensis Sonn.) and Longan (Dimocarpus longan Lour.)

The breeding barriers between commercial litchi (Litchi chinensisSonn.) and longan (Dimocarpus longan Lour.) cultivars were investigatedby conducting reciprocal pollinations. This work has shown thatit is possible to generate intergeneric hybrids using litchias the female parent. Investigation of comparative in vivo pollentube growth demonstrated that there is discrimination againstcross- compared to self-pollen at all sites in the pistil. Pollentubes were frequently observed in the ovary after cross-pollinationin litchi but rarely in longan. Fruit production was reducedafter crossing in both longan and litchi. Isozyme analysis usingphosphoglucose isomerase revealed that hybrid progeny only developedwhen litchi was the maternal parent. Morphologically the hybridplants were similar to the maternal parent but leaves were smaller.Three types of seeds developed in litchi following pollinationwith longan pollen. These were (1) normal seeds with a developedtesta and embryo, (2) seeds with aborted embryos but normaltesta development, and (3) seedless fruit where the ovule remainedthe same size as at anthesis without further development ofembryo or testa. The potential germplasm available to improvethese crops within the Sapindaceae is discussed.Copyright 1994,1999 Academic Press Litchi, Litchi Longan, Dimocarpus, hybridisation, isozyme     

EFFECTS OF DISTANCE BETWEEN POLLEN DONOR AND POLLEN RECIPIENT ON FITNESS COMPONENTS IN ESPELETIA SCHULTZII

The effect of flowering time and of distance between pollen donor and pollen recipient on the proportion of filled achenes, aborted seeds, and seedling survivorship was studied in populations of Espeletia schultzii in the Venezuelan Andes. Hand-pollinations were performed in two different years and at different times during the flowering season. Pollinations within-population included crosses between plants within a few meters to a maximum of 500 m apart and between-population pollinations included crosses between plants more than 10 km and up to 78 km away. Late in the flowering season, plants suffered a reduction in the proportion of filled achenes and an increase in aborted seeds. The proportion of filled achenes and aborted seeds did not vary significantly between the distances between pollen and ovules in crosses done early in the flowering season. However, the proportion of filled achenes in crosses between individuals within 30 m distance were very variable, either very successful or not successful. Beyond 30 m, for some of the populations, the frequency of unsuccessful crosses was almost 0. This pattern was observed at three elevation sites in two consecutive years. When crosses were done late in the flowering season, the proportion of filled achenes was lower in crosses between close individuals and between very distant ones. Seedling survivorship varied significantly between the crossing distances at the higher elevation only. The results show that a clear effect of the incompatibility alleles on the crossing success of the plants is present in the different populations examined, while they suggest that the effect of inbreeding or outcrossing depression is less clear but might still be present only under certain conditions. Late in the season, when plants might have fewer resources available for reproduction and at the high and intermediate site where cold and dry environmental conditions are less favorable for the plants, the discrimination among distances was stronger.     

INTERSPECIFIC INCOMPATIBILITY IN SOLANUM SPECIES

Pandey , K.K. (Crop Res. Div., D.S. & I.R., Lincoln, Christchurch, New Zealand.) Interspecific incompatibility in Solanum species. Amer. Jour. Bot. 49(8): 874–882. Illus. 1962.—A diallel cross involving 11 self-incompatible and 3 self-compatible species of Solanum was made to study the genetic basis of interspecific incompatibility. Interspecific incompatibility was not limited to crosses in which a self-compatible species was used as the male parent onto a self-incompatible species (unilateral incompatibility). A number of crosses between self-incompatible species were incompatible. In one cross, Q vernei X verrucosum, a self-compatible species was successful as a pollen parent with a self-incompatible species. Unlike other hybrids between self-compatible and self-incompatible species, which are self-incompatible, these F₁ hybrids were self-fertile, and cross-fertile among themselves and with both parents. The self-fertile S. polyadenium was cross-incompatible as a female as well as a male parent with all other species. It is suggested that the unilateral incompatibility is a property of the allele S_C which originated as a consequence of one kind of breakdown of the S_I gene; the S_C allele produces “bare” pollen growth substances which are inactivated in an incompatible style. It is proposed that the failure of the principle of unilateral interspecific incompatibility in solanaceous species may be due to the action of alleles at the second incompatibility locus revealed in certain Mexican species. It is assumed that the South American species are selected intraspecifically only for the action of S alleles but that in certain interspecific crosses and rarely in intraspecific crosses the alleles at the second locus may be expressed, thus interfering with the usual action of S alleles. The F₁ hybrids Q verrucosum (self-fertile) X simplicifolium (self-sterile) were self-incompatible at the tetraploid as well as the diploid level, and their cross-compatibility behavior was consistent with the expected activity of the S_C and S_I alleles of the 2 parents respectively.     

Prospects for interspecific hybridization of Lupinus atlanticus Gladst. with L. cosentinii Guss.

Summary Successful crossing is reported between L. atlanticus Gladst. (2n = 38) and L. cosentinii Guss. (2n = 32), using lines of both species selected for crossability followed by selection of relatively fertile progenies. In one cross, 82E75, from a single F₂ segregating plant, 22 F₃ seeds were obtained. Some other less crossable combinations were completely sterile in the f₁ or F₂. Backcrossing to both parent species was successful, but some crosses gave relatively more seed by using F₂ plants for backcrossing rather than F₂'s. It is concluded that potential exists for introgression of useful genes in both directions.     

A study of hybridisation involving the sweet potato and related species

Overwhelming evidence points to an American origin for the sweet potato Ipomoea batatas (L.) Lam. Attempts have been made to identify related diploid species from Mexico, and to use these in hybridisation experiments with I. batatas. The sweet potato is a poor seed setter but abundant bloom occurs in Jamaica very late in the year. Attempts at hybridisation between I. batatas (2n=90) and I. trichocarpa (Elliott) (2n=30) or I. gracilis (2n=30) has been tolerably successful. A very high degree of self-incompatibility was demonstrated in all three species investigated but successful crosses were made using different plants of I. trichocarpa. An investigation of pollen viability showed that in all cases pollen could germinate but pollen tube growth was abnormal in incompatible pollinations. I. trichocarpa hybridised readily with I. batatas when the former was used as female parent. Embryo development in such a cross proceeded slowly, and stopped before cotyledon formation. No viable seeds were obtained. A comparison of embryo development in hybrid and normal seeds brought to light anomalies in development and structure of endosperm and maternal tissue in the hybrid.     

Comparative Observations on the Polarity of Sprouting of Bulbils of Dioscorea bulbifera L. and Dioscorea alata L.

The sprouting process of aerial bulbils of D. bulbifera andD. alata was compared. In D. alata, sprouts originated normallyfrom the proximal pole, at or near to the point of abscision,and irrespective of moisture, light or orientation of the bulbil.In D. bulbifera, sprouts originated primarily in response tomoisture and were less influenced by polarity. Post-harvesttreatment with gibberellic acid delayed the sprouting of bulbilsof D. alata but not of D. bulbifera; treatment with 2-chloroethanolor ethanol promoted sprouting in both species. Physiologically,sprouting was characterized by a transient increase in respiratoryrate at the onset of, or just prior to, sprout emergence. Thepromotion of sprouting by chloroethanol was accompanied by asurge in respiratory activity. Dioscorea spp., yams, bulbil germination, polarity     

Polyploidy and sterility in relation to sex in Dioscorea alata L. (Dioscoreaceae)

Chromosome numbers and fertility studies of 73 male and 30 female flowering germplasm accessions of Dioscorea alata L. were carried out. All males were tetraploids showing the same chromosome number (n=20 or 2n=40) and were pollen fertile (10.9–96.2%), most of them being highly fertile. Among the female the majority were higher ploids (hexa-and octoploids; 2n=60 and 80) and sexually completely sterile. There were only two tetraploid female accessions which were sexually fertile. Pollination studies revealed that seed sterility in D. alata was due to female sterility associated with the occurrence of higher levels of ploidy. The female sex-limited occurrence of higher polyploidy and sterility observed in D. alata is a curious situation among dioecious higher plants.     

Pollen irradiation and possible gene transfer in Nicotiana species

Summary Progeny from crosses of Nicotiana langsdorffii with gamma irradiated pollen of Nicotiana alata Crimson Bedder showed skewed segregation in the F₂ favoring the maternal parent. This is probably not gene transfer in a strict sense, rather just an extreme case of reduced transmission of irradiated chromosomes, leading to massive overrepresentation of maternal genes. Gene transfer or mutational loss may explain some anomalous F₁ plants. Segregation in the F₂ progeny showed the presence of several genes from the irradiated pollen. Crosses of Nicotiana sylvestris, N. plumbaginifolia N. paniculata, and Petunia parodii with irradiated pollen from N. alata and Petunia hybrida showed no evidence of gene transfer, nor did experiments with irradiated mentor pollen. This indicates that gene transfer with irradiated pollen between non-crossing species or between species giving sterile hybrids is probably a rare phenomenon.     

Unilateral incongruity in crosses involvingLycopersicon pennellii andL. esculentum is distinct from self-incompatibility in expression,timing and location

Both interspecific and intraspecific mechanisms restrict the exchange of genes between plants. Much research has focused on self incompatibility (SI), an intraspecific barrier, but research on interspecific barriers lags behind. We are using crosses betweenLycopersicon esculentum andL. pennellii as a model with which to study interspecific crossing barriers. The crossL. esculentum×L. pennellii is successful, but the reciprocal cross fails. Since the cross can be successfully made in one direction but not the other, gross genomic imbalance or chromosomal abnormality are precluded as causes. We showed that the lack of seed set observed in the crossL. pennellii×L. esculentum is due to the inability of pollen tubes to grow more than 2–3 mm into the style, whereas S1 crosses show continued slow pollen tube growth but, also, fail to set seed. These results indicate that the unilateral response is a barrier distinct from SI, differing from SI in the timing and location of expression in the style. We therefore suggest that this unilateral response in theL. pennellii×L. esculentum cross is more accurately referred to as unilateral incongruity (UI) rather than interspecific incompatibility. Periclinal chimeras were used to determine the tissues involved in UI. The results of crosses with the available chimeras indicate that the female parent must beL. pennellii at either LI (layer 1) or both LI and LII (layer 2) and the male parent must beL. esculentum at either LII or both LI and LII to observe UI similar to that seen in theL. pennellii×L. esculentum cross. Pollinations with a mixture of pollen fromL. pennellii and from transgenicL. esculentum plants harboring a pollen-specific GUS reporter gene marker were used to ascertain whether the growth of the pollen tubes of either species was modified as a possible means of overcoming UI. We found no evidence of communication between the two types of pollen tubes to either enhance or restrict all pollen tube growth.     

Nature of 'Pollinator' Effect in Potato (Solanum tuberosum L.) Haploid Production

Haploids (2n =24) of the common tetraploid (2n=48) potato (SolanumtuberosumL.) provide promising material for attacking many problemsconcerned with the genetics, cytogenetics and breeding of thisspecies. Interspecific 4xx2xcrosses betweenSolanum tuberosumgp.Andigenaorgp.Tuberosumcultivars as pistillate parents andSolanum tuberosumgp.Phurejaassource of pollen (hereafter ‘pollinator’) have beenused to produce maternally derived haploids through parthenogenesis.This paper discusses the nature of the ‘pollinator’effect in haploid extraction. The ‘pollinator’ hada significant effect on haploid frequencies following 4xx2xcrosses.The ‘pollinator’ effect seems to operate via theendosperm, in which haploid (n=2x) embryos are associated withhexaploid endosperm. A superior ‘pollinator’ appearsto have its effect by contributing two haploid (n) gametes tothe central cell. 2n pollen; double fertilization; endosperm; ploidy manipulations; Solanum tuberosum     

Structure and Cytochemistry of the Stigma and Pollen--Pistil Interaction in Zephyranthes

The stigma in Zephyranthes candida and Z. citrina is of thedry type with a continuous cuticle—pellicle. In some papillae,however, the terminal portion of the cuticle—pellicleis lifted upwards and occasionally even disrupted by the accumulationof a secretion product below it. Both non-specific esterasesand acid phosphatases are present on the stigma surface. Thestyle is solid with a central core of transmitting tissue whichhas conspicuous intercellular spaces containing a matrix thatincludes proteins, polysaccharides and pectic substances. Zephyranthes citrina is self-compatible while Z. candida isself-incompatible. Followng incompatible pollination in Z. candida,pollen germination is normal but pollen tube growth is inhibitedat the junction of the stigma and style. Self-incompatibilitycan be overcome by bud pollination. Protein synthesis is necessaryfor pollen germination in both species. Concanavalin A bindsto the stigma surface of both species, but does not affect pollentube penetration in Z. candida. In crosses between the two speciestypical unilateral incompatibility is observed when Z. candidais used as the pistillate parent. Zephyranthes, stigma-surface enzymes, dry stigma, pollen-pistil interaction, self-incompatibility, unilateral-incompatibility     

Unilateral and bilateral hybridization barriers in inter-series crosses of 4x 2EBN Solanum stoloniferum, S. pinnatisectum, S. cardiophyllum, and 2x 2EBN S. tuberosum haploids and haploid-species hybrids

Wild Mexican potato species are an important untapped source of useful variation for potato improvement. Introgression methods such as 2n gametes, chromosome doubling, and crossing with disomic 4x 2 endosperm balance number (EBN) bridge species have been used to overcome post-zygotic endosperm failure according to the EBN hypothesis. Stylar barriers can prevent zygote formation, bilaterally when zygote formation is blocked in both directions of the cross or unilaterally when zygote formation is blocked in self incompatible (SI) × self compatible (SC) crosses. In several Solanaceae species, the S-locus for SI has been implicated in interspecific incompatibility. The objectives of this research were to determine if: (1) disomic 4x 2EBN Solanum stoloniferum can be used as a bridge species for introgression of the Mexican 2x 1EBN species Solanum cardiophyllum and Solanum pinnatisectum, (2) pre- and/or post-zygotic barriers limit hybridization among EBN compatible Solanum inter-series crosses, and (3) reproductive barriers act unilaterally or bilaterally. Fruit formation and seed set was recorded for inter-pollinations of S. stoloniferum, 4x 2EBN chromosome doubled S. cardiophyllum and S. pinnatisectum, and 2x 2EBN S. tuberosum haploids (HAP) or haploid-species hybrids (H-S). In vivo pollen tube growth was analyzed for each cross combination with fluorescence microscopy. Attempts to create bridge hybrids between S. stoloniferum, and S. cardiophyllum or S. pinnatisectum were not successful. Pre- and post-zygotic barriers prevented seed formation in crosses involving S. cardiophyllum and S. pinnatisectum. Self compatibility in S. stoloniferum and S. pinnatisectum suggests that the S-locus does not contribute to the stylar barriers observed with these species. Alternatively, the presence of functional and nonfunctional (SC) S-alleles may explain interspecific incompatibility in intra- and inter-ploidy crosses. A non-stylar unilateral incongruity was discovered in H-S/HAP × S. stoloniferum crosses, indicating either a post-zygotic barrier, or a pre-zygotic barrier acting at or within the ovary. Furthermore, lack of S. stoloniferum pollen rejection may occur through absence of S. stoloniferum pollen-active genes needed to initiate pollen rejection, or through competitive interaction in S-locus heterozygous S. stoloniferum pollen. Introgression strategies using these species would benefit potato breeding by introducing genetic diversity for several traits simultaneously through co-current introgression.     

Wide hybridization in Brassica

Summary Crosses were made to obtain interspecific hybrids between B. fruticulosa (wild species , 2n = 16) × B. campestris (cultivar , 2n = 20). Although many pollen grains germinated and their tubes entered the style, only about 30% of the ovules received pollen tubes. Fertilized ovules aborted at various stages of development. A few hybrid seeds resulted from hand pollinations in the field, and they showed poor germination and seedling establishment. The in vitro culture of ovaries, ovules, and seeds increased the frequency of obtaining hybrid seeds and plants: the most effective method was ovary culture followed by ovule culture. The hybrid nature of the plants was confirmed through morphological, cytological, and electrophoretic studies. A meiotic analysis of F₁ hybrids (2n = 18) showed that they had 0–5 bivalents and were completely pollen sterile. Electrophoretic analysis of leaf esterases and acid phosphatases of F₁ hybrids revealed bands derived from each parent. Induced amphidiploids of F₁ hybrids contained mostly bivalents, and had about 50% fertile pollen.     

Inheritance of resistance in water yam (Dioscorea alata) to anthracnose (Colletotrichum gloeosporioides)

Colletotrichum gloeosporioides causes anthracnose, the most severe foliar disease of field-grown water yam (Dioscorea alata). The inheritance of resistance to a moderately virulent (FGS) strain of the pathogen was investigated in crosses between tetraploid D. alata genotypes: TDa 95/00328 (resistant)×TDa 95–310 (susceptible) (cross A), and TDa 85/00257 (resistant)×TDa 92–2 (susceptible) (cross B). Segregation of F₁ progeny fitted genetic ratios of 3:1, 5:1 (crosses A and B) and 7:1 (cross A) resistant:susceptible when inoculated with the FGS strain, indicating that resistance is dominantly inherited and suggesting that more than one gene controls the inheritance of resistance to this strain in the accessions studied. When parental and progeny lines of cross A were inoculated with an aggressive (SGG) strain of the pathogen, all plants expressed a susceptible phenotype, indicating strain-specific resistance in TDa 95/00328. Screening of 20 cultivars/landraces confirmed the high susceptibility of D. alata accessions to the SGG strain and revealed the presence of apparent strain non-specific resistance in TDa 85/00257. TDa 85/00257 and TDa 87/01091 which were resistant to the SGG strain, will be useful both as sources of resistance and in the development of a host differential series for D. alata. Received: 15 May 2000 / Accepted: 18 October 2000     

The effect of crossing distances and population subdivision on floral morphology inScleranthus annuus (Caryophyllaceae), a selfing annual

I used a discontinuous population ofScleranthus annuus (Caryophyllaceae) to study the effect of crossing distances on flower morphology of the progeny. Four types of progeny were produced by artificial selfing, crossing with pollen-donors from the same patch in the population, crossing with pollen from donors from other patches in the population and inter-population crosses. The size of gynoecium parts and 12 sepal characters in this petal-lacking species were significantly influenced by the type of cross and the patch in the population from where the seed-parents originated. All comparisons of progeny types except selfed vs progeny produced by within-patch crosses were significantly separated from each other, while all four seed-parent patches used were significantly separated in a multidimensional space.