Teliospores of the smut fungus Sporisorium sorghi developed in galls on Johnson grass (Sorghum halapense) inflorescences. Pieces of gall tissue were freeze substituted and processed for study with transmission electron microscopy. This procedure yielded well-preserved spores in different stages of development and permitted detailed ultrastructural observation of the spore maturation process. Uninucleate teliospore initials developed from sporogenous hyphae of S. sorghi. Hyphal walls appeared to gelatinize during the formation of spore initials, leaving the initials embedded in a fibrillar matrix. Young teliospores became surrounded by a primary wall as they enlarged. Large and small electron dense spines developed adjacent to the plasma membrane of the spore and grew into the primary wall. As spines developed, the primary wall partially disintegrated, with remnants persisting as a sheath around the spines. Two additional wall layers were then deposited beneath the spines. The outermost layer, with which the spines appeared to be continuous, was extremely electron dense and the thicker of the two layers. The inner layer was of moderate electron density. Each teliospore contained a prominent nucleus, mitochondria, microbodies, strands of rough endoplasmic reticulum, microtubules, and multivesicular bodies. Numerous lipid droplets were also present in each spore, many closely associated with microbodies.
{"title":"Teliospore Maturation in the Smut Fungus Sporisorium sorghi: An Ultrastructural Study Using Freeze Substitution Fixation","authors":"C. Mims, K. Snetselaar","doi":"10.1086/337856","DOIUrl":"https://doi.org/10.1086/337856","url":null,"abstract":"Teliospores of the smut fungus Sporisorium sorghi developed in galls on Johnson grass (Sorghum halapense) inflorescences. Pieces of gall tissue were freeze substituted and processed for study with transmission electron microscopy. This procedure yielded well-preserved spores in different stages of development and permitted detailed ultrastructural observation of the spore maturation process. Uninucleate teliospore initials developed from sporogenous hyphae of S. sorghi. Hyphal walls appeared to gelatinize during the formation of spore initials, leaving the initials embedded in a fibrillar matrix. Young teliospores became surrounded by a primary wall as they enlarged. Large and small electron dense spines developed adjacent to the plasma membrane of the spore and grew into the primary wall. As spines developed, the primary wall partially disintegrated, with remnants persisting as a sheath around the spines. Two additional wall layers were then deposited beneath the spines. The outermost layer, with which the spines appeared to be continuous, was extremely electron dense and the thicker of the two layers. The inner layer was of moderate electron density. Each teliospore contained a prominent nucleus, mitochondria, microbodies, strands of rough endoplasmic reticulum, microtubules, and multivesicular bodies. Numerous lipid droplets were also present in each spore, many closely associated with microbodies.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"1 - 7"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337856","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Upon resupply of exogenous nitrogen to nitrogen-stressed plants, uptake rate of nitrogen is enhanced relative to nonstressed plants. Absorption of nitrogen presumably is dependent on availability of carbohydrates in the roots. A buildup in soluble carbohydrates thus should occur in roots of nitrogen-stressed plants, and upon resupply of exogenous nitrogen the increased uptake rate should be accompanied by a rapid decline in carbohydrates to prestress levels. To evaluate this relationship, three sets of tobacco plants growing in a complete hydroponic solution containing 1.0 mM NO3- were either continued in the complete solution for 21 d, transferred to a minus-nitrogen solution for 21 d, or transferred to a minus-nitrogen solution for 8-9 d and then returned to the 1.0 mM NO3- solution. These nitrogen treatments were imposed upon plants growing at photosynthetic photon flux densities of 700 and 350 micromoles m-2 s-1. Soluble carbohydrate levels in roots increased during onset of nitrogen stress to levels that were fourfold greater than in roots of non-stressed plants. Following resupply of external nitrogen, a rapid resumption of nitrogen uptake was accompanied by a decline in soluble carbohydrates in roots to levels characteristic of nonstressed plants. This pattern of soluble carbohydrate levels in roots during onset of and recovery from nitrogen stress occurred at both irradiance levels. The response of net photosynthetic rate to nitrogen stress could be expressed as a nonlinear function of concentration of reduced nitrogen in leaves. The net photosynthetic rate at a given concentration of reduced nitrogen, however, averaged 10% less at the lower than at the higher irradiance. The decline in net photosynthetic rate per unit of reduced nitrogen in leaves at the lower irradiance was accompanied by an increase in the nitrate fraction of total nitrogen in leaves from 20% at the higher irradiance to 38% at the lower irradiance.
{"title":"Soluble carbohydrate allocation to roots, photosynthetic rate of leaves, and nitrate assimilation as affected by nitrogen stress and irradiance.","authors":"L T Henry, C D Raper","doi":"10.1086/337859","DOIUrl":"10.1086/337859","url":null,"abstract":"<p><p>Upon resupply of exogenous nitrogen to nitrogen-stressed plants, uptake rate of nitrogen is enhanced relative to nonstressed plants. Absorption of nitrogen presumably is dependent on availability of carbohydrates in the roots. A buildup in soluble carbohydrates thus should occur in roots of nitrogen-stressed plants, and upon resupply of exogenous nitrogen the increased uptake rate should be accompanied by a rapid decline in carbohydrates to prestress levels. To evaluate this relationship, three sets of tobacco plants growing in a complete hydroponic solution containing 1.0 mM NO3- were either continued in the complete solution for 21 d, transferred to a minus-nitrogen solution for 21 d, or transferred to a minus-nitrogen solution for 8-9 d and then returned to the 1.0 mM NO3- solution. These nitrogen treatments were imposed upon plants growing at photosynthetic photon flux densities of 700 and 350 micromoles m-2 s-1. Soluble carbohydrate levels in roots increased during onset of nitrogen stress to levels that were fourfold greater than in roots of non-stressed plants. Following resupply of external nitrogen, a rapid resumption of nitrogen uptake was accompanied by a decline in soluble carbohydrates in roots to levels characteristic of nonstressed plants. This pattern of soluble carbohydrate levels in roots during onset of and recovery from nitrogen stress occurred at both irradiance levels. The response of net photosynthetic rate to nitrogen stress could be expressed as a nonlinear function of concentration of reduced nitrogen in leaves. The net photosynthetic rate at a given concentration of reduced nitrogen, however, averaged 10% less at the lower than at the higher irradiance. The decline in net photosynthetic rate per unit of reduced nitrogen in leaves at the lower irradiance was accompanied by an increase in the nitrate fraction of total nitrogen in leaves from 20% at the higher irradiance to 38% at the lower irradiance.</p>","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"23-33"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337859","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Plantlet regeneration of red spruce (Picea rubens Sarg.) was achieved from mature embryos, cotyledons, and hypocotyl explants. Optimal bud induction was observed on half-strength modified Bornman's (MCM) medium with 10 μM N6-benzyladenine for 14 d. Shoot elongation occurred after transfer to half-strength modified von Arnold and Eriksson's medium. Decreasing sucrose to 2% and addition of conifer-derived activated charcoal enhanced shoot elongation. Low concentrations of cytokinin (0.1 μM) promoted growth of axillary shoots. Rooting was induced on excised shoots by dipping in rooting powder or pulsing in high concentrations of indolebutyric acid plus indoleacetic acid or naphthaleneacetic acid prior to transfer to hormone-free medium. Plantlets grew after transfer to the greenhouse
{"title":"Plantlet Regeneration from Cultured Embryos and Seedling Parts of Red Spruce (Picea rubens Sarg.)","authors":"Chin-yi Lu, I. Harry, M. Thompson, T. Thorpe","doi":"10.1086/337861","DOIUrl":"https://doi.org/10.1086/337861","url":null,"abstract":"Plantlet regeneration of red spruce (Picea rubens Sarg.) was achieved from mature embryos, cotyledons, and hypocotyl explants. Optimal bud induction was observed on half-strength modified Bornman's (MCM) medium with 10 μM N6-benzyladenine for 14 d. Shoot elongation occurred after transfer to half-strength modified von Arnold and Eriksson's medium. Decreasing sucrose to 2% and addition of conifer-derived activated charcoal enhanced shoot elongation. Low concentrations of cytokinin (0.1 μM) promoted growth of axillary shoots. Rooting was induced on excised shoots by dipping in rooting powder or pulsing in high concentrations of indolebutyric acid plus indoleacetic acid or naphthaleneacetic acid prior to transfer to hormone-free medium. Plantlets grew after transfer to the greenhouse","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"42 - 50"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337861","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Trichome morphology of 136 species of Cuphea was studied using light and electron microscopy. Seven different trichome types were recognized, and three were found to have distinct taxonomic value at sectional and subsectional levels. Biarmed trichomes characterize the sections Heteranthus and Amazoniana. Flattened hyaline hairs define a group of species in section Melvilla subsection Pachycalyx. Globose, sessile, glandular trichomes are restricted to sections Archocuphea and Melicyathium. Other types are widely distributed in the genus and can be useful diagnostic characters at the species level. TEM studies of the glandular trichomes revealed subcellular structures thought to be involved in the secretion of resin.
{"title":"Trichome Morphology in the Genus Cuphea (Lythraceae)","authors":"V. Amarasinghe, S. Graham, A. Graham","doi":"10.1086/337866","DOIUrl":"https://doi.org/10.1086/337866","url":null,"abstract":"Trichome morphology of 136 species of Cuphea was studied using light and electron microscopy. Seven different trichome types were recognized, and three were found to have distinct taxonomic value at sectional and subsectional levels. Biarmed trichomes characterize the sections Heteranthus and Amazoniana. Flattened hyaline hairs define a group of species in section Melvilla subsection Pachycalyx. Globose, sessile, glandular trichomes are restricted to sections Archocuphea and Melicyathium. Other types are widely distributed in the genus and can be useful diagnostic characters at the species level. TEM studies of the glandular trichomes revealed subcellular structures thought to be involved in the secretion of resin.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"77 - 90"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337866","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sporophylls from strobili of 16 species among 11 genera of cycads were examined for idioblasts. Thin-walled secretory-like idioblasts were found in the majority of taxa and thick-walled sclerenchyma-type idioblasts were found in the minority. With the exception of Cycas rumphii and Stangeria eriopus, where secretory idioblasts were in the epidermis and/or hypodermis, none were found in the sporophyll parenchyma of these species. Most idioblasts stained ninhydrin-Schiff-positive, and tannins were present also. Sporophyll idioblasts appear to be related to interactions with insect predators and/or cosymbionts and may form part of a complex pollination syndrome. The lack of idioblasts in stem tissue and low concentration in leaflet tissue of Zamia furfuracea compared with sporophyll tissue is significant support to this hypothesis. On the basis of almost universal occurrence of these idioblasts in the sporophylls, we suggest that insect symbiosis related to pollination may be common to most cycad genera.
{"title":"Cone Idioblasts of Eleven Cycad Genera: Morphology, Distribution, and Significance","authors":"A. Vovides","doi":"10.1086/337867","DOIUrl":"https://doi.org/10.1086/337867","url":null,"abstract":"Sporophylls from strobili of 16 species among 11 genera of cycads were examined for idioblasts. Thin-walled secretory-like idioblasts were found in the majority of taxa and thick-walled sclerenchyma-type idioblasts were found in the minority. With the exception of Cycas rumphii and Stangeria eriopus, where secretory idioblasts were in the epidermis and/or hypodermis, none were found in the sporophyll parenchyma of these species. Most idioblasts stained ninhydrin-Schiff-positive, and tannins were present also. Sporophyll idioblasts appear to be related to interactions with insect predators and/or cosymbionts and may form part of a complex pollination syndrome. The lack of idioblasts in stem tissue and low concentration in leaflet tissue of Zamia furfuracea compared with sporophyll tissue is significant support to this hypothesis. On the basis of almost universal occurrence of these idioblasts in the sporophylls, we suggest that insect symbiosis related to pollination may be common to most cycad genera.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"91 - 99"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337867","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pollen tube growth in Juglans regia L. has been widely studied, with entry to the ovule variously reported as being porogamous or chalazogamous. We examined the processes involved by using fluorescence and bright field microscopy of sectioned material and whole mounts and squashes of flower parts and ovules. Results indicate that there is a single, consistent path for pollen tube growth from the stigma to the ovary, but within the ovary, pollen tube growth varies. Entry to the ovule is either chalazogamous or porogamous depending on the extent of development of the single, orthotropous ovule. Pollen germination is delayed in flowers pollinated early in the receptive period. These flowers have less well developed ovules with a gap between the base of the stylar canal and the ovule. Pollen tubes arriving at the ovule at this stage are apparently unable to traverse this open space and they bypass the micropyle. Instead, they grow along the surface of winged outgrowths that arise from the base of the ovule. These structures serve an obturator-like role in directing pollen tube growth in the ovary but, unlike a true obturator, they direct the pollen tubes to the base of the ovule where they penetrate the funiculus and enter the ovule through the chalaza. Pollination late in the anthesis period produces tubes that grow into the ovary after development of the ovule has progressed to the point that the integument is closely appressed to the base of the style. These tubes grow directly into the micropyle.
{"title":"Porogamy and Chalazogamy in Walnut (Juglans regia L.)","authors":"J. Luza, V. Polito","doi":"10.1086/337868","DOIUrl":"https://doi.org/10.1086/337868","url":null,"abstract":"Pollen tube growth in Juglans regia L. has been widely studied, with entry to the ovule variously reported as being porogamous or chalazogamous. We examined the processes involved by using fluorescence and bright field microscopy of sectioned material and whole mounts and squashes of flower parts and ovules. Results indicate that there is a single, consistent path for pollen tube growth from the stigma to the ovary, but within the ovary, pollen tube growth varies. Entry to the ovule is either chalazogamous or porogamous depending on the extent of development of the single, orthotropous ovule. Pollen germination is delayed in flowers pollinated early in the receptive period. These flowers have less well developed ovules with a gap between the base of the stylar canal and the ovule. Pollen tubes arriving at the ovule at this stage are apparently unable to traverse this open space and they bypass the micropyle. Instead, they grow along the surface of winged outgrowths that arise from the base of the ovule. These structures serve an obturator-like role in directing pollen tube growth in the ovary but, unlike a true obturator, they direct the pollen tubes to the base of the ovule where they penetrate the funiculus and enter the ovule through the chalaza. Pollination late in the anthesis period produces tubes that grow into the ovary after development of the ovule has progressed to the point that the integument is closely appressed to the base of the style. These tubes grow directly into the micropyle.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"100 - 106"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337868","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Banksia cuneata is a large floriferous shrub or tree confined to seven small populations in southwestern Western Australia. The stand at the study site consisted of groups of even-aged, fire-sensitive plants, suggesting recruitment is usually dependent on recurrent fire. Following a 4-yr juvenile period, annual fruit set increased exponentially, yielding 11,700 two-seeded follicles per plant over the subsequent 19 yr. Two major constraints restricted the number of seeds available for the next generation: low fruit set relative to flower production (1.5%) and decay of canopy-held follicles after 10 yr. There was no predation of reproductive parts and only minor abortion, senescence, and prefire release of seeds. Most of the 17,100 viable canopy-stored seeds in the 23-yr-old cohort were released within 24 h of a hot autumn fire, whereas wet/dry cycles were required following milder fires. Less than 5% of seeds germinated and only 0.1% of these survived the first summer drought. Seedlings transplanted to moister sites and/or watered regularly over summer were much larger and more likely to survive to the next winter than the controls. We conclude that population numbers are not limited by the size and dynamics of the canopy seed bank but by the weather pattern following fire-induced seed release.
{"title":"Seed Bank and Population Dynamics of Banksia cuneata: The Role of Time, Fire, and Moisture","authors":"B. Lamont, S. W. Connell, S. Bergl","doi":"10.1086/337870","DOIUrl":"https://doi.org/10.1086/337870","url":null,"abstract":"Banksia cuneata is a large floriferous shrub or tree confined to seven small populations in southwestern Western Australia. The stand at the study site consisted of groups of even-aged, fire-sensitive plants, suggesting recruitment is usually dependent on recurrent fire. Following a 4-yr juvenile period, annual fruit set increased exponentially, yielding 11,700 two-seeded follicles per plant over the subsequent 19 yr. Two major constraints restricted the number of seeds available for the next generation: low fruit set relative to flower production (1.5%) and decay of canopy-held follicles after 10 yr. There was no predation of reproductive parts and only minor abortion, senescence, and prefire release of seeds. Most of the 17,100 viable canopy-stored seeds in the 23-yr-old cohort were released within 24 h of a hot autumn fire, whereas wet/dry cycles were required following milder fires. Less than 5% of seeds germinated and only 0.1% of these survived the first summer drought. Seedlings transplanted to moister sites and/or watered regularly over summer were much larger and more likely to survive to the next winter than the controls. We conclude that population numbers are not limited by the size and dynamics of the canopy seed bank but by the weather pattern following fire-induced seed release.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"114 - 122"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337870","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The structure of actinorhizal nodules of Cowania subintegra (common name: Arizona cliffrose) was studied by transmission electron microscopy. Morphological forms of the actinomycete in host cortical cells included septate hyphae and nonseptate elliptically shaped vesicles. Vesicles were distributed randomly throughout the host cytoplasm and were surrounded by host plasma membrane. No sporangia were observed in these nodules. Both endophytic hyphae and endophytic vesicles contained nucleoid regions, vesicular mesosomes, and rosette-shaped granules. The fine structure of the microsymbiont was similar to that found in other Frankia-induced root nodules, especially those in other members of the Rosaceae.
{"title":"Ultrastructure of Actinorhizal Nodules of Cowania subintegra (Rosaceae)","authors":"C. B. Perry, V. Bess, J. Stutz","doi":"10.1086/337857","DOIUrl":"https://doi.org/10.1086/337857","url":null,"abstract":"The structure of actinorhizal nodules of Cowania subintegra (common name: Arizona cliffrose) was studied by transmission electron microscopy. Morphological forms of the actinomycete in host cortical cells included septate hyphae and nonseptate elliptically shaped vesicles. Vesicles were distributed randomly throughout the host cytoplasm and were surrounded by host plasma membrane. No sporangia were observed in these nodules. Both endophytic hyphae and endophytic vesicles contained nucleoid regions, vesicular mesosomes, and rosette-shaped granules. The fine structure of the microsymbiont was similar to that found in other Frankia-induced root nodules, especially those in other members of the Rosaceae.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"8 - 12"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Genetic incompatibility or other reproductive barriers are thought to be the main impediments to introgression of germplasm from wild to cultivated species of Arachis. Comparative morphological development of the peg, ovary, and ovule was undertaken in two A. hypogaea L. cultivars, cv NC 6 and cv Argentine, and two closely related diploid Arachis species, A. duranensis and A. stenosperma, to determine if probable impediments could be detected. Analysis showed that there were significant differences among the four genotypes with respect to length of both basal and apical locules The A. stenosperma basal locule was the longest but decreased slightly during development, while other genotypes had a positive linear slope Apical locule growth patterns varied, with wild species showing curvilinear growth. Basal and apical ovules were nearly the same size for all genotypes except cv NC 6, which was longer and grew more rapidly. Basal and apical embryos reached the eight-cell phase in all genotypes by d 5. Embryo growth of the basal ovules was linear, while that of apical ovules was quadratic, tapering off after 72 h. Cv NC 6 was longer and grew more rapidly than the other genotypes and A. duranensis had the smallest embryos. Embryo width showed a linear decrease in all genotypes, with the rate greatest in cv NC 6. Peg growth was initiated within 24 h after fertilization in all genotypes, at which time only A. duranensis had a significantly faster growth rate. Differences in various component growth rates controlled from information supplied by male gametes and female egg and/or polar nuclei could conflict with each other and restrict or accelerate growth in such a manner as to induce abortion.
{"title":"Comparative Peg, Ovary, and Ovule Ontogeny of Selected Cultivated and Wild-Type Arachis Species","authors":"H. Pattee, H. T. Stalker, F. Giesbrecht","doi":"10.1086/337864","DOIUrl":"https://doi.org/10.1086/337864","url":null,"abstract":"Genetic incompatibility or other reproductive barriers are thought to be the main impediments to introgression of germplasm from wild to cultivated species of Arachis. Comparative morphological development of the peg, ovary, and ovule was undertaken in two A. hypogaea L. cultivars, cv NC 6 and cv Argentine, and two closely related diploid Arachis species, A. duranensis and A. stenosperma, to determine if probable impediments could be detected. Analysis showed that there were significant differences among the four genotypes with respect to length of both basal and apical locules The A. stenosperma basal locule was the longest but decreased slightly during development, while other genotypes had a positive linear slope Apical locule growth patterns varied, with wild species showing curvilinear growth. Basal and apical ovules were nearly the same size for all genotypes except cv NC 6, which was longer and grew more rapidly. Basal and apical embryos reached the eight-cell phase in all genotypes by d 5. Embryo growth of the basal ovules was linear, while that of apical ovules was quadratic, tapering off after 72 h. Cv NC 6 was longer and grew more rapidly than the other genotypes and A. duranensis had the smallest embryos. Embryo width showed a linear decrease in all genotypes, with the rate greatest in cv NC 6. Peg growth was initiated within 24 h after fertilization in all genotypes, at which time only A. duranensis had a significantly faster growth rate. Differences in various component growth rates controlled from information supplied by male gametes and female egg and/or polar nuclei could conflict with each other and restrict or accelerate growth in such a manner as to induce abortion.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"64 - 71"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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