The soybean (Glycine max [L.] Merr.) is a quantitative short-day (SD) plant requiring two inductive cycles for floral initiation, which occurs first in the most undifferentiated meristem in an axil of a main stem leaf. Floral initiation at the main stem apex, however, requires additional SD inductive cycles. Under continuous SD the transition to flowering in the main stem apex is completed after 8 SD cycles. Differentiation and organogenesis of the first flower in the terminal raceme is apparent after 10 SD cycles. The changes in apical size and geometry, nuclear DNA, and rate of leaf initiation were followed daily during this 10-d period and compared with apices from plants kept under noninductive long days (LD). At emergence all plants had initiated three trifoliolate leaf primordia and during the vegetative stage of development maintained a plastochron of 2.0 d/leaf. The plastochron was shortened to 1.0 d/leaf in SD plants on day 7, just prior to the end of the transition. Apical size and geometry remained unchanged until after 6 SD cycles when height of the dome decreased and there was less elongation of the rib meristem. Earlier events included significantly lower amounts of nuclear DNA in cells of SD apices after 1 and 3 SD cycles. Later, the amount of nuclear DNA increased in cells of SD apices beginning after 5 SD and peaking after 6 SD before decreasing back to control levels. Shifts in increasing proportions of the population of nuclei from the 4C to 2C condition occurred after 1 SD and 3 SD. As in other species, both of these shifts are apparently essential components for the floral transition at the shoot apex in soybean. The first shift, or "mitotic" stimulus, signals that the process of the floral transition has begun, while the second shift, or "floral" stimulus, is required for completion of the process.
{"title":"Shoot Meristem Activity during Floral Transition in Glycine max (L.) Merr.","authors":"Judith F. Thomas, Malee L. Kanchanapoom","doi":"10.1086/337873","DOIUrl":"https://doi.org/10.1086/337873","url":null,"abstract":"The soybean (Glycine max [L.] Merr.) is a quantitative short-day (SD) plant requiring two inductive cycles for floral initiation, which occurs first in the most undifferentiated meristem in an axil of a main stem leaf. Floral initiation at the main stem apex, however, requires additional SD inductive cycles. Under continuous SD the transition to flowering in the main stem apex is completed after 8 SD cycles. Differentiation and organogenesis of the first flower in the terminal raceme is apparent after 10 SD cycles. The changes in apical size and geometry, nuclear DNA, and rate of leaf initiation were followed daily during this 10-d period and compared with apices from plants kept under noninductive long days (LD). At emergence all plants had initiated three trifoliolate leaf primordia and during the vegetative stage of development maintained a plastochron of 2.0 d/leaf. The plastochron was shortened to 1.0 d/leaf in SD plants on day 7, just prior to the end of the transition. Apical size and geometry remained unchanged until after 6 SD cycles when height of the dome decreased and there was less elongation of the rib meristem. Earlier events included significantly lower amounts of nuclear DNA in cells of SD apices after 1 and 3 SD cycles. Later, the amount of nuclear DNA increased in cells of SD apices beginning after 5 SD and peaking after 6 SD before decreasing back to control levels. Shifts in increasing proportions of the population of nuclei from the 4C to 2C condition occurred after 1 SD and 3 SD. As in other species, both of these shifts are apparently essential components for the floral transition at the shoot apex in soybean. The first shift, or \"mitotic\" stimulus, signals that the process of the floral transition has begun, while the second shift, or \"floral\" stimulus, is required for completion of the process.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"139 - 147"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337873","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238395","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}
Leaf anatomical characteristics under normal and reduced water supply in three high-level ABA (abscisic acid) drought-resistant (ZPBL 1304, L-155, and Polj 17) and three low-level ABA drought-sensitive (ZPL 389, B-432, and F-2) lines of Zea mays L. were investigated. The characteristics examined were (1) blade area, (2) thickness of leaf, epidermis, mesophyll, and bulliform cells, (3) stomatal frequency and size of stomatal apparatus, and (4) vessel cross-sectional area. Lines ZPBL 1304 and ZPL 389, L-155 and B-432, and Polj 17 and F-2 were compared. Plant recovery was estimated after exposure to water stress and high-temperature stress. Under normal water supply, the drought-resistant lines were more xeromorphic than the drought-susceptible lines. Water stress affected leaf structures in all lines. Association of xeromorphic features with the ability of the plant to withstand drought varied under dry conditions. Lines ZPL 389, L-155, and Polj 17 were more xeromorphic than lines ZPBL 1304, B-432, and F-2. High temperature induced considerable leaf structural disorganization; however, the changes were not the same in all lines. The greatest differences in leaf structure were observed after the recovery period. The drought-resistant lines showed greater recovery than the drought-sensitive lines. The results, in general, support the hypothesis that cultivars with higher levels of ABA and/or greater drought resistance are more xeromorphic than cultivars with lower levels of ABA and/or lower drought resistance.
{"title":"Leaf Anatomy of Zea mays L. in Response to Water Shortage and High Temperature: A Comparison of Drought-Resistant and Drought-Sensitive Lines","authors":"Z. Ristić, D. Cass","doi":"10.1086/337877","DOIUrl":"https://doi.org/10.1086/337877","url":null,"abstract":"Leaf anatomical characteristics under normal and reduced water supply in three high-level ABA (abscisic acid) drought-resistant (ZPBL 1304, L-155, and Polj 17) and three low-level ABA drought-sensitive (ZPL 389, B-432, and F-2) lines of Zea mays L. were investigated. The characteristics examined were (1) blade area, (2) thickness of leaf, epidermis, mesophyll, and bulliform cells, (3) stomatal frequency and size of stomatal apparatus, and (4) vessel cross-sectional area. Lines ZPBL 1304 and ZPL 389, L-155 and B-432, and Polj 17 and F-2 were compared. Plant recovery was estimated after exposure to water stress and high-temperature stress. Under normal water supply, the drought-resistant lines were more xeromorphic than the drought-susceptible lines. Water stress affected leaf structures in all lines. Association of xeromorphic features with the ability of the plant to withstand drought varied under dry conditions. Lines ZPL 389, L-155, and Polj 17 were more xeromorphic than lines ZPBL 1304, B-432, and F-2. High temperature induced considerable leaf structural disorganization; however, the changes were not the same in all lines. The greatest differences in leaf structure were observed after the recovery period. The drought-resistant lines showed greater recovery than the drought-sensitive lines. The results, in general, support the hypothesis that cultivars with higher levels of ABA and/or greater drought resistance are more xeromorphic than cultivars with lower levels of ABA and/or lower drought resistance.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"173 - 185"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337877","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238511","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}
Chloroplast structure in mesophyll cells from more xeromorphic drought-resistant (Polj 17) and less xeromorphic drought-sensitive (F-2) lines of Zea mays L. was studied in response to water stress and a combination of water and high-temperature stress. In the drought-resistant line water stress partly affected chloroplast structure; membranes of the chloroplast envelope were disrupted only in some chloroplasts, but grana were well preserved. Water stress and high-temperature stress affected chloroplasts to a greater extent but did not severely alter their structure. Grana were still visible, and only in some chloroplasts were they less distinguishable. Water shortage in the drought-sensitive line caused swelling of thylakoids and disappearance of outer membranes of the chloroplast envelope in many chloroplasts. Addition of temperature stress increased chloroplast disruption. The most striking difference was in the structural characteristics of chloroplasts after rehydration. Chloroplasts from the drought-resistant line appeared close to normal. In contrast, chloroplasts from the drought-sensitive line showed signs of additional deterioration in their structure. Differences in chloroplast structure under stress conditions between lines were likely the result of intraspecific differences in leaf dehydration, and possibly the result of intraspecific differences in the sensitivity of chloroplast membranes to high temperature.
{"title":"Chloroplast Structure after Water Shortage and High Temperature in Two Lines of Zea mays L. that Differ in Drought Resistance","authors":"Z. Ristić, D. Cass","doi":"10.1086/337878","DOIUrl":"https://doi.org/10.1086/337878","url":null,"abstract":"Chloroplast structure in mesophyll cells from more xeromorphic drought-resistant (Polj 17) and less xeromorphic drought-sensitive (F-2) lines of Zea mays L. was studied in response to water stress and a combination of water and high-temperature stress. In the drought-resistant line water stress partly affected chloroplast structure; membranes of the chloroplast envelope were disrupted only in some chloroplasts, but grana were well preserved. Water stress and high-temperature stress affected chloroplasts to a greater extent but did not severely alter their structure. Grana were still visible, and only in some chloroplasts were they less distinguishable. Water shortage in the drought-sensitive line caused swelling of thylakoids and disappearance of outer membranes of the chloroplast envelope in many chloroplasts. Addition of temperature stress increased chloroplast disruption. The most striking difference was in the structural characteristics of chloroplasts after rehydration. Chloroplasts from the drought-resistant line appeared close to normal. In contrast, chloroplasts from the drought-sensitive line showed signs of additional deterioration in their structure. Differences in chloroplast structure under stress conditions between lines were likely the result of intraspecific differences in leaf dehydration, and possibly the result of intraspecific differences in the sensitivity of chloroplast membranes to high temperature.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"186 - 194"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337878","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238531","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}
We have examined the effect of the temperature at which soybean plants produced seeds on the morphology and growth rate of plants produced from those seeds. We germinated Fiskeby V seeds at 20 C, then randomly assigned plants to either an 18 C or 25 C controlled environment chamber until they had produced mature seeds. Characteristics of the seedlots produced at 18 and 25 C were then compared in controlled environment chambers with three different thermal regimes and, also, in field trials. Mean seed size and emergence rate did not differ between seedlots. When grown at 25 C in a controlled environment, and when grown in the field, plants grown from the 25 C-grown seedlot had greater axillary stem weight than the 18 C-grown seedlot, at each of three growth stages. Total leaf area and dry weight were greater for the 25 C-grown seedlot than for the 18 C-grown seedlot at one growth stage, when grown in the controlled environment at 25 C and in the field. The results indicated that environment of the parent plants had an effect on the morphology and growth rate of the subsequent generation and indicate that caution should be used in inferring genetic differences between parent populations from morphological differences in the progeny.
{"title":"Influence of the Environment during Seed Development on the Morphology and Growth Rate of Soybean Seedlings","authors":"F. Caulfield, J. Bunce","doi":"10.1086/337863","DOIUrl":"https://doi.org/10.1086/337863","url":null,"abstract":"We have examined the effect of the temperature at which soybean plants produced seeds on the morphology and growth rate of plants produced from those seeds. We germinated Fiskeby V seeds at 20 C, then randomly assigned plants to either an 18 C or 25 C controlled environment chamber until they had produced mature seeds. Characteristics of the seedlots produced at 18 and 25 C were then compared in controlled environment chambers with three different thermal regimes and, also, in field trials. Mean seed size and emergence rate did not differ between seedlots. When grown at 25 C in a controlled environment, and when grown in the field, plants grown from the 25 C-grown seedlot had greater axillary stem weight than the 18 C-grown seedlot, at each of three growth stages. Total leaf area and dry weight were greater for the 25 C-grown seedlot than for the 18 C-grown seedlot at one growth stage, when grown in the controlled environment at 25 C and in the field. The results indicated that environment of the parent plants had an effect on the morphology and growth rate of the subsequent generation and indicate that caution should be used in inferring genetic differences between parent populations from morphological differences in the progeny.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"20 3 1","pages":"59 - 63"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337863","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237924","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 effect of salinization on development of the whole shoot and individual leaves of Lactuca sativa L. cv Black-seeded Simpson was studied nondestructively. Salinization by 80 mol m-3 NaCl (from the 10 mol m-3 control concentration) slowed shoot development. The lengthening of the plastochron because of salinization was evident in rates of leaf expansion, frequency of leaf emergence, and growth rate of the whole shoot. The plastochron effect on shoot development was sufficient to account for a 33% reduction in biomass of the shoot, equaling the entire growth inhibition measured during the first week following salinization. A second effect, reduction in maximum leaf size, could be measured after 2 more wk of plant growth. A 50% reduction in fresh weight of fully mature leaves of salinized plants was evident in leaves already beyond the most rapid phase of expansion at the time of salinization. Curtailment of the slow phase of leaf expansion seems, therefore, to reduce maximum leaf size. This cultivar lends itself to nondestructive growth study because of its rapid growth, high rate of leaf emergence, the open access to its leaves, and the absence of a significant contribution by the stem to shoot biomass. Mathematical reconstruction of the shoot allows comparison with results from destructive studies measuring growth of the bulked shoot.
{"title":"Growth and Development of the Lactuca sativa Shoot as Affected by NaCl Stress: Consideration of Leaf Developmental Stages","authors":"D. Lazof, N. Bernstein, A. Läuchli","doi":"10.1086/337865","DOIUrl":"https://doi.org/10.1086/337865","url":null,"abstract":"The effect of salinization on development of the whole shoot and individual leaves of Lactuca sativa L. cv Black-seeded Simpson was studied nondestructively. Salinization by 80 mol m-3 NaCl (from the 10 mol m-3 control concentration) slowed shoot development. The lengthening of the plastochron because of salinization was evident in rates of leaf expansion, frequency of leaf emergence, and growth rate of the whole shoot. The plastochron effect on shoot development was sufficient to account for a 33% reduction in biomass of the shoot, equaling the entire growth inhibition measured during the first week following salinization. A second effect, reduction in maximum leaf size, could be measured after 2 more wk of plant growth. A 50% reduction in fresh weight of fully mature leaves of salinized plants was evident in leaves already beyond the most rapid phase of expansion at the time of salinization. Curtailment of the slow phase of leaf expansion seems, therefore, to reduce maximum leaf size. This cultivar lends itself to nondestructive growth study because of its rapid growth, high rate of leaf emergence, the open access to its leaves, and the absence of a significant contribution by the stem to shoot biomass. Mathematical reconstruction of the shoot allows comparison with results from destructive studies measuring growth of the bulked shoot.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"72 - 76"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337865","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238015","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}
Naturally occurring postanthesis abscission in olive (Olea europaea L. Manzanillo) results in approximately 99% loss of flowers. Ethylene gas treatment induces sequential abscission of flowers, rachis branches and internodal sections, and peduncles of mature (expanded) inflorescences on shoot explants. Treatment with 2-chloroethyl phosphonic acid (ethephon) triggers sequential abscission of flowers and peduncles of mature inflorescences but only very infrequently rachises and never internodal sections. Immature (not fully expanded) inflorescences on shoot explants abscise intact in response to ethylene gas or ethephon. Sites of floral abscission on trees are limited to bracts, petals, individual flowers, and peduncles. With the exception of bracts, floral organs on trees do not abscise until after pollination. Naturally occurring abscission is preceded by plasmolysis of abscission zone cells, loss of cell wall materials as evidenced by changes in stain intensity, and lacunar cell separation. Abscission of floral organs of trees and of explants treated with ethephon or ethylene gas occurs at localized sites and is preceded by cell wall gelatinization and swelling (in ethephon-treated samples only), loss of cell wall and middle lamella pectins, lacunar cell separation, and senescence of cortical parenchyma cells. Phytotoxic symptoms, plasmolysis and cell senescence throughout all explant tissues occurred with ethephon treatments. All active abscission zone cells exhibit small size, isodiametric shape, dense cytoplasm, and starch accumulation. Cell division does not occur in any abscission zone with any treatment.
橄榄(Olea europaea L. Manzanillo)自然发生的花位脱落导致大约99%的花损失。乙烯气体处理导致花、轴枝、节间部分和芽外植体上成熟花序(展开花序)的序贯脱落。用2-氯乙基膦酸(乙烯利)处理会引起成熟花序的花和花序梗的序贯脱落，但只在很少的情况下发生于轴和节间部分。未成熟(未完全展开)花序在茎外植体上对乙烯气体或乙烯利的反应完整地脱落。在树上的花脱落地点限于苞片、花瓣、单花和花序梗。除苞片外，树上的花器官直到授粉后才脱落。自然发生的脱落发生在脱落带细胞的胞浆溶解、细胞壁材料的丧失(染色强度的变化证明了这一点)和腔隙细胞分离之前。用乙烯利或乙烯气体处理的树木和外植体的花器官脱落发生在局部部位，之前是细胞壁糊化和肿胀(仅在乙烯利处理的样品中)，细胞壁和中间薄片果胶的损失，腔室细胞分离和皮层薄壁细胞衰老。乙烯利处理后，所有外植体组织均出现植物毒性症状、质溶解和细胞衰老。所有活性脱落带细胞均表现为体积小、形状等径、细胞质致密和淀粉积累。细胞分裂不会发生在任何处理的脱落区。
{"title":"Inflorescence Abscission in Olive: Anatomy and Histochemistry in Response to Ethylene and Ethephon","authors":"K. Weis, B. D. Webster, R. Goren, G. Martin","doi":"10.1086/337862","DOIUrl":"https://doi.org/10.1086/337862","url":null,"abstract":"Naturally occurring postanthesis abscission in olive (Olea europaea L. Manzanillo) results in approximately 99% loss of flowers. Ethylene gas treatment induces sequential abscission of flowers, rachis branches and internodal sections, and peduncles of mature (expanded) inflorescences on shoot explants. Treatment with 2-chloroethyl phosphonic acid (ethephon) triggers sequential abscission of flowers and peduncles of mature inflorescences but only very infrequently rachises and never internodal sections. Immature (not fully expanded) inflorescences on shoot explants abscise intact in response to ethylene gas or ethephon. Sites of floral abscission on trees are limited to bracts, petals, individual flowers, and peduncles. With the exception of bracts, floral organs on trees do not abscise until after pollination. Naturally occurring abscission is preceded by plasmolysis of abscission zone cells, loss of cell wall materials as evidenced by changes in stain intensity, and lacunar cell separation. Abscission of floral organs of trees and of explants treated with ethephon or ethylene gas occurs at localized sites and is preceded by cell wall gelatinization and swelling (in ethephon-treated samples only), loss of cell wall and middle lamella pectins, lacunar cell separation, and senescence of cortical parenchyma cells. Phytotoxic symptoms, plasmolysis and cell senescence throughout all explant tissues occurred with ethephon treatments. All active abscission zone cells exhibit small size, isodiametric shape, dense cytoplasm, and starch accumulation. Cell division does not occur in any abscission zone with any treatment.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"51 - 58"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237912","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}
M. T. Nielsen, C. P. Akers, U. Järlfors, G. Wagner, S. Berger
A genotypic difference in Nicotiana tabacum L. for the secreting capability of glandular trichomes was used to determine if the secretory function had an ultrastructural basis. Ultrastructural features of young expanding leaves of two genotypes that differ in the secreting capability of their glandular trichomes were determined. The secreting glandular trichomes of T.I. 1068 and the nonsecreting glandular trichomes of T.I. 1406 had multicellular stalks and six- to eight-celled heads. The secreting type had well-developed chloroplasts and other cytoplasmic organelles, but no secretory pathway was evident. Nonsecreting trichomes lacked chloroplasts but did have unusual inclusions in the cytoplasm. These inclusions, which were either membrane-bound or free in the cytoplasm, appeared to develop from the aggregation of membranous material. We hypothesize that the gene responsible for the lack of secreting capability interrupted normal chloroplast development and that chloroplasts in N. tabacum trichomes are necessary for the synthesis of certain exudate compounds.
{"title":"Comparative Ultrastructural Features of Secreting and Nonsecreting Glandular Trichomes of Two Genotypes of Nicotiana tabacum L.","authors":"M. T. Nielsen, C. P. Akers, U. Järlfors, G. Wagner, S. Berger","doi":"10.1086/337858","DOIUrl":"https://doi.org/10.1086/337858","url":null,"abstract":"A genotypic difference in Nicotiana tabacum L. for the secreting capability of glandular trichomes was used to determine if the secretory function had an ultrastructural basis. Ultrastructural features of young expanding leaves of two genotypes that differ in the secreting capability of their glandular trichomes were determined. The secreting glandular trichomes of T.I. 1068 and the nonsecreting glandular trichomes of T.I. 1406 had multicellular stalks and six- to eight-celled heads. The secreting type had well-developed chloroplasts and other cytoplasmic organelles, but no secretory pathway was evident. Nonsecreting trichomes lacked chloroplasts but did have unusual inclusions in the cytoplasm. These inclusions, which were either membrane-bound or free in the cytoplasm, appeared to develop from the aggregation of membranous material. We hypothesize that the gene responsible for the lack of secreting capability interrupted normal chloroplast development and that chloroplasts in N. tabacum trichomes are necessary for the synthesis of certain exudate compounds.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"13 - 22"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337858","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237736","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}
Seed and pollen were collected from Great Basin bristlecone pine trees (Pinus longaeva D. K. Bailey) at Mammoth Creek (Utah) and the Methuselah Grove (California). Analyses determined whether seed and pollen viability, seed weight and germinability, and seedling biomass decreased with increasing age of the parent tree and whether putative mutations increased with increasing parent tree age. There were significant differences in seed weight and seedling biomass between the two locations. Seed from the Methuselah Grove was lighter and Methuselah seedling biomass was lower at all four harvest dates. However, regression analyses did not identify any relationship between tree age and any variable.
在美国犹他州的猛犸溪(Mammoth Creek)和加利福尼亚州的玛土撒拉林(Methuselah Grove)采集了大盆地狐尾松(Pinus longaeva D. K. Bailey)的种子和花粉。分析确定了种子和花粉活力、种子重量和发芽能力以及幼苗生物量是否随着母树树龄的增加而降低，以及推测的突变是否随着母树树龄的增加而增加。两个地点的种子质量和幼苗生物量差异显著。玛土撒拉林的种子重量较轻，玛土撒拉幼苗生物量在所有四个收获日期都较低。然而，回归分析没有发现树龄和任何变量之间的任何关系。
{"title":"Effects of Tree Age on Pollen, Seed, and Seedling Characteristics in Great Basin Bristlecone Pine","authors":"K. Connor, R. M. Lanner","doi":"10.1086/337869","DOIUrl":"https://doi.org/10.1086/337869","url":null,"abstract":"Seed and pollen were collected from Great Basin bristlecone pine trees (Pinus longaeva D. K. Bailey) at Mammoth Creek (Utah) and the Methuselah Grove (California). Analyses determined whether seed and pollen viability, seed weight and germinability, and seedling biomass decreased with increasing age of the parent tree and whether putative mutations increased with increasing parent tree age. There were significant differences in seed weight and seedling biomass between the two locations. Seed from the Methuselah Grove was lighter and Methuselah seedling biomass was lower at all four harvest dates. However, regression analyses did not identify any relationship between tree age and any variable.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"107 - 113"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238087","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 paraveinal mesophyll (PVM) in trifoliolate soybean leaves is a one-cell-thick reticulum extending between the vascular bundles at phloem level. This study describes various features of PVM differentiation in relation to other tissues during leaf ontogeny and also gives quantitative data on cell, vacuole, cytoplasm, and nucleus compartment size in mature leaves. The mitotic index and cell expansion dynamics during leaf development showed that the PVM stopped dividing and began differentiating 4-5 d before the palisade mesophyll. The PVM vacuole begins expansion while the other mesophyll layers still show cell division, reaching 80% of the mature cell volume vs. 30% for mesophyll vacuoles. Almost 40% of the mesophyll vacuolar volume in mature leaves is in PVM. PVM nuclei are twice the diameter of mesophyll nuclei and incorporate higher levels of 3H-thymidine, an indication of greater turnover or perhaps gene amplification or endoreduplication. This temporal quantification of mitotic activity and cell and vacuole expansion rates is important in understanding how the anatomical and physiological differentiation seen in soybean leaf is generated. We show that the large cell and vacuole size of the PVM and its netlike planar extension are a consequence of a combination of early cessation of mitosis, persistant cell expansion, and proportionally greater vacuole to cytoplasm growth relative to surrounding mesophyll cells. An intriguing variation in anatomy occurs in the unifoliolate primary leaf, which has two layers of PVM cells instead of the one layer found in trifoliolate leaves. It was determined that the first layer of PVM begins to differentiate before the second layer is created. The second layer of PVM is derived from an asymmetric division of a second layer of palisade mesophyll initials Both PVM layers then show dynamics of differentiation relative to surrounding mesophyll that is similar to that described for trifoliolate leaves. The mechanism by which two layers of PVM are formed in primary leaves does not represent a simple modification of the trifoliolate leaf ontogeny or anatomy, such as division of an existing PVM initial layer as we hypothesized. PVM formation in the two leaf types may provide a good system for elucidating factors controlling programmed development of tissue types and tissue quantity.
{"title":"Differentiation of Mesophyll and Paraveinal Mesophyll in Soybean Leaf","authors":"K. Liljebjelke, V. Franceschi","doi":"10.1086/337860","DOIUrl":"https://doi.org/10.1086/337860","url":null,"abstract":"The paraveinal mesophyll (PVM) in trifoliolate soybean leaves is a one-cell-thick reticulum extending between the vascular bundles at phloem level. This study describes various features of PVM differentiation in relation to other tissues during leaf ontogeny and also gives quantitative data on cell, vacuole, cytoplasm, and nucleus compartment size in mature leaves. The mitotic index and cell expansion dynamics during leaf development showed that the PVM stopped dividing and began differentiating 4-5 d before the palisade mesophyll. The PVM vacuole begins expansion while the other mesophyll layers still show cell division, reaching 80% of the mature cell volume vs. 30% for mesophyll vacuoles. Almost 40% of the mesophyll vacuolar volume in mature leaves is in PVM. PVM nuclei are twice the diameter of mesophyll nuclei and incorporate higher levels of 3H-thymidine, an indication of greater turnover or perhaps gene amplification or endoreduplication. This temporal quantification of mitotic activity and cell and vacuole expansion rates is important in understanding how the anatomical and physiological differentiation seen in soybean leaf is generated. We show that the large cell and vacuole size of the PVM and its netlike planar extension are a consequence of a combination of early cessation of mitosis, persistant cell expansion, and proportionally greater vacuole to cytoplasm growth relative to surrounding mesophyll cells. An intriguing variation in anatomy occurs in the unifoliolate primary leaf, which has two layers of PVM cells instead of the one layer found in trifoliolate leaves. It was determined that the first layer of PVM begins to differentiate before the second layer is created. The second layer of PVM is derived from an asymmetric division of a second layer of palisade mesophyll initials Both PVM layers then show dynamics of differentiation relative to surrounding mesophyll that is similar to that described for trifoliolate leaves. The mechanism by which two layers of PVM are formed in primary leaves does not represent a simple modification of the trifoliolate leaf ontogeny or anatomy, such as division of an existing PVM initial layer as we hypothesized. PVM formation in the two leaf types may provide a good system for elucidating factors controlling programmed development of tissue types and tissue quantity.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"34 - 41"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237849","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}
A recently discovered Upper Triassic leaf shows many of the characters of the leaves of the living cycads and is assigned to the Cycadales. The leaf, however, does not match any previously described fossil or living cycad leaf in all features and is assigned to a new genus and species, Aricycas paulae. The leaf bears oppositely arranged linear-lanceolate pinnae with pointed apices and contracted bases Pinnae contain prominent midribs and anastomosing lateral veins which end freely near the margins. The ordinary epidermal cells are rectangular with straight to slightly curving side walls and haplocheilic stomata. Pinnae in this leaf are apparently wrinkled and shriveled and in some cases fell before the parent leaves were shed, as is typical of the living cycads. It appears that this character has never been reported in fossil cycad leaves. Since A. paulae is Late Carnian age, it is one of the oldest known cycad leaves and thus supports the suggestion by Delevoryas (1982) that there is as much evidence that plants with compound leaves could have given rise to the Cycadales as plants with entire leaves have.
{"title":"A New Pinnate Cycad Leaf from the Upper Triassic Chinle Formation of Arizona","authors":"S. Ash","doi":"10.1086/337871","DOIUrl":"https://doi.org/10.1086/337871","url":null,"abstract":"A recently discovered Upper Triassic leaf shows many of the characters of the leaves of the living cycads and is assigned to the Cycadales. The leaf, however, does not match any previously described fossil or living cycad leaf in all features and is assigned to a new genus and species, Aricycas paulae. The leaf bears oppositely arranged linear-lanceolate pinnae with pointed apices and contracted bases Pinnae contain prominent midribs and anastomosing lateral veins which end freely near the margins. The ordinary epidermal cells are rectangular with straight to slightly curving side walls and haplocheilic stomata. Pinnae in this leaf are apparently wrinkled and shriveled and in some cases fell before the parent leaves were shed, as is typical of the living cycads. It appears that this character has never been reported in fossil cycad leaves. Since A. paulae is Late Carnian age, it is one of the oldest known cycad leaves and thus supports the suggestion by Delevoryas (1982) that there is as much evidence that plants with compound leaves could have given rise to the Cycadales as plants with entire leaves have.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"123 - 131"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337871","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238282","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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