Premise of research. Maternal environment can influence the seed ecophysiology, for example, of species that produce fruits in different seasons. Due to seasonal variations in environmental factors, differences in germination responses, seed traits, and seedling size may occur. Using seeds of Piper umbellatum produced in the same population in both the rainy and dry seasons, we evaluated the effects of temperature variations and water availability on germination parameters, root growth, and seed traits. Methodology. Eight temperature treatments (15°C, 20°C, 23°C, 25°C, 28°C, 30°C, 35°C, and alternation between 30°C and 20°C) and four water potentials (0, −0.3, −0.6, and −1.2 MPa) were performed. The following parameters were analyzed: germination onset, germination percentage (G%), mean germination time (MGT), root elongation, seed longevity during ex situ storage, and dry mass of seeds. Pivotal results. All parameters analyzed differed according to the seed production period. The rainy-season seeds had greater germinability and longevity, as they started to germinate first with higher G% and lower MGT values than the dry-season seeds, which were more sensitive to the effects of water deficit in relation to germination parameters. Dry-season seeds had higher dry mass, and their seedlings had greater root growth than those from rainy-season seeds. This balance between germination parameters and traits of seeds and seedlings reflects the existence of an intergenerational memory of stress. Conclusions. The maternal environment during the seed production period influenced germination responses, seed traits, and root growth. The first stages of plant development can be strongly impacted by climate change, and the responses to these changes can vary according to the period of seed production in the same species.
{"title":"Remember its origin: maternal effects during seed production influence the germination responses, seed traits, and initial root growth of Piper umbellatum","authors":"A. Valentin-Silva, Felipe Della Torre, M. França","doi":"10.1086/726625","DOIUrl":"https://doi.org/10.1086/726625","url":null,"abstract":"Premise of research. Maternal environment can influence the seed ecophysiology, for example, of species that produce fruits in different seasons. Due to seasonal variations in environmental factors, differences in germination responses, seed traits, and seedling size may occur. Using seeds of Piper umbellatum produced in the same population in both the rainy and dry seasons, we evaluated the effects of temperature variations and water availability on germination parameters, root growth, and seed traits. Methodology. Eight temperature treatments (15°C, 20°C, 23°C, 25°C, 28°C, 30°C, 35°C, and alternation between 30°C and 20°C) and four water potentials (0, −0.3, −0.6, and −1.2 MPa) were performed. The following parameters were analyzed: germination onset, germination percentage (G%), mean germination time (MGT), root elongation, seed longevity during ex situ storage, and dry mass of seeds. Pivotal results. All parameters analyzed differed according to the seed production period. The rainy-season seeds had greater germinability and longevity, as they started to germinate first with higher G% and lower MGT values than the dry-season seeds, which were more sensitive to the effects of water deficit in relation to germination parameters. Dry-season seeds had higher dry mass, and their seedlings had greater root growth than those from rainy-season seeds. This balance between germination parameters and traits of seeds and seedlings reflects the existence of an intergenerational memory of stress. Conclusions. The maternal environment during the seed production period influenced germination responses, seed traits, and root growth. The first stages of plant development can be strongly impacted by climate change, and the responses to these changes can vary according to the period of seed production in the same species.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"28 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74041210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Premise of research. Organisms that reproduce asexually must respond to abiotic stresses in their environment while contending with the potential disadvantage of the reduced ability for genetic variation through recombination. Common duckweed (Lemna minor) is an aquatic plant that reproduces predominantly asexually through the budding of ramets. As a freshwater plant, duckweed experiences stress from salt (e.g., NaCl), which detrimentally affects growth, photosynthesis, and cellular processes. We took a demographic approach to examine whether ancestral exposure to salt stress affects the ability of duckweed offspring to tolerate immediate exposure to the same stress. Methodology. We placed three consecutive clonal generations of duckweed in an environment with 2 g L−1 NaCl (nonlethal salt stress) or 0 g L−1 NaCl (control), followed by an additional zero to three generations in the control environment to vary the presence and schedule of ancestral stress. After these treatments, we used the offspring produced as focal plants for the experiment. Half were placed into the salt stress environment, and half were placed in control conditions; focal plants were tracked longitudinally. Pivotal results. Immediate stress decreased fitness as a result of a slowing of reproduction, suggesting a cost of stress tolerance. The effects of ancestral stress, and the interaction of immediate and ancestral stress, were more complex. Specifically, recent ancestral stress induced plants to produce offspring more quickly but with the potential cost of lowered offspring quality. Conclusions. Our results amplify findings that responses to, and fitness consequences of, current stressors can be contingent on past exposure.
研究的前提。无性繁殖的生物体必须对其环境中的非生物胁迫作出反应，同时与通过重组降低遗传变异能力的潜在劣势作斗争。普通浮萍(Lemna minor)是一种水生植物，主要通过分株发芽进行无性繁殖。作为一种淡水植物，浮萍会受到盐(如NaCl)的胁迫，这会对其生长、光合作用和细胞过程产生不利影响。我们采用人口统计学方法来研究祖代暴露于盐胁迫是否会影响浮萍后代耐受立即暴露于相同胁迫的能力。方法。我们将3个连续的浮萍无性系置于2 g L−1 NaCl(非致死盐胁迫)或0 g L−1 NaCl(对照)环境中，然后在对照环境中增加0到3个无性系，以改变祖先胁迫的存在和时间。经过这些处理后，我们将产生的后代作为实验的焦点植物。一半放置在盐胁迫环境中，一半放置在对照环境中;对焦点植物进行纵向追踪。关键的结果。直接的压力降低了适应力，这是繁殖速度减慢的结果，表明压力耐受性是有代价的。祖先压力的影响以及直接压力和祖先压力的相互作用更为复杂。具体来说，最近的祖先胁迫诱导植物更快地产生后代，但潜在的代价是后代质量降低。结论。我们的研究结果扩大了对当前压力源的反应和健康后果可能取决于过去的暴露的发现。
{"title":"Interactive Effects of Immediate and Ancestral Salt Stress on Fitness in Duckweed","authors":"Suzanne L. Chmilar, Lauren Zink, R. Laird","doi":"10.1086/726083","DOIUrl":"https://doi.org/10.1086/726083","url":null,"abstract":"Premise of research. Organisms that reproduce asexually must respond to abiotic stresses in their environment while contending with the potential disadvantage of the reduced ability for genetic variation through recombination. Common duckweed (Lemna minor) is an aquatic plant that reproduces predominantly asexually through the budding of ramets. As a freshwater plant, duckweed experiences stress from salt (e.g., NaCl), which detrimentally affects growth, photosynthesis, and cellular processes. We took a demographic approach to examine whether ancestral exposure to salt stress affects the ability of duckweed offspring to tolerate immediate exposure to the same stress. Methodology. We placed three consecutive clonal generations of duckweed in an environment with 2 g L−1 NaCl (nonlethal salt stress) or 0 g L−1 NaCl (control), followed by an additional zero to three generations in the control environment to vary the presence and schedule of ancestral stress. After these treatments, we used the offspring produced as focal plants for the experiment. Half were placed into the salt stress environment, and half were placed in control conditions; focal plants were tracked longitudinally. Pivotal results. Immediate stress decreased fitness as a result of a slowing of reproduction, suggesting a cost of stress tolerance. The effects of ancestral stress, and the interaction of immediate and ancestral stress, were more complex. Specifically, recent ancestral stress induced plants to produce offspring more quickly but with the potential cost of lowered offspring quality. Conclusions. Our results amplify findings that responses to, and fitness consequences of, current stressors can be contingent on past exposure.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"48 1","pages":"577 - 585"},"PeriodicalIF":2.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77939466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Premise of research. Intraspecific differences in plant reproductive traits affect ecological interactions at the population level, leading to evolutionary shifts. Abiotic and biotic factors exert strong selective pressures on functional traits, such as phenology, affecting reproductive success and thereby plant fitness. Here we evaluated the occurrence of intraspecific variation in the reproductive ecology and reproductive success among three naturally isolated populations of Microlicia laniflora, a narrow-endemic shrub from Brazilian campo rupestre. We asked (i) do isolated populations of M. laniflora differ in their reproductive phenology, floral biology, pollination, and reproductive success and (ii) which abiotic and biotic factors are related to interpopulation differences in reproductive success? Methodology. We sampled three sites varying in altitude and local environment in a tropical mountain vegetation system, the campos rupestres of Serra do Cipó, and tested for interpopulation differences in reproductive phenology, floral biology, pollination interactions, and reproductive success. Pivotal results. Microlicia laniflora populations differed in their reproductive phenology, pollination (frequency of visits and pollinators), and reproductive success, mainly between the lowest-altitude site and the two higher-altitude sites. Flowering and fruiting phenology were strongly seasonal, driven primarily by temperature variation during the reproductive season, with earlier flowering at the higher-altitude sites. There, lower temperatures, larger floral displays, and a higher frequency of pollinator visits positively influenced reproductive success. Conclusions. Our results support the assumption that abiotic and biotic factors jointly act as selective pressures driving phenology and shaping plant reproductive ecology. Our findings evidence the central role played by interpopulation variability in flowering phenology and in pollinator attraction in the evolution of floral and reproductive traits of plant species that are spatially isolated in stressful and megadiverse environments.
研究的前提。植物生殖性状的种内差异影响种群水平上的生态相互作用，导致进化转变。非生物和生物因素对物候等功能性状施加强大的选择压力，从而影响生殖成功，从而影响植物的适合度。在此，我们评估了三个自然隔离的巴西小灌木(Microlicia laniflora)种群的生殖生态和繁殖成功率的种内变异。我们的问题是:(1)分离种群在繁殖物候、花生物学、授粉和繁殖成功方面是否存在差异;(2)哪些非生物和生物因素与繁殖成功的种群间差异有关?方法。在热带山地植被系统(Serra do Cipó的campos ruperes)中，我们选取了三个不同海拔和当地环境的地点，测试了种群间在生殖物候学、花生物学、授粉相互作用和繁殖成功率方面的差异。关键的结果。低海拔地和高海拔地的小毛虱种群在繁殖物候、授粉(访花频率和传粉者)和繁殖成功率方面存在差异。开花和结果物候具有强烈的季节性，主要受繁殖季节温度变化的影响，高海拔地区开花时间早。在那里，较低的温度、较大的花展示和更高的传粉者访问频率对繁殖成功率有积极影响。结论。我们的研究结果支持了非生物和生物因素共同作为选择压力驱动物候和塑造植物生殖生态的假设。我们的研究结果证明，在空间隔离的压力和大多样性环境中，开花物候和传粉者吸引的种群间变异在植物物种的花和生殖性状进化中发挥了核心作用。
{"title":"Intraspecific Variation in Phenology and Reproductive Success of Microlicia laniflora: A Narrow-Endemic Species, Naturally Isolated on Rocky Outcrops","authors":"Natalia Costa Soares, L. Morellato","doi":"10.1086/726040","DOIUrl":"https://doi.org/10.1086/726040","url":null,"abstract":"Premise of research. Intraspecific differences in plant reproductive traits affect ecological interactions at the population level, leading to evolutionary shifts. Abiotic and biotic factors exert strong selective pressures on functional traits, such as phenology, affecting reproductive success and thereby plant fitness. Here we evaluated the occurrence of intraspecific variation in the reproductive ecology and reproductive success among three naturally isolated populations of Microlicia laniflora, a narrow-endemic shrub from Brazilian campo rupestre. We asked (i) do isolated populations of M. laniflora differ in their reproductive phenology, floral biology, pollination, and reproductive success and (ii) which abiotic and biotic factors are related to interpopulation differences in reproductive success? Methodology. We sampled three sites varying in altitude and local environment in a tropical mountain vegetation system, the campos rupestres of Serra do Cipó, and tested for interpopulation differences in reproductive phenology, floral biology, pollination interactions, and reproductive success. Pivotal results. Microlicia laniflora populations differed in their reproductive phenology, pollination (frequency of visits and pollinators), and reproductive success, mainly between the lowest-altitude site and the two higher-altitude sites. Flowering and fruiting phenology were strongly seasonal, driven primarily by temperature variation during the reproductive season, with earlier flowering at the higher-altitude sites. There, lower temperatures, larger floral displays, and a higher frequency of pollinator visits positively influenced reproductive success. Conclusions. Our results support the assumption that abiotic and biotic factors jointly act as selective pressures driving phenology and shaping plant reproductive ecology. Our findings evidence the central role played by interpopulation variability in flowering phenology and in pollinator attraction in the evolution of floral and reproductive traits of plant species that are spatially isolated in stressful and megadiverse environments.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"12 1","pages":"562 - 575"},"PeriodicalIF":2.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75550341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Premise of research. Ten anatomically preserved conifer seed cone specimens are preserved on the surfaces of, and within, three interlocking rock fragments of terrestrial limestone discovered as float along the Colville River on the North Slope of Alaska, providing additional evidence for the diversification of taiwanioid Cupressaceae during the Upper Cretaceous–Cenozoic interval. Methodology. Specimens on rock surfaces were measured and photographed, and then serial anatomical thin sections were prepared by the cellulose acetate peel technique. Three-dimensional images of selected specimens were also captured using micro–computed tomography (micro-CT). Pivotal results. The structure of these seed cones is similar to that of living Taiwania cryptomerioides in cone shape, the presence of subtending scalelike leaves, helically arranged and imbricating foliate ovuliferous complexes (OCs), the absence of a separate ovuliferous scale tip, variation in numbers of OCs, and by having two adaxially positioned winged seeds per complex. However, abruptly upturned OC, details of OC vasculature, and distinctive histological features reveal that these seed cones represent a new species of the extinct genus Mukawastrobus. Conclusions. When added to the existing record of fossil seed cones, the new species Mukawastrobus arnoldii highlights the recent discovery that among early-diverging lineages of Cupressaceae, there has been considerable Cretaceous, Paleogene, and Neogene evolution that is reflected by variations among subtle characters that are not recognizable in any but the most completely preserved specimens.
{"title":"Additional Evidence for the Diversification of Taiwanioid Conifers in the Upper Cretaceous Based on a New Species from the North Slope of Alaska","authors":"G. Rothwell, R. Stockey, Selena Y. Smith","doi":"10.1086/726082","DOIUrl":"https://doi.org/10.1086/726082","url":null,"abstract":"Premise of research. Ten anatomically preserved conifer seed cone specimens are preserved on the surfaces of, and within, three interlocking rock fragments of terrestrial limestone discovered as float along the Colville River on the North Slope of Alaska, providing additional evidence for the diversification of taiwanioid Cupressaceae during the Upper Cretaceous–Cenozoic interval. Methodology. Specimens on rock surfaces were measured and photographed, and then serial anatomical thin sections were prepared by the cellulose acetate peel technique. Three-dimensional images of selected specimens were also captured using micro–computed tomography (micro-CT). Pivotal results. The structure of these seed cones is similar to that of living Taiwania cryptomerioides in cone shape, the presence of subtending scalelike leaves, helically arranged and imbricating foliate ovuliferous complexes (OCs), the absence of a separate ovuliferous scale tip, variation in numbers of OCs, and by having two adaxially positioned winged seeds per complex. However, abruptly upturned OC, details of OC vasculature, and distinctive histological features reveal that these seed cones represent a new species of the extinct genus Mukawastrobus. Conclusions. When added to the existing record of fossil seed cones, the new species Mukawastrobus arnoldii highlights the recent discovery that among early-diverging lineages of Cupressaceae, there has been considerable Cretaceous, Paleogene, and Neogene evolution that is reflected by variations among subtle characters that are not recognizable in any but the most completely preserved specimens.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"19 1","pages":"628 - 639"},"PeriodicalIF":2.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84928453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Miriam A. Slodownik, I. Escapa, C. Mays, Gregory J. Jordan, R. Carpenter, R. Hill
Premise of research. The fossil assemblage of the Macquarie Harbour Formation (MHF) in Tasmania, Australia, represents a subpolar (65°S–70°S) lowland forest during the early Eocene climatic optimum (∼53–50 Ma) and bears fossils of Araucarioides linearis Bigwood et Hill, 1985 emend (Araucariaceae). New fossils, including isolated leaves, female ovuliferous complexes (=bract/scale complexes), a possible seed, and dispersed pollen, were recovered from the Lowana Road site near the type locality and offered the opportunity to clarify the previously poorly constrained relationship of Araucarioides within the Araucariaceae. Methodology. Macrofossils and cuticles were described and compared with other Araucariaceae. Palynological analyses were conducted to identify associated pollen. Tree Analysis Using New Technology (TNT) was used for phylogenetic analyses. To confirm conspecificity of leaves and reproductive remains, the whole-plant hypothesis was tested using multiple methods, including optical and fluorescence photo(micro)graphy, scanning electron microscopy, and X-ray computed tomography. Paleobiogeographic comparisons with other Araucarioides assemblages were undertaken. Pivotal results. New Araucarioides linearis fossils included two distinct leaf populations and the first putative female reproductive remains of this species. The generic and specific diagnoses of A. linearis were emended based on new data. Co-occurring Araucarioides sinuosa was designated a junior synonym of A. linearis. The fossils are associated with abundant Dilwynites tuberculatus pollen. The phylogenetic analyses revealed affinity with the agathioid clade (Wollemia + Agathis) of Araucariaceae. The whole-plant hypothesis was supported. Conclusions. Phylogenetic analyses indicated that A. linearis was a non-Agathis agathioid that represents the sister to the clade formed by Agathis and Wollemia. The polar Campanian Araucarioides falcata in New Zealand supports the Cretaceous divergence of Araucaria and agathioid lineages. The restriction of Araucarioides to high paleolatitudes and their adaptations to seasonal environments such as broad leaves and possibly winter deciduousness may have facilitated survival through the impact winter and photosynthetic crisis during the end-Cretaceous extinction. Continuous northward movement of Australia and New Zealand and resulting climatic and light regime changes likely contributed to its extinction.
研究的前提。澳大利亚塔斯马尼亚麦夸里港组(MHF)的化石组合代表了始新世早期气候最佳时期(~ 53 ~ 50 Ma)的亚极地(65°S - 70°S)低地森林和Bigwood et Hill 1985年修订的Araucarioides linear化石(Araucariaceae)。新的化石，包括孤立的叶子，雌性的胚珠复合体(=苞片/鳞片复合体)，一个可能的种子和分散的花粉，在类型地点附近的Lowana Road遗址被发现，并提供了机会澄清以前缺乏限制的Araucarioides在Araucariaceae中的关系。方法。描述了巨化石和角质层，并与其他龙葵科进行了比较。孢粉学分析鉴定了伴生花粉。系统发育分析采用TNT树分析法。为了确认叶片和生殖残体的同一性，采用多种方法对整株假说进行了验证，包括光学和荧光照片(显微)摄影，扫描电子显微镜和x射线计算机断层扫描。进行了与其它Araucarioides组合的古地理比较。关键的结果。新Araucarioides linearis化石包括两个不同的叶片数量和第一公认的女性生殖的物种。根据新资料对线性弧菌的一般诊断和特异性诊断进行了修订。共同发生的Araucarioides sinuosa被指定为Araucarioides linearis的初级同义词。该化石与丰富的铁云母结核孢粉有关。系统发育分析表明，该植物与龙葵科龙葵属(wolleia + Agathis)有亲缘关系。整个植物假说得到了支持。结论。系统发育分析表明，a. linearis是一个非Agathis的agathioid，代表Agathis和Wollemia组成的分支的姐妹。在新西兰的极地坎帕尼亚的Araucarioides falcata支持白垩纪Araucaria和agathioid谱系的分化。Araucarioides在古高纬度地区的生存，以及它们对季节性环境的适应，如宽阔的树叶和可能的冬季落叶，可能有助于它们在白垩纪末期的冬季和光合危机中生存下来。澳大利亚和新西兰的持续北移以及由此产生的气候和光照变化可能是导致其灭绝的原因。
{"title":"Araucarioides: A Polar Lineage of Araucariaceae with New Paleogene Fossils from Tasmania, Australia","authors":"Miriam A. Slodownik, I. Escapa, C. Mays, Gregory J. Jordan, R. Carpenter, R. Hill","doi":"10.1086/726183","DOIUrl":"https://doi.org/10.1086/726183","url":null,"abstract":"Premise of research. The fossil assemblage of the Macquarie Harbour Formation (MHF) in Tasmania, Australia, represents a subpolar (65°S–70°S) lowland forest during the early Eocene climatic optimum (∼53–50 Ma) and bears fossils of Araucarioides linearis Bigwood et Hill, 1985 emend (Araucariaceae). New fossils, including isolated leaves, female ovuliferous complexes (=bract/scale complexes), a possible seed, and dispersed pollen, were recovered from the Lowana Road site near the type locality and offered the opportunity to clarify the previously poorly constrained relationship of Araucarioides within the Araucariaceae. Methodology. Macrofossils and cuticles were described and compared with other Araucariaceae. Palynological analyses were conducted to identify associated pollen. Tree Analysis Using New Technology (TNT) was used for phylogenetic analyses. To confirm conspecificity of leaves and reproductive remains, the whole-plant hypothesis was tested using multiple methods, including optical and fluorescence photo(micro)graphy, scanning electron microscopy, and X-ray computed tomography. Paleobiogeographic comparisons with other Araucarioides assemblages were undertaken. Pivotal results. New Araucarioides linearis fossils included two distinct leaf populations and the first putative female reproductive remains of this species. The generic and specific diagnoses of A. linearis were emended based on new data. Co-occurring Araucarioides sinuosa was designated a junior synonym of A. linearis. The fossils are associated with abundant Dilwynites tuberculatus pollen. The phylogenetic analyses revealed affinity with the agathioid clade (Wollemia + Agathis) of Araucariaceae. The whole-plant hypothesis was supported. Conclusions. Phylogenetic analyses indicated that A. linearis was a non-Agathis agathioid that represents the sister to the clade formed by Agathis and Wollemia. The polar Campanian Araucarioides falcata in New Zealand supports the Cretaceous divergence of Araucaria and agathioid lineages. The restriction of Araucarioides to high paleolatitudes and their adaptations to seasonal environments such as broad leaves and possibly winter deciduousness may have facilitated survival through the impact winter and photosynthetic crisis during the end-Cretaceous extinction. Continuous northward movement of Australia and New Zealand and resulting climatic and light regime changes likely contributed to its extinction.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"1 1","pages":"640 - 658"},"PeriodicalIF":2.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82762922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. Stein, C. M. Berry, L. V. Hernick, Frank Mannolini
Premise of research. Pseudosporochnales (Cladoxylopsida) were conspicuous elements of the Earth’s earliest forests. Recent evidence has done much to clarify basic aspects of the pseudosporochnalean architecture, but important questions remain about the developmental processes responsible for growth from juvenile individuals to trees of sometimes considerable size. Methodology. Presented here is combined compression/permineralization evidence of a young member of the group from a late Devonian (early Frasnian) locality also containing Eospermatopteris (Wattieza), currently the largest reconstructed pseudosporochnalean tree. Standard pyrite preparations were made and analyzed with reflected light. Pivotal results. The anatomically preserved portion of the trunk with an expanded base lacking a central vascular column shows abundant evidence of appendages with apparent rooting function supplied by traces comprised of primary and often secondary xylem. Traces arise within parenchyma near the trunk center and follow lax courses with multiple divisions outward and downward to the surface, finally enveloping the plant base for some distance. In the upper portion of the specimen, likely near the transition between the base bearing rooting appendages and the aerial shoot, the traces form a vascular plexus toward the periphery of the stem, with the bulk of vascular tissues comprising secondary xylem. Similar but differently oriented vascularization also occurs near the base. Conclusions. Here we hypothesize a unique form of “bipolar” development in this specimen, and potentially all pseudosporochnaleans, by means of a trunk base bearing an appendicular system of positively geotropic rooting appendages. In addition, we hypothesize that diffuse meristematic activity of the base plus the vascular plexus may have a previously unrecognized role in the development of pseudosporochnaleans from the small specimen observed here to large body size. We also suggest that this tissue offers an explanation for the enigmatic genus Xenocladia known from tissue fragments of large size found in coeval marine sediments of New York State. Given current incomplete understanding of development within the Pseudosprochnales, considering the rooting system as sui generis confers the advantage of adequate description of this organ, without necessarily specifying correspondence or homology with other groups.
{"title":"Rooting Portions of a Young Pseudosporochnalean from the Catskill Delta Complex of New York","authors":"W. Stein, C. M. Berry, L. V. Hernick, Frank Mannolini","doi":"10.1086/726108","DOIUrl":"https://doi.org/10.1086/726108","url":null,"abstract":"Premise of research. Pseudosporochnales (Cladoxylopsida) were conspicuous elements of the Earth’s earliest forests. Recent evidence has done much to clarify basic aspects of the pseudosporochnalean architecture, but important questions remain about the developmental processes responsible for growth from juvenile individuals to trees of sometimes considerable size. Methodology. Presented here is combined compression/permineralization evidence of a young member of the group from a late Devonian (early Frasnian) locality also containing Eospermatopteris (Wattieza), currently the largest reconstructed pseudosporochnalean tree. Standard pyrite preparations were made and analyzed with reflected light. Pivotal results. The anatomically preserved portion of the trunk with an expanded base lacking a central vascular column shows abundant evidence of appendages with apparent rooting function supplied by traces comprised of primary and often secondary xylem. Traces arise within parenchyma near the trunk center and follow lax courses with multiple divisions outward and downward to the surface, finally enveloping the plant base for some distance. In the upper portion of the specimen, likely near the transition between the base bearing rooting appendages and the aerial shoot, the traces form a vascular plexus toward the periphery of the stem, with the bulk of vascular tissues comprising secondary xylem. Similar but differently oriented vascularization also occurs near the base. Conclusions. Here we hypothesize a unique form of “bipolar” development in this specimen, and potentially all pseudosporochnaleans, by means of a trunk base bearing an appendicular system of positively geotropic rooting appendages. In addition, we hypothesize that diffuse meristematic activity of the base plus the vascular plexus may have a previously unrecognized role in the development of pseudosporochnaleans from the small specimen observed here to large body size. We also suggest that this tissue offers an explanation for the enigmatic genus Xenocladia known from tissue fragments of large size found in coeval marine sediments of New York State. Given current incomplete understanding of development within the Pseudosprochnales, considering the rooting system as sui generis confers the advantage of adequate description of this organ, without necessarily specifying correspondence or homology with other groups.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"6 1","pages":"601 - 627"},"PeriodicalIF":2.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73672980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The timing of flowering and other components of phenology such as duration and synchrony can affect reproductive success and recruitment by influencing the environment a plant will experience throughout its flowering period. Pollination is a common explanation for why flowering phenology may affect reproduction, but it is not well understood how variation in pollination might interact with the abiotic environment to affect plant reproduction. Here we monitored a population of spring ephemerals, Claytonia virginica, for one flowering season and examined the effects of flowering phenology and the environment on plant reproduction in two treatments: plants supplemented with additional outcross pollen and unmanipulated control plants. Different aspects of reproduction were measured at both the population and within-plant levels: number of seeds produced by individual plants (seed production), per-fruit seed viability (the proportion of viable seeds out of the total number of seeds per fruit), percent germination, and number of days to germination. Soil surface temperature, light, and moisture data were also collected. The flowering phenology and environmental predictors most important for each measurement of reproduction differed between control and pollen-supplemented plants. For example, in both pollen treatment groups, more days in flower was consistently a positive predictor of seed production, but the environmental factors affecting seed production varied, with increasing pollinator visitation mostly affecting seed production in the nonsupplemented group and soil moisture positively affecting it in supplemented plants. Phenological and environmental predictors also differed for proportion of viable seeds and timing of germination. Our germination results support the hypothesis that the mechanisms that control early flowering time in the maternal plant may affect the timing of other life history events such as seed germination. Additionally, we show some evidence that changes in the maternal abiotic environment, particularly temperature, may alter progeny phenotype. No clear seasonal resource trade-offs were evident, as has been shown in other studies of spring ephemerals. Our results show that the abiotic environment interacts with the pollination environment to affect plant reproduction, with different environmental factors predicting reproduction in control versus pollen-supplemented plants.
{"title":"Pollen Supplementation Alters How Flowering Phenology Affects Reproduction in a Spring-Flowering Herb","authors":"Samantha Danguilan, A. Iler","doi":"10.1086/726084","DOIUrl":"https://doi.org/10.1086/726084","url":null,"abstract":"The timing of flowering and other components of phenology such as duration and synchrony can affect reproductive success and recruitment by influencing the environment a plant will experience throughout its flowering period. Pollination is a common explanation for why flowering phenology may affect reproduction, but it is not well understood how variation in pollination might interact with the abiotic environment to affect plant reproduction. Here we monitored a population of spring ephemerals, Claytonia virginica, for one flowering season and examined the effects of flowering phenology and the environment on plant reproduction in two treatments: plants supplemented with additional outcross pollen and unmanipulated control plants. Different aspects of reproduction were measured at both the population and within-plant levels: number of seeds produced by individual plants (seed production), per-fruit seed viability (the proportion of viable seeds out of the total number of seeds per fruit), percent germination, and number of days to germination. Soil surface temperature, light, and moisture data were also collected. The flowering phenology and environmental predictors most important for each measurement of reproduction differed between control and pollen-supplemented plants. For example, in both pollen treatment groups, more days in flower was consistently a positive predictor of seed production, but the environmental factors affecting seed production varied, with increasing pollinator visitation mostly affecting seed production in the nonsupplemented group and soil moisture positively affecting it in supplemented plants. Phenological and environmental predictors also differed for proportion of viable seeds and timing of germination. Our germination results support the hypothesis that the mechanisms that control early flowering time in the maternal plant may affect the timing of other life history events such as seed germination. Additionally, we show some evidence that changes in the maternal abiotic environment, particularly temperature, may alter progeny phenotype. No clear seasonal resource trade-offs were evident, as has been shown in other studies of spring ephemerals. Our results show that the abiotic environment interacts with the pollination environment to affect plant reproduction, with different environmental factors predicting reproduction in control versus pollen-supplemented plants.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"9 1","pages":"586 - 600"},"PeriodicalIF":2.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84807028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Premise of research. Herbivore damage is generally higher in the sun than in the shade. The influence of shade tolerance on herbivory has been mainly related to the fact that light-demanding plant species show lower defense investments—and hence higher herbivory—than shade-tolerant species. The pattern of increased herbivory with increasing light availability may take different forms, depending on the drivers of herbivore damage across the light gradient: (1) herbivory pressure alone, (2) herbivory pressure together with plant resistance associated with shade tolerance, or (3) the two drivers seen in scenario 2 added to a differential effect of light availability on plant resistance depending on shade tolerance. Elucidating the specific patterns behind the general pattern of increased herbivory with increasing light availability may contribute to understanding and aid prediction of herbivory patterns in forest communities under natural or anthropogenic disturbance. Methodology. In a field study with 15 tree species distributed across the light gradient in a temperate rainforest (1.6%–26.2% canopy openness), we evaluated the relationship between canopy openness and seedling herbivory, with 755 seedlings surveyed for herbivore damage. Specifically, we evaluated the consistency between the observed herbivory–canopy openness relationship and the three scenarios described above. Pivotal results. We found steeper slopes for the herbivory–canopy openness relationship in tree species with lower shade tolerance; that is, we verified scenario 3. Conclusions. Shade tolerance determined the slope of the herbivory–canopy openness relationship across the light gradient. This finding expands our understanding of the recognized influence of shade tolerance on the interplay between herbivory and the light environment.
{"title":"Shade Tolerance and the Relationship between Herbivory and Light Availability","authors":"E. Gianoli, C. Salgado‐Luarte, V. Escobedo","doi":"10.1086/726006","DOIUrl":"https://doi.org/10.1086/726006","url":null,"abstract":"Premise of research. Herbivore damage is generally higher in the sun than in the shade. The influence of shade tolerance on herbivory has been mainly related to the fact that light-demanding plant species show lower defense investments—and hence higher herbivory—than shade-tolerant species. The pattern of increased herbivory with increasing light availability may take different forms, depending on the drivers of herbivore damage across the light gradient: (1) herbivory pressure alone, (2) herbivory pressure together with plant resistance associated with shade tolerance, or (3) the two drivers seen in scenario 2 added to a differential effect of light availability on plant resistance depending on shade tolerance. Elucidating the specific patterns behind the general pattern of increased herbivory with increasing light availability may contribute to understanding and aid prediction of herbivory patterns in forest communities under natural or anthropogenic disturbance. Methodology. In a field study with 15 tree species distributed across the light gradient in a temperate rainforest (1.6%–26.2% canopy openness), we evaluated the relationship between canopy openness and seedling herbivory, with 755 seedlings surveyed for herbivore damage. Specifically, we evaluated the consistency between the observed herbivory–canopy openness relationship and the three scenarios described above. Pivotal results. We found steeper slopes for the herbivory–canopy openness relationship in tree species with lower shade tolerance; that is, we verified scenario 3. Conclusions. Shade tolerance determined the slope of the herbivory–canopy openness relationship across the light gradient. This finding expands our understanding of the recognized influence of shade tolerance on the interplay between herbivory and the light environment.","PeriodicalId":14306,"journal":{"name":"INTERNATIONAL JOURNAL OF PLANT SCIENCES","volume":"7 1","pages":"519 - 524"},"PeriodicalIF":2.3,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79869525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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