Esporogénesis, esporodermo y ornamentación de esporas maduras en Lycopodiaceae

• DOI: 10.15517/rbt.v62i3.12330
• Publication Date: 2014-07-29T22:48:06Z
• Authors: Edgar Javier Rinc...; Cristina Hilda Ro...; Lilian M. Passarelli; Silvia Espinosa M...; Alba Marina Torre...
• Keywords: Spores; 0106 biological sciences; Biología; Plant Science; Lycopodium; Herbarium; Biochemistry; Gene; 01 natural sciences; spore ornamentation; Agricultural and Biological Sciences; Lycopodiaceae; ornamentación de las esporas; Biology (General); sporoderm; Sporogenesis; Esporogénesis; Life Sciences; esporogénesis; Evolution and Classification of Flowering Plants; Strigolactone Signaling in Plant Interactions; ultraestructura; ultrastructure; Meiosis; esporogénesi; Ultrastructure; Esporas; sporangium ontogeny; Pollen; sporogenesis; Microspore; 570; esporodermo; Licopodiales - Esporas; QH301-705.5; ontogenia del esporangio; Colombia; Esporodermo; Stamen; Ciencias Naturales; Tapetum; Biology; Ecology, Evolution, Behavior and Systematics; 580; Evolution and Diversity of Vascular Epiphytes and Ferns; Mycelium; Sporangia; Ornamentación; Botánica; Botany; Spore; Microscopy, Electron, Scanning; Angiosperm Phylogeny

Études sur les aspects reproductifs, la morphologie des spores et l'ultrastructure des Lycopodiacées ne sont pas très communs dans la littérature scientifique, et constituent des informations essentielles pour le soutien des relations taxonomiques et systématiques entre le groupe. In order to complete existing information, adding new and broader contributions on these topics, a comparative analysis of the sporogenesis ultrastructure, with emphasis on cytological aspects of the sporocyte coat development, tapetum, monoplastidic and polyplastidic meiosis, sporoderm ontogeny and ornamentation of the mature spores, was carried out in 43 taxia of eight genera of the Lycopodiaceae : Austrolycopodium, Diphasium, Diphasiastrum, Huperzia (including Phlegmariurus), Lycopodium, Lycopodiella, Palhinhaea and Pseudolycopodiella growing in the Andes of Colombia and the Neotropics. For this study, the transmission electron microscopy (TEM) samples were collected in Cauca and Valle del Cauca Departments, while most of the spores for scanning electron microscopy (SEM) analysis were obtained from herbarium samples. We followed standard preparation procedures for spore observation by SEM and SEM. Results showed that the sporocyte coat is largely composd by primary wall components ; the sporocyte develop much of their metabolic activity in the production of their coat, which is retained until the spores release ; protective functions for the diploid cells undergoing meiosis is postulated here for this layer. The abondance of dictyosomes in the sporocyte cytoplasm was related to the formation and development of the sporocyte coat. Besides microtubule activity, the membrane of sporocyte folds, associated with electrodense material, and would early determine the final patterns of spore ornamentation. Monoplastidic condition is common in Lycopodium s.l., whereas polyplastidic condition was observd in species of Huperzia and Lycopodiella s. l.. In monoplastidic species, the tapetum presents abundant multivesicular bodies, while in polyplastidic species, the secretory activity of the tapetum is less intense. Sporoderm development is centripetal, exospore is the first formed layer, then the endospore and, if present, perispore is the final deposited layer. Adult spores of the Lycopodiaceae showed two patterns of ornamentation : negative or caviform (foveolate spores) and positive or muriform ornamentation, the latter with two subtypes (rugate and reticulate spores). The spores of Huperzia are characteristically foveolate, the rugate spores were found in a few species of Huperzia and in all of the Lycopodiella s. l. taxa studied, while Lycopodium s.l. spores bear reticulate ornamentation. Numerous ornamentation traits are diagnostic at the specific level. The types of ornamentation found do not support the recent extreme fragmentation of the family in several genera, but could match, a priori, with the idea of three subfamilies. The findings of sporogenesis, extremely similar in all taxa studied, point more to consider fewer genera, more comprehensive, than the recent, marked splitting of the family.<br/>الدراسات حول الجوانب الإنجابية وبوغ المورفولوجيا والبنية التحتية الفائقة للليكوبودياسي ليست شائعة جدًا في الأدبيات العلمية، وتشكل معلومات أساسية لدعم العلاقات التصنيفية والمنهجية بين المجموعة. من أجل إكمال المعلومات الموجودة، وإضافة مساهمات جديدة وأوسع نطاقًا حول هذه الموضوعات، تم إجراء تحليل مقارن للبنية التحتية لتكوين الأبواغ، مع التركيز على الجوانب الخلوية لتطور معطف الخلايا البوغية، والبساط، والانقسام الاختزالي الأحادي والمتعدد، وتكوين الجراثيم البوغية وتزيين الجراثيم الناضجة، في 43 تصنيفًا من ثمانية أجناس من ذوات الأرجل: المنجلية النمساوية، والدفاسيوم، والدفاسياستروم، وهوبيرزيا (بما في ذلك البلغماريور)، والليكوبوديوم، والليكوبوديلا، وبالهينيا، والكوديلا الزائفة التي تنمو في جبال الأنديز في كولومبيا والمناطق المدارية الحديثة. بالنسبة لهذه الدراسة، تم جمع عينات المجهر الإلكتروني للإرسال (TEM) في أقسام Cauca و Valle del Cauca، في حين تم الحصول على معظم الجراثيم لمسح المجهر الإلكتروني (SEM) من عينات الأعشاب. اتبعنا إجراءات التحضير القياسية لمراقبة الأبواغ من قبل TEM و SEM. أظهرت النتائج أن طبقة الخلايا البوغية تتكون إلى حد كبير من مكونات الجدار الأولية ؛ تطور الخلايا البوغية الكثير من نشاطها الأيضي في إنتاج معطفها، والذي يتم الاحتفاظ به حتى تطلق الجراثيم ؛ يتم افتراض وظائف الحماية للخلايا ثنائية الصيغة الصبغية التي تخضع للانقسام الاختزالي هنا لهذه الطبقة. كانت وفرة الديكتيوزومات في السيتوبلازم البوغية مرتبطة بتكوين وتطور طبقة الخلايا البوغية. بالإضافة إلى نشاط الأنابيب الدقيقة، فإن غشاء طيات الخلايا البوغية، المرتبطة بمادة كثيفة الكهرباء، سيحدد في وقت مبكر الأنماط النهائية لزخرفة الأبواغ. حالة أحادية الجبلة شائعة في Lycopodium s.l.، في حين لوحظت حالة متعددة الجبلة في أنواع Huperzia و Lycopodiella s.l... في الأنواع أحادية الجبلة، يقدم البساط أجسامًا متعددة الحبيبات وفيرة، بينما في الأنواع متعددة الجبلة، يكون النشاط الإفرازي للبساط أقل كثافة. تطور الأدمة البوغية هو الجاذبية المركزية، والبوغ الخارجي هو الطبقة المتكونة الأولى، ثم البوغ الداخلي، وإذا كان موجودًا، فإن البوغ المحيطي هو الطبقة المترسبة النهائية. أظهرت الجراثيم البالغة لليكوبودياسي نمطين من الزخرفة: سلبية أو جوفية (جراثيم منقورة) وزخرفة إيجابية أو فموية، والأخير مع نوعين فرعيين (الندى والجراثيم الشبكية). جراثيم هوبيرزيا منقورة بشكل مميز، تم العثور على جراثيم روغات في عدد قليل من أنواع هوبيرزيا وفي جميع أنواع الليكوبوديلا التي تمت دراستها، في حين تحمل جراثيم الليكوبوديوم زخرفة شبكية. يتم تشخيص العديد من سمات الزخرفة على المستوى المحدد. لا تدعم أنواع الزخارف الموجودة التجزئة الشديدة الأخيرة للعائلة في العديد من الأجناس، ولكن يمكن أن تتطابق، بداهة، مع فكرة ثلاث عائلات فرعية. تشير نتائج تكوين الأبواغ، المتشابهة للغاية في جميع الأصناف التي تمت دراستها، إلى النظر في عدد أقل من الأجناس، وأكثر شمولاً، من الانقسام الملحوظ الأخير للعائلة.<br/>Studies on reproductive aspects, spore morphology and ultrastructure of Lycopodiaceae are not very common in the scientific literature, and constitute essential information to support taxonomic and systematic relationships among the group. In order to complete existing information, adding new and broader contributions on these topics, a comparative analysis of the sporogenesis ultrastructure, with emphasis on cytological aspects of the sporocyte coat development, tapetum, monoplastidic and polyplastidic meiosis, sporoderm ontogeny and ornamentation of the mature spores, was carried out in 43 taxa of eight genera of the Lycopodiaceae: Austrolycopodium, Diphasium, Diphasiastrum, Huperzia (including Phlegmariurus), Lycopodium, Lycopodiella, Palhinhaea and Pseudolycopodiella growing in the Andes of Colombia and the Neotropics. For this study, the transmission electron microscopy (TEM) samples were collected in Cauca and Valle del Cauca Departments, while most of the spores for scanning electron microscopy (SEM) analysis were obtained from herbarium samples. We followed standard preparation procedures for spore observation by TEM and SEM. Results showed that the sporocyte coat is largely composed by primary wall components; the sporocyte develop much of their metabolic activity in the production of their coat, which is retained until the spores release; protective functions for the diploid cells undergoing meiosis is postulated here for this layer. The abundance of dictyosomes in the sporocyte cytoplasm was related to the formation and development of the sporocyte coat. Besides microtubule activity, the membrane of sporocyte folds, associated with electrodense material, and would early determine the final patterns of spore ornamentation. Monoplastidic condition is common in Lycopodium s.l., whereas polyplastidic condition was observed in species of Huperzia and Lycopodiella s. l.. In monoplastidic species, the tapetum presents abundant multivesicular bodies, while in polyplastidic species, the secretory activity of the tapetum is less intense. Sporoderm development is centripetal, exospore is the first formed layer, then the endospore and, if present, perispore is the final deposited layer. Adult spores of the Lycopodiaceae showed two patterns of ornamentation: negative or caviform (foveolate spores) and positive or muriform ornamentation, the latter with two subtypes (rugate and reticulate spores). The spores of Huperzia are characteristically foveolate, the rugate spores were found in a few species of Huperzia and in all of the Lycopodiella s. l. taxa studied, while Lycopodium s.l. spores bear reticulate ornamentation. Numerous ornamentation traits are diagnostic at the specific level. The types of ornamentation found do not support the recent extreme fragmentation of the family in several genera, but could match, a priori, with the idea of three subfamilies. The findings of sporogenesis, extremely similar in all taxa studied, point more to consider fewer genera, more comprehensive, than the recent, marked splitting of the family.<br/>Studies on reproductive aspects, spore morphology and ultrastructure of Lycopodiaceae are not very common in the scientific literature, and constitute essential information to support taxonomic and systematic relationships among the group. In order to complete existing information, adding new and broader contributions on these topics, a comparative analysis of the sporogenesis ultrastructure, with emphasis on cytological aspects of the sporocyte coat development, tapetum, monoplastidic and polyplastidic meiosis, sporoderm ontogeny and ornamentation of the mature spores, was carried out in 43 taxa of eight genera of the Lycopodiaceae: Austrolycopodium, Diphasium, Diphasiastrum, Huperzia (including Phlegmariurus), Lycopodium, Lycopodiella, Palhinhaea and Pseudolycopodiella growing in the Andes of Colombia and the Neotropics. For this study, the transmission electron microscopy (TEM) samples were collected in Cauca and Valle del Cauca Departments, while most of the spores for scanning electron microscopy (SEM) analysis were obtained from herbarium samples. We followed standard preparation procedures for spore observation by TEM and SEM. Results showed that the sporocyte coat is largely composed of primary wall components; the sporocyte develop much of their metabolic activity in the production of their coat, which is retained until the spores release; protective functions for the diploid cells undergoing meiosis is postulated here for this layer. The abundance of dictyosomes in the sporocyte cytoplasm was related to the formation and development of the sporocyte coat. In addition to microtubule activity, the membrane of sporocyte folds, associated with electrodense material, and would early determine the final patterns of spore ornamentation. Monoplastidic condition is common in Lycopodium s.l., whereas polyplastidic condition was observed in species of Huperzia and Lycopodiella s.l.. In monoplastidic species, the tapetum presents abundant multivesicular bodies, while in polyplastidic species, the secretory activity of the tapetum is less intense. Sporoderm development is centripetal, exospore is the first formed layer, then the endospore and, if present, perispore is the final deposited layer. Adult spores of the Lycopodiaceae showed two patterns of ornamentation: negative or caviform (foveolate spores) and positive or muriform ornamentation, the latter with two subtypes (dew and reticulate spores). The spores of Huperzia are characteristically foveolate, the rugate spores were found in a few species of Huperzia and in all of the Lycopodiella s. l. taxa studied, while Lycopodium s.l. spores bear reticulate ornamentation. Numerous ornamentation traits are diagnostic at the specific level. The types of ornamentation found do not support the recent extreme fragmentation of the family in several genera, but could match, a priori, with the idea of three subfamilies. The findings of sporogenesis, extremely similar in all taxa studied, point more to consider fewer genera, more comprehensive, than the recent, marked splitting of the family.<br/>