microsporangium

　

WordNet

1. a plant structure that produces microspores

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/08/07 23:57:55」(JST)

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Microsporangium is a sporangium that produces spores that give rise to male gametophytes. Microsporangia are notable in spikemosses, and a minority of ferns. In Gymnosperms and Angiosperms (Flowering plants), the microsporangium produce the microsporocyte, also known as the microspore mother cell, which then creates four microspores through meiosis. The microspores divide to create pollen grains. The term is not used for Bryophytes.

Development of Pollen Sacs

A very young anther consists of actively dividing meristamatic cells surrounded by a layer of epidermis. It then becomes two lobed. Each anther lobe develops two pollen sacs. Thus, a bilobed anther develops four pollen sacs situated at four corners of the anther. Development of pollen sacs begins with the differentiation of archesporial cells in the hypodermal region below epidermis at four corners of the young anther. The archesporial cell divide by periclinal division to give a subepidermal primary parietal layer and a primary sporogenous layer. The cells of the primary parietal layer divide by successive periclinal and anticlinal divisions to form concentric layers of pollen sac wall. The wall layers from periphery to centre consist of:

1. A single layer of epidermis between which becomes stretched and shrivels off at maturity
2. A single layer of endothecium. The cells of endothecium possess fibrous thickenings. They remain thin walled and constitute stomium (line of dehiscence) in the shallow groove in between the two microsporangia of the anther lobe
3. One to three middle layers. cells of these layer generally disintegrate in the mature anther
4. A single layer of tapetum. The tapetal cells may be uni-, bi- or multinucleate and possess dense cytoplasm. The cells of primary sporogenous layer divide further and give rise to diploid sporogenous tissue.

English Journal

• The Arabidopsis thaliana GRF-INTERACTING FACTOR gene family plays an essential role in control of male and female reproductive development.

• Lee BH1, Wynn AN2, Franks RG2, Hwang YS3, Lim J3, Kim JH4.Author information 1Department of Biology, Kyungpook National University, Daegu 702-701, Republic of Korea.2Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA.3Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Republic of Korea.4Department of Biology, Kyungpook National University, Daegu 702-701, Republic of Korea. Electronic address: kimjeon4@knu.ac.kr.AbstractReproductive success of angiosperms relies on the precise development of the gynoecium and the anther, because their primary function is to bear and to nurture the embryo sac/female gametophyte and pollen, in which the egg and sperm cells, respectively, are generated. It has been known that the GRF-INTERACTING FACTOR (GIF) transcription co-activator family of Arabidopsis thaliana (Arabidopsis) consists of three members and acts as a positive regulator of cell proliferation. Here, we demonstrate that GIF proteins also play an essential role in development of reproductive organs and generation of the gamete cells. The gif1 gif2 gif3 triple mutant, but not the single or double mutants, failed to establish normal carpel margin meristem (CMM) and its derivative tissues, such as the ovule and the septum, resulting in a split gynoecium and no observable embryo sac. The gif triple mutant also displayed severe structural and functional defects in the anther, producing neither microsporangium nor pollen grains. Therefore, we propose that the GIF family of Arabidopsis is a novel and essential component required for the cell specification maintenance during reproductive organ development and, ultimately, for the reproductive competence.
• Developmental biology.Dev Biol.2013 Dec 16. pii: S0012-1606(13)00654-4. doi: 10.1016/j.ydbio.2013.12.009. [Epub ahead of print]
• Reproductive success of angiosperms relies on the precise development of the gynoecium and the anther, because their primary function is to bear and to nurture the embryo sac/female gametophyte and pollen, in which the egg and sperm cells, respectively, are generated. It has been known that the GRF-
• PMID 24355747

• Proteomic analysis of the low mutation rate of diploid male gametes induced by colchicine in Ginkgo biloba L.

• Yang N, Sun Y, Wang Y, Long C, Li Y, Li Y.Author information National Engineering Laboratory for Tree Breeding, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of the Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China.AbstractColchicine treatment of G. biloba microsporocytes results in a low mutation rate in the diploid (2n) male gamete. The mutation rate is significantly lower as compared to other tree species and impedes the breeding of new economic varieties. Proteomic analysis was done to identify the proteins that influence the process of 2n gamete formation in G. biloba. The microsporangia of G. biloba were treated with colchicine solution for 48 h and the proteins were analyzed using 2-D gel electrophoresis and compared to protein profiles of untreated microsporangia. A total of 66 proteins showed difference in expression levels. Twenty-seven of these proteins were identified by mass spectrometry. Among the 27 proteins, 14 were found to be up-regulated and the rest 13 were down-regulated. The identified proteins belonged to five different functional classes: ATP generation, transport and carbohydrate metabolism; protein metabolism; ROS scavenging and detoxifying enzymes; cell wall remodeling and metabolism; transcription, cell cycle and signal transduction. The identification of these differentially expressed proteins and their function could help in analysing the mechanism of lower mutation rate of diploid male gamete when the microsporangium of G. biloba was induced by colchicine.
• PloS one.PLoS One.2013 Oct 22;8(10):e76088. doi: 10.1371/journal.pone.0076088.
• Colchicine treatment of G. biloba microsporocytes results in a low mutation rate in the diploid (2n) male gamete. The mutation rate is significantly lower as compared to other tree species and impedes the breeding of new economic varieties. Proteomic analysis was done to identify the proteins that i
• PMID 24167543

• Temporal and spatial characteristics of male cone development in Metasequoia glyptostroboides Hu et Cheng.

• Jin B, Tang L, Lu Y, Wang D, Zhang M, Ma J.Author information College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, Jiangsu, PR China. bjin@yzu.edu.cnAbstractMetasequoia glyptostroboides, a famous relic species of conifer that survived in China, has been successfully planted in large numbers across the world. However, limited information on male cone development in the species is available. In this study, we observed the morphological and anatomical changes that occur during male cone development in M. glyptostroboides using semi-thin sections and scanning electron microscopy. The male cones were borne oppositely on one-year-old twigs that were mainly located around the outer and sunlit parts of crown. Male cones were initiated from early September and shed pollen in the following February. Each cone consisted of spirally arranged microsporophylls subtended by decussate sterile scales, and each microsporophyll commonly consisted of three microsporangia and a phylloclade. The microsporangial wall was composed of an epidermis, endothecium, and tapetum. In mid-February, the endothecium and tapetum layers disintegrated, and in the epidermal layer the cell walls were thickened with inner protrusions. Subsequently, dehiscence of the microsporangia occurred through rupturing of the microsporangial wall along the dehiscence line. These results suggest that the structure, morphology, architecture and arrangement of male cones of M. glyptostroboides are mainly associated with the production, protection and dispersal of pollen for optimization of wind pollination.
• Plant signaling & behavior.Plant Signal Behav.2012 Dec;7(12):1687-94. doi: 10.4161/psb.22898. Epub 2012 Dec 1.
• Metasequoia glyptostroboides, a famous relic species of conifer that survived in China, has been successfully planted in large numbers across the world. However, limited information on male cone development in the species is available. In this study, we observed the morphological and anatomical chan
• PMID 23221679

Japanese Journal

• Syncyte formation in the microsporangium of Chrysanthemum (Asteraceae) : a pathway to infraspecific polyploidy

• Journal of plant research 122(4), 439-444, 2009-07-01
• NAID 10025180698

• Meiosis at Microsporogenesis in Siberian Fir (Abies sibirica Ledeb.) in Natural Populations and in an Arboretum

• Eurasian Journal of Forest Research 11(1), 41-49, 2008-03
• NAID 120000952021

• Persistent Cytomixis in Ocimum basilicum L. (Lamiaceae) and Withania somnifera (L.) Dun. (Solanaceae)

• CYTOLOGIA 70(3), 309-313, 2005
• NAID 130004447896

Related Links

• microsporangium - Definition of microsporangium

microsporangium [mī′krō spō ran ′jē əm] noun pl. microsporangia a sporangium containing microspores, as the pollen sac of the anther in seed plants Origin: Modern Latin Webster's New World College Dictionary Used by noun ...

• Microsporangium - Definition and More from the Free ...

mi·cro·spo·ran·gi·um noun \ ˌ mī-krō-spə-ˈ ran-jē-əm\ Definition of MICROSPORANGIUM: a sporangium that develops only microspores — mi·cro·spo·ran·gi·ate \-jē-ət\ adjective Origin of MICROSPORANGIUM New Latin First Known ...

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