合欢种皮结构及其与吸水的关系
|
摘要
【目的】研究合欢种皮结构及其对种子吸水的影响,探索种子的吸水机制,为硬实性种子休眠的解除提供理论依据。【方法】以籽粒饱满、无病虫害的合欢种子为试材,利用体视显微镜和扫描电镜观察种皮结构,并结合染色法和凡士林密封试验,探究合欢种皮结构对吸水的影响。【结果】合欢种子的种皮具有不透水性,采用始温60、70、80℃的热水浸种处理均能有效解除其硬实性,但种子生活力随热水温度的升高而降低。合欢种子呈不规则的扁椭圆形,种皮坚硬,黄褐色,背腹面各有一条向外突出且长轴与种子侧缘平行的椭圆形棱。扫描电镜结果表明,椭圆形棱是种皮表面的一道较宽的裂痕。合欢种子种皮由外到内依次为:表皮层、栅栏层、骨状石细胞层、厚壁细胞层、薄壁细胞层。种子表面有许多大小、形状及深度不同的裂缝。种孔和种脊紧闭,种脐被致密的蜡质所覆盖,维管束由种脐开始平行于种皮表面向其深处延伸。热水处理后,种孔开启,种脊处细胞开裂,种脐处的蜡质减少。凡士林密封实验发现,解除硬实性后,种子各部位均可吸水,但子叶末端区域的吸水量始终最低。吸水4 h时,种脐部位的吸水量最大,显著高于其他处理;随后中间部位吸水加快,吸水至24 h,种脐部位和中间部位的吸水率差异不显著,均高于子叶末端部位,该差异趋势一直保持至种子吸水饱和。苯胺蓝染色发现,种皮有3种吸水途径:水分最先由种脊进入种皮并沿其内的维管束移动;随后种孔和种脐处也有水分进入;水分还可以透过表皮层,但没有继续向内穿过栅栏层进入种子内部。TTC染色发现,种子的胚根端最先吸水并被染成红色,随后水分由胚根端向种子另一端即子叶末端迁移,在同一水平位置水分由子叶侧缘向中间渗透。【结论】解除合欢种子硬实性的最佳方法是始温70℃的热水处理5 min。种脊是合欢种子的初始吸水部位,随后水分也由种孔和种脐进入种胚,并由胚根端向子叶末端迁移。种皮的栅栏层、明线、厚壁细胞层、覆盖于种脐表面的蜡质层和填充于种皮维管束中的蜡质可能均与合欢种子的硬实性有关。
【Objective】 The seeds of Albizia julibrissin, collected from Suqian of Jiangsu Province, were used to identify the main water entry sites during imbibition. The structure of seed coat of A. julibrissin and the relationship with water uptake were studied to explore the mechanism of dormancy breaking of A. julibrissin seeds. 【Method】 Taking the healthy full seeds without pest and disease as material, the structure of seed coat of A. julibrissin was observed by a stereo microscopy and a scanning electron microscopy(SEM). The effect of seed coat structure on water absorption was studied by dye-tracking and vaseline sealing experiments. 【Result】 The seed coat of A. julibrissin is impervious to water. Soaking treatment with hot water at different temperatures(60 ℃,70 ℃,80 ℃) was able to ef?ciently break the hardness of the seeds, however the seed viability decreased with the increase of hot water temperature. Structural characteristics of the seed coat were also examined. A. julibrissin seeds were irregular flat ellipse and had a hard and opaque seed coat with a yellowish-brown colour. There was a protruding oval-shaped edge which was a large fissure in the seed coat parallel to the macroaxis of seed. SEM images showed that from exterior to the interior the seed coat consisted of five layers: the epidermal layer, the palisade layer, the osteosclereid layer, the stereid layer, and the parenchymal cell. There were many cracks with different size, shape and depth in the seed coat. Micropyle and lens were closed and its hilum was covered by wax, vascular bundles extended parallel to the surface of the seed coat from the hilum. Morphological changes during dormancy breaking were also evaluated. Micropyle opened, the thickness of wax layer in hilum reduced, and a large crack appeared in the lens after the hot water treatment. Blocking experiments showed that all parts of treated seeds could absorb water, but the quantity of water uptake at the end of cotyledon was always the lowest. After incubation for 4 h, the most of water was imbibed by the hilum region. Subsequently, water uptake in the middle of seeds quickly increased. It was notable that water absorption was not significantly different between treatments exposing the hilum region and the middle part of seeds, but these two treatments had significantly higher water absorption values than the treatment exposing the cotyledons extremities after 12 h steeping conditions. The difference trend remained until the water absorptivity of A. julibrissin seeds reached saturation. Aniline blue staining showed that the seed coat could absorb water in 3 ways: 1) crack at lens, 2) gaps in the micropyle and hilum, and 3) the epidermis layer of the seed. Water first entered the seed coat from the lens and moved along the vascular bundles within it. Then there was water entering the seed through micropyle and hilum. After that, water also permeated through the epidermal layer which was the outermost layer of seed coat. However, palisade layer hindered the further entry of water into the seed. The first red staining appeared in the radicle after 2 h of soaking in TTC solution, then water moved to the end of cotyledon. In horizontal direction, water penetrated from the edge of the cotyledons to the middle. 【Conclusion】 Treated in water at 70 ℃ for 5 minutes was the optimum method to break dormancy of A. julibrissin seeds. The series experiments indicated that nondormant seeds could absorb water throughout the entire seed coat, but the initial site of water absorption was the lens followed by the micropylar and hilum. After water entered the embryo it moved from the radicle to the terminal cotyledon. The hardness of seeds possibly relates to the structures of palisade layer, light line, parenchymal cell and the wax which covered the hilum and filled in vascular bundle.
【Objective】 The seeds of Albizia julibrissin, collected from Suqian of Jiangsu Province, were used to identify the main water entry sites during imbibition. The structure of seed coat of A. julibrissin and the relationship with water uptake were studied to explore the mechanism of dormancy breaking of A. julibrissin seeds. 【Method】 Taking the healthy full seeds without pest and disease as material, the structure of seed coat of A. julibrissin was observed by a stereo microscopy and a scanning electron microscopy(SEM). The effect of seed coat structure on water absorption was studied by dye-tracking and vaseline sealing experiments. 【Result】 The seed coat of A. julibrissin is impervious to water. Soaking treatment with hot water at different temperatures(60 ℃,70 ℃,80 ℃) was able to ef?ciently break the hardness of the seeds, however the seed viability decreased with the increase of hot water temperature. Structural characteristics of the seed coat were also examined. A. julibrissin seeds were irregular flat ellipse and had a hard and opaque seed coat with a yellowish-brown colour. There was a protruding oval-shaped edge which was a large fissure in the seed coat parallel to the macroaxis of seed. SEM images showed that from exterior to the interior the seed coat consisted of five layers: the epidermal layer, the palisade layer, the osteosclereid layer, the stereid layer, and the parenchymal cell. There were many cracks with different size, shape and depth in the seed coat. Micropyle and lens were closed and its hilum was covered by wax, vascular bundles extended parallel to the surface of the seed coat from the hilum. Morphological changes during dormancy breaking were also evaluated. Micropyle opened, the thickness of wax layer in hilum reduced, and a large crack appeared in the lens after the hot water treatment. Blocking experiments showed that all parts of treated seeds could absorb water, but the quantity of water uptake at the end of cotyledon was always the lowest. After incubation for 4 h, the most of water was imbibed by the hilum region. Subsequently, water uptake in the middle of seeds quickly increased. It was notable that water absorption was not significantly different between treatments exposing the hilum region and the middle part of seeds, but these two treatments had significantly higher water absorption values than the treatment exposing the cotyledons extremities after 12 h steeping conditions. The difference trend remained until the water absorptivity of A. julibrissin seeds reached saturation. Aniline blue staining showed that the seed coat could absorb water in 3 ways: 1) crack at lens, 2) gaps in the micropyle and hilum, and 3) the epidermis layer of the seed. Water first entered the seed coat from the lens and moved along the vascular bundles within it. Then there was water entering the seed through micropyle and hilum. After that, water also permeated through the epidermal layer which was the outermost layer of seed coat. However, palisade layer hindered the further entry of water into the seed. The first red staining appeared in the radicle after 2 h of soaking in TTC solution, then water moved to the end of cotyledon. In horizontal direction, water penetrated from the edge of the cotyledons to the middle. 【Conclusion】 Treated in water at 70 ℃ for 5 minutes was the optimum method to break dormancy of A. julibrissin seeds. The series experiments indicated that nondormant seeds could absorb water throughout the entire seed coat, but the initial site of water absorption was the lens followed by the micropylar and hilum. After water entered the embryo it moved from the radicle to the terminal cotyledon. The hardness of seeds possibly relates to the structures of palisade layer, light line, parenchymal cell and the wax which covered the hilum and filled in vascular bundle.
引文
方芳,彭祚登,郭志民,等.2006.刺槐种子硬实特性及萌发促进的研究.中南林业科技大学学报,33(7):72-76.(Fang F,Peng Z D,Guo Z M,et al.2006.Study on seed hardness characteristic and germination promoting of Robinia pseudoacacia seeds.Journal of Central South University of Forestry & Technology,33(7):72-76.[in Chinese])
郭学民,徐兴友,孟宪东,等.2006.合欢种子硬实与萌发特征及种皮微观形态与结构特征的研究.内蒙古农业大学学报:自然科学版,27(3):13-18.(Guo X M,Xu X Y,Meng X D,et al.2006.Bourgeon characteristics of hard seed of Albizia julibrissn Durazz.and its testa micro-morphology and structure.Journal of Inner Mongolia Agricultural University:Natural Science Edition,27(3):13-18.[in Chinese])
国家质量技术监督局.1999.GB2772—1999林木种子检验规程.北京:中国标准出版社,13-20.(State Bureau of Quality and Technical Supervision.1999.GB 2772—1999 Rules for forest tree seed testing.Beijing:Standards Press of China,13-20.[in Chinese])
胡小文,武艳培,王彦荣,等.2009.苦豆子种子休眠的形成及其解剖结构变化.西北植物学报,29(1):16-21.(Hu X W,Wu Y P,Wang Y R,et al.2009.Sophora alopecuroides seed dormancy formation and the change of seed anatomical structure.Acta Botanica Boreali-Occidentalia Sinica,29(1):16-21.[in Chinese])
连洁琼.2013.三种豆科树种硬实形成机制及破除方法的初步研究.泰安:山东农业大学硕士学位论文.(Lian J Q.2013.The preliminary studies on hard seed formation mechanism and breaking methods of three legume species.Taian:MS thesis of Shandong Agricultural University.[in Chinese])
李然,李振川,陈珊珊,等.2009.应用低场核磁共振研究绿豆浸泡过程.食品科学,30(15):137-141.(Li R,Li Z C,Chen S S,et al.2009.Study of water absorption of mung beans based on low-field nuclear magnetic resonance technology.Food Science,30(15):137-141.[in Chinese])
文婷婷,田艺心,朱岩芳,等.2013.蚕豆种皮结构、细胞壁成分及其与透水性的关系.科技通报,29(5):63-67.(Wen T T,Tian Y X,Zhu Y F,et al.2013.Structure and cell wall components of broad bean (Vicia faba L.) seed coat and their relationship with water permeability.Bulletin of Science and Technology,29(5):63-67.[in Chinese])
肖媛,刘伟,汪艳,等.2013.生物样品的扫描电镜制样干燥方法.实验室研究与探索,32(5):45-53.(Xiao Y,Liu W,Wang Y,et al.2013.Drying methods of biological sample preparation for scanning electron microscope.Research and Exploration in Laboratory,32(5):45-53.[in Chinese])
杨期和,尹小娟,叶万辉.2006.硬实种子休眠的机制和解除方法.植物学报,23(1):108-118.(Yang Q H,Yin X J,Ye W H.2006.Dormancy mechanism and breaking methods for hard seeds.Chinese Bulletin of Botany,23(1):108-118.[in Chinese])
臧德奎.2012.园林树木学.2版.北京:中国建筑工业出版社,276-277.(Zang D K.2012.Landscape dendrology.2nd ed.Beijing:China Construction Industry Press,276-277.[in Chinese])
中国科学院中国植物志编著委员会.1988.中国植物志第三十九卷.2版.北京:科学出版社,59.(The Chinese Academy of Sciences Compilation Committee of Chinese Flora.1988.Chinese flora thirty-ninth volume.2nd ed.Beijing:Science Press,59.[in Chinese])
周健.2016.紫荆种子休眠特性及其吸水机制研究.南京:南京林业大学硕士学位论文(Zhou J.2016.The mechanism of water absorbing and dormancy in Cercis chinensis seeds.Nanjing:MS thesis of Nanjing Forestry University.[in Chinese])
周元.2003.滇青冈种子的萌发.植物生理学报,39(4):325-326.(Zhou Y.2003.Seed germination of Cyclobalanopsis glaucoides.Journal of Plant Physiology,39(4):325-326.[in Chinese])
Baskin C C.2003.Breaking Physical dormancy in seeds focusing on the lens.New Phytologist,158:227-238.
Bewley J D.1997.Seed germination and dormancy.The Plant Cell,9(7):1055-1066.
Burns R E.1959.Effect of acid scarification on lupine seed impermeability.Plant Physiology,34(2):107-108.
Desouza F H D,Marcos F J.2001.The seed coat as a modulator of seed-environment relationships in Fabaceae.Revista Brasileira de Botanica,24(4):365-375.
Gama-Arachchige N S,Baskin J M,Geneve R L,et al.2010.Identification and characterization of the water gap in physically dormant seeds of Geraniaceae,with special reference to Geranium carolinianum.Annals of Botany,105(6):977-990.
Geisler G E,Pinto T T,Santos M,et al.2017.Seed structures in water uptake,dormancy release,and germination of two tropical forest Fabaceae species with physically dormant seeds.Brazilian Journal of Botany,40(1):67-77.
International Seed Testing Association.2013.International rules for seed testing.Seed Science and Technology,27(Supplement):33-35.
Jayasuriya K M G G,Baskin J M,Geneve R L,et al.2008.Physical dormancy in seeds of the holoparasitic angiosperm Cuscuta australis (Convolvulaceae,Cuscuteae):dormancy-breaking requirements,anatomy of the water gap and sensitivity cycling.Annals of Botany,102(1):39-48.
Kestring D,Klein J,de Menezes L C C R,et al.2009.Imbibition phases and germination response of Mimosa bimucronata (Fabaceae:Mimosoideae) to water submersion.Aquatic Botany,91(2):105-109.
Kikuchi K,Koizumi M,Ishida N,et al.2006.Water uptake by dry beans observed by micro-magnetic resonance imaging.Annals of Botany,98(3):545-553.
Krishnan P,Joshi D K,Nagarajan S,et al.2004.Characterization of germinating and non-viable soybean seeds by nuclear magnetic resonance (NMR) spectroscopy.Seed Science Research,14(4):355-362.
Lush M W,Evans L T.1980.The seed coats of cowpeas and other grain legumes structure in relation to function.Field Crops Research,3(3):267-286.
Ma F S,Cholewa E,Mohamed T,et al.2004.Cracks in the palisade cuticle of soybean seed coats correlate with their permeability to water.Annals of Botany,94(2):213-228.
Mo?se J A,Han S,Gudynait?savitch L,et al.2005.Seed coats:Structure,development,composition,and biotechnology.In Vitro Cellular & Developmental Biology-Plant,41(5):620-644.
Paula A S D,Delgado C M L,Paulilo M T S,et al.2012.Breaking physical dormancy of Cassia leptophylla and Senna macranthera seeds water absorption and alternating temperatures.Seed Science Research,22(4):1-9.
Perissé P,Planchuelo A M.2004.Seed coat morphology of Lupinus albus L.and Lupinus angustifolius L.in relation to water uptake.Seed Science & Technology,32(1):69-77.
Rodrigues-Junior A G,Faria J M R,Vaz T A A,et al.2014.Physical dormancy in Senna multijuga (Fabaceae:Caesalpinioideae) seeds:The role of seed structures in water uptake.Seed Science Research,24(2):147-157.
Zhang L F,Wu X W,She Y H.2012.Study on characters of hard seeds of Amphicarpaea edgeworthii Benth.(Leguminosae) and methods for breaking dormancy.Agricultural Science & Technology,13(9):1885-1890.
Zhou J,Yin Y T,Qian C M,et al.2015.Seed coat morphology in Sapium sebiferum in relation to its mechanism of water uptake.Journal of Horticultural Science & Biotechnology,90(6):613-618.
郭学民,徐兴友,孟宪东,等.2006.合欢种子硬实与萌发特征及种皮微观形态与结构特征的研究.内蒙古农业大学学报:自然科学版,27(3):13-18.(Guo X M,Xu X Y,Meng X D,et al.2006.Bourgeon characteristics of hard seed of Albizia julibrissn Durazz.and its testa micro-morphology and structure.Journal of Inner Mongolia Agricultural University:Natural Science Edition,27(3):13-18.[in Chinese])
国家质量技术监督局.1999.GB2772—1999林木种子检验规程.北京:中国标准出版社,13-20.(State Bureau of Quality and Technical Supervision.1999.GB 2772—1999 Rules for forest tree seed testing.Beijing:Standards Press of China,13-20.[in Chinese])
胡小文,武艳培,王彦荣,等.2009.苦豆子种子休眠的形成及其解剖结构变化.西北植物学报,29(1):16-21.(Hu X W,Wu Y P,Wang Y R,et al.2009.Sophora alopecuroides seed dormancy formation and the change of seed anatomical structure.Acta Botanica Boreali-Occidentalia Sinica,29(1):16-21.[in Chinese])
连洁琼.2013.三种豆科树种硬实形成机制及破除方法的初步研究.泰安:山东农业大学硕士学位论文.(Lian J Q.2013.The preliminary studies on hard seed formation mechanism and breaking methods of three legume species.Taian:MS thesis of Shandong Agricultural University.[in Chinese])
李然,李振川,陈珊珊,等.2009.应用低场核磁共振研究绿豆浸泡过程.食品科学,30(15):137-141.(Li R,Li Z C,Chen S S,et al.2009.Study of water absorption of mung beans based on low-field nuclear magnetic resonance technology.Food Science,30(15):137-141.[in Chinese])
文婷婷,田艺心,朱岩芳,等.2013.蚕豆种皮结构、细胞壁成分及其与透水性的关系.科技通报,29(5):63-67.(Wen T T,Tian Y X,Zhu Y F,et al.2013.Structure and cell wall components of broad bean (Vicia faba L.) seed coat and their relationship with water permeability.Bulletin of Science and Technology,29(5):63-67.[in Chinese])
肖媛,刘伟,汪艳,等.2013.生物样品的扫描电镜制样干燥方法.实验室研究与探索,32(5):45-53.(Xiao Y,Liu W,Wang Y,et al.2013.Drying methods of biological sample preparation for scanning electron microscope.Research and Exploration in Laboratory,32(5):45-53.[in Chinese])
杨期和,尹小娟,叶万辉.2006.硬实种子休眠的机制和解除方法.植物学报,23(1):108-118.(Yang Q H,Yin X J,Ye W H.2006.Dormancy mechanism and breaking methods for hard seeds.Chinese Bulletin of Botany,23(1):108-118.[in Chinese])
臧德奎.2012.园林树木学.2版.北京:中国建筑工业出版社,276-277.(Zang D K.2012.Landscape dendrology.2nd ed.Beijing:China Construction Industry Press,276-277.[in Chinese])
中国科学院中国植物志编著委员会.1988.中国植物志第三十九卷.2版.北京:科学出版社,59.(The Chinese Academy of Sciences Compilation Committee of Chinese Flora.1988.Chinese flora thirty-ninth volume.2nd ed.Beijing:Science Press,59.[in Chinese])
周健.2016.紫荆种子休眠特性及其吸水机制研究.南京:南京林业大学硕士学位论文(Zhou J.2016.The mechanism of water absorbing and dormancy in Cercis chinensis seeds.Nanjing:MS thesis of Nanjing Forestry University.[in Chinese])
周元.2003.滇青冈种子的萌发.植物生理学报,39(4):325-326.(Zhou Y.2003.Seed germination of Cyclobalanopsis glaucoides.Journal of Plant Physiology,39(4):325-326.[in Chinese])
Baskin C C.2003.Breaking Physical dormancy in seeds focusing on the lens.New Phytologist,158:227-238.
Bewley J D.1997.Seed germination and dormancy.The Plant Cell,9(7):1055-1066.
Burns R E.1959.Effect of acid scarification on lupine seed impermeability.Plant Physiology,34(2):107-108.
Desouza F H D,Marcos F J.2001.The seed coat as a modulator of seed-environment relationships in Fabaceae.Revista Brasileira de Botanica,24(4):365-375.
Gama-Arachchige N S,Baskin J M,Geneve R L,et al.2010.Identification and characterization of the water gap in physically dormant seeds of Geraniaceae,with special reference to Geranium carolinianum.Annals of Botany,105(6):977-990.
Geisler G E,Pinto T T,Santos M,et al.2017.Seed structures in water uptake,dormancy release,and germination of two tropical forest Fabaceae species with physically dormant seeds.Brazilian Journal of Botany,40(1):67-77.
International Seed Testing Association.2013.International rules for seed testing.Seed Science and Technology,27(Supplement):33-35.
Jayasuriya K M G G,Baskin J M,Geneve R L,et al.2008.Physical dormancy in seeds of the holoparasitic angiosperm Cuscuta australis (Convolvulaceae,Cuscuteae):dormancy-breaking requirements,anatomy of the water gap and sensitivity cycling.Annals of Botany,102(1):39-48.
Kestring D,Klein J,de Menezes L C C R,et al.2009.Imbibition phases and germination response of Mimosa bimucronata (Fabaceae:Mimosoideae) to water submersion.Aquatic Botany,91(2):105-109.
Kikuchi K,Koizumi M,Ishida N,et al.2006.Water uptake by dry beans observed by micro-magnetic resonance imaging.Annals of Botany,98(3):545-553.
Krishnan P,Joshi D K,Nagarajan S,et al.2004.Characterization of germinating and non-viable soybean seeds by nuclear magnetic resonance (NMR) spectroscopy.Seed Science Research,14(4):355-362.
Lush M W,Evans L T.1980.The seed coats of cowpeas and other grain legumes structure in relation to function.Field Crops Research,3(3):267-286.
Ma F S,Cholewa E,Mohamed T,et al.2004.Cracks in the palisade cuticle of soybean seed coats correlate with their permeability to water.Annals of Botany,94(2):213-228.
Mo?se J A,Han S,Gudynait?savitch L,et al.2005.Seed coats:Structure,development,composition,and biotechnology.In Vitro Cellular & Developmental Biology-Plant,41(5):620-644.
Paula A S D,Delgado C M L,Paulilo M T S,et al.2012.Breaking physical dormancy of Cassia leptophylla and Senna macranthera seeds water absorption and alternating temperatures.Seed Science Research,22(4):1-9.
Perissé P,Planchuelo A M.2004.Seed coat morphology of Lupinus albus L.and Lupinus angustifolius L.in relation to water uptake.Seed Science & Technology,32(1):69-77.
Rodrigues-Junior A G,Faria J M R,Vaz T A A,et al.2014.Physical dormancy in Senna multijuga (Fabaceae:Caesalpinioideae) seeds:The role of seed structures in water uptake.Seed Science Research,24(2):147-157.
Zhang L F,Wu X W,She Y H.2012.Study on characters of hard seeds of Amphicarpaea edgeworthii Benth.(Leguminosae) and methods for breaking dormancy.Agricultural Science & Technology,13(9):1885-1890.
Zhou J,Yin Y T,Qian C M,et al.2015.Seed coat morphology in Sapium sebiferum in relation to its mechanism of water uptake.Journal of Horticultural Science & Biotechnology,90(6):613-618.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |