云南红豆杉新采收种子的形态与离体胚的萌发特性
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摘要
通过云南红豆杉新采收种子形态观察、透水性测定、种子大小以及所带胚乳多少对离体胚萌发率的影响等试验,探讨云南红豆杉种子的休眠与萌发机理。结果表明,云南红豆杉种子呈倒卵形和三棱形;胚酒瓶形,白色;胚乳淡黄色,油质。种子千粒重为72.934g;种皮、种仁和种胚分别占种子鲜重的50.56%、40.45%和8.99%;胚与种子的体积比(E∶S)为0.074。胚的体积为0.156—1.012mm~3,种子为51.658—109.649mm~3,两者呈显著正相关(P<0.05,r=0.810)。完整种子的吸水率明显低于破裂种皮、酸蚀40min和酸蚀20min的种子,但差异随着浸泡时间延长而缩小;种子含水量饱和时,完整种子、破皮种子与酸蚀种子的吸水率无显著差异(前者为23.7%,后两者约28.0%)。不同大小种子离体胚的萌发率差异显著(P<0.05),特大、大、中、小和特小种子的离体胚的萌发率为80%、77.8%、67.5%、62.0%和44.0%。胚乳抑制离体胚的萌发,不带胚乳离体胚的萌发率为41.3%,显著高于带胚乳的萌发率(P<0.05),带部分胚乳的胚为9.7%—13.3%,带全胚乳的胚为0。同时离体胚培养过程中所用种胚的新鲜程度也严重影响胚的萌发率。云南红豆杉种子休眠属于中度生理休眠类型,种子中的抑制物质含量随时间的动态变化和胚乳中抑制物质含量的多少对胚萌发率的影响是以后云南红豆杉休眠研究的重点。
Taxus yunnanensis( Taxus wallichiana var. wallichiana) is an endangered species on China's national protection list. This plant is located mainly in Yunnan,Sichuan,Chongqing,and Tibet. In nature,the seeds of T. yunnanensis need about 2 years to eliminate dormant factors for germination. To shorten the time of seed germination and improve the germination rate,many studies of seeds on biology,physiological ecology,and cultivation have been conducted. However,there are no consistent views and conclusions about how to improve germination rates. Thus,clarification of the embryonal germination characteristics and the water permeability of seed coats form the basis for understanding causes of seed dormancy. In order to explore the mechanisms of T. yunnanensis seed dormancy and germination,fresh seeds were used for morphological observation,water permeability tests,and tests on the effects of different seed sizes and endosperm quantities on the germination rate for in vitro embryos. Our results showed that T. yunnanensis seeds were obovate three-sided prisms,embryos were white and bottle shaped,and the endosperm was pale yellow and oily. One thousand seeds weighed 72.934 g.The relative weights of seed coat,kernel,and embryo accounted for 50.56%,40.45%,and 8.99% of total seed weight,respectively. The volume ratio of an embryo versus a seed( E ∶ S) was 7.4%. The volume range for embryos and seeds was0.156—1.012 and 51.658—109.649 mm~3,respectively. Mantel tests showed that there was a significant positive correlation between the volume of embryos and that of seeds( P<0.05,r = 0.810). The water absorption rate of intact seeds was lower than that of cut seeds. However,the differences of water absorption rates for seeds corroded by acids for 40 and 20 min were reduced with the extension of soaking time. When the moisture content of a seed was saturated,there was no significant difference of water absorption rate among intact( 23. 7%),cut( 28. 7%),and acid-corroded( 28. 0%) seeds. The germination rate of in vitro embryos was markedly different for different seed sizes( P<0.05). Specifically,the germination rate of in vitro embryos for superlarge seeds( 98.051—109.649mm~3),large seeds( 86.453—98.050mm~3),medium seeds( 74.855—86.452 mm~3),small seeds( 63.257—74.854mm~3),and supersmall seeds( 51.658—63.256mm~3) was 80%,77.8%,67.5%,62.0%,and 44.0%,respectively. Moreover,the endosperm inhibits the germination of embryos,and the germination rate of embryos without endosperm( 41.3%) was significantly higher than that for embryos with endosperm( P<0.05). The respective germination rates for seeds with a portion of the endosperm and full endosperm was 9.7% —13.3%,and 0%. Finally,the freshness of in vitro embryos also affected their germination rates. In conclusion,the present study showed that sampling materials and their cultivation conditions should be consistent between studies. In addition,the seed dormancy of T. yunnanensis was moderate and caused by physiological dormancy. Many factors can contribute to physiological dormancy; this study confirmed that inhibitors within seeds are the most important causes of T. yunnanensis seed dormancy. Additional studies should focus on the changes in quantity of inhibitors over time and their effects on the germination rates for in vitro embryos.
Taxus yunnanensis( Taxus wallichiana var. wallichiana) is an endangered species on China's national protection list. This plant is located mainly in Yunnan,Sichuan,Chongqing,and Tibet. In nature,the seeds of T. yunnanensis need about 2 years to eliminate dormant factors for germination. To shorten the time of seed germination and improve the germination rate,many studies of seeds on biology,physiological ecology,and cultivation have been conducted. However,there are no consistent views and conclusions about how to improve germination rates. Thus,clarification of the embryonal germination characteristics and the water permeability of seed coats form the basis for understanding causes of seed dormancy. In order to explore the mechanisms of T. yunnanensis seed dormancy and germination,fresh seeds were used for morphological observation,water permeability tests,and tests on the effects of different seed sizes and endosperm quantities on the germination rate for in vitro embryos. Our results showed that T. yunnanensis seeds were obovate three-sided prisms,embryos were white and bottle shaped,and the endosperm was pale yellow and oily. One thousand seeds weighed 72.934 g.The relative weights of seed coat,kernel,and embryo accounted for 50.56%,40.45%,and 8.99% of total seed weight,respectively. The volume ratio of an embryo versus a seed( E ∶ S) was 7.4%. The volume range for embryos and seeds was0.156—1.012 and 51.658—109.649 mm~3,respectively. Mantel tests showed that there was a significant positive correlation between the volume of embryos and that of seeds( P<0.05,r = 0.810). The water absorption rate of intact seeds was lower than that of cut seeds. However,the differences of water absorption rates for seeds corroded by acids for 40 and 20 min were reduced with the extension of soaking time. When the moisture content of a seed was saturated,there was no significant difference of water absorption rate among intact( 23. 7%),cut( 28. 7%),and acid-corroded( 28. 0%) seeds. The germination rate of in vitro embryos was markedly different for different seed sizes( P<0.05). Specifically,the germination rate of in vitro embryos for superlarge seeds( 98.051—109.649mm~3),large seeds( 86.453—98.050mm~3),medium seeds( 74.855—86.452 mm~3),small seeds( 63.257—74.854mm~3),and supersmall seeds( 51.658—63.256mm~3) was 80%,77.8%,67.5%,62.0%,and 44.0%,respectively. Moreover,the endosperm inhibits the germination of embryos,and the germination rate of embryos without endosperm( 41.3%) was significantly higher than that for embryos with endosperm( P<0.05). The respective germination rates for seeds with a portion of the endosperm and full endosperm was 9.7% —13.3%,and 0%. Finally,the freshness of in vitro embryos also affected their germination rates. In conclusion,the present study showed that sampling materials and their cultivation conditions should be consistent between studies. In addition,the seed dormancy of T. yunnanensis was moderate and caused by physiological dormancy. Many factors can contribute to physiological dormancy; this study confirmed that inhibitors within seeds are the most important causes of T. yunnanensis seed dormancy. Additional studies should focus on the changes in quantity of inhibitors over time and their effects on the germination rates for in vitro embryos.
引文
[1]苏建荣,张志钧,邓疆,李国松.云南红豆杉的地理分布与气候关系.林业科学研究,2005,18(5):510-515.
[2]Cragg G M,Schepartz S A,Suffness M,Grever M R.The taxol supply crisis.New NCI policies for handling the large-scale production of novel natural product anticancer and anti-HIV agents.Journal of Natural Products,1993,56(10):1657-1668.
[3]苏建荣,张志钧,邓疆.不同树龄、不同地理种源云南红豆杉紫杉醇含量变化的研究.林业科学研究,2005,18(4):369-374.
[4]苏建荣,缪迎春,张志钧.云南红豆杉紫杉醇含量变异及其相关的RAPD分子标记.林业科学,2009,45(7):26-28.
[5]美国农业部林务局.美国木本植物种子手册.李霆,陈幼生,译.北京:中国林业出版社,1984.
[6]黄儒珠,方兴添,郭祥泉,郑珂晖,罗荔仙.南方红豆杉种子的化学成分分析.应用与环境生物学报,2002,8(4):392-394.
[7]程广有,唐晓杰,高红兵,沈熙环.东北红豆杉种子休眠机理与解除技术探讨.北京林业大学学报,2004,26(1):5-9.
[8]张志权,廖文波,钟翎,陈志明.南方红豆杉种子萌发生物学研究.林业科学研究,2000,13(3):280-285.
[9]张艳杰,申慧,饶玮,鲁顺保,高捍东.南方红豆杉种子生物学特性研究.安徽农业科学,2010,38(1):440-442.
[10]王卫斌,王达明.云南红豆杉.昆明:云南大学出版社,2006.
[11]赵盛军.云南红豆杉种子休眠原因的初步研究.林业调查规划,1996,(1):44-46.
[12]臧新,吕晓辉,杨冬之,黄象男.2种红豆杉的离体胚培养.郑州大学学报:理学版,2006,38(2):107-112.
[13]赵沛基,沈月毛,彭丽萍,甘烦远.云南红豆杉离体胚的培养.植物生理学通讯,2003,39(4):327-329.
[14]王兵益,苏建荣,张志钧.云南红豆杉种子贮藏过程中胚的变化.林业科学研究,2009,22(1):26-28.
[15]杨玲,陈虎庚,牛祖林,石文雅.浸种催芽对打破云南红豆杉种子休眠的初步研究.湖北农业科学,2011,50(10):2057-2059,2063-2063.
[16]Baskin J M,Baskin C C.A classification system for seed dormancy.Seed Science Research,2004,14(1):1-16.
[17]Finch-Savage W E,Leubner-Metzger G.Seed dormancy and the control of germination.New Phytologist,2006,171(3):501-523.
[18]Baskin J M,Baskin C C.Some considerations for adoption of Nikolaeva's formula system into seed dormancy classification.Seed Science Research,2008,18(3):131-137.
[19]付婷婷,程红焱,宋松泉.种子休眠的研究进展.植物学报,2009,44(5):629-641.
[20]张雪梅,龙雯虹,荣剑.红豆杉种子休眠机理及休眠解除研究进展.西南林业大学学报,2012,32(5):92-95.
[21]国家标准总局.GB 2772—1999,林木种子检验规程.北京:中国标准出版社,1999.
[22]宋松泉,程红炎,龙春林,姜孝成.种子生物学研究指南.北京:科学出版社.2005.
[23]尚旭岚,徐锡增,方升佐.青钱柳种子休眠机制.林业科学,2011,47(3):68-74.
[24]Le Page Degivry M T.Non-acidic inhibitors and embryo dormancy in Taxus baccata.Physiologia Plantarum,1977,41(1):85-88.
[25]高红兵,吴榜华,孙振良.东北红豆杉种子层积过程中内源生长素和脱落酸含量的变化.吉林林学院学报,1998,14(4):187-189.
[26]朱念德,刘蔚秋,伍建军,廖文波.影响南方红豆杉种子萌发因素的研究.中山大学学报:自然科学版,1999,38(2):75-79.
[27]黄儒珠,郭祥泉,方兴添,李玉蕾.变温层积处理对南方红豆杉种子生理生化特性的影响.福建师范大学学报:自然科学版,2006,22(2):95-98.
[28]张艳杰,高捍东,鲁顺保.南方红豆杉种子中发芽抑制物的研究.南京林业大学学报:自然科学版,2007,31(4):51-56.
[2]Cragg G M,Schepartz S A,Suffness M,Grever M R.The taxol supply crisis.New NCI policies for handling the large-scale production of novel natural product anticancer and anti-HIV agents.Journal of Natural Products,1993,56(10):1657-1668.
[3]苏建荣,张志钧,邓疆.不同树龄、不同地理种源云南红豆杉紫杉醇含量变化的研究.林业科学研究,2005,18(4):369-374.
[4]苏建荣,缪迎春,张志钧.云南红豆杉紫杉醇含量变异及其相关的RAPD分子标记.林业科学,2009,45(7):26-28.
[5]美国农业部林务局.美国木本植物种子手册.李霆,陈幼生,译.北京:中国林业出版社,1984.
[6]黄儒珠,方兴添,郭祥泉,郑珂晖,罗荔仙.南方红豆杉种子的化学成分分析.应用与环境生物学报,2002,8(4):392-394.
[7]程广有,唐晓杰,高红兵,沈熙环.东北红豆杉种子休眠机理与解除技术探讨.北京林业大学学报,2004,26(1):5-9.
[8]张志权,廖文波,钟翎,陈志明.南方红豆杉种子萌发生物学研究.林业科学研究,2000,13(3):280-285.
[9]张艳杰,申慧,饶玮,鲁顺保,高捍东.南方红豆杉种子生物学特性研究.安徽农业科学,2010,38(1):440-442.
[10]王卫斌,王达明.云南红豆杉.昆明:云南大学出版社,2006.
[11]赵盛军.云南红豆杉种子休眠原因的初步研究.林业调查规划,1996,(1):44-46.
[12]臧新,吕晓辉,杨冬之,黄象男.2种红豆杉的离体胚培养.郑州大学学报:理学版,2006,38(2):107-112.
[13]赵沛基,沈月毛,彭丽萍,甘烦远.云南红豆杉离体胚的培养.植物生理学通讯,2003,39(4):327-329.
[14]王兵益,苏建荣,张志钧.云南红豆杉种子贮藏过程中胚的变化.林业科学研究,2009,22(1):26-28.
[15]杨玲,陈虎庚,牛祖林,石文雅.浸种催芽对打破云南红豆杉种子休眠的初步研究.湖北农业科学,2011,50(10):2057-2059,2063-2063.
[16]Baskin J M,Baskin C C.A classification system for seed dormancy.Seed Science Research,2004,14(1):1-16.
[17]Finch-Savage W E,Leubner-Metzger G.Seed dormancy and the control of germination.New Phytologist,2006,171(3):501-523.
[18]Baskin J M,Baskin C C.Some considerations for adoption of Nikolaeva's formula system into seed dormancy classification.Seed Science Research,2008,18(3):131-137.
[19]付婷婷,程红焱,宋松泉.种子休眠的研究进展.植物学报,2009,44(5):629-641.
[20]张雪梅,龙雯虹,荣剑.红豆杉种子休眠机理及休眠解除研究进展.西南林业大学学报,2012,32(5):92-95.
[21]国家标准总局.GB 2772—1999,林木种子检验规程.北京:中国标准出版社,1999.
[22]宋松泉,程红炎,龙春林,姜孝成.种子生物学研究指南.北京:科学出版社.2005.
[23]尚旭岚,徐锡增,方升佐.青钱柳种子休眠机制.林业科学,2011,47(3):68-74.
[24]Le Page Degivry M T.Non-acidic inhibitors and embryo dormancy in Taxus baccata.Physiologia Plantarum,1977,41(1):85-88.
[25]高红兵,吴榜华,孙振良.东北红豆杉种子层积过程中内源生长素和脱落酸含量的变化.吉林林学院学报,1998,14(4):187-189.
[26]朱念德,刘蔚秋,伍建军,廖文波.影响南方红豆杉种子萌发因素的研究.中山大学学报:自然科学版,1999,38(2):75-79.
[27]黄儒珠,郭祥泉,方兴添,李玉蕾.变温层积处理对南方红豆杉种子生理生化特性的影响.福建师范大学学报:自然科学版,2006,22(2):95-98.
[28]张艳杰,高捍东,鲁顺保.南方红豆杉种子中发芽抑制物的研究.南京林业大学学报:自然科学版,2007,31(4):51-56.