2021年9月21日 星期二
宝华玉兰大小孢子发生和雌雄配子体发育过程中 解剖结构的变化
Change of anatomical structure in the process of mega and microsporogenesis and female and male gametophyte development of Yulania zenii
2021年 第30卷 第3期 页码[46-53]    下载全文[19.5MB]  
摘要


摘要: 采用石蜡切片技术对宝华玉兰〔Yulania zenii (W. C. Cheng) D. L. Fu〕大小孢子发生和雌雄配子体发育过程中的解剖结构进行观察。结果显示:宝华玉兰的小孢子发生和雄配子体发育从8月上旬开始,至翌年3月上旬结束;其大孢子发生和雌配子体发育从12月中下旬开始,至翌年4月上旬结束,雌配子体成熟时间比雄配子体晚约30 d。宝华玉兰有雄蕊64~72个,离生,由下至上螺旋状排列,每个成熟花药具4个花粉囊;从孢原细胞开始,在经历了“孢原细胞分化期、小孢子母细胞形成期、单核绒毡层形成期、双核绒毡层形成期、小孢子发育期、二分体期、四分体期、单核居中期、单核靠边期、单核花粉期、双核花粉期”等过程后形成成熟花药。其成熟花粉为二细胞型;同一个花药中花粉囊发育不同步且小孢子四分体的排列方式不同;其雄配子体发育异常现象主要出现在四分体小孢子释放后,即在单核居中期前出现发育停滞现象,最终成熟花粉的败育率达61.3%。宝华玉兰的雌蕊由146~150个浅紫色离生心皮组成,由下至上螺旋状排列;每个心皮含2个胚珠,倒生、双珠被、厚珠心、边缘胎座;从胚珠原基开始,在经历了“胚珠发育初期、孢原细胞形成期、大孢子母细胞形成期、功能大孢子形成期、单核胚囊期、二核胚囊期、四核胚囊期、八核胚囊期”等过程后形成成熟胚囊。其大孢子为单孢子发生型,四分体直线型排列,合点端为功能大孢子,成熟胚囊为7胞8核蓼型胚囊;其雌配子体发育异常现象主要出现在二核胚囊期至八核胚囊期,最终成熟胚囊的卵细胞败育率达79.5%。研究结果表明:在宝华玉兰大小孢子发生和雌雄配子体发育过程中均出现发育异常现象,导致大部分的花药和卵细胞败育,这是宝华玉兰结实率低的重要致因之一。

Abstract

 Anatomical structure in the process of mega- and microsporogenesis and female and male gametophyte development of Yulania zenii (W. C. Cheng) D. L. Fu were observed by using paraffin section technology. The results show that microsporogenesis and male gametophyte development of Y. zenii is from early August to early March next year; megasporogenesis and female gametophyte development is from mid-to-late December to early April next year, and the maturation of female gametophyte is about 30 d later than that of male gametophyte. Y. zenii has 64-72 distinct stamens with a bottom-up spiral arrangement, and each mature anther has four pollen sacs; initiating from sporogonium cell, the mature anthers are formed after the process of “sporogenic cell differentiation stage, microspore mother cell formation stage, mononuclear tapetum formation stage, binuclear tapetum formation stage, microspore development stage, dyad stage, tetrad stage, mononuclear middle stage, mononuclear marginal stage, mononuclear pollen stage and binuclear pollen stage” and so on. Its mature pollen is of twocelled type; the development of pollen sacs in the same anther is asynchronous and the arrangement of microspore tetrad is different; the abnormal development of male gametophyte mainly appears after the release of tetrad microspore, namely the stasis of development appears before mononuclear middle stage, and the rate of mature pollen abortion reaches 61.3% finally. Y. zenii has 146-150 light purple distinct carpels with a bottomup spiral arrangement; there are two ovules, which are anatropous, double integument, thick nucellus and marginal placentation; initiating from ovule primordium, the mature embryo sacs are formed after the process of on ventral wall of each carpel “early stage of ovule development, sporogenic cell formation stage, megaspore mother cell formation stage, functional megaspore formation stage, mononuclear embryo sac stage, binuclear embryo sac stage, tetranuclear embryo sac stage and octanuclear embryo sac stage” and so on. Its megaspore is of monosporogenesis type, tetrads are arranged in straight lines, the chalazal end is functional megaspore, and mature embryo sac is 7-cell 8-nuclear polygonum type embryo sac; the abnormal development of its female gametophyte mainly appears from binuclear embryo sac stage to octanuclear embryo sac stage, and the rate of oocyte abortion in mature embryo sac reaches 79.5% finally. It is suggested that abnormal development appears in the process of mega- and microsporogenesis and female and male gametophyte development of Y. zenii, and causes abortion of most anthers and egg cells, which may be one of the major cause of low seed-setting rate of Y. zenii.

关键词宝华玉兰; 大孢子; 小孢子; 雌配子体; 雄配子体; 解剖结构
Key wordsYulania zenii (W. C. Cheng) D. L. Fu; megaspore; microspore; female gametophyte; male gametophyte; anatomical structure
作者王姗1a,1b,1c,2, 沈永宝1a,1b,1c, 鲍华鹏2, 何洪宇2
所在单位1. 南京林业大学: a. 林学院, b. 南方现代林业协同创新中心, c. 国家林业和草原局南方林木种子检验中心, 江苏 南京 210037;2. 江苏农林职业技术学院 江苏现代园艺工程技术中心, 江苏 镇江 212400
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基金项目江苏高校优势学科建设工程资助项目(PAPD); 江苏省高等学校自然科学研究面上项目(20KJB220002); 江苏农林职业技术学院科技项目(2019kj040)