摘要
【目的】芍药属牡丹组革质花盘亚组与肉质花盘亚组间的远缘杂交是现代牡丹育种的重要方向之一。然而,亚组间杂种普遍高度不育,很难继续用于杂交育种。‘正午’牡丹是一个观赏性好、适应性强的亚组间杂交品种,虽然其通常高度不育,但仍被用作亲本培育出一些优异的杂交后代,表现出一定的育性。研究其减数分裂的染色体行为,可为揭示其极低育性的形成机制提供重要的信息。【方法】本研究以‘正午’幼嫩花蕾中的雌蕊为材料,进行体细胞染色体核型分析;以花药为材料进行花粉母细胞减数分裂观察。【结果】‘正午’牡丹为二倍体,核型公式为2n=2x=10=7m+1sm+2st(1SAT)。其花粉母细胞可通过正常的减数分裂形成四分体及小孢子,减数第一次分裂中约有70%的花粉母细胞发生染色体行为异常,包括单价体及多价体、染色体桥、断片、落后染色体、不等分裂等,其中染色体桥出现频率最高;减数第二次分裂中,染色体行为异常率同样高达70%,常见的异常类型包括纺锤体定位异常、不同步分裂、染色体桥、断片、落后染色体等,最后形成二分体、三分体、微核或特小的额外小孢子。【结论】‘正午’减数分裂存在大量异常可能与其高度杂合的核型有关。普遍存在的单价体及多价体引起的不等分裂和染色体桥及断片造成的染色体片段缺失等染色体行为异常可能是导致‘正午’牡丹高度不育的重要原因。同时,仍有一小部分花粉母细胞能够顺利完成减数分裂,形成小孢子。其中一部分通过二分体或三分体形成未减数小孢子,表明其具有用于培育多倍体牡丹的潜力。
[Objective] The inter-subsectional distant hybridization between subsect. Delacayanae and subsect. Vaginatae of Paeonia sect. Moutan is a significant direction in modern tree peony breeding.Nevertheless, the inter-subsectional hybrids are generally sterile, therefore hard to be used as breeding parents subsequently. Paeonia × lemoinei ‘High Noon ’ is an inter-subsectional cultivar with good ornamental and resistant traits. In spite of its sterility in most cases, ‘High Noon’ was still the parent of a few excellent hybrids, showing some degree of fertility. The research on the meiotic chromosome behavior of‘High Noon ’ could provide important messages to uncover the forming mechanisms of its low fertility.[Method] We employed the pistils from the young flower buds to detect the somatic karyotype, and the anthers to observe the meiotic chromosome behaviors during microsporogenesis in this study.[Result] ‘High Noon’ was a diploid, whose karyotype formula was 2 n = 2 x = 10 = 7 m + 1 sm + 2 st(1 SAT).The pollen mother cells(PMCs) of ‘High Noon’ could generate tetrads and microspores through regular meiosis. The meiotic abnormalities in the first meiotic division took place in about 70% of PMCs, including univalent, multivalent, chromosome bridge, chromosome segmentation, lagging chromosome, unequal chromosome segregation, etc., among which, the chromosome bridge emerged most frequently. In the second meiotic division, meiotic abnormalities occurred in 70% of PMCs as well, involving abnormal spindle orientation, chromosome segregation asynchronicity, chromosome bridge, chromosome segmentation, lagging chromosome, etc., resulting in the formation of the dyad, triad, micronucleus, and extra microspores. [Conclusion] The vast number of abnormality in meiosis of ‘High Noon ’ might attributed to its heterozygous karyotype. The abnormal meiotic chromosome behaviors including the widespread unequal chromosome segregation caused by univalent or multivalent, and the chromosome segment missing due to the chromosome bridge and chromosome segmentation, might be the leading causes for the high sterility of ‘High Noon’. Meanwhile, a fraction of PMCs could accomplish the meiosis process successfully, forming the microspores. Therein some unreduced microspores were produced via dyad or triad formation, indicating its potential for polyploid tree peony breeding.
作者
钟原
杜明杰
刘羽心
成仿云
Zhong Yuan;Du Mingjie;Liu Yuxin;Cheng Fangyun(School of Landscape Architecture,Beijing Forestry University,Peony International Institute,National Engineering Research Center for Floriculture,Beijing 100083,China)
出处
《北京林业大学学报》
CAS
CSCD
北大核心
2019年第10期68-73,共6页
Journal of Beijing Forestry University
基金
北京林业大学青年教师科学研究中长期项目（2015ZCQ-YL-03）,北京林业大学建设世界一流学科和特色发展引导专项资金（2019XKJS0324）
北京市科技计划项目（Z181100002518001）
关键词
'正午’牡丹
亚组间杂种
减数分裂
染色体
Paeonia × lemoinei ‘High Noon’
inter-subsectional hybrids
meiosis
chromosome
