【作者】 莫饶；

【导师】 郑成木； 王文泉；

【作者基本信息】 华南热带农业大学 ， 作物遗传育种， 2005， 博士

【摘要】 咖啡(Coffea)是世界三大饮料作物之一,是典型的热带经济作物。培育结合中粒种和小粒种优良性状于一体的种间杂种是咖啡育种的一个主要方向。常规杂交育种存在周期长,优良个体的选择困难与繁殖系数低等问题,因而培育一个优良新品种需要二十年甚至更长的时间。然而利用无融合生殖特性进行育种将可能大大缩短育种年限,固定杂种优势。咖啡属植物遗传类型丰富,具有多个倍性水平,偶见种子的多胚豆和双生苗现象,但是对于咖啡属植物中是否存在无融合生殖遗传特性,有关报道甚少,目前尚无无融合生殖材料选育的报道。本研究对咖啡的多胚现象及多胚苗生长发育进行较为系统的观察,对咖啡材料进行去雄处理、细胞学观察以及POD同工酶与SSR分子标记分析,并进行高频率多胚种质以及无融合生殖种质的筛选。初步确定咖啡中存在无融合生殖特性,并筛选出较高频率的多胚种质以及无融合生殖种质。所获得的主要结果如下: 1) 揭示了咖啡中存在多胚现象及其发生频率与类型。咖啡普遍存在多胚现象,胚数为1～4个,多为双胚。多胚率较低,一般在2.80%0～40.30‰之间。四倍体的双胚率和多胚率一般比二倍体高。依胚的大小和发育的完整性可将双胚豆划分为4种类型:双同胚、大小胚、大残胚、双残胚。依多胚在种子内的着生位置可将双胚豆划分为2种类型:双胚紧靠着生型;双胚分离着生型。双胚再生植株的形态可归纳为5种类型:双同株、大小株、大残株、双残株、连体株。 2) 通过去雄处理、细胞遗传学观察和SSR分子标记检测,证实咖啡中存在兼性无融合生殖遗传特性。细胞遗传学观察发现咖啡四倍体类型材料(2n=4x=44)的多胚和多胚苗中含有天然的单倍体胚和单倍体小苗(2n=2X=22);去雄处理后,可见子房膨大,其中5份材料获得了果实和种子,初步说明无融合生殖现象的存在;对小粒种品种间杂交F1代个体的SSR分析,发现多胚苗中存在与母本图谱相同且不携带父本特异带的后代以及携带双亲特异带的有性后代,表明子代有仅来自母本的无融合生殖个体分离出来。 3) 建立了咖啡无融合生殖的分子鉴别方法。通过对多胚材料的SSR标记和POD更多还原

【Abstract】 Coffee (Coffea) is known globally as one of the most important beverage crops and extensively cultivated and distributed in many tropical countries. Production of inter-specific hybrids between Robusta and Arabica with both parents’ elite genes is a major goal of coffee breeding presently. In traditional hybridization breeding program, it would taken more than 20 years to develop a new cultivar because of long vegetable growth period, difficulty in selection and lower propagation rate of elite individuals. But utilization of apomixis in breeding procedure could significantly shorten time of selection and fix heterosis. Although high genetic diversity including variation of ploidy level, polyembryony and twin-embryonic phenomenon existed in the genus Coffea (Rubiaceae), there was less study on how about the apomixes in coffee. No bred apomictic materials have been reported still now. In this study, it is confirmed that being of apomixes in coffee and discovered that higher frequent polyembryony and apomixes types took place in coffee populations by ways of observation of plants with polyembryonic and apomictic phenomenon, morphology and cytogenetic identification, and analysis to fingerprint of peroxidase (POD) isozyme and simple sequence repeat (SSR) marker. The principal results shown as following:(1) Polyembryonic phenomenon is commonly occurred in coffee cultivars with embryo number of 1-4 and a majority of them being twin-embryos. The polyembryonic frequencies are 2.80‰~40.30‰. The frequency of polyembryony and twin-embryony in tetraploid species are generally higher than those of diploid. Four types of twin-embryonic bud (big-big type, big-small type, big-abnormal type, abnormal-abnormal type)_can be classified in according with the size and developmental intactness of twin embryos. And two types of bud (near close location and separate location of the twin-embryos at the base of the seed) can be divided in the light of the rooting position of twin embryos. There are five morphological types of in vitro seedlings geminated in twin-embryonic seeds: big-big type, big-small type, big-abnormal type, abnormal-abnormal and Siamese twin type.(2) It was confirmed that facultative apomixes is existed in coffee species based on emasculating treatment, cyto-genetic observe and SSR marker detection. It was found that更多还原