Distyly and cryptic heteromorphic self-incompatibility in A4ussaenda macrophylla （Rubiaceae）  

作　　者：Xiao-Qin Wu Pei-Xing Li Xiao-Fang Deng Dian-Xiang Zhang 

机构地区：[1]Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences,Guangzhou 510650, China [2]State Academy of Forestry Administration, Beijing 102600, China [3]University of Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Journal of Systematics and Evolution》2015年第2期166-178,共13页植物分类学报（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China （Grant Nos. 3117o295 and 31170184） and the Foundation of Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botani- cal Garden, the Chinese Academy of Sciences. The authors are indebted to Dr. Pei-Wu Xie and Dr. Zhong-Lai Luo for field assistance.

摘　　要：Typical distylous species display both reciprocal herkogamy and heteromorphic incompatibility, which exclude self- and intramorph pollination and accordingly promote intermorph pollination. Here we explore an unusual distylous flower associated with self- and intramorph compatibility in Mussaenda macrophylla Wall. The species did not exhibit a precise reciprocal herkogamy, and the populations studied had a slight bias in favor of the short-styled morph （S-morph）. In addition, pollen tube growth in intermorph pollination was faster than either in intramorph or self-pollination, indicating that cryptic heteromorphic self-incompatibility occurred in M. macrophylla. Specifically, pollen tube growth rates after legitimate and illegitimate pollination were much more highly differentiated in long-styled morph （L-morph） than in S-morph, which might be attributed to the increased de- esterified pectin in the tip of L-morph pollen tube wall in comparison with S-morph. Transmission electron microscopic observation revealed illegitimate self-pollinated pollen tubes of two morphs were seriously degraded with the large autolysosome-like vacuoles in cytoplasm of L-morph pollen tube but accumulating small vacuoles in that of S-morph pollen tube, suggesting that incompatible pollen tubes might undergo autophagic programmed cell death except self-incompatible S-morph pollen tubes. Our results indicate that M. macrophylla is morphologically distylous with a cryptic heteromorphic self-incompatibility breeding system, which functions differently in S-morph with self-pollination compared with other illegitimate pollination.Typical distylous species display both reciprocal herkogamy and heteromorphic incompatibility, which exclude self- and intramorph pollination and accordingly promote intermorph pollination. Here we explore an unusual distylous flower associated with self- and intramorph compatibility in Mussaenda macrophylla Wall. The species did not exhibit a precise reciprocal herkogamy, and the populations studied had a slight bias in favor of the short-styled morph （S-morph）. In addition, pollen tube growth in intermorph pollination was faster than either in intramorph or self-pollination, indicating that cryptic heteromorphic self-incompatibility occurred in M. macrophylla. Specifically, pollen tube growth rates after legitimate and illegitimate pollination were much more highly differentiated in long-styled morph （L-morph） than in S-morph, which might be attributed to the increased de- esterified pectin in the tip of L-morph pollen tube wall in comparison with S-morph. Transmission electron microscopic observation revealed illegitimate self-pollinated pollen tubes of two morphs were seriously degraded with the large autolysosome-like vacuoles in cytoplasm of L-morph pollen tube but accumulating small vacuoles in that of S-morph pollen tube, suggesting that incompatible pollen tubes might undergo autophagic programmed cell death except self-incompatible S-morph pollen tubes. Our results indicate that M. macrophylla is morphologically distylous with a cryptic heteromorphic self-incompatibility breeding system, which functions differently in S-morph with self-pollination compared with other illegitimate pollination.

关 键 词：cryptic self-incompatibility distyly  Mussaenda macrophylla pollen tube growth  Rubiaceae. 

分 类 号：S635[农业科学—蔬菜学] TQ342.2[农业科学—园艺学]