Dos Santos Rayane C, Ribeiro Leonardo M, Mercadante-Simões Maria Olívia, Costa Márcia R, Nietsche Silvia, Pereira Marlon C T
Laboratório de Biotecnologia, Departamento de Ciências Agrárias, Unimontes, Janaúba, MG, Brasil.
Laboratório de Micropropagação, Departamento de Biologia Geral, Unimontes, Montes Claros, MG, Brasil.
An Acad Bras Cienc. 2014 Dec;86(4):2101-8. doi: 10.1590/0001-3765201420140206.
Stenospermy was identified in naturally occurring sugar-apple (Annona squamosa) mutants with great potential for use in genetic improvement programs. However, to date, there have been no detailed studies of the development of aspermic fruit in this species. The aim of the present study was to characterize the anatomy of developing fruit in the 'Brazilian Seedless' mutant. Flower buds in pre-anthesis and developing fruits were subjected to common plant anatomy techniques. The abnormal ovules are unitegmic and orthotropic and have a long funiculus. There is evidence of fertilization, including the presence of embryos in early development and the proliferation of starch grains in the embryo sac. However, the embryos and embryo sac degenerate, although this does not affect pericarp development. Ovule abortion does not occur. The perisperm, which is formed from the peripheral layers of the nucellus, fills the cavity left by the embryo sac. The mature fruit contains numerous small sterile seeds with abundant perisperm and unlignified integument that is restricted to the micropylar region. The majority of perisperm cells are living and appear to be metabolically active in the periphery. Therefore, stenospermy leads to the formation of sterile seeds in A. squamosa, and the perisperm possibly play an important role in fruit development.
在天然存在的番荔枝（Annona squamosa）突变体中发现了种子败育现象，这些突变体在遗传改良计划中具有巨大的应用潜力。然而，迄今为止，尚未对该物种中无籽果实的发育进行详细研究。本研究的目的是对‘巴西无籽’突变体发育中的果实进行解剖学特征分析。对花前的花芽和发育中的果实采用常规植物解剖技术。异常胚珠为单珠被且直生，具长珠柄。有受精的证据，包括早期发育的胚的存在以及胚囊中淀粉粒的增殖。然而，胚和胚囊退化，尽管这并不影响果皮发育。胚珠不发生败育。由珠心外周层形成的外胚乳填充了胚囊留下的空腔。成熟果实含有许多小的不育种子，外胚乳丰富，珠被未木质化，仅局限于珠孔区域。大多数外胚乳细胞是活的，并且在外围似乎具有活跃的代谢。因此，种子败育导致番荔枝中不育种子的形成，外胚乳可能在果实发育中起重要作用。
