Abstract
ABSTRACT This study was performed to evaluate the meiotic behavior and fertility of four hybrids obtained from the crossing of Capsicum baccatum and its botanical forms with Capsicum chinense and Capsicum frutescens. We aimed to identify the causes of the low fertility in interspecific hybrids involving species from different gene pools of Capsicum. Hybrid flower buds were fixed in fixative solution and the slides were prepared using 1%-acetic carmine solution. Meiosis was observed in all phases and the main meiotic abnormality observed was the complete or partial lack of chromosome pairing, indicating that the species are either genetically distant or that some asynaptic gene was present in the hybrids. Meiotic index (MI), the frequency of unreduced gametes (type 2n), and pollen viability were estimated. MI and pollen viability of the hybrids were low. We concluded that due to the complete or partial lack of chromosome pairing, the species used in the hybrid combinations are genetically distant. We also noticed that the low-fertility hybrids are a consequence of the lack of chromosome homology between the two genomes involved. The hybrids were considered partially sterile since their pollen viability percentage was lower than 50%.
Highlights
Esta pesquisa teve o objetivo de estudar o comportamento meiótico e a fertilidade de quatro híbridos, obtidos do cruzamento entre acessos das espécies Capsicum baccatum e suas formas botânicas com Capsicum chinense e Capsicum frutescens, afim de identificar as possíveis causas da baixa fertilidade observada em híbridos interespecíficos envolvendo espécies pertencentes a diferentes complexos gênicos de Capsicum
The genus Capsicum, green peppers and chili consist of only five domesticated species: Capsicum annuum, Capsicum chinense, Capsicum frutescens, Capsicum baccatum and Capsicum pubescens (Moscone et al, 2007)
C. annuum complex consists of C. annuum, C. chinense, C. frutescens, C. chacoense and C. galapagoense; C. baccatum complex consists of C. baccatum var. baccatum, C. baccatum var. pendulum, and C. praetermissum and C. pubescens complex shows some wild species
Summary
Esta pesquisa teve o objetivo de estudar o comportamento meiótico e a fertilidade de quatro híbridos, obtidos do cruzamento entre acessos das espécies Capsicum baccatum e suas formas botânicas com Capsicum chinense e Capsicum frutescens, afim de identificar as possíveis causas da baixa fertilidade observada em híbridos interespecíficos envolvendo espécies pertencentes a diferentes complexos gênicos de Capsicum. Sometimes hybrids are obtained between Capsicum species which belong to different gene pools; these hybrids are sterile or show very low pollen fertility (Egawa & Tanaka, 1986; Yoon et al, 2006; Manzur et al, 2015) which prevents or hinders gene transfer. This hybrid infertility is explained by the low pollen viability of the obtained combinations, which is due to the genetic distance between the species participating in crossing. If no chromosomal homology between parents is noticed, chromosome pairing in interspecific hybrids will be impaired and the gene transfer between species will not occur, as no pairing between chromosomes will be verified, no crossing will occur (Brambatti et al, 2016)
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