Abstract
The inheritance of the seedless fruit characteristic of Annona squamosa has not yet been explained. Molecular techniques may aid breeding programs, mainly in the assisted selection of the target gene. The INO gene may be related to seed development in these fruits. The objective of the present paper was to investigate the inheritance of seedlessness in the 'Brazilian seedless' sugar apple and INO gene conservation in Annona squamosa and Annona cherimola x Annona squamosa genotypes by assessing their homology with the INO database genes. The F1 generation was obtained by crossing the mutant 'Brazilian seedless' (male genitor) (P1) with the wild-type A. squamosa with seeds (M1 and M2, female genitors). The INO gene was studied in mutant and wild-type A. squamosa (P1, M1, M2 and M3) and in the Gefner atemoya (A. cherimola x A. squamosa) (M4) cultivar. The DNA was extracted from young leaves, and four sets of specific primers flanking the INO gene were amplified. The seedless characteristic was identified as stenospermatic in the fruits of parental P1, suggesting monogenic inheritance with complete dominance. High sequence similarity of the INO gene amplifications in the sugar apple accessions (M1, M2, M3) and the atemoya cultivar Gefner (M4) reinforces the hypothesis of their conservation.
Highlights
Annona fruits are tasty, with a sweet, creamy flesh and fragrant flavor when fully ripe (Pareek et al, 2011) in addition to presenting bioactive components with medicinal potential (Vilar et al, 2008, 2011; Quílez et al, 2018)
The seedless characteristic was observed only in the fruits of the male parent P1, cultivar Brazilian seedless (Figure 1). These preliminary data suggest a monogenic inheritance with complete dominance-type allelic interaction
The seedlessness of the Annona Brazilian seedless variety was due to the formation of a stenospermal fruit with partially formed seeds due to their abortion after fertilization, as reported for Vitis vinifera and Annona squamosa (Bouquet and Danglot, 1996; Lora et al, 2011; Mendes et al, 2012; Santos et al, 2014)
Summary
With a sweet, creamy flesh and fragrant flavor when fully ripe (Pareek et al, 2011) in addition to presenting bioactive components with medicinal potential (Vilar et al, 2008, 2011; Quílez et al, 2018). The development of seedless varieties of these plants adapted to Brazilian conditions remains limited (Pereira et al, 2019). An aspermic A. squamosa variety designated ‘Thai seedless’ produces normal size, seedless fruits following pollination. The stenospermy in this mutant is due to the suppression of the INO gene, leading to a loss of the outer integument of the ovule, which affects seed development (Lora et al, 2011). The first reports regarding the aspermic condition of the ‘Brazilian seedless’ variety appeared starting from 2014, together with the stenospermy type, which may be related to the suppression of the INO gene (Santos et al, 2014)
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Schedule a callMore From: Brazilian journal of biology = Revista brasleira de biologia
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