02752naa a2200241 a 450000100080000000500110000800800410001902400420006010000240010224500940012626000090022050000850022952020150031465000180232965000110234765000180235865000110237665000140238770000220240170000160242370000130243977300580245221527762023-04-12       2023    bl uuuu     u00u1 u    #d7 a10.17660/ActaHortic.2023.1359.142DOI1 aANGELO, P. C. da S.  aCoffee microspore cultivation to attain doubled-haploid plantlets.h[electronic resource]  c2023  aApresentado no INTERNATIONAL HORTICULTURAL CONGRESS, 31., 2022, Angers, França.  aIntrogression of disease resistance from related Coffea species to C. arabica has been done by inter-specific hybridization. C. arabica (tetraploid) × C. racemosa (diploid) hybrids were obtained at the IDR-Paraná, Brazil. Some of the hybrids display impaired self-pollination, despite backcrossed to C. arabica. As an attempt to regenerate stable doubled-haploid plants, anthers and isolated microspores have been cultivated in vitro. It was considered that chromosomes captured in a microspore following meiosis could acquire homo and/or homeologous stability faster in vitro than in vivo. A C. arabica progeny was taken as control. Flowers were collected at the IDR campus in Londrina, when young microspores were uninucleate, and treated with 8% active chlorine. Microspores were extracted in 90 mM mannitol using a food mixer set to function for a few seconds, washed and centrifuged at 100× g twice, and cultivated in modified N6 liquid medium (105 cells mL-1 in 35 mm diameter plates). Anthers were excised using scalpels and cultivated in solid medium. Explants were kept for six months of continuous cultivation on that induction medium containing 6.5 mg L-1 auxins, 1.0 mg L-1 cytokinins and 0.5 mg L-1 gibberellin (GA3), at 27°C under dark. Microspores produced embryo-like structures or microcalli in very low frequencies (0.3 per plate). Anthers, on the other hand, produced embryogenic calli. Colonization by an invariant morphotype of fungus took away 70% of Arabica coffee control anthers and 5% of the asseptic anthers produced friable calli, some embryogenic but arrested when compared with calli produced by the inter-specific hybrid anthers. Colonization by an invariant morphotype of bacteria took away 25% of hybrid anthers and 8% of produced embryogenic tissue, with globular embryos simultaneously multiplying and maturing upon transfer to N6 medium. Embryo conversion and photomorphogenesis under light on auxin/cytokinin ratio = 2 plus GA3 are going on, 1.2 year after inoculation.  aEmbryogenesis  aPollen  aEmbriogénese  aPólen  aRubiaceae1 aPEREIRA, L. F. P.1 aSERA, G. H.1 aSETA, T.  tActa Horticulturaegv. 31, n. 1359, p. 123-130, 2023.