Breeding is a long process in the rose industry. Premature death of developing embryos due to incompatibility and delayed germination, caused by seed dormancy, are the main causes. Immature seed rescue may offer a valuable way to increase hybridisation efficiency, to introduce genotypes with interesting ornamental traits, and to shorten time needed to obtain seedlings. In this study, in vitro immature seed rescue was carried out in Rosa hybrid L. Seeds from 7 to 28 days after pollination (DAP) were sterilized and placed onto two germination media: Murashige and Skoog medium (full strength macro and micro nutrients and vitamins, MS0) and MS0 with 6-benzylaminopurine (BAP; 2.5 mg/L) and gibberellic acid 3 (GA3; 0.5 mg/L). Four different conditions of light and temperature were applied. At 15 and 30 DAP, the abscisic acid (ABA) concentration was quantified in fully formed embryos of two different genotypes of hybrid roses. Preliminary data showed that only seeds harvested at 21 DAP germinated in both media, this after 2 months of in vitro culture. This result is supported by the observation that basal levels of ABA were found in embryos at 30 DAP. The general role of ABA on preventing precocious germination and vivipary suggests an early and transient endodormancy in embryos of hybrid roses. The integration of these two approaches with the aim of defining protocols for precocious in vitro germination and investigating the pathway of dormancy in R. hybrid is highlighted.
IMMATURE SEED RESCUE AND ABSCISIC ACID QUANTIFICATION IN ROSA HYBRIDA L. SUGGEST EARLY AND TRANSIENT ENDODORMANCY
CASER, Matteo;PIPINO, LUCA;SCARIOT, VALENTINA
2012-01-01
Abstract
Breeding is a long process in the rose industry. Premature death of developing embryos due to incompatibility and delayed germination, caused by seed dormancy, are the main causes. Immature seed rescue may offer a valuable way to increase hybridisation efficiency, to introduce genotypes with interesting ornamental traits, and to shorten time needed to obtain seedlings. In this study, in vitro immature seed rescue was carried out in Rosa hybrid L. Seeds from 7 to 28 days after pollination (DAP) were sterilized and placed onto two germination media: Murashige and Skoog medium (full strength macro and micro nutrients and vitamins, MS0) and MS0 with 6-benzylaminopurine (BAP; 2.5 mg/L) and gibberellic acid 3 (GA3; 0.5 mg/L). Four different conditions of light and temperature were applied. At 15 and 30 DAP, the abscisic acid (ABA) concentration was quantified in fully formed embryos of two different genotypes of hybrid roses. Preliminary data showed that only seeds harvested at 21 DAP germinated in both media, this after 2 months of in vitro culture. This result is supported by the observation that basal levels of ABA were found in embryos at 30 DAP. The general role of ABA on preventing precocious germination and vivipary suggests an early and transient endodormancy in embryos of hybrid roses. The integration of these two approaches with the aim of defining protocols for precocious in vitro germination and investigating the pathway of dormancy in R. hybrid is highlighted.
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