preprints.org > biology and life sciences > horticulture > doi: 10.20944/preprints202409.0305.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 3 September 2024 / Approved: 4 September 2024 / Online: 4 September 2024 (08:29:47 CEST)

Major factors affecting in vitro immature embryo rescue efficiencies from Prunus persica or P. armeniaca accessions, have been identified along with improving its economic feasibility. Three culture media, based on Woody Plant Medium (WPM) have been used depending on the embryo size. Embryos less than 5-mm-long were cultured in WPM supplemented with 1 mM BAP and 1 mM GA3, while embryos bigger than 5-mm-long were cultured in hormone-free medium, with or without vermiculite. Environmental in vitro culture conditions consisted of three phases, a (I) stratification at 4 C during a 3 to 5-month-long period in the dark, followed by (II) growth of germinated embryos at 14 C for 4-week-long period, with 12h light a day, which favors plantlet development, and finally (III) growth at 24 C, with 16h light a day, until the plantlets were moved to the greenhouse for acclimatization. Germination of smaller embryos, at the end of the phase I, ranged from 82.2% to 22.1%, for apricot and flat peaches, respectively, whereas for bigger embryos the germination varied from 97.4% to 53.2% for the same type of fruits. Embryo germination for peaches and nectarines ranged from 40.1% to 30.3% for smaller embryos, and from 91.9% to 64.0% for bigger embryos. Endo- and exophytic contamination, affecting from 7.4% to 52.9% of cultured embryos depending on the fruit type and conservation conditions, and the capacity to acclimate to soil conditions, ranging from 50.4% to 93.2%, were the two most important factors influencing protocol’s efficiency and economic feasibility. Considering the overall efficiencies, expressed as hardened plants transferred to field plots over clean uncontaminated embryo, values ranged from 55.8% for nectarines, 54.0% for peaches, 45.6% for apricot, and 23.3% for flat fruits. Addition of vermiculite to the culture medium significantly improved plantlet development, avoiding subculture to fresh medium when an extension of the phase III was required before acclimatization. Compared to laboratory glassware, use of food glass containers with air-permeable sealing film, along with vermiculite-containing medium significantly reduced costs, when handling the large number of embryos required for breeding programs.

embryo; rescue; peach; nectarine; apricot; vermiculite; container; acclimatization

Biology and Life Sciences, Horticulture

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