Embryo rescue in wide crosses in Arachis 3. In vitro culture of peg tips of A. hypogaea selfs and interspecific hybrids
JP Moss; HT Stalker
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Abstract: Embryo rescue in wide crosses in Arachis has only been achieved from culturing ovules excised from well developed pods, or from immature pods derived from flowers treated with gibberellic acid (GA) and which had embryos large enough to dissect without injury. The objectives of this study was to determine whether reproductive tissues could grow in vitro without the need to dissect them from the peg tip and to determine the effects of GA application on flowers at the time of pollination, age of peg when cultured, and the presence of the peg meristem on reproductive growth, callus production, and peg elongation in vitro. Pegs elongated in culture only when the peg meristem was not removed. Ovules enlarged and grew out of the surrounding peg tissue in 3.8 to 32.8% of the cultures. Significantly more ovules grew when the peg meristem was removed (p < 0.01) and when 10- and 20- day-old pegs were cultured (p < 0.05). Overall, the most successful treatment for growth of ovules was treating flowers with GA at pollination and culturing without the peg meristem 10 days after pollination when 25.0 and 32.8% of all hybrid and selfed ovules, respectively, grew. Embryo growth was observed in an average of 8.4 and 17.6% of embryo sacs in hybrid and self peg tips, respectively, with several embryos reaching the globular stage after 21 days in vitro. This illustrates the potential for culturing young reproductive tissues of Arachis to recover interspecific hybrids.