IN VITRO GROWTH AND DEVELOPMENT OF IMMATURE EMBRYOS IN FLORDA PRINCE PEACH CULTIVAR

doi:10.12816/ejpb.2022.260881

IN VITRO GROWTH AND DEVELOPMENT OF IMMATURE EMBRYOS IN FLORDA PRINCE PEACH CULTIVAR

Document Type : Original research

10.12816/ejpb.2022.260881

Abstract

In early cultivars, fruit maturation precedes embryo maturation. Thus, this study was conducted during the 2020 and 2021 seasons to overcome an embryo abortion problem in early maturing Florda Prince peach cultivar through in vitro embryo rescue and culture technique. Then induce germination, growth and development of these rescued embryos up to complete seedlings and to determine the optimal time of successful excision of these embryos as well as the best media and supplements for embryo formation and germination under in vitro conditions. Open-pollinated immature fruits were collected at five developmental stages; 40, 50, 60, 70, and 80 days after full bloom (DAFB), and then the ovules were in vitro separated and cultured on three embryo formation media; MS1, Nitsch1, and WPM1, supplemented with 1.5 mgl^-1 IAA and 1 mgl^-1 GA₃. Ovule cultures subjected to cold pre-treatment were 1) stratified in the dark at 4°C and 2) without stratification in the dark at 25°C. For embryo germination, all formed embryos were excised and then transferred to MS2, Nitsch2, and WPM2 media supplemented with 0.5 mgl^-1 BA and 3 mgl^-1 GA₃. The WPM1 medium with stratification treatment at 60 DAFB, recorded a higher significant value of embryo formation (83.33%) in the first season and at 60 and 70 DAFB (80.00 and 81.82%) in the second season, respectively, than other media. In the first season, WPM2 medium, at 70 DAFB, recorded the highest value of embryo germination (62.09%) in the first season and at 60 and 70 DAFB (61.73 and 61.84%) in the second season, respectively. The addition of 3.0 mgl^-1 IBA or NAA to half strength MS medium resulted in the highest percentage of rooting, the greatest average number of roots per shoot, and the longest root length. It can be recommended for breeding and improvement programs in Florda Prince peach that the optimal time for embryo excision is 60-70 days after pollination or full bloom by in vitro ovule culture on WPM1 medium with stratification at 4° C for 4 weeks, and then transferring excised embryos to WPM2 medium for germination.

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