بهینه‌سازی القای جنین‌زایی سوماتیکی در گوجه‌فرنگی (solanum lycopersicum l.) رقم money maker

پژوهش حاضر با هدف القای جنین­زایی سوماتیکی با تنظیم‌کننده‌های رشدی در گیاه گوجه فرنگی انجام شد. بدین منظور آزمایش فاکتوریل در قالب طرح کامل تصادفی با سه تکرار طراحی شد. در این آزمایش از سه نوع محیط کشت ms ، b5 و ms + vitamin b5 با ترکیب‌های هورمونی 2,4-d (2 میلی‌گرم در لیتر)+ ba (5/1 میلی‌گرم در لیتر)، 2,4-d (8 میلی‌گرم در لیتر)+ ba (6 میلی‌گرم در لیتر) و iaa (2 میلی‌گرم در لیتر) + ba (5 میلی‌گرم در لیتر) و سه نوع ریزنمونه کوتیلدون، هیپوکوتیل و ریشه استفاده شد. نتایج نشان داد بیشترین تعداد جنین نابالغ تولید شده، در ریزنمونه کوتیلدون در محیط کشت ms با ترکیب هورمونی 2,4-d (2 میلی‌گرم در لیتر)+ ba (5/1 میلی‌گرم در لیتر) و در ریزنمونه هیپوکوتیل در محیط کشت mb با ترکیب هورمونی 2,4-d (8 میلی‌گرم در لیتر)+ ba (6 میلی‌گرم در لیتر) (33/20 عدد در هر ریزنمونه) بود. بیشترین درصد جنین زایی در محیط کشت ms با ترکیب هورمونی iaa (2 میلی‌گرم در لیتر) + ba (5 میلی‌گرم در لیتر) و در ریزنمونه هیپوکوتیل (33/93%) بود. با انتقال ریزنمونه به روشنایی و سپس محیط کشت بدون هورمون، جنین‌ها مراحل تکاملی را طی کرده و به بلوغ رسیدند. نتایج بدست آمده نشان داد، امکان تولید جنین سوماتیکی در حجم انبوه در گیاه گوجه فرنگی وجود دارد و می‌توان از این جنین­‌ها در تولید بذر مصنوعی استفاده کرد.

optimizing the induction of somatic embryogenesis in tomato (solanum lycopersicum l.) variety money maker

the factorial experiment conducted in this study aimed to induce somatic embryogenesis in tomato cultivar money maker using different culture media and growth regulator combinations. the experiment was done in a completely randomized design with three replications. three types of culture media, namely ms, b5, and ms + vitamin b5, were used in combination with three hormonal combinations: 2,4-d (2 mg/l) + ba (1.5 mg/l), 2,4-d (8 mg/l) + ba (6 mg/l), and iaa (2 mg/l) + ba (5 mg/l). additionally, three types of explants (cotyledon, hypocotyl and root) were utilized to induce somatic embryos. to promote embryo maturation, the explants were transferred to a hormone-free culture medium. the results revealed that the highest number of immature embryos was obtained from cotyledon explants cultured in ms medium with the hormonal combination of 2,4-d (2 mg/l) + ba (1.5 mg/l) and in hypocotyl explants in mb medium supplemented with the hormonal combination of 2,4-d (8 mg/l) + ba (6 mg/l), with an average of 20.33 embryos per explant. also, the highest percentage of embryogenesis (93.33%) was in hypocotyl explants at ms culture medium with the hormonal combination of iaa (2 mg/l) + ba (5 mg/l). after two weeks of cultivation, the presence of globular embryos was visible on the surface of the explants under binoculars. by transferring the explants to light conditions and subsequently to a hormone-free culture medium, the embryos further developed and matured. introductiontomatoes belong to the solanaceae family. in recent years, there has been an increasing interest among scientists in utilizing tomato as a model plant due to its importance. somatic embryogenesis, a process in which embryos develop from somatic or non-reproductive cells, represents a means of inducing totipotency in plant cells. standardizing successful regeneration methods for agrobacterium-mediated gene transfer to somatic embryos in tomato can establish a sustainable transfer approach. during the induction of somatic embryogenesis, one of the major factors influencing cell behavior is the presence of high concentrations of auxin in the culture medium. cytokinin, in combination with auxins, stimulates cell division, which both act synergistically. by investigating the induction of somatic embryos under treatments of auxin and cytokinin hormones in vitro, this research contributes to the advancement of propagation techniques for stress-tolerant varieties and genetic improvement in tomato under laboratory conditions. in conclusion, the study highlights the potential of somatic embryogenesis as a powerful tool for plant propagation and genetic manipulation in tomato. the optimization of hormone treatments and culture conditions can enhance the efficiency and success rate of somatic embryogenesis, leading to improved techniques to produce stress-tolerant varieties and the advancement of genetic improvement strategies in tomato. materials and methodsthe seeds were surface sterilized with 1.5% sodium hypochlorite and sterile distilled water for 10 minutes and were cultured on ms medium without hormones. 14-day-old tomato seedlings were used to obtain explants (cotyledon leaves, cotyledon axis and root) for somatic embryo induction. the explants were cultured on three different types of culture media: ms, b5, and ms + vitamin b5 (mb). the culture media were supplemented with specific hormonal compounds: 2,4-d (2 mg/l) + ba (1.5 mg/l), 2,4-d (8 mg/l) + ba (6 mg/l), and iaa (2 mg/l) + ba (5 mg/l) 30 g/l sucrose and 8 g/l agar. the cultures were incubated at 25°c for 2 weeks of darkness and one week of light. after three weeks, the explants containing somatic embryos were transferred to ms, b5, and mb culture media without hormones for one week to promote embryo maturation. microscopic images were taken from embryonic calli. the stages of embryo induction and development were documented. the following traits were measured at the end of the experiment: callus formation percentage, embryogenesis percentage, and the number of embryos in each explant. the experiment was conducted with three replications. the data were analyzed by jmp software. the average values were compared using the lsd test at a significance level of 5%. results and discussionsomatic embryogenesis was successfully induced in tomato explants under different hormonal treatments and culture media conditions. callus formation was observed in the explants starting from the second week of cultivation. the highest percentage of callus formation (100%) was achieved in all three types of culture media when using cotyledon explants and the hormonal combinations of 2,4-d (1 mg/l) + ba (1.5 mg/l) and 2,4-d (8 mg/l) + ba (6 mg/l). the formation of embryos was mainly observed on the explants from the 14th day of cultivation. the highest percentage of embryogenesis (90.33%) was observed in hypocotyl explants cultured on ms culture medium with the hormonal combination of iaa (2 mg/l) + ba (5 mg/l). the highest number of immature embryos (20.33) was produced in cotyledon explants cultured on ms culture medium with the hormonal combination of 2,4-d (2 mg/l) + ba (1.5 mg/l) and in hypocotyl explants, the highest number of immature embryos was obtained in the mb medium with the hormonal combination of 2,4-d (6 mg/l) + ba (8 mg/l).  after three weeks, the growth of the embryos stopped at the globular and heart-shaped stage. the calluses were initially light green, but with time, they turned brown and lost their embryonic tissue. however, in the hormonal treatment of iaa (2 mg/l) + ba (5 mg/l), globular embryos were observed on the surface of the explant after two weeks of culture. by transferring the explant to light and then to a hormone-free culture medium, the embryos underwent further developmental stages and reached maturity. this treatment resulted in the highest number of somatic embryos in hypocotyl explants. conclusionthe results of the experiment indicate that the hormonal treatment of iaa (2 mg/l) + ba (5 mg/l) was particularly effective in promoting the formation of embryonic callus and somatic embryogenesis in tomato hypocotyl explants. the successful production of somatic embryos can provide possibilities for further investigations into artificial seed production in tomato plants.