دانشگاه اصفهان علوم زیستی گیاهی 3041-9603 17 1 2025 05 22 The effects of gibberellic acid application and Serendipita indica inoculation on salinity stress tolerance in cuttings from two grape cultivars grown in an aeroponic system تأثیر کاربرد اسید جیبرلیک و قارچ Serendipita indica بر تحمّل قلمه‌های دو رقم انگور به تنش شوری در سیستم هواکشت 1 30 29840 10.22108/ijpb.2025.143593.1381 FA اکبر رحیمی گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه ملایر، ملایر، ایران مهدی قبولی گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه ملایر، ملایر، ایران زهرا موحدی گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه ملایر، ملایر، ایران محمد عبدلی گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه ملایر، ملایر، ایران Journal Article 2024 12 04 Salt stress is one of the most critical limiting factors in plant growth and yield. The endophytic fungus Serendipita indica stimulates the growth of many plant species, thereby enhancing their tolerance to abiotic stresses. The effect of S. indica inoculation and foliar application of gibberellic acid on the morphophysiological traits of two grape cultivars, white seedless and Turkmen 4, under salt stress conditions in an aeroponic system was investigated. The experimental treatments included different levels of gibberellic acid (0 and 150 mg/L gibberellic acid), inoculation with S. indica (non-inoculated and inoculated with the fungus), and two levels of salinity (0 and 100mM sodium chloride) with three replications. The results showed that treatment with gibberellic acid and fungal inoculation increased several morphophysiological indices, including chlorophyll, soluble sugars, proline, phenols, flavonoids, and potassium, in both grape cultivars. Meanwhile, it decreased the levels of traits such as malondialdehyde, hydrogen peroxide, and sodium. The results also showed that salt stress reduced the amount of root dry weight (26%), and increased flavonoids (52%), proline (41%), sodium (5.8 times), malondialdehyde (41%), and hydrogen peroxide (38%) in both cultivars. Overall, the results demonstrated that treatment with gibberellic acid and inoculation with S. indica increased osmolytes such as soluble sugars (37%), proline (38%), and phenol (2%); on the other hand, oxidative stress was reduced through decreased hydrogen peroxide (34%) and malondialdehyde (31%) levels. These effects collectively enhanced plant growth and performance under stress conditions while improving stress tolerance. Introduction Biological methods that utilize beneficial soil organisms and horticultural practices, such as applying plant growth regulators, play a significant role in promoting tolerance to different abiotic stresses. The endophytic fungus, Serendipita indica has attracted attention due to its growth-promoting functions, broader host range compared to mycorrhizal fungi, and ability to be cultured in synthetic media. This fungus has been successfully utilized to enhance growth and promote tolerance to abiotic stresses in various plants. Given the significant impact of salinity stress on reducing agricultural productivity and the importance of grapevine plants, it is of paramount importance to study and develop strategies to mitigate the adverse effects of salinity stress in grapevine plants. This research aimed to investigate the potential impact of gibberellic acid application, along with root colonization by S. indica, on salinity stress tolerance in two grape cultivars, White Seedless and Turkmen 4, in an aeroponic system. Materials and Methods This research was conducted as a factorial experiment in a completely randomized design with three replications. The experimental treatments included two levels of gibberellic acid (0 and 150 mg/L), two fungal treatments (inoculated and non-inoculated), and two stress levels (0 and 100 mM NaCl). The experiment was conducted in four tanks, with 12 cuttings (6 of each variety) placed in each tank. In each tank, three cuttings of each variety were untreated with gibberellic acid. Tank 1 included control samples without inoculation with fungus and those treated with NaCl. In Tank 2, salinity stress was induced on non-inoculated plants. Tank 3 included samples inoculated with fungi and exposed to salinity stress. Tank 4 included samples inoculated with fungi under non-stressed conditions. Inoculation with fungus was performed in two stages: one before transferring the cuttings to the system, and the other after root emergence, by spraying the fungus spores onto the roots. Control cuttings were treated with distilled water. Salinity stress was induced by adding a sodium chloride solution to the tanks over a period of four weeks. Treatment with gibberellic acid was performed in a single step. Sampling was conducted 4 weeks after stress, and traits such as dry and wet weight of root and shoot, chlorophyll a, b, and total chlorophyll, carotenoids, phenols, flavonoids, proline, malondialdehyde, hydrogen peroxide, total soluble sugars, antioxidant enzymes, and sodium and potassium levels were evaluated. Results and Discussion The results showed that salinity stress, fungus, gibberellic acid, and their interactions had a significant effect on the most measured traits. Salinity stress increased the levels of soluble sugars, malondialdehyde, proline, phenols, and flavonoids, while also increasing sodium levels and catalase activity, but decreased membrane stability and chlorophyll content. Inoculation with the fungus and gibberellic acid application, as well as their interactions, had a positive effect on reducing the effects of stress by improving morphophysiological traits. Several mechanisms have been proposed for the positive impact of the fungus on increasing growth, including increased cytokinin production and improved transport through the vascular system. Fungal mycelia increase the absorption surface, thereby enhancing the absorption of water and elements. By stimulating cell growth and increasing root length, gibberellic acid enables the plant to achieve greater depth in absorbing water and minerals, thereby better coping with saline conditions. The fungus increases the levels of carbohydrates, proteins, and proline through certain hexose transporters and affects plant hormone synthesis. Gibberellin induces qualitative and quantitative changes in the synthesis of specific amino acids, including proline, by affecting the transcription or translation of specific genes. Additionally, the reduction in lipid peroxidation can be attributed to gibberellin's role in destroying reactive oxygen radicals. This may reduce the content of superoxide and hydrogen peroxide radicals by influencing the activity of free radical scavenging enzymes. The effect of the fungus on reducing ROS production is one of the reasons why membrane stability is higher in inoculated plants under stress conditions. The fungus and gibberellic acid may play a crucial role in eliminating reactive oxygen species by enhancing the activity of antioxidant enzymes, which is consistent with their effects on carotenoid levels, membrane stability, and malondialdehyde content. This demonstrates that these plants reduce the detrimental effects of salinity stress more than control plants. Conclusion Based on the results, inoculation with the endophytic fungus and treatment with gibberellic acid increased chlorophyll, phenol, potassium, and catalase levels, while decreasing hydrogen peroxide, malondialdehyde, and sodium levels. This positively affected tolerance to salt stress in both cultivars, with the White Seedless variety showing more improvement than Turkmen 4. Overall, the results indicated that fungus inoculation had a greater effect than gibberellic acid in both cultivars. Future research could investigate the molecular mechanisms of PGRs and the effect of fungi on salt stress tolerance in grapes. This knowledge is crucial for ensuring sustainable grape cultivation under changing environmental conditions. تنش شوری یکی از مهمترین عوامل محدود کننده رشد و عملکرد گیاهان محسوب می‌شود. قارچ Serendipita indica با تحریک رشد بسیاری از گونه‌های گیاهی سبب تحمل به تنش‌های غیر زیستی می‌شود. در این پژوهش، اثر قارچ‌ S. indica و محلول‌پاشی اسید جیبرلیک بر صفات مورفوفیزیولوژیک دو رقم انگور بیدانه سفید و ترکمن 4 در شرایط تنش شوری در سیستم هواکشت به صورت آزمایش فاکتوریل در قالب طرح کامل تصادفی در سه تکرار بررسی شد. تیمارهای آزمایش شامل محلول‌پاشی 150 میلی‌گرم/لیتر اسید جیبرلیک و عدم محلول‌پاشی، تلقیح با قارچ S. indica (عدم تلقیح و تلقیح‌ با قارچ) و دو سطح شوری (صفر و 100 میلی‌مولار کلرید سدیم) بودند. نتایج نشان دادند تیمار توسط اسید جیبرلیک و تلقیح با قارچ سبب افزایش برخی از شاخص‌های مورفوفیزیولوژیکی مانند کلروفیل، قند محلول، پرولین، فنول، فلاوونوئید و پتاسیم در هر دو رقم انگور شدند؛ در حالی‌که میزان صفاتی مانند مالون دی‌آلدئید، پراکسید هیدروژن و سدیم را کاهش دادند. همچنین نتایج نشان دادند تنش شوری سبب کاهش وزن خشک (26%) و افزایش فلاوونوئید (52%)، پرولین (41%)، سدیم (8/5 برابر)، مالون دی آلدئید (41%) و پراکسید هیدروژن (38%) در هر دو رقم شد. در مجموع، نتایج نشان داد تیمار توسط اسید جیبرلیک و تلقیح با قارچ S. indica، سبب افزایش اسمولیت‌هایی مانند قند محلول (37%)، پرولین (38%) و فنول (2%) شد؛ از سوی دیگر، تنش اکسیداتیو را با کاهش پراکسید هیدروژن (34%) و مالون دی‌آلدئید (31%) تخفیف داده‌اند که سبب می‌شود گیاهان از رشد و عملکرد بهتری برخوردار بوده و تحمل آنها به تنش افزایش یابد.

https://ijpb.ui.ac.ir/article_29840_5a97490e1d5c85b9a6b0969d25242749.pdf