β-estradiol application improves potato in-vitro plantlet growth and microtuber production under drought conditions

Introduction: potato (solanum tuberosum l.) is an important agricultural crop valued for its high nutritional content, including protein, starch, carbohydrates, vitamins, and minerals. however, both biotic and abiotic stresses, especially drought, can hurt potato growth and yield. studies have found that treating plants with animal sex hormones such as β-estradiol can have a positive effect on cell division, growth, and development of aerial organs, flowering, callus tissue regeneration, and fertility (erdal & dumlupinar, 2011). applying these hormones can also enhance the content of inorganic elements in the plant and increase levels of chlorophyll, carotenoids, soluble sugars, and protein (erdal, 2012; janeczko et al., 2012). there is limited information available on the effects of mammalian steroid hormones on crop plants, indicating the need for further research to better understand the impacts of these hormones on the growth and development of crops. materials and methods: this in vitro experiment examined the effects of drought stress and β-estradiol on 10 potato genotypes. treatments included polyethylene glycol at concentrations of 0, -3, and -6 bars, and β-estradiol at 10-6, and 10-12 mol, as well as a control. the study utilized a completely randomized factorial design with three replications. ms medium (murashige & skoog, 1962) was prepared with agar and sucrose at ph 5.8, had polyethylene glycol added, and was set for use after 24 hours. plantlets were maintained under controlled conditions for 20-25 days. to produce microtubers, additional hormones and nutrients were introduced into the culture medium, and the plantlets were exposed to dark until microtuber formation, which took 6-8 weeks. results and discussion: the analysis of variance revealed significant effects of β-estradiol, genotype, drought, and their interaction effects on plantlet length, node count, microtuber count, and average microtuber weight, at the 1% probability level. the control group (no drought) combined with 10-6 molar and no hormone levels showed the highest plantlet heights (11.66 cm and 11.30 cm, respectively). the lowest height was observed in the treatment with -6 bar drought stress in combination with the no application of β-estradiol. it was found that genotypes g5 and g2 had the highest plantlet heights of 9.48 cm and 8.91 cm, respectively. the study indicates that drought stress reduces plantlet height. the highest number of nodes (6.04) was observed in the control group (no drought) combined with 10-12 molar β-estradiol, while the lowest (3.01) was in the -6 bar drought treatment with no hormone. genotype g3 showed the highest number of nodes (6.14) with 10-12 molar hormone levels, although the differences with genotypes g4 and g5 were not statistically significant. the highest average number of microtubers per plantlet (1.83) was found in the control group with 10-12 molar β-estradiol, while the lowest (0.35 and 0.40) occurred at -6 bar drought with the control or 10-12 molar hormone. the application of 10-12 molar hormone in both the control treatment and -3 bar drought stress increased the number of microtubers compared to the control. the number of microtubers is a key component of potato seed production (gautam et al., 2021). the findings suggested that genotypes g5 and g3 with 10-12 molar β-estradiol had the highest number of microtubers. the highest microtuber average weight (0.70 g) was observed in the control group (no drought) combined with 10-12 molar β-estradiol. the lowest microtuber average weight was recorded at -6 bar drought treatment with no application of β-estradiol. the application of 10-12 molar β-estradiol significantly increased the microtuber average weight compared to the control treatment, both under normal conditions and at -3 and -6 bar drought levels. conclusion overall, β-estradiol application positively affected plantlet height, node counts, microtuber counts, and weight under both normal and drought stress conditions. the hormonal treatments were linked to increased levels of essential minerals, which are vital for organic compound formation and plant growth. previous research indicates that steroid hormones can boost photosynthetic activity and cell development in various plant species (janeczko et al., 2012; türkoğlu et al., 2022). this study suggests that β-estradiol helps mitigate the negative impacts of drought stress on plantlet growth, emphasizing its significant influence on potato plantlet growth characteristics, particularly regarding node count and microtuber formation. keywords: β-estradiol, drought stress, in vitro growth, microtuber, seed potato references erdal, s. 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