مطالعۀ تکوین اندام زایشی نر و ماده در گیاه بادرشبو ‏dracocephalum moldavica l.‎‏ (تیرۀ نعنائیان) ‏

گیاه بادرشبو (متعلق به تیرۀ نعنائیان) به‌طور طبیعی در اروپا، سیبری و آسیای مرکزی پراکنش دارد و به‌علت داشتن ارزش دارویی فراوان، در استان‌های مختلف ایران کاشته می‌شود. در پژوهش حاضر، تکوین اندام زایشی نر و مادۀ گیاه بادرشبو مطالعه شد. غنچه‌ها و گل‌ها در مراحل مختلف نمو به‌منظور تهیۀ برش‌های میکروتومی با محلول‌‌های مناسب تثبیت، نگهداری و در پارافین قالب‌گیری شدند. از هماتوکسیلین- ائوزین برای رنگ‌آمیزی برش‌ها استفاده شد. بر اساس نتایج، باوجود هم‌زمانی نسبی تشکیل پریموردیوم پرچمی و برچه، نمو پرچم‌ها سریع‌تر از تخمک انجام می‌شود. بساک‌ها چهارکیسه‌گرده‌ای هستند و لایۀ تاپی به شکل‌های مستطیلی، دوکی‌شکل، تک‌هسته‌ای یا بیشتر و به دو حالت ترشحی و پلاسمودیومی وجود دارد. تترادهای میکروسپوری از نوع تتراهیدرال هستند، دانۀ گرده شش‌شیاره و اگزین دارای تزئینات مشبک است. تخمک از نوع واژگون، تک‌پوششی با دیوارۀ نازک است. سلول عملکردی با موقعیت سُفتی و کیسۀ رویانی تیپ پلی‌گونوم از دیگر ویژگی‌های این گونه است.

development of male and female reproduction organs in ‎moldavian dragonhead, dracocephalum moldavica l. (lamiaceae)‎

due to its great medicinal value, the moldavian dragonhead, belonging to lamiaceae, is naturally distributed in europe, siberia, and central asia and planted in different iranian provinces. this research studied the development of male/female reproductive organs. flowers and buds in different stages of development were fixed and preserved in order to prepare microtome sections using appropriate solutions and embed them in paraffin. hematoxylin-eosin was used to stain the slices. based on the results, despite the relative simultaneity of the formation of stamen primordium and carpel, stamens develop faster than ovules. nurses’ cells in secretory and plasmodium types are rectangular, spindle-shaped, and often mononuclear or more. the microspore’s tetrads had tetrahedral ornamentations, and mature pollen grains were hexacolpate with reticulate ornamentation of the exine. the ovules were anatropous, unitegmic, and tenuinucellate. the functional megaspore has a micropillar position, and the embryo sac development belongs to the polygonum type. introductionthe origin of dracocephalum moldavica l., known as &zarrin giah& in persian, is in the mountainous regions of central asia (botanica, 2009). this plant is mostly perennial and rarely annual or semi-shrub (dastmalchi et al., 2007). the dracocephalum species, which naturally grows in europe, siberia, and central asia, is cultivated in iran in western and eastern provinces, mazandaran, yazd, and tehran (mozaffarian, 2013; dastmalchi et al., 2007). the lamiaceae family, commonly known as the mint family, has always been of interest to researchers due to its significant medicinal properties. the formation of the male and female reproductive structures, pollen grain formation, and various stages of embryo formation in plants of this family have been studied by various researchers (daskalova, 2004; tajadod et al., 2015; jafari marandi et al., 2017). the anatomical structure of vegetative organs, secretory tissue structure, trichomes, and the nectary tissue structure of d. moldavica have been studied by some researchers (dmitruk et al., 2019, 2018; liapunova, 1975). however, to date, no information has been provided regarding the anatomical structure of the male reproductive organs and their development. considering the importance of developmental studies in biological, agricultural, horticultural, and botanical sciences, studying the development of this valuable medicinal plant can contribute to the advancement of biological knowledge and increased productivity. materials and methodsafter the plants grew to the flowering stage, samples were collected from the buds and flowers at different stages and at the appropriate time. the samples were fixed in faa70 solution, which contained formalin, glacial acetic acid, and 70% ethanol in a 5:5:90 ratio for 16 hours to preserve the buds and flowers. then, dehydration of the samples was performed with different concentrations of ethanol. the samples were embedded in paraffin and sectioned with a thickness of 8 micrometers using a microtome (cut 4040, co., mainz, germany) for studying the developmental stages. staining was carried out using hematoxylin-eosin based on the yeung’s method (1984). more than 10 samples were studied for each developmental stage, and examination of the samples and preparation of images was conducted using a nikon light microscope (nikon, tokyo, japan). results and discussionaccording to the results, despite the relative simultaneity of primordium formation and the cotyledon, cotyledon growth occurs more rapidly than ovule development. the growth of cotyledons and petals occurs closely spaced, and pollen grains mature before the flower blooms, while the ovules are still in the ovule sac formation stage. unlike plants such as mango (jonoubi et al., 2015; mohsenzadeh et al., 2012), where the epidermal layer of cotyledons disintegrates during maturation, in d.  moldavica, as in other members of the mint family like basil, thyme, catnip, and marjoram (kameli et al., 2018; jafari marandi et al., 2017; tahmasebi et al., 2016; tajadod et al., 2015), the mechanical layer, along with the epidermal layer, remains until the end of flowering and the maturation of pollen grains. pollen sacs exist in four-pollinium and various shapes, including rectangular, double, single-core, or more, and are of exine secretion or plasmoid type. contrary to plants such as mint (jafari marandi et al., 2017), catnip (daskalova, 2004), and species of brassicaceae like brassica jordanoffri (yankova-tsvetkoya et al., 2016) and arabidopsis thaliana (basiri et al., 2021), where two-nucleate cells of the middle layer are reported, in this medicinal plant, the middle layer cells are polygenomic. the type of ovule in this plant is anatropous, bitegmic, and with a thin integument. the functional megaspore is of the monosporic type and ultimately becomes a megaspore mother cell. the structural features of the hypostase, androecium, and the nectary conductor tissue, as well as the pollen tube conductive tissue, are observed in this plant. conclusionpollen grains of d. moldavica reach maturity before flowering. the middle layer that exists until the formation of immature pollen grains is lost before the formation of the top layer. during flowering, cotyledonary and mechanical layers remain intact. the top layer is of secretory and amoeboid type and exists as mononucleate, binucleate, or more. ovaries in this plant have four pollen sacs with various shapes. pollen grains are hexacolpate and exine is reticulate. the ovule is anatropous, bitegmic, and with a thin integument. the functional megaspore is monosporic, and eventually, the megaspore mother cell becomes a pollen sac. the structure of the hypostase, androecium, and the nectary conductor tissue, as well as the pollen tube conductive tissue, are present in this plant.