Adventitious Shoots Research Articles

Dynamic changes of endogenous phytohormones and carbohydrates during spontaneous morphogenesis of Centaurium erythraea Rafn

Common centaury (Centaurium eryhtraea Rafn) is a medicinal plant species with vigorous morphogenic potential in vitro. The process of spontaneous shoot regeneration in a solid root culture is characteristic for this plant species. In this context, the aim of this work was to investigate the dynamic changes of endogenous phytohormones and carbohydrates content in root explants at different time points (0, 2, 4, 7, 14, 21, 28, and 60 days) during spontaneous centaury morphogenesis in vitro. Detailed analysis of cytokinins (CKs) showed that trans-zeatin (tZ) was the major bioactive CK at all time points. The corresponding riboside, tZ9R, was also determined in the majority of the identified transport forms, at all time-points. Further analysis of endogenous auxin revealed a significant increase in endogenous indole-3-acetic acid (IAA) after 21 days, when a huge jump in the ratio of IAA/bioactive CKs was also observed. The maximum total soluble sugar content was measured after 14 days, while a significant decrease was determined after 21 days, when the first regenerated adventitious shoots appeared. This undoubtedly indicates an increased energy requirement prior to the actual regeneration of the shoots. The obtained results indicate that the period from day 14 to day 21 involves the most dramatic disturbances in endogenous bioactive CKs, IAA and carbohydrate balance, which are very important and valuable factors for the onset of shoot regeneration.

Establishment of clary sage (Salvia sclarea L.) regeneration system and development of glyphosate-tolerant clary sage plants through Agrobacterium-mediated genetic transformation

Clary sage (Salvia sclarea L.) is well known as a highly aromatic herbaceous plant and is commonly used in aromatic products and medicine. The biggest problem in the cultivation of clary sage is weeds, which not only entails a great cost of labor for weeding, but also leads to a great fluctuation in the yield and quality of its products. Therefore, there is a need to breed herbicide-resistant clary sage using genetic engineering. However, the lack of suitable regeneration and genetic transformation systems for clary sage has limited the process of molecular breeding. In this study, we firstly reported the regeneration system of clary sage, where explants from hypocotyls of sage induced adventitious shoots at a rate of 22.22% when cultured on MS medium supplemented with 2.5mg·L-1 6-BA, 0.15mg·L-1 IAA, and 0.25mg·L-1 VC. Rooting of adventitious shoots was achieved at a rate of 94.44% on 1/2 MS medium containing 0.125mg·L-1 NAA, 0.5mg·L-1 IAA, and 0.1mg·L-1 IBA. Secondly, based on the regeneration system, an efficient and stable Agrobacterium-mediated genetic transformation system was established in this paper, and the rate of genetic transformation was determined to be in the range of 3%-5% by transforming the hypocotyls of clary sage with pCAMBIA1301 vector and pCAMBIA1301-GR79-GAT vector. Finally, glyphosate tolerance was obtained from GR79 and GAT co-expressed clary sage plants in this study. This study not only lays the foundation of genetic transformation for the functional gene research and in-depth investigation of various biological problems of clary sage, but also provides a feasible genetic engineering solution for its industry to solve the weed problem, as well as a promotional role for precise molecular breeding of clary sage.

Efficient Plantlet Regeneration from Branches in Mangifera indica L.

Mango (Mangifera indica L.) is one of the most significant tropical and subtropical fruit species, with high ecological and economic value. However, research on the in vitro culture of mangoes is relatively weak, so establishing an efficient and stable mango plant regeneration system is of great significance. In this study, a preliminary mango regeneration system was established with Mangifera indica L. cv. Keitt from young branches as the starting explants. The results showed that the optimal plant growth regulator (PGR) formula for direct adventitious shoot induction on the branches was 1 mg/L 6-benzylaminopurine (6-BA) + 0.1 mg/L a-naphthaleneacetic acid (NAA), with an adventitious shoot induction rate of 73.63% and an average of 6.76 adventitious shoots. The optimal basal medium for adventitious shoot induction was wood plant medium (WPM), with an adventitious shoot induction rate of 63.87% and an average of 5.21 adventitious shoots. The optimal culture medium for adventitious shoot elongation was WPM + 1 mg/L 6-BA + 0.5 mg/L NAA, with an adventitious shoot elongation rate of 89.33% and an average length of 5.17 cm. The optimal formula for the induction of mango rooting was Douglas fir cotyledon revised medium (DCR) + 3 mg/L indole-3-butyric acid (IBA), with a maximum rooting rate of 66.13% and an average rooting quantity of 6.43. The genetic fidelity of the in vitro-regenerated plants was evaluated using inter-simple sequence repeat (ISSR) molecular markers. There was no difference between the in vitro-regenerated plants and the parent plant. This study provides an efficient and stable propagation system for Mangifera indica L., laying the foundation for its rapid propagation and genetic improvement.

Adventitious shoot organogenesis from immature leaves of sugarcane (Saccharum spp. hybrid) cultivar Yuetang 03-373 improving shoot proliferation and industrial scale-up of plants

Adventitious shoot organogenesis from immature leaves of sugarcane (Saccharum spp. hybrid) cultivar Yuetang 03-373 improving shoot proliferation and industrial scale-up of plants

In vitro shoot regeneration system from leaves wrapped by bud scales of a multipurpose tree (Neolamarckia cadamba)

Neolamarckia cadamba (N. cadamba) is an evergreen tree species known for its rapid growth, remarkable wood properties, and significant value in medicine, feeding, and landscape. In order to clone a N. cadamba individual with excellent genotype, a plant regeneration protocol was successfully established with leaves wrapped by bud scales as explants. The optimal sterilization method for the leaves was 0.1% Mercury Chloride (HgCl2) treatment for 1 min before culturing on Murashige and Skoog’s medium (MS) supplemented with 3.0 mg/L Thidiazuron (TDZ), 0.1 mg/L 2–4 Dichlorophenoxyacetic acid (2-4D), 0.05 mg/L α-Naphthaleneacetic acid (NAA) and 1 mL/L Plant Preservative Mixture (PPM) to induce calluses. The medium containing 1 mL/L PPM could effectively inhibit explant contamination without an unfavorable impact on the final induction rate of callus from the leaves. Three types of calluses were induced from the leaves cultured on the above medium. Among them, only the Type II callus, which was green and nodular, had few particle masses, could differentiate into adventitious shoots on the MS medium supplemented with 1.5 mg/L 6–Benzylaminopurine (6-BA) and 0.05 mg/L NAA, with the induction rate of 78.89% and adventitious shoot number per callus of 11.67. The adventitious shoots were proliferated on the MS medium supplemented with 1.0 mg/L 6-BA and 0.05 mg/L Indole-3- butyric acid (IBA) with the proliferation coefficient of 3.37. And the micro-shoots developed roots in the MS medium supplemented with 0.05 mg/L NAA and 0.05 mg/L IBA. The regeneration protocol can be used in the propagation and large scale production of seedlings with the same genotype as an excellent individual of N. cadamba in the field.

Nano-silicon stabilized biometric and foliar micro-morpho-anatomical traits during in vitro propagation of Cyperus rotundus L. – A model C4 ecotype

Advancements in micropropagation techniques facilitated the incorporation of nanoparticles in the propagation of many commercially important plants. Under in vitro conditions, the adventitious shoots are regenerated with undesirable structural disorders, which increase the rate of mortality of in vitro-produced propagules. In the present study, the effect of Silicon nanoparticles (SiNPs) along with the optimized plant growth regulators (PGRs) in the nutrient medium were tested for their growth-promoting effects on in vitro developing shoots of Cyperus rotundus L. Silicon NPs at 5.0 mg/L induced a higher number of shoots (23 shoots/culture vessel) with improved shoot morphology, rhizogenesis (7.0 roots with 4.0 cm root length), photopigments [(chl a - 474.0 μg/g fresh weight (FW); chl b- 509.0 μg/g FW)] and biomass (3.0 g FW), which were comparatively superior to the morphometric outcomes of the control experiments. The occurrence of morphometric and anatomical disorders in the leaves such as non-functional stomata with increased stomatal density, underdeveloped epidermal cells, undifferentiated costal and intercostal regions, and reduced mesophyll, sclerenchyma, xylem vessels, and phloem elements was observed in the controlled shoots. Silicon NPs at 5.0 mg/L in the medium reduced the in vitro-induced structural abnormalities and modulated foliar micro-morpho-structural differentiation of leaves by promoting positive structural alterations in the leaf thickness, differentiation of dermal tissues, Kranz anatomy, vascularization, stomatal complex, and mechanical tissues. These overall developmentssupported the hardening and survival of plantlets ex vitro. The present findings report the role of SiNPs as the ‘structural stabilizer’ during in vitro plantlet development of C. rotundus, as a target species and representative model for the C4 plants.

Optimization of in vitro adventitious shoot regeneration in Brassica juncea L. of different origins for application in genetic transformation and genome editing

Optimization of in vitro adventitious shoot regeneration in Brassica juncea L. of different origins for application in genetic transformation and genome editing

Influence of growth regulators on callus induction and plant regeneration from anthers of Tagetes spp.

Marigold (Tagetes spp.) belongs to family Asteraceae, native to Mexico, is one of the most important flower crop grown commercially in different parts of India. The application of haploid techniques as anther culture can considerably accelerate marigold breeding programmes by providing homozygous doubled haploid (DH) lines for F1 hybrid seed production. Therefore, the objective of the present investigation was to study the effect of growth regulators for in vitro regeneration in both African marigold and French marigold genotypes viz., Pusa Basanti Gainda and Pusa Arpita, respectively for haploid induction. Among the different treatments tested for callus induction, anthers cultured on MS medium supplemented with 1.0 mg/l BAP + 1.0 mg/l 2,4-D + 45 g/l sucrose significantly induced highest (38.74%) callus in the shortest period of time (16 days). Among two genotypes tested, embryogenic callus induction (27.70%) was significantly higher in Pusa Arpita over Pusa Basanti Gainda (23.37%). Among the different regeneration treatments, the highest adventitious shoot bud induction (13.32%), maximum (1.09) number of buds/callus in shortest duration (19.47 days) was observed in anther derived callus cultured on MS medium supplemented with 2.0 mg/l BAP + 0.5mg/l NAA + 30 g/l sucrose. Among two genotypes evaluated for shoot bud induction, maximum (3.81%) regeneration was recorded in Pusa Arpita over Pusa Basanti Gainda (2.90%). In French genotype, the whole regeneration process was completed in 30 days whereas in African genotype it took nearly 40 days. This rapid regeneration system from anthers is highly useful in inducing haploids and di-haploids in African and French marigold lines, respectively.

Establishment of an efficient regeneration system of ‘ZiKui’ tea with hypocotyl as explants

Zikui (Camellia sinensis cv. Zikui) is a recently discovered cultivar of local purple tea in Guizhou, China. It is a purple leaf bud mutation material of Meitan Taicha (Camellia sinensis cv. ‘Meitan-taicha’) ‘N61’ strain, which is an important local germplasm resource in Guizhou. It is also a model plant for the study of anthocyanins, but the limited germplasm resources and the limitation of traditional reproduction hinder its application. Here, an efficient regeneration system is established by using hypocotyl as explants for the first time. Different plant growth regulators (PGRs) are evaluated during different regeneration processes including callus and root induction. According to our findings, using the optimal disinfection conditions, the seed embryo contamination rate is 17.58%. Additionally, the mortality rate is 9.69%, while the survival rate is measured as 72.73%. Moreover, the highest germination rate of 93.64% is observed under MS + 2.40 mg/L GA3 medium conditions. The optimal callus induction rate is 95.19%, while the optimal adventitious bud differentiation rate is 20.74%, Medium with 1.6 mg/L IBA achieved 68.6% rooting of the adventitious shoots. The survival rate is more than 65% after 6 days growth in the cultivated matrix. In summary, our research aims to establish a regeneration system for Zikui tea plants and design a transformation system for tea plant tissue seedlings. This will enable transfer of the target gene and ultimately facilitate the cultivation of new tea varieties with unique characteristics.

Regenerative potential and its variability in different topophysical zones of Kalanchoe daigremontiana leaves in in vitro culture conditions

Plants of the genus Kalanchoe are the most frequently purchased potted plants because of their decorative qualities and easy cultivation. Modern commercial plants have unique shapes that are usually not genetically determined; hence, in vitro cultures are used to propagate such specimens. The efficiency of regeneration is significantly affected by the type of explant used when that explant was previously located on one of several parts of a complex plant organ. The study aimed to investigate the influence of the topophysical location of collected explants on the regeneration efficiency of adventitious shoots. Various regeneration pathways were observed in the in vitro micropropagation of Kalanchoe daigremontiana leaf fragments, i.e., direct and indirect organogenesis from the callus stage. The results show a dependent relationship between the location of the collected explant and its regenerative potential. The most remarkable regenerative capacity of K. daigremontiana was found in leaf blade fragments taken from the middle and proximal zones. In addition, the explants collected from the marginal zone of the leaf blade were notably more valuable than those from the part located near the midrib. The research results indicate that the growth and development of new seedlings propagated vegetatively with the in vitro method depends on their location on the mother plant.

An efficient in vitro organogenesis protocol for the endangered relic tree species Bretschneidera sinensis and genetic fidelity assessment using DNA markers.

Bretschneidera sinensis is a monotypic species of rare and tertiary relic trees mainly distributed in China. B. sinensis is a potentially valuable horticultural plant, which has significant ornamental and research value, and is a crucial tool for the study of phylogeography. The artificial cultivation of B. sinensis is of great scientific value and practical significance. In this study, we developed a direct organogenesis process of B. sinensis using mature zygotic embryos as initial materials. The highest sterile germination induction (54.5%) from the mature zygotic embryo was obtained in a Murashige and Skoog (MS) medium with 2.0 mg·L-1 6-benzylaminopurine (6-BA) and 0.2 mg·L-1 α-naphthaleneacetic acid (NAA). The highest percentage of shoot regeneration (90.37%) was attained using 1.0 mg·L-1 6-BA and 0.01 mg·L-1 NAA in the MS medium. The Woody Plant Medium (WPM) had the greatest adventitious shoot elongation rate of 93.33%. The most optimized rooting rate was 88.89% in a half-strength MS medium containing 2.0 mg·L-1 indole-3-butyric acid (IBA) and 1.0 mg·L-1 NAA. The genetic fidelity of in vitro regenerated plantlets was assessed using inter-simple sequence repeats and random amplified polymorphic DNA molecular markers, confirming the genetic uniformity and stability of regenerated B. sinensis plantlets. Our research presents an effective in vitro propagation system for B. sinensis, laying the groundwork for its germplasm conservation and large-scale production while maintaining high genetic integrity.

In Vitro Conservation of Prunus Avium, an Endangered Species in Tunisia, Using a Plant Extract of Rubus Fruticosus Compared to Indole-3-Butyric Acid

Prunus avium L. is the rarest forest fruit tree in northwestern Tunisia, with strong socio-economic, agronomic, and commercial potential. The aim of this study was to provide more information about the domestication of this species by using an inexpensive in vitro culture technique for micropropagation of meristems. The plant extract used in this study was Rubus fruticosus. The results showed that the best concentration of the extract of R. fruticosus applied for the budding of meristematic microcuttings was 15 g/L, with a 100% success rate. The maximum number of adventitious shoots (7.15 ± 0.35) was obtained for the meristematic microcuttings at a concentration of 15 g/L of the extract. These results indicated that the extracted R. fruticosus plant promotes the neoformation of adventitious shoots and leaves. Rhizogenesis was strongly favored by the addition of 1 mg/L of IBA and 15 g/L of plant extract to the MS medium, which leads to the formation of roots for the meristematic micro-cuttings with percentages of about 80.36% and 53.32%, respectively. The current investigation proved that in vitro micropropagation could constitute a good alternative to the regeneration of this rare forest fruit species and may be applicable to other endangered plants.

Development of an Efficient and Reproducible Embryonic Axis-targeted Tissue Culture-based Transformation Protocol for Pigeonpea (Cajanus cajan)

Background: Tissue culture-based transformation approach poses significant challenges for genetic modification of recalcitrant pigeonpea due to poor regeneration efficiency. In this study, we present a comprehensive high-frequency regeneration and transformation protocol using embryonic axesas explants. Methods: Optimization of transformation parameters and culture conditions for different stages of adventitious shoot regeneration, including shoot induction, elongation and rooting, significantly enhanced transformation efficiency. Agrobacterium-mediated transformation was carried out using embryonic axes explants with pCAMBIA 2301 vector. Culturing of explants on MS basal media supplemented with BAP 2.5 in Preculture, BAP 2.5 in Selection Medium I, IAA 0.5, GA 0.5 and Zeatin 1 in Selection Medium II resulted in formation of numerous multiple shoots from primordia-forming calli at axillary bud regions. Result: Shooting efficiency was 82% and 77%, for cultivars, Pusa 992 and Asha respectively. Rooting efficiency was nearly 100% for both when cultured on half-strength MScontaining 15 g/l sucrose and 0.5 mg/l IAA. Regenerated plants exhibited a high level ofsurvival of 90% upon transplantation into pots. Successful gene integration and expression were confirmed through GUS histochemical and molecular analyses, with approximately 57% and 65% transformation efficiencies for cultivars Pusa 992 and Asha, respectively. This study presents a robust and reproducible tissue culture-based transformation system for pigeonpea, applicable across diverse genotypes, offering new possibilities for genetic improvement in this crucial legume crop.

Establishing an efficient callus genetic transformation system for the tung tree (Vernicia fordii)

Tung tree (Vernicia fordii) as an important industrial raw material used to produce tung oil in China. Genetic transformation system has not been established for the tung tree, hindering research on the functions of tung tree genes and the cultivation of new stress-resistant varieties. In this study, we optimized the tissue culture regeneration system of tung tree hypocotyls, screened out a callus state suitable for Agrobacterium tumefaciens infection, and improved the efficiency of genetic transformation. RNA interference (RNAi) vector was constructed using FAD2 as the target gene. Adventitious shoots were obtained by infecting the hypocotyl calli cultured for 25 days through Agrobacterium-mediated infection. The positive adventitious shoot transformation rate of the pBI121 vector was 22.86%, and the adventitious shoot transformation rate of the RNAi vector was 7.84%. We established a complete genetic transformation system using two vectors, and the system was verified via GUS staining and real-time fluorescence quantitative analyses to ensure its stability. This system solves the technical problem of a genetic transformation system for the tung tree, and will provide technical support for studying the functions of tung tree genes and molecular breeding.

Plant Regeneration via Adventitious Shoot Formation from Immature Zygotic Embryo Explants of Camelina.

Camelina is an oil seed crop that is enjoying increasing interest because it has a particularly valuable fatty acid profile, is modest regarding its water and nutrient requirements, and is comparatively resilient to abiotic and biotic stress factors. The regeneration of plants from cells accessible to genetic manipulation is an essential prerequisite for the generation of genetically engineered plants, be it by transgenesis or genome editing. Here, immature embryos were used on the assumption that their incomplete differentiation was associated with totipotency. In culture, regenerative structures appeared adventitiously at the embryos' hypocotyls. For this, the application of auxin- or cytokinin-type growth regulators was essential. The formation of regenerative structures was most efficient when indole-3-acetic acid was added to the induction medium at 1 mg/L, zygotic embryos of the medium walking stick stage were used, and their hypocotyls were stimulated by pricking to a wound response. Histological examinations revealed that the formation of adventitious shoots was initiated by locally activated cell division and proliferation in the epidermis and the outer cortex of the hypocotyl. While the regeneration of plants was established in principle using the experimental line Cam139, the method proved to be similarly applicable to the current cultivar Ligena, and hence it constitutes a vital basis for future genetic engineering approaches.

In Vitro Regeneration from Leaf Explants of Helianthus verticillatus, a Critically Endangered Sunflower.

Helianthus verticillatus (Asteraceae), a whorled sunflower, is a perennial species restricted to a few locations in the southeastern United States and is now considered endangered. Therefore, restoring and protecting H. verticillatus as a species is a priority. This study introduces a highly efficient in vitro adventitious plant regeneration system from leaf explants, utilizing five diverse specimens of H. verticillatus, each representing distinct genotypes with phenotypic variations in leaf and stem morphology. Key factors influencing in vitro morphogenesis, including genetic constitution, explant source, and plant growth regulators (PGRs), were identified. The study revealed a remarkably strong genotype-dependent impact on the regeneration efficiency of the investigated H. verticillatus genotypes, ranging from a lack of regeneration to highly effective regeneration. The selection of two genotypes with varying regeneration abilities provides valuable models for genetic analyses, offering insights into factors influencing the regeneration potential of this endangered species. Optimum adventitious shoot regeneration results were achieved using Murashige and Skoog basal media (MS) supplemented with 8.8 µM N6-benzyladenine (BA) and 1.08 µM α-naphthalene acetic acid (NAA). This combination yielded the highest adventitious shoot production. Subsequent successful rooting on ½ MS medium without PGRs further solidified the efficiency of the developed protocol. Regenerated plantlets, demonstrating robust shoots and roots, were successfully acclimatized to greenhouse conditions with a 95% survival rate. The protocol developed in this study is the first such report for this endangered species and is expected to contribute to future genetic manipulation and modification studies.

Comprehensive Analysis of Highbush Blueberry Plants Propagated In Vitro and Conventionally.

In vitro culture allows the production of numerous plants with both desirable and undesirable traits. To investigate the impact of the propagation method on highbush blueberry plants, an analysis was performed on four groups of differentially propagated plants: in vitro with axillary (TC-Ax) or adventitious shoots (TC-Ad), conventionally (SC) and using a mixed method (TC/SC). The analysis included plant features (shoot length and branching, chlorophyll and fluorescence and DNA methylation) and fruit properties (antioxidant compounds). The data obtained indicated significant differences between plants propagated conventionally and in vitro, as well as variations among plants derived from in vitro cultures with different types of explants. SC plants generally exhibited the lowest values of morphological and physiological parameters but produced fruits richest in antioxidant compounds. TC/SC plants were dominant in length, branching and fluorescence. Conversely, TC-Ax plants produced fruits with the lowest levels of antioxidant compounds. The methylation-sensitive amplified polymorphism (MSAP) technique was employed to detect molecular differences. TC-Ad plants showed the highest methylation level, whereas SC plants had the lowest. The overall methylation level varied among differentially propagated plants. It can be speculated that the differences among the analysed plants may be attributed to variations in DNA methylation.

Development of rapid and genotype-independent in vitro adventitious shoot differentiation in C4 bioenergy crop Cenchrus ciliaris L.

Development of rapid and genotype-independent in vitro adventitious shoot differentiation in C4 bioenergy crop Cenchrus ciliaris L.

In Vitro Regeneration, Conservation, and Field Evaluation of a Medicinal Plant– Greater Burdock (Arctium Lappa L.)

A suitable micropropagation protocol and ex vitro acclimation method have been developed from in vitro grown seedling explants through cotyledonary node and leaf explants in consideration of the vegetable and medicinal properties of Greater Burdock. MS medium with 0.5-4.0 μM BAP showed highest percentage of axillary shoot regeneration from the cotyledonary nodal explants. Direct shoot regeneration was achieved by culturing 1.0 cm2 sections of about 25 days old leaves of in vitro grown shoot on MS medium enriched with 4.0 μM BAP and 2.0 μM IBA or NAA after 5 weeks of culture. Within six weeks of incubation on medium enriched with 4.0 M BAP and 2.0 M IBA or NAA, the leaf explants also developed callus from the cut margins. The greatest number of adventitious shoots could then be formed from the leaf-derived callus within 10 weeks of culture on the same media mix. More than 20 shoots were formed per callus clump at the third subculture, which had the highest rate of shoot multiplication. A. lappa's shoot and callus were both preserved at 5 ºC in MS medium with 4.0 μM Kn and 2.0 μM IBA, as well as 4.0 μM BAP and 2.0 μM IBA, respectively. The in vitro proliferated and elongated shoots were separated from callus clump for rooting. A root-induction MS medium with 6.0 μM IBA or NAA was used to cultivate the microshoots individually. All of the cultured microshoots generated 2-16 roots within 4 weeks of being moved to the rooting medium. Regenerated plantlets were transferred to vermiculite and successfully established in an ex vivo environment with a 98% survival rate. J. Bio-Sci. 31(1): 1-15, 2023

Colleter Formation on the Leaves of Sweet Potato Microclones (Ipomoea batatas L.) under In Vitro Conditions

Microclones of in vitro vegetable sweet potato (Ipomoea batatas L.) were received and the formation of colors on their leaves was studied. The studies were carried out on three varieties of sweet potato that differ in the color of their pulp and the peel of the tubers as well as in different ripening periods: Purple, Jewel, and Muskatny. The effect of ½ norm of mineral salts MS medium, 1 norm MS and 1½ norm MS on the morphometric parameters of sweet potato microclones was studied. It was established that the use of ½ norm of mineral salts according to MS medium led to the production of rapidly growing axillary and adventitious shoots and the formation of a powerful root system in the basal part of microcuttings. The formation of secretory outgrowths was found for the first time on the leaves of sweet potato microclones when cultured under in vitro conditions. Neoplasms were referred to colleters and their characteristics were given. The dependence of the colleter formation on the microclone leaves on the cycles of culture is shown.