Primary morphogenesis of Sorbus Torminalis L. (Grantz) into in vitro culture

Nowadays in vitro methods, combined with ex situ and becoming an increasingly important means of preserving and maintaining the level of phytodiversity stability. Sorbus torminalis L. is a tree of the Rosaceae family, which grows on the territory of Ukraine, belongs to rare, valuable aboriginal species and is listed in the Red Book of Ukraine, with its protection status - endangered. The peculiarities of introduction of in vitro culture of perennial representatives of S. torminalis with the use of different types of explants, sterilizing substances, cultivation conditions and nutrient medium composition are presented in the paper. For in vitro culture of S. torminalis, annual shoots with apical and lateral buds 15-25 cm long are optimal. The influence of different sterilization options on the development of primary microshoots has been studied. For sterilization of artificially awakened and young shoots it is most effective to use 0.1% solution of AgNO3 (7 min) and 15% solution of H2O2 (10 min). The developed method of sterilization of S. torminalis explants provided 80-90% yield of aseptic plant material. It was found that the sterilization regime did not significantly affect the primary morphogenesis of explants and was uniform. The optimal components of nutrient media at the stage of introduction into vitro culture and primary morphogenesis of S. torminalis have been established. For the cultivation of different types of explants of S. torminalis, used WPM nutrient media with the addition of synthetic plant growth regulators 6-benzylaminopurine, thidiazuron, kinetin 0,5-1,5 mg mg∙l-1 and α-naphthylacetic acid 0,01-0,05 mg∙l-1 both alone and in combination with each other. In particular, for the regeneration of plants from the lateral and apical buds of explants is effective WPM medium with the addition of BAP 1,5 mg∙l-1 + 0,5 mg∙l-1 NAA and WPM + TDZ medium 0,5 mg∙l-1 with adding PVP 200 mg∙l-1. To induce the laying of additional buds and shoots on the explant from the apical meristems in the medium should be added 4,0 mg∙l-1 BAP + 0,01 mg∙l-1 NAA with the addition of PVP 200 mg∙l-1.

Refinement of the methodology for assessing the resistance of hazel (hazelnuts) to stress factors

The aim of the research is to clarify the methodology for assessing the resistance of hazel (hazelnuts) to stress factors on the basis of uniform approaches adopted in walnut farming. The assessment of resistance to biotic and abiotic factors has been carried out according to the methods recommended for the walnut, and the state of the vegetative and generative organs of hazel (hazelnuts) has been correlated with the program requirements. The result has been the development of 7 point assessment scales and the numerical values of the degree of damage correlated with them. Score 0 corresponds to the absence of lesions, 1 – lesions up to 5%, 2 – lesions up to 6–10%, 3 – lesions up to 11–25%, 4 – lesions up to 26–50%, 5 – lesions up to 51–75%, 6 – lesions more than 75% or death of the whole plant (depending on the studied indicator). The assessment scale for the winter hardiness of vegetative organs takes into account the degree of damage to the apical buds, annual shoots, branches of two years and older, the stem and the whole plant. Damage to male inflorescences is determined by the length of their dead part, to the female flowers – by the number of damaged ones, expressed as a percentage. The degree of drought resistance is revealed on the basis of studying the state of the entire plant, the percentage of damaged and fallen leaves. The influence of drought on the loss of food part is established by the degree of shrinkage of the kernel. Susceptibility to diseases and pests is estimated in percentage points separately for leaves by area, shoots in length, nuts by the ratio of damaged and undamaged ones. We have distinguished 6 groups of resistance, depending on the degree of vulnerability of varieties and forms of hazel (hazelnuts). It has been proposed to draw conclusions on the basis of at least three years of observations, and the final conclusion should be focused on specific breeding goals.

ADAPTABILITY OF INTRODUCED HONEYSUCKLE VARIETIES IN THE PRE-URALS OF BASHKORTOSTAN

The article presents an assessment of the adaptability of introduced varieties of honeysuckle to the conditions of the Pre-Urals of Bashkortostan. The research was carried out at the primary variety study site of the Kushnarenkovsky breeding center of the BNIISKH UFIC RAS. Landing scheme 3.0´1.0 m. 7 varieties were selected as objects: varieties of selection of M.A. Lisavenko Research Institute of Horticulture - Zoluska, Galochka, Berel; varieties of YUUNIIPK - Chelyabinka, Chernichka; variety of Bakcharskaya experimental horticulture station - Bakcharskaya. As a control, the variety of the M. A. Lisavenko NIISS - Goluboe vereteno - was taken. The studies were conducted from 2016 to 2020. in accordance with the "Program and methodology of variety study of fruit, berry and nut crops". During the study, it was found out that all the studied varieties showed good winter hardiness. In 2017, damage to the apical buds of the winter desiccation type was observed in the varieties Chelyabinka and Zolushka by 23-25%. Dry conditions had a negative impact on productivity, leading to shedding of the ovary, a decrease in the weight of the fruit. The studied varieties differed among themselves in the degree of shedding. The control variety Goluboe vereteno is classified as highly crumbling, the weakly crumbling variety is Zolushka Chelyabinka, Bakcharskaya and the non - crumbling variety is Galochka, Chernichka and Berel. In the varieties Bakcharskaya, Berel and Goluboe vereteno, the extension of terminal buds was noted in the years of research. By weight of one berry, the following varieties were distinguished: Bakcharskaya (0.72 g), Galochka (0.75 g), Chernichka (0.81 g). The Chernichka (2.8 kg per bush) and Galochka (3.1 kg per bush) varieties were distinguished by high yield, on average, for 5 years. In general, the introduced varieties of honeysuckle show high adaptability in the natural and climatic conditions of the Pre-Urals of Bashkortostan.

Distinct within-host bacterial populations ensure function, colonization and transmission in leaf symbiosis

Hereditary symbioses have the potential to drive transgenerational effects, yet the mechanisms responsible for transmission of heritable plant symbionts are still poorly understood. The leaf symbiosis between Dioscorea sansibarensis and the bacterium Orrella dioscoreae offers an appealing model system to study how heritable bacteria are transmitted to the next generation. Here, we demonstrate that inoculation of apical buds with a bacterial suspension is sufficient to colonize newly-formed leaves and propagules, and to ensure transmission to the next plant generation. Flagellar motility is not required for movement inside the plant, but is important for the colonization of new hosts. Further, stringent tissue-specific regulation of putative symbiotic functions highlight the presence of two distinct subpopulations of bacteria in the leaf gland and at the shoot meristem. We propose that bacteria in the leaf gland dedicate resources to symbiotic functions, while dividing bacteria in the shoot tip ensure successful colonization of meristematic tissue, glands and propagules. Compartmentalization of intra-host populations, together with tissue-specific regulation may serve as a robust mechanism for the maintenance of mutualism in leaf symbiosis.ImportanceSeveral plant species form associations with bacteria in their leaves, called leaf symbiosis. These associations are highly specific, but the mechanisms responsible for symbiont transmission are poorly understood. Using the association between the yam species Dioscorea sansibarensis and Orrella dioscoreae as a model leaf symbiosis, we provide experimental evidence that bacteria are transmitted vertically and distributed to specific leaf structures via association with shoot meristems. Flagellar motility is required for initial infection, but does not contribute to spread within host tissue. We also provide evidence that bacterial subpopulations at the meristem or in the symbiotic leaf gland differentially express key symbiotic genes. We argue that this separation of functional symbiont populations, coupled to tight control over bacterial infection and transmission, explain the evolutionary robustness of leaf symbiosis. These findings may provide insights into how plants may recruit and maintain beneficial symbionts at the leaf surface.

Morphogenetic and physiological effects of LED spectra on the apical buds of Ficus carica var. Black Jack

The use of artificial light sources such as light-emitting diodes (LEDs) has become a prerequisite in tissue culture studies to obtain morphogenetic enhancements on in vitro plants. This technology is essential for developmental enhancements in the growing plant cultures due to its light quality and intensity greatly influencing the in vitro growing explants at a cellular level. The current study investigates the effects of different light-emitting diode (LED) spectra on the growth of apical buds of Ficus carica var. Black Jack. Ficus carica, commonly known as figs is rich in vitamins, minerals, and phytochemicals capable of treating microbial infections and gastric, inflammatory, and cardiac disorders. Apical buds of Ficus carica var. Black Jack, presented morphogenetic changes when grown under six different LED spectra. The highest multiple shoots (1.80 per growing explant) and healthy growing cultures were observed under the blue + red LED spectrum. Wound-induced callus formation was observed on apical buds grown under green LED spectrum and discolouration of the growing shoots were observed on the cultures grown under far-red LED spectrum. Multiple shoots obtained from the blue + red LED treatment were rooted using 8 µM indole-3-acetic acid (IAA), and the rooted plantlets were successfully acclimatised. Compared with the other monochromatic LEDs, blue + red proved to be significantly better for producing excellent plant morphogeny. It is apparent that blue and red LED is the most suitable spectra for the healthy development of plants. The findings have confirmed that the combination of blue + red LED can potentially be used for enhancing growth yields of medicinally and commercially important plants.

Perspectivele microclonării și micropropagării speciei Rosa canina L.

Rosehip fruits are characterized by high concentrations of vitamin C and antioxidants, which we can say that rosehip is a reservoir of vitamins for the human body. The aim of this study is to improve the in vitro propagation efficiency of this valuable plant species. In this study, apical buds were inoculated on 100% MS medium supplemented with BAP of 0.5-1.0 mg/l and FeNaEDDHA 50 mg/l - Sequestrene 138, to avoid the phenomenon of leaf chlorosis. Due to the multiple characteristics, Rosa canina is of practical interest for our country, which leads to the need to produce propagating material through in vitro culture.

Comparative Transcriptomic Analysis of Differentially Expressed Transcripts Associated with Flowering Time of Loquat (Eriobotya japonica Lindl.)

Flowering is an important phenophase of plant species, however, knowledge about the regulatory mechanism controlling flowering cues in loquat is limited. To identify candidate genes regulating flowering time in loquat, we used RNA-Seq technology to conduct a comparative transcriptome analysis of differentiating apical buds collected from the early-flowering variety ‘Baiyu’ and the late-flowering variety ‘Huoju’. A total of 28,842 differentially expressed transcripts (DETs) were identified. Of these, 42 DETs controlled flowering time while 17 other DETs were associated with the ABA signaling pathway. Compared with those in ‘Huoju’, EjFT, EjFY, EjFLK, and EjCAL1-like were significantly upregulated in ‘Baiyu’. Moreover, transcripts of the ABA 8′-hydroxylases (EjABH2, EjABH4, and EjABH4-like2), the ABA receptors (EjPYL4/8), and the bZIP transcription factor EjABI5-like were upregulated in ‘Baiyu’ compared with ‘Huoju’. Hence, they might regulate loquat flowering time. There was no significant difference between ‘Baiyu’ and ‘Huoju’ in terms of IAA content. However, the ABA content was about ten-fold higher in the apical buds of ‘Baiyu’ than in those of ‘Huoju’. The ABA:IAA ratio sharply rose and attained a peak during bud differentiation. Thus, ABA is vital in regulating floral bud formation in loquat. The results of the present study help clarify gene transcription during loquat flowering.

Floral Induction of Longan (Dimocarpus longan) by Potassium Chlorate: Application, Mechanism, and Future Perspectives

Longan (Dimocarpus longan L.) is one of the most important tropical and subtropical fruits in the world. Longan fruit has high nutritional and medical value, and is regarded as a treasure among fruits. Since it was first reported that potassium chlorate (KClO3) could be successfully applied to promote flowering in longan, this compound has been widely used in the production of on-season and off-season longan fruits. KClO3 has thus played a great role in promoting the development of the longan industry. In this review, we summarize the application methods, influencing factors, and physiological and molecular mechanisms associated with KClO3-mediated induction of longan flowering. It can be deduced that leaves may play a crucial role in the transport of and response to KClO3. Leaves supply carbon and nitrogen nutrition, and hormone and signaling molecules needed for the differentiation of apical buds. Moreover, cytokinins may be crucial for KClO3-mediated induction of longan flowering. More effort should be focused on studying the molecular mechanisms underlying this process. This will not only help us to better understand floral induction by KClO3 in longan but also enrich our understanding of flowering regulation mechanisms in woody plants.