Citokininek hatásvizsgálata alma in vitro hajtás regenerációjában = Role of cytokinins in shoot regeneration of apple in vitro

Hat alma fajtánál (Royal Gala, M.26, Idared, Freedom, McIntosh, Húsvéti rozmaring) fajtánként optimalizáltuk az előkezelő táptalaj citokinin tartalmát (citokinin típusa és koncentrációja), tisztáztuk hatásukat az adott genotípus morfogenetikus képességére. Kimutattuk a különböző típusú citokininek különböző koncentrációja okozta szöveti változásokat az in vitro hajtások leveleiben. Megállapítottuk, hogy a regenerációra használt levelek szöveti szerkezete és a regenerációs válaszuk jó korrelációt mutat. Fajtánként optimalizáltuk a regenerációs táptalaj citokinin tartalmát. Kimutattuk a különböző citokininek és az alma fajták közötti különbségeket a hajtások differenciálódásának időbeli alakulásában. Elvégeztük 65 almafajta molekuláris analízisét és elkülönítését mikroszatellit primerekkel (SSR markerek). Elkészítettük a 6 SSR lókusz alapján a fajták dendrogramját is, amely az ismert pedigré adatokkal jól összhangban áll. | Cytokinin content (its type and concentration) was optimalized in the pre-treatment media in each cultivar examined (Royal Gala, M.26, Idared, Freedom, McIntosh, Húsvéti rozmaring) and the effects of different cytokinins on the morphogenic capacity were determined. Anatomical differences were detected in the leaves of in vitro plantlets treated with different cytokinins. There was a positive correlation between the histological status and regeneration capacity of in vitro leaves. Cytokinin content of regeneration media also was optimalized. Differences between effects of the different cytokinins and differences between the examined cultivars were proved considering the time curve of shoot regeneration. Molecular analysis of 65 apple cultivars were fulfilled by microsatellite primers (SSR) and we were able to distinguish the cultivars. Based on 6 SSR loci we prepared the dendogram of cultivars, which fits in with the well-known pedigree-data

In vitro tissue culture of apple and other Malus species: recent advances and applications

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Shoot tip necrosis of in vitro plant cultures: a reappraisal of possible causes and solutions

Shoot tip necrosis is a physiological condition and disorder that can arise in plantlets or shoots in vitro that results in death of the shoot tip. This condition, which can spread basipetally and affect the emergence of axillary shoots from buds lower down the stem, is due to the cessation of apical dominance. STN can occur at both shoot multiplication and rooting stages. One of the most common factors that cause STN is nutrient deficiency or imbalance. Moreover, the presence or absence of plant growth regulators (auxins or cytokinins) at specific developmental stages may impact STN. The cytokinin to auxin ratio within an in vitro plant can be modified by varying the concentration of cytokinins used in the culture medium. The supply of nutrients to in vitro shoots or plantlets might also affect their hormonal balance, thus modifying the occurrence of STN. High relative humidity within culture vessels and hyperhydricity are associated with STN. An adequate supply of calcium as the divalent cation (Ca2+) can hinder STN by inhibiting the accumulation of phenolic compounds and thus programmed cell death. Moreover, the level of Ca2+ affects auxin transport and ethylene production, and higher ethylene production, which can occur as a result of high relative humidity in or poor ventilation of the in vitro culture vessel, induces STN. High relative humidity can decrease the mobility of Ca2+ within a plant, resulting in Ca2+ deficiency and STN. STN of in vitro shoots or plantlets can be halted or reversed by altering the basal medium, mainly the concentration of Ca2+, adjusting the levels of auxins or cytokinins, or modifying culture conditions. This review examines the literature related to STN, seeks to discover the associated factors and relations between them, proposes practical solutions, and attempts to better understand the mechanism(s) underlying this condition in vitroThis research was financed by the Higher Education Institutional Excellence Programme (NKFIH-1150-6/2019) of the Ministry of Innovation and Technology in Hungary, within the framework of the Biotechnology thematic programme of the University of Debrecen. The study and submission for publication were approved by the University of Debrecen (BPTR/DEENK/0008/2019). Esmaeil Nezami-Alanagh thanks the Biotechnology Department at Imam Khomeini International University (IKIU) for their assistance in carrying out a part of the experiment work and also to Science and Technology Park of East-Azarbaijan, Islamic Republic of Iran, for financial support. The Spanish work on STN modeling was funded by Xunta de Galicia, Spain (CITACA Strategic Partnership, Reference: ED431E 2018/07 and REDES, Reference: ED431D-2017/19)S