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

Abstract

Main conclusion Shoot tip necrosis is a physiological condition that negatively impacts the growth and development of in vitro plant shoot cultures across a wide range of species. Abstract 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 vitro.

Machine Learning Unmasked Nutritional Imbalances on the Medicinal Plant Bryophyllum sp. Cultured in vitro

“…Due to the high heterogeneity of ingredients that make part of culture media formulations and other additional factors, such as plant genotype or growth conditions, the study of nutritional requirements applied to unknown medicinal plants leads to the design of complex multivariate experimental designs (Nezami-Alanagh et al, 2017;Teixeira da Silva et al, 2020). In the last decade (Hesami and Jones, 2020;Niazian and Niedbala, 2020), several ML algorithms have been successfully employed as alternative to traditional statistical methods and/or response surface methodology (RSM) to identify factors and interactions on complex, non-linear and non-deterministic process such as PTC (Landin et al, 2009;Gago et al, 2010a,c;Nezami-Alanagh et al, 2017).…”

In vitro propagation of the Amazonian medicinal plant guayusa (Ilex guayusa) and effects of light in the growth and development of this shade tolerant plant

“…STN is a physiological condition that can emerge in in vitro plantlets or shoots and affect propagation by causing tissue death (Bairu et al 2009). STN has been reported in several arboreal and shrubby plants (Teixeira da Silva et al 2020). Furthermore, the usage of short shoots (less than 0.5 cm in length) affects the elongation phase and delays roots appearance, which can lead to nutrient deficiency in the plant (Martínez et al 2017).…”

Sodium Toxicity: Should NaOH Be Substituted by KOH in Plant Tissue Culture?

“…Thus, in vitro cultures may be adversely affected by NaOHinduced nutritional disorders since it has been demonstrated that the concentrations and ratio of certain nutrients can affect the sensitivity of cells to growth regulators and other component of the medium as well as morphogenesis and differentiation (Leifert et al, 1995;Oberschelp and Goncalves, 2018). Nutrient deficiency or imbalance can cause abnormal physiological responses in plant cultures such as hyperhydricity, callus formation and necrosis (Reed et al, 2013;Teixeira da Silva et al, 2020). Additionally, plant cells and tissues performance may also be adversely affected by the alteration of metabolic pathways and osmotic adjustments.…”