Plant cell

Despite the general eukaryotic plan of organization, cells of higher plants exhibit a number of fundamental differences from animal cells, reflecting the features of their autotrophic lifestyle and fixed position in space (Serebryakova et al., 2006; Graham et al., 2014).

The first and most obvious difference is the presence of a rigid cell wall located outside the plasmalemma. Unlike animal cells, which lack any external coat, the plant cell is surrounded by a complex polymeric framework based on cellulose, as well as hemicelluloses, pectins, and often lignin (Evert, 2006). The cell wall not only determines the shape of the cell and provides mechanical support to the whole plant, but also serves as a barrier protecting the protoplast from osmotic rupture upon water uptake (Graham et al., 2014). Animal cells, in contrast, usually have only a glycocalyx and cannot withstand significant osmotic pressure.

The second key difference is the presence in plants of plastids — double‑membrane organelles absent in animals. Most important are chloroplasts, which contain chlorophyll and carry out photosynthesis — the process of converting light energy into chemical energy, making the plant autotrophic (Beck, 2010). Derivatives of plastids are chromoplasts, which colour flowers and fruits, and leucoplasts (e.g., amyloplasts), which store starch (Evert, 2006). Animal cells, being heterotrophs, obtain energy solely by oxidizing ready‑made organic substances in mitochondria and do not contain plastids.

The third difference is the presence of a large central vacuole. In mature plant cells, the vacuole bounded by the tonoplast occupies up to 90% of the cell volume and performs many functions: maintaining turgor pressure, storing reserve substances (sucrose, proteins), depositing secondary metabolites and end products of metabolism, including pigments (anthocyanins) and calcium oxalate crystals (Andreev, 2001; Yakovlev et al., 2001). In animal cells, vacuoles are generally small (e.g., digestive and contractile vacuoles in protists) and do not play such a significant role in maintaining shape and metabolism.

The fourth difference concerns the organization of the cytoskeleton and cell division. Plant cells generally lack centrioles — structures that in animal cells participate in the formation of microtubule organizing centers of the spindle apparatus (Mauseth, 2017). Spindle formation in plant cells occurs differently. Furthermore, cytokinesis (division of the cytoplasm) in plants does not occur by furrowing (as in animals) but by the formation of a phragmoplast and a cell plate — a new cell wall that grows centrifugally and separates the daughter cells (Evert, 2006; Graham et al., 2014).

The fifth important difference is the mode of communication between cells. Adjacent plant cells are connected to each other by plasmodesmata — cytoplasmic channels passing through the cell walls (Serebryakova et al., 2006). This network unites the protoplasts of cells into a single whole — the symplast — providing rapid transport of ions and small molecules. Animal cells, lacking cell walls, are connected differently (e.g., via gap junctions), and their cytoplasm does not normally form such an extensive continuous compartment.

Thus, all the listed differences — cell wall, plastids, large vacuole, absence of centrioles, type of cytokinesis, and presence of plasmodesmata — are systemic traits that evolved to provide autotrophic nutrition, osmoregulation, and fixed growth of plants (Beck, 2010).

The vital activity of the plant cell is determined by several unique properties that distinguish it from heterotrophic eukaryotic cells and enable its autotrophic, sessile lifestyle. These properties — totipotency, osmotic activity (turgor), ability to synthesize a cellulose wall, and photoautotrophy — evolved together and are closely interrelated (Beck, 2010).

Totipotency. Totipotency is the ability of a somatic plant cell to realize the full genetic potential inherent to its species and, under certain conditions, to regenerate a whole organism (Fehér, 2019). Unlike animal cells, many differentiated plant cells (e.g., parenchyma cells) retain the ability to return to a meristematic state through dedifferentiation, which underlies methods of in vitro culture and vegetative propagation (Fehér, 2019). Totipotency is not a constitutive property of any somatic cell but rather an inducible state that requires reprogramming of gene expression and changes in the epigenetic landscape (Fehér, 2019). Detailed mechanisms of this phenomenon will be discussed in a separate article of the series.

Osmotic activity and turgor. The plant cell is an osmotic system in which the large central vacuole, filled with cell sap, is separated from the cytosol by the semipermeable tonoplast. Active accumulation of ions (K⁺, Na^\+, Ca²⁺) and low‑molecular‑weight organic compounds (sucrose, proline) in the vacuole creates a more negative water potential compared to the environment, causing water uptake and the development of hydrostatic pressure against the cell wall — turgor (Andreev, 2001; Graham et al., 2014). Turgor provides tissue rigidity, maintains the shape of non‑lignified organs (leaves, stems), and is the driving force for cell expansion during growth (Evert, 2006). Regulation of turgor includes both passive water transport through aquaporins and active transport of ions and metabolites (Andreev, 2001). When dehydrated, cells lose turgor, which clinically manifests as plant wilting.

Ability to synthesize a cellulose cell wall. Unlike animal cells surrounded only by the plasmalemma, the plant cell forms an extracellular matrix — the cell wall — whose main structural component is cellulose (β‑1,4‑glucan) (Evert, 2006). Cellulose microfibrils are synthesized by enzyme complexes (cellulose synthase rosettes) located in the plasmalemma and are oriented by microtubules of the cytoskeleton (Mauseth, 2017). In addition to cellulose, the wall contains hemicelluloses, pectins, and (secondarily) lignin, which give it mechanical strength, elasticity, and protective properties. The presence of the wall not only determines cell shape but also restricts its motility, a key factor in the sessile lifestyle of plants (Graham et al., 2014).

Autotrophy. The plant cell is capable of photosynthesis — the process of converting sunlight energy into chemical energy of organic compounds (Beck, 2010). This ability is provided by specialized organelles — chloroplasts, containing chlorophyll a and b, as well as carotenoids, which are localized in the thylakoid membranes (Evert, 2006). During the light reactions, ATP and NADPH are synthesized, and in the chloroplast stroma, in the Calvin cycle, CO₂ is fixed to form carbohydrates (Mauseth, 2017). Autotrophy makes the plant a primary producer of organic matter in ecosystems and determines its independence from external sources of organic nutrition.

Taken together, the listed fundamental properties — totipotency, turgor, ability to synthesize a cellulose wall, and autotrophy — are inextricably linked. For example, the existence of turgor as hydrostatic pressure is possible only in the presence of a rigid cell wall that counteracts the osmotic expansion of the protoplast. In turn, the cell wall, synthesized from products of photosynthesis, creates mechanical support for photosynthetic organs, and totipotency provides the regenerative potential necessary to replace damaged tissues during growth and development (Lee and Torii, 2026).

The living contents of a plant cell — the protoplast — are separated from the external environment by the cell wall and are characterized by complex internal organization. The protoplast is subdivided into functionally distinct compartments, allowing many biochemical processes to occur simultaneously and independently (Evert, 2006). The most important components of the protoplast are the plasmalemma, nucleus, cytoplasm (cytosol and organelles), vacuole, and the system of internal membranes.

Components of the plant cell are divided into several categories depending on their structural organization (Evert, 2006; Graham et al., 2014):

Cells of higher plants, despite a common structural plan, exhibit significant morphological and functional diversity, which is the result of differentiation during ontogeny. Depending on the functional state and tissue affiliation, several main types of cells are distinguished (Evert, 2006; Serebryakova et al., 2006).

Main page: Cell division

The life cycle of a dividing somatic cell encompasses two sequential processes: interphase (preparation for division) and mitosis (nuclear division), usually followed by cytokinesis (division of the cytoplasm and formation of two daughter cells) (Dewitte and Murray, 2003; Francis, 2007). Unlike animal cells, plants lack centrioles, and cytokinesis occurs by forming a cell plate rather than by furrowing (Evert, 2006).

Cytology (from Greek kytos — cell and logos — study) is a branch of biology that studies the structure, chemical composition, functions, development, and reproduction of cells. In its application to plants, cytology is a fundamental basis for understanding tissue organization, physiological processes, and biotechnological approaches in agronomy (Evert, 2006; Yakovlev et al., 2001).

Object and subject of cytology. The object of cytology is the plant cell at all levels of structural organization — from the intact protoplast to the molecular organization of membranes and the cytoskeleton. The subject of research includes: 1) morphology and ultrastructure of cellular compartments; 2) physicochemical properties of the cytoplasm and its organelles; 3) the cell cycle, mitosis, and meiosis; 4) differentiation, totipotency, and cellular aging; 5) cell responses to external signals and stress (Mauseth, 2017; Graham et al., 2014).

Historical outline. The foundations of cytology were laid in the second half of the 17th century, when R. Hooke (1665) first described cells in a slice of cork. In 1831, R. Brown discovered the nucleus, and in 1838–1839, M. Schleiden and T. Schwann formulated the cell theory, asserting that all living organisms are composed of cells (Serebryakova et al., 2006). Later, R. Virchow (1855) added the principle “omnis cellula e cellula” — every cell arises from another cell. In the second half of the 19th — early 20th century, mitochondria (R. Altmann, 1890; K. Benda, 1898), plastids (A. Schimper, 1883), the Golgi apparatus (C. Golgi, 1898) were discovered, and mitosis was described (E. Strasburger, W. Flemming). A landmark achievement was the discovery of the DNA structure (J. Watson and F. Crick, 1953), which enabled the transition to molecular cytology (Beck, 2010).

Main methods of cytology. Progress in cell science is inextricably linked to the development of microscopic and biochemical methods (Evert, 2006; Graham et al., 2014):

Significance for agricultural sciences. Cytological research underpins plant breeding (karyotype analysis, identification of polyploid forms, cytogenetic control of hybrids), biotechnology (clonal micropropagation, somatic hybridization, production of haploid plants), phytopathology (diagnosis of viral and bacterial infections by intracellular inclusions, studying pathogen–plant cell interactions), and stress physiology (cytological markers of drought and salt tolerance, assessment of membrane damage) (Mauseth, 2017; Fehér, 2019).

Thus, plant cytology is a comprehensive discipline that combines structural, functional, genetic, and molecular approaches to the study of the cell. Its achievements create a theoretical basis for increasing the productivity of agricultural crops, plant resistance to stress, and the implementation of modern biotechnologies.

Modern plant cytology is undergoing a stage of integration of classical microscopic methods with advanced technologies of molecular biology, biophysics, and bioinformatics. This allows cellular processes to be studied not only statically but also dynamically — in living cells and tissues, and with unprecedented spatiotemporal resolution (Evert, 2006; Graham et al., 2014).

New methods and approaches. The key technological drivers of modern cytology are:

Current research directions. At the forefront of plant cytology are the following problems:

Significance for agricultural sciences. Modern cytology is directly implemented in agricultural practice:

Open questions. Despite enormous progress, fundamental mysteries remain: how exactly does a cell assess its size and coordinate division with growth; what molecular switches determine the choice between mitosis and endoreduplication; how do plasmodesmata regulate their permeability, and how are signals transmitted from the cell wall to the nucleus? Answers to these questions will be obtained using new technologies — from super‑resolution microscopy to artificial intelligence for analyzing large image datasets (Sablowski and Gutierrez, 2022; Lee and Torii, 2026).