Plant physiology: yesterday, today and what will bring tomorrow?

Rozwój fizjologii roślin przedstawiono w ujęciu historycznym, prezentując najważniejsze, ale subiektywnie wybrane osiągnięcia. Wynikają one głównie z możliwości wykorzystania nowych technik, pozwalających na prowadzenie badań metodami nieinwazyjnymi. Na przełomie XX i XXI wieku w centrum uwagi znajdują się próby wyjaśnienia mechanizmów regulacji i koordynacji procesów życiowych na poszczególnych poziomach organizacji: genetycznym, molekularnym, organizmalnym, dających holistyczny obraz funkcjonowania roślin. Wynika on z integracji badań różnych dyscyplin naukowych, składających się na biologię roślin. Wyjaśniane są zagadnienia przekazywania i odbioru sygnałów. W mechanizmach regulacji procesów życiowych kluczową rolę odgrywają fitohormony z funkcją plejotropową. Współdziałają one z licznymi regulatorami procesów życiowych, w tym z tlenkiem azotu (NO) i reaktywnymi formami tlenu (ROS). Stwierdzono precyzyjnie funkcjonujący system ligaz ubikwitynowo-białkowych, uczestniczący między innymi w degradacji biologicznie zbędnych, w danym okresie, lub zdenaturowanych białek. Ponadto przedyskutowano badania dotyczące perspektyw wzrostu aktywności i produktywności fotosyntezy. Optymalna dystrybucja fotoasymilatów i związków sygnałowych, z udziałem ksylemu i floemu, zapewnia zaopatrzenie akceptorów w związki pokarmowe i utrzymanie prawidłowej homeostazy organizmu. Przedyskutowano integracje powyższych procesów w aspekcie wzrostu plonu rolniczego roślin uprawnych. W zakończeniu przedstawiono konieczność badań zwiększenia produkcji żywności, odporności roślin na stresy i likwidacji globalnych zagrożeń, wynikających z zanieczyszczeń środowiska. Jako nowe dyscypliny zasygnalizowano neurobiologię roślin, biologię systemów i biologię syntetyczną.In this paper, the history of plant physiology is shortly reviewed with the main emphasis put on a limited number of subjectively chosen developments connected for the most part with the application of new noninvasive experimental methods. Since the turn of XIX and XX centuries, multidisciplinary studies towards understanding of the mechanisms of regulation and coordination of life processes at various level of organization: genetic, molecular and organismal become dominant allowing for more and more holistic description of plant functioning. The coordination of particular processes as a response to internal and external signals is one of the better understood key problems discussed in this review. In these processes important pleiotropic role is played by phytohormones which cross-talk with one another and cooperate with other regulators like nitrogen monoxide and reactive oxygen species (ROS). Next, a central and new area of research in biology, namely the process of proteins ubiquitination, is the matter at issue. Targeting of proteins for degradation with the use of ubiquitin proteasome system underlies the mechanism of degradation of denatured or nonfunctional proteins. Another discussed problem is the necessity of global crop improvement connected with an increase in photosynthetic activity and reduction of photorespiration. Special attention is paid to the function of plant phloem and ksylem systems in translocation and distribution of products of photosynthesis and nutrients, and a great number of signaling substances. The role of phloem is presented as "superhigway of information". Integration of these processes is discussed in connection with possible improvement of crop yield. The necessity of further studies directed towards increase in plant crop, resistance of plants to environmental stress and suppression of global threats linked to environmental pollution is underlined. Finally, emergence of few new disciplines like plant neurobiology, system biology and synthetic biology is noted

The role of conductive system in nutrient supply and coordination of plant

The review presents actual knowledge of the role of conductive system (phloem and xylem) in plants. Conductive system transfer organic and inorganic products of absorbed nutrients and photoassimilates. Far distance transport of water and ions as well as various metabolites and phytohormones also take plays in the phloem in interaction with the xylem. Phloem functions as superhighway of information by transporting signalling molecules (hormones, proteins, mRNAs and not coded RNAs) to different plant organs. The movement of these macromolecules from companion cells into sieve tubes occurs via plasmodesmata and involves selectively regulated mechanisms. Some proteins and RNAs in the sieve tubes are non-cell autonomous molecules. Therefore it may be concluded that phloem takes part in long distance communication between different plant organs. It allows plant to respond efficiently to ontogenetic changes and external conditions as well as to coordinate transport and distribution of resources required in various proportion for growth and development. It is stressed, that understanding of function of conductive systems may be relevant for modelling of carbon partitioning between competing sinks and finally of plant growth

Multiple functions of carbon and nitrogen in plants

The paper reviews recent progress in knowledge of multiple functions played by carbon and nitrogen in plants, of assimilation and metabolism of these elements and of their role as signaling molecules. Special attention is paid to the relationship between photosynthetic production of carbohydrates and their reoxidation in respiration yielding energy required for nitrogen assimilation. Integration of these processes takes place at intracellular, intercellular and interorgan levels. The role of vegetative storage proteins (VSp) and starch, as storage substances, as well as regulatory function of trehalose is presented, especially under stress conditions. Sugars and nitrogen metabolites (nitrate and ammonium) function as signals of plant current status of the C/N ratio at various level of its organization: from regulation of gene expression to growth rate of shoot and root. This allows quick modification of nitrate or amonia uptake and, in consequence, of the program of plant growth. Changes of environmental conditions affecting assimilation and metabolism of carbon and nitrogen may cause plant starvation and a disproportion in the C/N ratio. plants must therefore regulate sophistically cross-talk between carbon and nitrogen metabolism to ensure their homeostasis