The role of fructan in stress responses

Authors: LIVINGSTON, DAVID; HEYER, ARND - STUTTGART UNIVERSITY; KIRTEL, ONUR - UNIVERSITY OF MARMARA

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 3/15/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fructan is a fructose-based carbohydrate that is a short-term storage compound in plants. Many plants that store fructan have been found with fructan levels that correlate with the ability to withstand drought and freezing stress. This chapter in “The Book of Fructan” reviews literature on how carbohydrates, resulting from fructan breakdown, are related to freezing and drought stress. In addition, it has been shown that fructan can impact the stability of membranes, which can help protect plants from freezing and drought damage. Numerous studies have been conducted on the genetic transformation of various species, such as tobacco, which normally does not synthesize fructan, with the ability to produce fructan. In this case the transformed plant was able to withstand colder temperatures than normal, which confirmed the effect fructan has on the ability of plants to withstand stresses caused by the environment. Also discussed is the ability of microbes to withstand stress caused by high salt content. Microbes can form colonies on various surfaces that are interconnect with biofilms. These films are able to withstand detrimental effects of high salt content due to the secretion of fructan into the matrix of the films. From the diverse studies as early as 1935 up to the present it is clear that fructan is a very important compound used by plants and microbes to withstand a variety of environmental stresses.

Technical Abstract: Fructan has been correlated in numerous studies with the ability of a plant to withstand abiotic stress. This chapter summarizes the research on attempts to move beyond correlation and establish causal mechanisms to explain numerous examples of fructan apparently conferring freezing and drought tolerance to plants. Research is discussed that describes studies as early as 1935 where fructan was likely first recognized as a factor in freezing tolerance of wheat. Originally, osmotic protection was considered a likely explanation for the correlation of fructan and freezing tolerance but other research seemed to contradict this hypothesis. When it was established that membrane rupture was the primary means of damage from freezing and drought, studies were conducted that demonstrated in detail how fructan is able to stabilize membranes as freezing progresses. Also summarized are numerous studies that used genetic transformation to unequivocally confirm the relationship of fructan and abiotic stress tolerance as well as provide a basis for transforming important crop plants to make them more stress tolerant. The relationship of microbes and their biofilms to fructan is discussed and makes a case for the need of more research since the mechanism of protection of microbes from abiotic stress (primarily from salinity) is an important aspect of biological life. Abiotic stress is arguably the most important restriction to growing crops on Earth and discovering how fructan is involved will provide breeders and physiologists crucial information to modify plants to better respond to changes in climatic conditions.