General mechanisms of drought response and their application in drought resistance improvement in plants

Abstract

Plants often encounter unfavorable environmental conditions because of their sessile lifestyle. These adverse factors greatly affect the geographic distribution of plants, as well as their growth and productivity. Drought stress is one of the premier limitations to global agricultural production due to the complexity of the water-limiting environment and changing climate. Plants have evolved a series of mechanisms at the morphological, physiological, biochemical, cellular, and molecular levels to overcome water deficit or drought stress conditions. The drought resistance of plants can be divided into four basic types-drought avoidance, drought tolerance, drought escape, and drought recovery. Various drought-related traits, including root traits, leaf traits, osmotic adjustment capabilities, water potential, ABA content, and stability of the cell membrane, have been used as indicators to evaluate the drought resistance of plants. In the last decade, scientists have investigated the genetic and molecular mechanisms of drought resistance to enhance the drought resistance of various crops, and significant progress has been made with regard to drought avoidance and drought tolerance. With increasing knowledge to comprehensively decipher the complicated mechanisms of drought resistance in model plants, it still remains an enormous challenge to develop water-saving and drought-resistant crops to cope with the water shortage and increasing demand for food production in the future.

Key plant products and common mechanisms utilized by plants in water deficit stress responses

“…escaping drought, dehydration tolerance/avoidance and desiccation tolerance. In some references, drought resistance is described as the adaptation of plant involving drought avoidance, drought tolerance, drought escape and drought recovery (Fang & Xiong 2015). Since, drought tolerance is characterized by the capability of plants to grow satisfactorily under water deficit condition (Turner 1979).…”

“…In this review four main mechanisms of tolerance are described: Osmotic adjustment.-While available water is decreasing in the soil, the accumulation of additional solutes and ions will occur in order to retain water content of the cell through reducing the osmotic potential (Taiz & Zeiger 2002, Fang & Xiong 2015. This mechanism is called osmotic adjustment, and these solutes are known as compatible solutes, because with their increase, plant metabolism is not disturbed and they are not toxic even in higher concentrations (Yancey et al 1982, Slama et al 2015.…”

“…Dehydrins were observed in response to various abiotic stresses including drought, but its detailed function is not well understood (Cellier et al 2000). LEAs have multiple tasks ranging from maturity in seeds to protection of membrane structure, stabilizing enzymes and promoting ion sequestration in vegetative organs (Close 1997, Garay-Arroyo et al 2000, Fang & Xiong 2015. Another class of proteins known as molecular chaperones (or originally known as HSP: Heat Shock proteins) has been reported under abiotic stress conditions such as drought (Alamillo et al 1995, Alpert & Oliver 2002.…”

Grain Sorghum Response to Water Supply and Environment

“…There are four mechanisms for drought response by plants: drought avoidance, drought tolerance, drought escape, and drought recovery (Fang and Xiong, 2015).…”

“…The two major mechanisms used by crops are drought avoidance and tolerance which refer to the plant's ability to maintain a higher water potential and the ability to maintain functions under a lower water potential, respectively (Fang and Xiong, 2015). Drought occurring before flowering reduces seed number by reducing plant stands, tillering, number of heads, and/or seeds per head; but drought after flowering reduces seed size by reducing transpiration efficiency, CO2 fixation, and carbohydrate translocation (Beyene et al, 2015).…”