Biotechnology COR-Coronatine Brings New Surprises For Crops To Resist Low Temperature, Drought, Salt, Lodging and Increase Yield

1. Harm Caused By Abiotic Stress of Environmental Adversity

With the rapid development of human civilization, the global ecological environment is deteriorating, and agricultural production is facing the double harm of biotic stress and abiotic stress. All kinds of biotic stresses, such as diseases, insects and weeds, which caused by biological factors are unfavorable to plant survival and development, and can be timely prevented and treated through artificial measures, such as fungicides, herbicides and insecticides. However, abiotic stresses, including salinity, flooding, low temperature, high temperature, drought, excessive light, ultraviolet radiation, oxygen deficiency, strong wind, and pollution of air, soil or water, are generally uncontrollable. Once occur, the harm is wide and with high degeree., which are not conducive to the survival and growth of plants, and even lead to injury, destruction and death. Taking climate warming as an example, by 2017, the temperature of climate warming caused by human activities had increased by 1 ℃ (0.8-1.2 ℃) compared with that before industrialization, and now it is increasing at the rate of 0.2 ℃ every 10 years. The impact of global warming on agriculture is mainly due to more frequent and large-scale extreme weather, changes in precipitation and expansion of some desert areas.

From Y.Xu；The Crop Journal.2021

Fig. 1: Trend of Global Climate Change

Abiotic stresses such as drought, high temperature, cold damage and salt damage restrict the normal growth of crops. According to statistics, 60%~80% of crop yield loss is caused by abiotic stress. Under these abiotic stress conditions, crop growth is inhibited, seedling quality is reduced, and serious damage are caused to plnat for its immume of disease, nutritional growth and reproductive growth, which has brought great economic losses to human beings. In particular, extreme weather has become more and more frequent in recent years, which will aggravate the adverse impact of abiotic stress on global agricultural production [1]. Research has found that under the scenarios of high and low emissions, by 2050, under the extreme climate events that occur once every 100 years, 20-36% and 11-33% of the world's population will face hunger respectively. In some affected regions, such as South Asia, the amount of food needed to offset this impact is three times the current food reserves in the region [2]. In 2016, due to the continuous drought caused by El Nino in South Africa, about 14 million people in southern Africa faced the risk of hunger [3]. According to the data released by FAO in 2020, the frequency and time of duration of global drought have increased by 29% compared with that in 2000 [4]. In terms of soil salinization, about 8% of the world's land is threatened by salinization. Most of them are distributed in the natural arid or semi-arid regions of Africa, Asia and Latin America. For 20% to 50% of irrigated soil in all continents, the salinity is too high, which means that more than 1.5 billion people around the world are facing major challenges in food production due to soil degradation [5].

Fig. 2: Medium and long-term development trend of global soil salinity 2031-2060 vs 1961-1990

Due to frequent global extreme weather, the quality of cultivated land has declined sharply, and the growth rate of global grain production is facing a precipitous decline. The world's major food producing areas are the Mississippi Plain in North America, the Laplata Plain in South America, the Niger Plain and Zambezi River Basin in Africa, and the Nile Delta, the Eastern European Plain and Western European Plain, as well as the Indian Plain and Indonesia, and Northeast and North China Plains which are the world's largest food producing areas. Among these regions, Africa, Latin America, the Caribbean and other warmer regions were the most affected, with the growth rate dropping by 26% to 34%. While the growth rate of the United States, the world's largest exporter of agricultural products, also dropped by 5% to 15%. The growth rate of grain production in other regions, such as India and Southeast Asia, has also slowed down to varying degrees [6].

2. New Options For Solving Abiotic Stresses Such As Low Temperature, High Temperature And Drought To Increase Grain Yield

Sustainable, stable and safe food production is imminently need. At present, the world is using plant science to solve the challenges of agriculture after the green revolution, and actively exploring ways to enhance sustainable crop production in the context of climate change.

Ways include those improving crop yield traits, such as fruit/panicle traits and root traits , to improving crop resistance to minimize growth loss, and also include the new methods, such as using techniques of natural genetic variation, genetic engineering and editing, and using beneficial soil or leaf microorganisms to improve the crop or the environment to ensure yield. Among them, improving global crop stress resistance can minimize crop yield loss under abiotic stresses such as floods, droughts, soil salinity and extreme temperatures around the world.

Plant growth regulators are widely used in inducing crops to improve stress resistance, which can alleviate the damage caused by stress to plants and enhance the stress resistance of plants [7]. According to literature reports, treated by 15 mg/L abscisic acid or 900 mg/L paclobutrazol can effectively alleviate salt stress [8] and reduce the damage caused by soil salinization to crops. However, most plant growth regulators have single functions and strict requirements on the use of concentration. In 2021, the world's first industrialized jasmonic acid signal molecule regulator, Coronatine (COR), lauched. The molecular structure of COR is formed by the combination of one molecule of coronamic acid (CMA) and one molecule of coronafacic acid (CFA) through amide bonds, while the molecular structure of coronamic acid is similar to that of jasmonic acid (Figure 3). COR is a structural analog of jasmonic acid (JA). As an environment-friendly biological source plant growth regulator, it can works at very low concentration, and its biological activity is 100~10000 times that of jasmonic acid. Coronatine signaling molecules are involved in the regulation of many physiological processes in plant growth and development, including seed germination under low temperature, stress resistance, disease resistance and yield increase, promotion of fruit color improvement and sugar content increase, and also defoliation, biological weeding, etc.

Under natural conditions such as low temperature, frost and drought, COR can promote the expression of a series of defense genes and the synthesis of defense response components by combining with JA receptor COI1 (COR sensitive 1), regulate the "immune" and "stress" responses of plants, induce plants to produce resistance factors, improve the "resistance" of plants, and reduce the damage of adverse environment to plants [9]. For example, under low temperature conditions, COR can increase the activities of antioxidant enzymes such as SOD, POD and CA in cells, and the content of soluble protein, chlorophyll, soluble sugar and glutathione in the plants to improve the cold resistance of crops. When under salinization stress, COR can increase the content of proline and also abscisic acid in the leaves of crops, and also decrease the content of H₂O₂.

Fig. 3: Structural comparison of Coronatine and Methyl Jasmonate

3. R&D And Industrialization History Of Coronatine

In 1977, Ichihara et al. first isolated Coronatine (COR) from the culture medium of the crimson pathogenic variety of Pseudomonas syringae. It was initially found that it can induce Italian ryegrass to appear chlorosis. Since 1992, Young and others have successively found that Coronatine has similar functions with abscisic acid and jasmonic acid, and has physiological functions such as regulating growth, inhibiting aging, promoting cell differentiation, increasing chlorophyll content and plant resistance. In 1999, Blechert et al. reported that COR can make the tendril spiral of Bryonia dioica, and jasmonic acid (JA) also has this effect, but the physiological activity of COR is higher [10].

Since the discovery of Coronatine, the chemical synthesis of Coronatine has always been a research focus in order to obtain higher content of Coronatine. The chemical synthesis of Coronatine has been deeply studied by Shimin, Hokkaido University, Japan. However, the synthesis process is complex, the cost is high, and it is difficult to carry out industrial production. The utilization of Coronatine is severely limited [11].

With the continuous and in-depth research of scientific research teams in various countries over the years, including the confirmation of the molecular structure, the verification of functions, the breeding of production strains, the optimization of fermentation conditions and the improvement of separation and purification technology, the industrialization of Coronatine has gradually become possible. According to the data, the world's first fermentation production line of Coronatine has been established in Chengdu Newsun Crop Science Co., Ltd., which has solved the problem of low fermentation potency and yield of Coronatine from the source. The industrial production of Coronatine has been realized in terms of fermentation, extraction process, production cost, etc., fully meeting the needs of large-scale production and application promotion. At present, Chengdu Newsun Crop Science Co., Ltd. has obtained two registration certificate: Coronatine 98% TC and Coronatine 0.006% SL, and successfully promoted Coronatine 0.006% SL to the market.

4. COR-Coronatine on Crop Stress Resistance and Yield Increasing

In recent years, more and more research reports on COR focus on the stress resistance of plants. Some studies use corn as experimental material, and find that the growth of corn seedlings under low temperature is inhibited to a certain extent. COR enhances the cold resistance of corn by regulating the growth, cell membrane system, osmotic regulation system, photosynthetic system and antioxidant system of seedlings under low temperature [12].

Low temperature and frost can affect the membrane lipid status and enzyme activity of plant cells, resulting in water loss of plant cells, damage of cell membrane structure, decrease of enzyme activity, etc., thus causing plant metabolism disorder and affecting the normal growth of plants. Coronatine can enhance the resistance of crops to low temperature and reduce damage by improving ATP synthesis and photosynthesis of plants.

4.1 Application of Coronatine on Cotton

Li Jin et al. studied the effect of Coronatine (COR) on the ascorbic acid-glutathione cycle system of the vegetative organs of cotton seedlings under low temperature stress, and found that COR can regulate the ascorbic acid-glutathione cycle system of cotton seedlings, alleviate the damage caused by low temperature to cotton seedlings, and has the strongest mitigation effect on leaves [13].

From Xie Zhixia, Cotton Science, 2012

Fig. 4: Effect of Coronatine on Cotton Growth under Salt Stress

The experiment shows that 0.1 μMol/L of Coronatine can reduce the content of hydrogen peroxide in cotton leaves and leaf damage under high salt stress[14]. Cotton seeds soaking with 0.01 μmol/L of Coronatine for 12 hours, it can improve seed vigor under salt stress, promote germination and seedling growth, and enhance salt tolerance of cotton seedlings [15]. The results of the yield increase test of 0.006% Coronatine SL on cotton in the filed showed that the plant stem diameter, the number of cotton bolls and the weight of bolls in the plot treated with Coronatine were all increased, and the calculated yield was 353.61kg, which was 15.99% higher than that in the control plot (Fig. 5).

Fig. 5: Effect of Coronatine on Cotton Quality and Yield

4.2 Application of Coronatine on Wheat

The seed coating or seed dressing treatment with COR before wheat sowing can effectively prevent the diseases and insects after sowing, and has the effect of promoting seedling growth. The combined use of Coronatine with seed coating product can remove the inhibition of some seed coating products on seed germination, significantly improve the germination rate of wheat. Especially under low temperature conditions, it can germinate early, and the emergence of seedlings is neat and the vitality of seedlings is high (Fig. 6).

Fig. 6: Effect of Coronatine by Coating Treatment on Wheat Germination at Low Temperature

It has been found that under drought stress, spraying 1 µmol/L of Coronatine can increase the plant height, fresh weight, dry weight of winter wheat seedlings, and increase the relative water content, chlorophyll content, and soluble protein content of seedling leaves, which can significantly enhance the drought resistance of winter wheat seedlings [16]. In the wheat field demonstration test, the application of Coronatine twice at the elongation stage and the grain filling stage showed a good adjustment and yield increase effect on wheat. As shown in Figure 7, 0.006% Coronatine with dosage 2000 times dilution can increase the panical length and the number of grains per panicle, thereby improving the yield of winter wheat and spring wheat (Fig. 8).

Fig. 7: Effect of Coronatine on Wheat Panicals

Fig. 8: Effect of Coronatine on Wheat Yield

4.3 Application of Coronatine on Rice

Coronatine can be used on rice by seed dressing before sowing, and also by foliar spray at early and end of heading stage respectively. The results of rice field demonstration test show that, compared with the control, the emergence rate of rice in the plot treated with Coronatine is higher, the seedlings are stronger, the ear length of rice at maturity is increased, the number of grains per ear is increased (Fig. 9), the yield is increased by 18%, and the head rice rate, amylose content and protein content of rice are also increased (Fig. 10).

Fig. 9: Effect of Coronatine on Rice Ear Length

Fig. 10: Analysis results of the experiment of improving quality and increasing yield of rice by Coronatine

4.4 Application of Coronatine on Corn

0.006% Coronatine SL (15-20ml/100kg seeds) was mixed in the process of corn seed coating to increase the germination rate of corn in the field by more than 10%. At the same time, the treatment of Coronatine can promote the formation of root morphology at seedling stage of corn and make corn roots stronger.

Fig. 11: Effect of Coronatine by Seed Coating on Corn Germination

Fig. 12: Effect of Coronatine by Seed Coating on Roots of Corn Seedlings

4.5 Application of Coronatine on Soybean

Soybean is one of the most important crops in the world and one of the fastest growing commodities in the world. The coating of the seed with Coronatine can promote the sprouting and seedling strengthen of soybean seeds under low temperature. The indoor germination experiment results showed that 0.006% COR combined with seed coating agent by coating treatment of soybean could promote the germination rate of soybean seeds under the low temperature of 5 ℃, and improve the root activity of soybean seedlings (Fig. 13-14). Coronatine by foliar spray regulates the morphogenesis of soybean plants and increases the number of branches and pods (Fig. 15-16).

Fig. 13: Effect of Coronatine by seed coating on germination rate of soybean

Fig. 14: Effect of Coronatine by seed coating on germination rate of soybean

Fig. 15: Effect of integrated treatment of Coronatine on soybean morphogenesis

Fig. 16: Effect of integrated treatment of Coronatine on soybean morphological indexes

Coronatine in combination with NPK water-soluble fertilizer and seed coating agent on soybean is integrated to use together. The Coronatine has good resistance to low temperature at soybean seedling stage, which can improve the low temperature resistance of soybean and increase the emergence rate of soybean. It also has good control effect on soybean root rot, brown streak, harrow spot and soybean aphid.

Fig. 17: Effect of integrated treatment of Coronatine on germination rate and root rot of soybean

5. Market Prospect of COR Coronatine

In 2019, the UN World Population Outlook 2019 report pointed out that the global population is expected to increase from 7.7 billion in 2019 to 9.7 billion in 2050 [17]. By the end of this century, the global population will reach about 11 billion. According to the current crop output, it will be not enough to meet the food needs of global population. Therefore, solving the crop yield reduction caused by the deterioration of global climate and agricultural ecological environment is crucial to the world food security. It is a very critical core technical means for future global agricultural development and food security to take crop chemical control technology as a means, and make full use of new plant growth regulators to improve the ability of crops to resist low temperature, high temperature, drought and other stresses, enhance crop productivity, and ensure yield and quality. The new plant growth regulator COR-Coronatine, as a biological source of plant growth regulator, is safer for the environment and agricultural products, widely used in the main food and cash crops rice, corn, soybean, cotton, and has great significance in increasing food production, improving food security, and ensuring the healthy and sustainable development of global agriculture.


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