Biotechnology Coronatine Has A Significant Effect On Color Improvement And Sugar Increasing In Fruits
1. Global Fruit Color Conversion Issues And Demand
In recent years, the concept of “green and natural” has become popular, and people’s demand for fruits is increasing day by day. The concept of “superfood” is popular in North America, Japan, Australia, and some European countries, with various fruits such as apples, strawberries, figs, blueberries, guava, and kiwifruit being referred to as “superfood” (“superfood” refers to a variety of foods that can provide high energy and nutrients, provide the energy needed by the human body, improve dietary habits, and not only provide rich nutrition, but also be grown in an environmentally friendly manner). However, fruits all over the world are generally faced with the problem of color change. The appearance quality of fruits is seriously affected by slow coloring, non coloring, and turning green after coloring during the color change period, and the market value, processing use, and quality of processed products of fresh fruits and vegetables are greatly affected [1]. According to production calculations, among the top ten global fruits in 2019, seven types, including bananas, oranges, apples, grapes, peaches, pineapples, and plums, had a demand for early release of “coloring improvement and sugar content increasing”, accounting for over 90% of the global fruit production. Conservatively, the current color conversion market capacity is estimated to be billions of dollars.
2. Global Fruit Color improvement Solutions
Previous studies have shown that the color of fruits is the result of highly modified pigments such as chlorophyll, carotenoids, and anthocyanins [2], which are determined by genetic factors and also influenced by external environment and cultivation measures. Chlorophyll and carotenoids determine the base color, while anthocyanins determine the surface color. The combination of base color and surface color can combine to form different appearance colors. This process is accompanied by the metabolism of internal cell walls of fruits, the accumulation of aromatic compounds antioxidant and polyphenol synthesis, hormone content changes, ultimately reaching an edible level, gradually exhibiting the inherent color and aroma of the variety [3-5]. Therefore, regulating the synthesis of characteristic pigments, the synthesis of mature related metabolites, and changes in hormone content are the key to uniform fruit coloring and quality improvement.
At present, among the main color conversion products in the market, the requirements for the use time and dosage of growth regulators (ethephon) are relatively strict. If there is a slight mistake, the fruits may become soft, dark, easy to fall off, the storage and transportation resistance of the fruit may decrease, and even cause many problems such as defoliation and tree vigor decline [6-7]. Biostimulants (peptides, enzymes, active molecules, etc.) are expensive and have different color conversion effects. Nutritional color conversion products are mostly registered and sold as amino acid water-soluble fertilizers or organic water-soluble fertilizers, with strict usage requirements and multiple uses. Under adverse conditions, color conversion effects cannot be guaranteed. Therefore, the market urgently needs a green, safe, and effective color conversion product to solve the above problems.
How to regulate the ordered changes of characteristic pigments, ripening related metabolites, and hormones during the color transformation process is the key to solving the problem of fruit color transformation and quality improvement. The new plant growth regulator COR, brand name “Sweet Crown”, provides a solution to the global fruit color change problem. As a jasmonic acid molecular signal regulator, the main component of “Sweet Crown”,CORONATINE, activates anthocyanin, anthocyanidin and other biosynthetic pathways by inducing plant gene expression, improves the accumulation of photosynthetic rate, internal proteins, amino acids, sugars and other substances, and solves the problem of fruit color conversion.The key issue in the ripening process is to promote uniform fruit coloring and quality improvement.
3. Novel Plant Growth Regulators Coronatine
3.1 The Discovery Of Coronatine
CORONATINE (COR) is a newly developed plant growth regulator that exists in natural plants and is non-toxic and harmless to humans and animals. In 1977, Ichihara et al. separated it from the culture medium of Pseudomonas syringae pv. atropurpurea and named it Coronatine (COR)[10]. It is a biological toxin that can cause verticillium wilt in plants at high concentrations. Later studies found that the physiological function of this ingredient is similar to that of jasmonic acid, abscisic acid, etc.. Finally, it was renamed as Coronatine on May 3, 2013, led by Chengdu Newsun Crop Science Co., Ltd. and approved by the China Standardization Technical Committee.
Fig.1: Mechanism of action of COR
3.2 The Industrialization Road Of Coronatine
Since the discovery of Coronatine in 1977, how to efficiently obtain Coronatine product has always been a hot topic in Coronatine related research. After years of research and exploration, two synthetic methods, chemical synthesis and biosynthesis, have been established for the synthesis of Coronatine. However, both methods have their own shortcomings. The chemical synthesis of Coronatine is cumbersome and the yield is low, and the production capacity of wild strains fermented by microorganisms is generally low, which cannot meet the requirements of current industrial production. In addition, there are also problems such as low yield, long fermentation cycle, high energy consumption, and high production costs, The slow progress in the industrialization of Coronatine has greatly affected its application in agriculture. With the global emphasis on the development and application of new, safe, and efficient pesticides, China has taken the lead in launching relevant high-tech research and development plans. After 20 years of scientific research, it has successfully used transposon induced mutation, gene recombination, and other methods to construct genetically engineered bacteria with high yield of Coronatine, increasing the production of Coronatine by more than 10 times. And established the world’s first Coronatine fermentation production line at Chengdu Newsun Crop Science Co., Ltd. Afterwards, the industrialization of Coronatine has developed rapidly, with membrane concentration, recrystallization and other Coronatine extraction and purification technologies optimized for nutrition, solving the problems of low fermentation potency and yield of Coronatine. Currently, fermentation technology, extraction process, production costs, and other aspects have met the requirements of Coronatine industrialization production. According to the China Pesticide Information Network, in September 2021, Chengdu Newsun Crop Science Co., Ltd. officially obtained the world’s first 98% Coronatine TC Registration Certificate (registration certificate number: PD20211351) and the world’s first 0.006% Coronatine SL Registration Certificate (registration certificate number: PD20211370).
3.3 Notable Functions And Mechanism Of Action Of Coronatine
Coronatine (COR) is a structural analog of Jasmonic Acid (JA). Studies have found that COR is 100-10000 times more active than Jasmonic Acid (JA) by binding to JA receptor COI1 (COR sensitive 1) [11], showing different application effects at different concentrations [12]. When COR enters plant cells, it generates two signal branches, one of which is the hormone system. COR and JA share a common receptor, COI1. The receptors for IAA, JA, and gibberellin are SCF complexes composed of ASK, CUL, and RBX. Therefore, COR can affect the IAA, JA, and gibberellin pathways through receptor COI1; COR also promotes stomatal reopening through the E3 ligase subunit COI1, and the pathway of stomatal closure involves triggering salicylic acid (SA) and abscisic acid (ABA) signaling pathways; Due to the similarity between the precursor ACC of ethylene and the precursor CMA of COR, COR can increase the production of ethylene in plants. In short, COR can manipulate almost all hormone signaling pathways, which is also the reason why coronamycin can regulate many physiological and chemical processes such as plant growth and development and stress. Another signal branch is physiological metabolism. COR induces upregulation of protein expression levels, regulating the cell membrane system, osmotic regulation, photosynthesis system, and antioxidant system, helping plants resist stress damage.
4. Application Of Fruit Coloring Enhancement And Sugar Content Increasing Of Coronatine
Transcriptome and metabolome studies have shown that moderate concentrations of COR (1-10 μM) can directly or indirectly stimulate ethylene synthesis to induce plant gene expression, promote the activation of biosynthetic pathways such as anthocyanins and anthocyanidin, as well as the accumulation of high-level anthocyanins in the peel and flesh [13], promote uniform fruit coloring, and improve fruit color and sweetness. A large number of field trials have also verified its correctness.
4.1 The Effect of COR on the Quality of Grape (Summer Black)
The experimental results showed that applying one application of COR during the grape coloring stage can accelerate the color conversion process, complete the conversion 5-7 days earlier, increase the sugar content by 60%, reduce acidity by 22.8%, and improve quality .
4.2 The Effect of COR on the Quality of Apple
The experimental results showed that using one application of COR on apples can significantly improve the coloring rate, achieve more uniform coloring, reach a coloring index of over 95%, far higher than the control group, and significantly improve fruit quality. Among them, the soluble sugar content of the fruit increased by more than 30%
4.3 The Effect of COR on the Quality of Citrus
The experimental results showed that using COR twice on the citrus by foliar spray every 15 days resulted in the entire fruit being colored, with a beautiful red color and almost no turning green phenomenon. However, the control group had partially colored and dark colors, and the taste of the fruit in the COR group was significantly improved during the picking period, with an average increase of about 20% in soluble solids content.
Fig.2: The Effect of COR on the Quality of Citrus
4.4 The Effect of COR on the Quality of Pitaya
The experimental results showed that after using COR during the coloring stage of pitaya, the color was bright, with green scales that did not age, and the quality was significantly improved.
4.5 The Effect of COR on the Quality of Tomato
The experimental results showed that after using COR on tomatoes, the color conversion was completed 7-10 days earlier, resulting in a significant improvement in color and taste, and enhanced commercial value (Figure 4).
Fig. 3: The Effect of COR on the Quality of Tomato
4.6 The Effect of COR on the Quality of Strawberry
The experimental results showed that after using COR on strawberries, the color conversion was completed 4-6 days in advance, with uniform color and significant improvement in color and taste (Figure 5).
Fig. 4: The Effect of COR on the Quality of Strawberry
In summary, as an environmentally friendly biological plant growth regulator, COR can not only improve the external quality of fruits by making them evenly colored and more marketable, but also improve the internal quality by increasing sugar content, balancing sugar acid ratio, improving taste significantly, and solving problems such as “shady fruits” caused by uneven lighting in apples, grapes, citrus, etc. In addition, as an environmentally friendly new plant growth regulator with high physiological activity, COR not only improves the quality of agricultural products, but also inhibits the increase of unnecessary reactive oxygen species levels in plants, reduces the risk of plant fruit softening and rapid cell disintegration, and prolongs the storage and shelf life of the fruit. This will play an increasingly important role in the healthy and fast sweetening and coloring of fruits.
5. The Market Potential Of COR In Fruit Color Conversion And Sugar Content Increasing
With the continuous development and progress of science and technology, the call to reduce the use of chemical pesticides and protect the human living environment is increasing. Research, development and utilization, and the development of green and healthy color conversion products have become one of the important research topics for global scientific workers. As a new plant growth regulator worldwide, COR fundamentally solves the problems of uneven fruit coloring and decreased quality by regulating characteristic pigment synthesis, maturation related metabolite synthesis, and hormone content changes. While promoting fruit coloring, it can also reduce acidity and increase sugar, making the taste of the fruit better, without causing the weakness of soft fruits and tree vigor. Compared to traditional color conversion extraction products, the effective active ingredients of COR are completely present and sourced from natural ecosystems, with no residue after use, and the impact on non target organisms is relatively small. It is safe for the environment and agricultural products, and more in line with the global consumer demand for safe and environmentally friendly inputs. Coronatine is a major trend in the development of green and healthy color conversion products, and the best choice for “uniform coloring and increased sugar content” in fruit cultivation, with broad global application prospects.
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