Method for improving salt tolerance of fresh corn seedlings

Abstract

The invention provides a method for improving salt tolerance of fresh corn seedlings, which comprises the following steps: in corn seedling culture, treating by using Met with the concentration of 0.1-1.0 mmol / L; in the treated corn seedlings, the MDA content is reduced, the CAT activity is improved, the POD activity is improved, the SOD activity is improved, and the anthocyanin content is improved; the plant height, the stem diameter, the fresh weight and the dry weight of the fresh corn seedlings are remarkably improved, and the purpose of improving the salt tolerance of the fresh corn seedlings is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of crop planting, and in particular to a method for improving the salt tolerance of fresh corn seedlings. Background Art

[0002] Salt stress is one of the abiotic stresses that seriously affects the growth and development of crops, and can lead to reduced or even complete crop failure. According to statistics, about 800 million hectares of arable land in the world are affected by soil salinization, and at least 20% of crop production in irrigated soils is affected. Every year, about 2 million hectares (about 1%) of agricultural land is rapidly salinizing. It is urgent to improve the growth and production of crops on salinized soils, breed new varieties of salt-alkali-tolerant crops, and improve the utilization rate of salinized soils.

[0003] Soil salinization has a negative impact on the growth of crops. For example, salt stress can cause osmotic stress, ion poisoning and oxidative stress to plants. Under salt stress, reactive oxygen species (ROS) accumulate in large quantities in plants, breaking the balance between the production and elimination of ROS, causing damage to cell membranes, affecting intracellular material exchange, and causing imbalance in cell osmotic regulation. Excessive accumulation of ROS can also damage proteins, membrane lipids and DNA, ultimately having a negative impact on major plant processes such as protein synthesis, energy and lipid metabolism. Excessive accumulation of sodium ions interferes with many physiological processes of plants. The absorption of excessive sodium and chloride ions leads to calcium and potassium ion deficiency in plants, resulting in nutritional imbalance and other problems. Ion stress causes excessive accumulation of sodium ions in leaves and premature aging of old leaves. Osmotic stress leads to water deficit, inhibition of leaf extension, stomata closure, and ultimately inhibition of photosynthesis, affecting growth.

[0004] In order to cope with osmotic stress and ion stress, plants have developed different stress defense mechanisms, such as changes in plant morphology (organelle morphology, self-morphology), osmotic regulation, ion regulation, and antioxidant systems. Among them, plant osmotic regulation substances include organic solutes such as proline, betaine, soluble sugars, and inorganic salt solutes such as calcium ions and potassium ions. SOS1 , HKT1 , SOS2 , SOS3 Genes maintain ion homeostasis in plants by regulating the entry and exit of ions; under salt stress, plants accelerate the removal of reactive oxygen by increasing the levels of non-enzymatic antioxidants such as ascorbic acid, glutathione, and enzymatic antioxidants such as superoxide dismutase, catalase, and peroxidase.

[0005] As the largest crop in my country, corn has made important contributions in many aspects such as food, feed production and industrial raw materials. Fresh corn is popular among consumers because of its good taste and rich nutrition. At the same time, fresh corn has high added value and planting can bring more income, so the planting of fresh corn has received widespread attention. Fresh corn is sensitive to salt stress, and soil salinization can significantly affect the growth and yield of fresh corn. Therefore, it is extremely important to improve the tolerance of fresh corn to salt stress. Summary of the invention

[0006] In view of this, the present invention provides a method for improving the salt tolerance of fresh corn seedlings, specifically a method for watering the seedlings at the two-leaf and one-heart stage with Met at a concentration of 0.1-1.0 mmol / L, which can significantly reduce the MDA content, increase the CAT activity, POD activity, SOD activity and anthocyanin content under the condition of a salt concentration of 100 mmol / L. The method has the advantages of being simple and easy to implement, low cost, harmless to the human body and the environment, and easy to carry out large-scale operation.

[0007] The technical solution of the present invention is as follows: A method for improving the salt tolerance of fresh corn seedlings, comprising: treating the corn seedlings with Met at a concentration of 0.1-1.0 mmol / L during cultivation; in the treated corn seedlings, the MDA content decreases, the CAT activity increases, the POD activity increases, the SOD activity increases, and the anthocyanin content increases.

[0008] Preferably, the concentration of Met is 0.1 mmol / L.

[0009] Preferably, the fresh-eating corn includes salt-sensitive varieties and salt-tolerant varieties.

[0010] Preferably, when this method is used in salt-sensitive varieties, the MDA content decreases more significantly, the CAT activity increases more significantly, the POD activity increases more significantly, the SOD activity increases more significantly, and the anthocyanin content increases more significantly.

[0011] Preferably, the salt-sensitive fresh-eating corn varieties are LNX021 and LTX005; and the salt-tolerant varieties are LTN193, LN133, LN121 and LN176.

[0012] Preferably, the fresh-eating corn seedlings are seedlings with two leaves and one heart.

[0013] Methionine (Met) belongs to the aspartate family of amino acids, is a nutritionally essential amino acid, and is an essential amino acid in all organisms. In addition to being an important component of protein synthesis and playing a core role in the initiation of mRNA translation, methionine, as a direct precursor of S-adenosylmethionine (SAM), indirectly plays an essential role in important physiological and metabolic activities such as the methylation of proteins, RNA, and DNA.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. In the present invention, the seedlings in the two-leaf and one-heart stage were irrigated with Met at a concentration of 0.1-1.0 mmol / L. Under the condition of a salt concentration of 100 mmol / L, the MDA content was significantly reduced, and the CAT activity, POD activity, SOD activity and anthocyanin content were increased.

[0015] 2. The method provided by the present invention significantly improves the plant height, stem thickness, fresh weight and dry weight of fresh corn seedlings, thereby achieving the purpose of improving the salt tolerance of fresh corn seedlings.

[0016] 3. The method of the present invention has the advantages of being simple, easy to operate, low cost, harmless to human body and environment, and easy to carry out large-scale operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This study shows the effect of exogenous application of different concentrations of methionine on the seedling phenotype of a salt-sensitive variety (LNX021) under salt stress.

[0019] Figure 2 This study shows the effect of exogenous application of different concentrations of methionine on the seedling phenotype of a salt-tolerant variety (LTN193) under salt stress.

[0020] Figure 3 To investigate the effects of exogenous application of different concentrations of methionine on the plant height, stem diameter, fresh weight and dry weight of LNX021 seedlings under salt stress.

[0021] Figure 4 To investigate the effects of exogenous application of different concentrations of methionine on plant height, stem diameter, fresh weight and dry weight of LTN193 seedlings under salt stress.

[0022] Figure 5Figure 2 shows the root MDA and Na concentrations of LNX021 under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / L Met +100 mmol / L NaCl). + Content, antioxidant enzyme activity and leaf anthocyanin content were determined.

[0023] Figure 6 Figure 2 shows the root MDA and Na concentrations of LTN193 under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / L Met +100 mmol / L NaCl). + Content, antioxidant enzyme activity and leaf anthocyanin content were determined.

[0024] Figure 7 The phenotypes of LN133 seedlings under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl).

[0025] Figure 8 Plant height, stem diameter, fresh weight and dry weight of LN133 under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl).

[0026] Fig. 9 The phenotypes of LTX005 seedlings under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl).

[0027] Fig.10 Plant height, stem diameter, fresh weight and dry weight of LTX005 under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl).

[0028] Fig.11 The phenotypes of LN121 seedlings under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl).

[0029] Fig.12Plant height, stem diameter, fresh weight and dry weight of LN121 under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl).

[0030] Fig.13 The phenotypes of LN176 seedlings under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl).

[0031] Fig.14 Plant height, stem diameter, fresh weight and dry weight of LN176 under different methionine treatments (0, 100 mmol / L NaCl, 0.1 mmol / L Met, 0.1 mmol / LMet +100 mmol / L NaCl). DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] Example 1 1. Seedling cultivation: Select full, uniform, and uniform-sized corn kernels of different varieties and place them in a square pot (40 cm in length, 26 cm in width, and 15 cm in height) filled with 5 cm of vermiculite. After sowing evenly, cover the surface with 1 cm of vermiculite. Water thoroughly with tap water for the first time and cover with plastic wrap to retain moisture. After four days of cultivation, the film was removed and the seedlings with good and uniform germination were carefully transplanted into pots (10 cm in diameter, 8.5 cm in height), 6 plants per pot, and watered with tap water until they grew to two leaves and one heart. 2. Processing Treatment solution: Deionized water was used to prepare the solution. The concentrations of Met were 0.1 mmol / L, 0.5 mmol / L, and 1 mmol / L respectively. Treatment 1 (CK): no NaCl and no Met added; Treatment 2: 100 mmol / L NaCl; Treatment 3: 0.1 mmol / L Met; Treatment 4: 0.1 mmol / L Met +100 mmol / L NaCl; Treatment 5: 0.5 mmol / L Met; Treatment 6: 0.5 mmol / L Met +100 mmol / L NaCl; Treatment 7: 1 mmol / L Met; Treatment 8: 1 mmol / L Met + 100 mmol / L NaCl; see Table 1, as follows: Table 1 Treatment groups

[0034] The seedlings were watered according to the above settings, with 30 plants in each treatment, and the treatment solution was watered every 3 days. They were placed in an artificial climate chamber for cultivation with a light / dark cycle of 16 / 8 h, a light intensity of 8000-10000 lx, a relative humidity of 65%, and a temperature of 26±2℃. After 15 days of treatment, the plant height, stem diameter, fresh weight and dry weight of the seedlings were tested; and the MDA, CAT activity, POD activity, SOD activity and anthocyanin content of the roots were tested.

[0035] 3. Experiment Experiment 1: Phenotype, plant height, stem diameter, fresh weight and dry weight of seedlings (2) The corn variety used was the salt-sensitive variety LNX021; the results after 15 days of treatment are shown in Figure 1 , Figure 3 ; Combination Figure 1 A shows that, in the absence of salt stress, compared with treatment 1 (CK, no NaCl and no Met added), the use of Met treatment solution can significantly promote the growth of corn seedlings; Combination Figure 3 It can be seen that without salt stress, the plant height, stem diameter, fresh weight and dry weight of the plants treated with Met solution were significantly higher than those of treatment 1; Combination Figure 1 B shows that under salt stress, Met can improve the salt tolerance of sensitive corn. Compared with treatment 2 (100 mmol / L NaCl), the plants in treatments 4 (0.1 mmol / L Met +100 mmol / L NaCl), 6 (0.5 mmol / L Met+100 mmol / L NaCl) and 8 (1 mmol / L Met +100 mmol / LNaCl) grew better and had lower leaf wilting. Among them, the plants in treatments 4 and 6 grew better and had lower leaf wilting than those in treatment 8, which shows that the concentration of Met can affect plant growth. Combination Figure 3 It can be seen that under salt stress, after using Met treatment solution, the plant height, stem diameter, fresh weight and dry weight of the plants were significantly higher than those of treatment 2; (2) The corn variety used was the salt-tolerant variety LTN193; the results after 15 days of treatment are shown in Figure 2 , Figure 4 ; Combination Figure 2 A shows that in the absence of salt stress, compared with treatment 1 (CK, no NaCl and no Met added), the use of Met treatment solution can significantly promote the growth of corn seedlings; however, compared with the salt-sensitive variety LNX021, the promotion effect is slightly lower; Combination Figure 4 It can be seen that without salt stress, after using Met treatment solution, the plant height, stem diameter, fresh weight and dry weight of the plants were higher than those of treatment 1, among which treatments 4 and 6 had more significant effects; Combination Figure 2 B shows that under salt stress, the plant height, stem diameter, fresh weight and dry weight of treatments 4, 6 and 8 were all higher than those of treatment 2, among which the difference between the plant height of treatments 4, 6 and 8 and that of treatment 2 was the most significant; Combination Figure 4 It can be seen that under salt stress, after using Met treatment solution, the plant height, stem diameter, fresh weight and dry weight of the plants were significantly higher than those of treatment 2; Combined with the above results, it can be seen that the use of Met treatment solution in the present invention can promote the growth of fresh corn seedlings with or without salt stress; among them, under salt stress conditions, treatment 4 (0.1 mmol / L Met +100 mmol / LNaCl) has the best effect.

[0036] Experiment 2: Results of MDA content, CAT activity, POD activity, SOD activity and anthocyanin content Based on the results of Experiment 1, the salt-sensitive and salt-tolerant varieties had the best effect of improving salt stress damage under salt stress conditions with the lowest cost after using Met at a concentration of Treatment 4 (0.1mmol / L Met +100mmol / L NaCl). Therefore, the roots of plants after treatments 1 (CK), 2 (100mmol / L NaCl), 3 (0.1mmol / L Met) and 4 (0.1mmol / L Met +100mmol / L NaCl) were measured for MDA content, Na + The content, CAT activity, POD activity, SOD activity and anthocyanin content in leaves were determined. The results are shown in Figure 5 and Figure 6 ; (2) Salt-sensitive variety LNX021 Combination Figure 5 A shows that under treatment 2, the root MDA content of the salt-sensitive variety LNX021 increased significantly. Although the MDA content of treatment 4 increased compared with treatments 1 and 3, the increase was significantly lower than that of treatment 2; that is, Met can reduce the increase of MDA. Combination Figure 5 B shows that the Na + Compared with the Na content in treatment 2 + The content has decreased to a certain extent; Combination Figure 5 C shows that the CAT activity of treatment 2 is significantly lower than that of treatment 1, while the CAT activity of treatment 4 is significantly higher than that of treatment 2 and treatment 1; Combination Figure 5 D shows that there is no significant difference in POD activity among treatments 1, 2 and 3, but the POD activity of treatment 4 is significantly increased; Combination Figure 5 E shows that the SOD activity of treatment 2 is significantly higher than that of treatment 1, and the SOD activity of treatment 3 is significantly higher than that of treatment 1 and treatment 2; and the increase of SOD activity in treatment 4 is more significant; Combination Figure 5 F shows that the anthocyanin content of treatment 4 is significantly higher than that of treatment 1, treatment 2 and treatment 3; It can be seen that the application of Met can significantly improve the salt tolerance of corn seedlings. This process is mainly achieved by increasing the activity of CAT, POD and SOD and increasing the content of osmotic regulating substances such as anthocyanins.

[0037] (2) Salt-tolerant variety LTN193 Combination Figure 6 A shows that the root MDA content of salt-tolerant variety LTN193 in treatment 3 was not significantly different from that in treatment 1, and the MDA content in treatment 4 was not significantly different from that in treatment 2. Combination Figure 6 B shows that under salt stress conditions, treatment 4 can reduce Na + This indicates that applying methionine under salt stress can reduce Na + accumulation of Combination Figure 6 C shows that under salt stress conditions, CAT activity is significantly reduced (comparison between treatment 2 and treatment 1); under salt stress conditions, the application of Met can effectively increase CAT activity (treatment 4 and treatment 2), and the effect is significant; Combination Figure 6D shows that the root POD activity of treatment 1 and treatment 3 is not much different; while the POD activity of treatment 2 and treatment 4 is significantly higher than that of treatment 1, and the POD activity of treatment 4 is the strongest; Combination Figure 6 E shows that the root SOD activity of treatment 1 and treatment 3 is not much different; while the SOD activity of treatment 2 and treatment 4 is significantly higher than that of treatment 1, and the SOD activity of treatment 4 is the strongest; Combination Figure 6 F shows that the anthocyanin content of treatment 1 and treatment 3 is not much different; while the anthocyanin content of treatment 2 and treatment 4 is significantly higher than that of treatment 1, and the anthocyanin content of treatment 4 is the highest; Combination Figure 5 and Figure 6 It can be seen that compared with the salt-sensitive variety LNX021, the POD activity and SOD activity of the salt-tolerant variety LTN193 are significantly higher than those of the salt-sensitive variety LNX021, which may also be one of the key factors for its strong salt tolerance; the application of Met further increased the activity of CAT, POD and SOD, increased the accumulation of osmotic regulating substances such as anthocyanins, thereby improving its tolerance to salt stress.

[0038] Combining Experiment 1 and Experiment 2, it can be seen that applying methionine at the seedling stage can improve the salt tolerance of fresh corn seedlings, and the promoting effect is more significant for salt-sensitive varieties. Among them, the optimal concentration of methionine is 0.1 mmol / L; the application of methionine is simple, and the operation is convenient and feasible.

[0039] Example 2 Select LN133 corn varieties and place them in a square pot (40 cm in length, 26 cm in width, and 15 cm in height) filled with 5 cm of vermiculite. After sowing evenly, cover the surface with 1 cm of vermiculite, water thoroughly with tap water for the first time, and cover with plastic wrap to keep moisture. After four days of cultivation, the film was removed and the seedlings with good and consistent germination were carefully transplanted into pots (10 cm in diameter, 8.5 cm in height), with 4 plants in each pot. They were irrigated with tap water and were treated with treatment 1 (CK, 0), treatment 2 (100 mmol / L NaCl), treatment 3 (0.1 mmol / L Met), and treatment 4 (0.1 mmol / L Met +100 mmol / L NaCl) when they grew to two leaves and one heart. After 15 days, observe the phenotypic changes of the plants. Figure 7 ; Plant height, stem diameter, fresh weight and dry weight were measured. Figure 8 ; Combination Figure 7 It can be seen that under salt stress conditions, plant growth was restricted, while the application of Met effectively promoted plant growth (treatment 4); Combination Figure 8 It can be seen that compared with treatment 1, treatment 2 significantly reduced the plant height, stem diameter, fresh weight and dry weight of the plants; after the application of Met, treatment 4 significantly increased the plant height, stem diameter, fresh weight and dry weight compared with treatment 2; and there was little difference between treatment 4 and treatment 1; this shows that the application of 0.1 mmol / L Met can significantly improve the plant's tolerance to salt stress, thereby reducing the damage of salt stress to the plants.

[0040] Example 3 The kernels of three maize varieties, LTX005, LN121 and LN176, were selected and placed in square pots (40 cm in length, 26 cm in width and 15 cm in height) filled with 5 cm of vermiculite. After being sown evenly, the surface was covered with 1 cm of vermiculite. The seeds were irrigated with tap water for the first time and covered with plastic wrap to retain moisture. After four days of cultivation, the film was removed and the seedlings with good and consistent germination were carefully transplanted into pots (18 cm in diameter, 12 cm in height) filled with clean sand and watered with Hoagland's nutrient solution. When they grew to two leaves and one heart, they were treated with treatment 1 (CK, 0), treatment 2 (100 mmol / L NaCl), treatment 3 (0.1 mmol / L Met), and treatment 4 (0.1 mmol / L Met +100mmol / L NaCl). After 15 days, observe the phenotypic changes of the plants. Fig. 9 , Fig.11 and Fig.13 ; Plant height, stem diameter, fresh weight and dry weight were measured. Fig.10 , Fig.12 and Fig.14 ; Combination Fig. 9 , Fig.11 and Fig.13 It can be seen that under treatment 4, the plant height, fresh weight and dry weight of the three varieties LTX005, LN121 and LN176 were higher than those in treatment 2. Except for LN176, the stem diameter of LTX005 and LN121 was also higher than that in treatment 2, indicating that the application of 0.1 mmol / L Met under sand culture conditions can also significantly improve the plant's tolerance to salt stress, thereby reducing the damage of salt stress to the plant.

[0041] Although the present invention has been described in detail by reference to the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for improving the salt tolerance of fresh corn seedlings, characterized in that: In the culture of corn seedlings, Met at a concentration of 0.1-1.0 mmol / L was used for treatment; in the treated corn seedlings, the MDA content decreased, the CAT activity increased, the POD activity increased, the SOD activity increased, and the anthocyanin content increased.

2. The method for improving salt tolerance of fresh corn seedlings according to claim 1, characterized in that: The concentration of Met is 0.1 mmol / L.

3. The method for improving salt tolerance of fresh corn seedlings according to claim 1, characterized in that: The fresh-eating corn includes salt-sensitive varieties and salt-tolerant varieties.

4. The method for improving salt tolerance of fresh corn seedlings according to claim 3, characterized in that: When this method was used in salt-sensitive varieties, the MDA content decreased more significantly, the CAT activity increased more significantly, the POD activity increased more significantly, the SOD activity increased more significantly, and the anthocyanin content increased more significantly.

5. The method for improving salt tolerance of fresh corn seedlings according to claim 3, characterized in that: The salt-sensitive fresh-eating corn varieties are LNX021 and LTX005; the salt-tolerant varieties are LTN193, LN133, LN121 and LN176.

6. The method for improving salt tolerance of fresh corn seedlings according to claim 1, characterized in that: The fresh-edible corn seedlings are seedlings with two leaves and one heart.

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