Effects Of Putrescine And Salicylic Acid On Low Temperature Stress Of Tomato And Arabidopsis Thaliana Seedlings

As a common facility of crop production, low temperature will lead to the decrease of crop growth, yield and quality. Tomato as a thermophilic vegetable, it is sensitive to low temperature. While in the north of China in early spring and autumn season of tomato production, low temperature stress will seriously affect its yield and quality.Polyamines (PAs) is a kind of small molecule, widely exist in various organisms. In addition, exogenous PAs also have been shown to induce plant response to various environmental stresses such as drought tolerance, salt and low temperature and heavy metal stress Salicylic acid (SA) as an important plant hormone, it can protect plants from various environmental stresses, such as low temperature, high temperature, salt and heavy metal stress. In addition, SA as a signal molecule is particularly important, it may also with some plant hormonesto regulate of plant defense responses in adversity.PAs and SA can induce plant resistance to low temperature stress, then they in the induction of plant response to low temperature stress, improve plant tolerance and whether there is a certain relationship? At present, the relevant reports are relatively few. Therefore, in this paper, tomato (Lycopersicon esculentum Mill.) and wild type Arabidopsis (Arabidopsis thaliana) and SA mutant "NahG" as the test material, by exogenous putrescine (Put), D-arginine (D-Arg) and SA treatments, the changes of gene expression under low temperature stress in tomato and Arabidopsis seedlings of endogenous PAs, SA, polyamine metabolism enzymes,and SA metabolism key enzymes gene expression. The experimental results are as follows:1. Tomato and Arabidopsis wild type and mutant seedlings were Put, D-Arg, SA spraying and spraying D-Arg+SA treatment,1d after treatment at low temperature on the seedling (4℃) for 3d, then the normal temperature for 3d. The results showed that the exogenous Put, SA treatmenst by improving tomato and Arabidopsis seedlings of Fv/Fm, reduceed their conductivity, MDA and Pro contents, alleviated low temperature stress caused by light inhibition, decreased the osmotic adjustment substance contents, alleviated the plant cell membrane lipid peroxidation, and relieved the damage of plants caused by low temperature stress, D-Arg treatment exacerbated the damage to plants caused by low temperature stress, D-Arg+SA treatment could alleviate the damage.2.Application of exogenous Put significantly increased the low temperature stress of tomato and Arabidopsis seedlings in endogenous SA accumulation, D-Arg treatment had significantly reduced the accumulation of endogenous SA, and exogenous application of SA significantly increased the contents of endogenous Put, spermidine (Spd), but has little effect on spermine (Spm). D-Arg treatment could inhibit PAs, SA treatment could alleviate this situation. In tomato mutant D-Arg, SA treatment increased the contents of Put, which may be due to the decrease in the SA contents of the mutant triggered by a large number of Put generation.3.The exogenous SA treatment increased the gene expression of tomato PAs key biosynthetic arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) and exogenous Put treatment significantly increased the gene expression in Arabidopsis seedlings phenylalanine ammonia lyase (PAL) and different branch acid synthase (ICS), which enhanced the accumulation of Put and SA in plants, alleviated damage caused by low temperature on plants.In summary, SA and Put can regulate each other, and jointly control the cold tolerance of plants.