Physiological Effects Of Exogenous Trehalose On Chilling Tolerance Of Roots Of Maize Seedlings

Heilongjiang Province is an important maize producing area in China,which planting area and total output ranked the first in the country.Low temperature in spring is one of the common meteorological disasters in Heilongjiang Province.Low temperature has become an important factor limiting the high and stable production of maize in our province.Recent studies have shown that trehalose as a metabolite of plants to adapt the environmental stress,which can increase crop yields and protect the normal growth and development of crops.In order to explore the regulation of trehalose on the root system of maize seedlings under low temperature stress,a large area popularized variety Xianyu335 in Heilongjiang Province was used as the experimental material.After preliminary concentration screening,it was confirmed that 12 mmol?L^-1trehalose was used for root pouring,and 60 mmol?L^-11 trehalose was used for soaking.In this paper,we studied the effects of trehalose on maize seedlings growth,antioxidant system,osmotic adjustment substances,cell membrane stability,key enzymes of aerobic respiratory pathways,and respiratory metabolites under low temperature stress.The aim was to clarify the physiological pathway of trehalose to improve the low temperature tolerance of maize.The results of the study show that:（1）The application of a certain concentration of trehalose could effectively alleviate the low temperature stress on the inhibition of root growth of maize seedlings,enhanced the activity of antioxidant enzymes,and reduced the membrane damage.The mitogenic effect of the roots poured 12mmol?L^-1trehalose and soaking seeds 60 mmol?L^-11 trehalose was better than that of other concentrations of trehalose.Compared with pure low temperature stress,root root length,root surface area and root fresh weight increased by 32.16%,15.87%,41.14%,and 55.11%,respectively,and the activities of SOD and POD were increased by root-injection of 12 mmol?L^-1 trehalose.The MDA content and relative conductance decreased by 50.23%and 42.53%,respectively,while the trehalose soaking of 60mmol?L^-1 trehalose increased the root length,root surface area,and root fresh weight of the seedling by14.99%,respectively,by 44.16%and 62.17%.The activities of SOD and POD increased by 32.46%and45.89%,and the contents of MDA and relative conductivities decreased by 46.52%and 46.58%,respectively,4.45%,16.83%and 59%.（2）Under low temperature,applying exogenous trehalose could alleviate growth inhibition of the roots of maize seedlings,and which was conducive to root morphogenesis and material accumulation;enhanced the antioxidant enzyme activity of seedling roots,maintain the balance of active oxygen metabolism;reduced MDA content,reduced the relative electrical conductivity prevents a large amount of extravasation of the electrolyte;increased the content of proline,soluble protein,and soluble sugar in the cell,enhanced the ability of cell osmotic adjustment,and stabilized the integrity of the biofilm.The effect of trehalose relieving low temperature stress pouring on root was better than that of trehalose soaking.（3）Under low temperature,applying exogenous trehalose increased the activity of MDH,SDH,PK,PFK,G-6-PDH and 6-P-GDH in the roots of maize seedlings,and regulated the EMP pathway,TCA pathway and PPP pathway in aerobic respiration,increased the amount of intracellular ATP production,increased cell respiration rate,increased plant adaptation to low temperature and resistance.（4）The content of malic acid in the roots of seedlings under low temperature stress decreased significantly,the content of succinic acid increased significantly,and aerobic respiration was inhibited.After application of trehalose,the content of malic acid in the roots of seedlings increased and the succinic acid content decreased.Trehalose alleviated the injury of cold stress by regulating the balance of aerobic respiratory metabolites,and improved the cold resistance of maize seedlings.