Studies On Effects Of Exogenous Nitric Oxide Alleviating The Stress Of Copper In Tomato Seedlings

Tomato （Lycopersicon esculentum Mill.）, an annual vegetable of Lycopersicon ofSolanaceae,is one of the major greenhouse vegetables loved by many people. Along with thefrequent use of organic fertilizer, chemical fertilizer containing a great deal of heavy metal,copper have become increasingly hazardous due to their involvement among pollutants ofcultivated vegetable soils, resulted in the worse pollution vegetable and led to a series ofphysiological barriers. Therefore, it is very important to study the physiological mechanismsof copper in tomato and take measures to decrease the toxicity. As a signal molecular, nitricoxide participated in the growth, development, disease resistance and stress resistance. In thispaper, solution culture experiments were conducted to investigate the effects of exogenousnitric oxide on physiological and biochemical metabolism in tomato under Cu stress. Themain results were as follows:1. Under50μmol·L^-1Cu stress, exogenous NO could increase tomato seedling’s biomass,plant height, root length and diameter of stem, root activity was increased. And exogenousNO improve root length, root diameter, root surface area and root volume, alleviated the hurtof tomato seedlings microstructure （nuclear, chloroplast, mitochondria, vacuoles, nuclear）induced by copper stress, and maintained tomato tissue structure stable, slowed growthinhibition led by excess copper;2.Copper concentration and accumulation on tomato seedling tissue declined in the orderof root, stem, petiole, leaf；In view of iron, the concentration and accumulation, thedecreasing order isroot, stem, leaf and petiole.About manganese concentration andaccumulation,the decreasing order is following root, leaf, petiole and stem. The trend ofzincconcentration and accumulation were similar to copper,followed by root, stem, petiole,leaves.3.Exogenous NO significantly made the excess copper sequester in vacuole and cellwallfraction, meanwhile the copper in organelles reduced, which lessened excessive copperdamage cytoplasm to benefitregular metabolic balance.Meanwhile exogenous NO improvedCu acetic acid extraction state (F_HAc) in root，sodium chloride extract state (F_NaCl) in thestem，F_HAcin petiole, the ethanol extract state if flexion-extension （F_E） radiographs and F_NaCl,realized the relief of stress of Cu characteristics. 4.Exogenous NO significantly improved tomato plants PCs content and increased totalamino acids in leaves （aspartic acid, glutamic acid, valine were the mainly preponderant）,reduced the total amino acids in root （aspartate valine, glutamic acid were the mainlypreponderant）, of which the changing trends of glutamic acid, homocysteine and glycine wereinagredient in the leaf of the total amino acids.5. Exogenous NO significant increased ABA contentin root and IAA, GA₃andZRcontent inleaf, significantly reduced ABA and IAA, GA₃and ZR content in root, andregulated to plant growth of different tissue, and alleviated copper stress on the inhibition oftomato seedlings;6．Under copper stress the100μmol·L^-1SNP could significantly reduce root secretion oforganic acid, like oxalic acid, lactic acid, acetic acid and succinic acid, made the rootsecretion of sugar （glucose and fructose, sucrose） increase significantly, thus increased thetomato plants roots complexing power with copper; The increase of the sugar benefitcellulose biosynthesis, and enhance secondary wall thickening, and better the destruction ofcells, and strengthen the adaptabilityof tomato root to the copper stress.