The Transformation And Expression Of NR Gene Of Tomato In Relation To The Ethylene Response In Stress Condition

When plant is subject to a variety of stresses, they often exhibit symptoms of exposure toethylene. This complex relationship between stress and ethylene-like symptoms is heretermed the stress ethylene syndrome. NR gene exists as an ethylene receptor, which isdifferentially regulated, many by various stresses and affects the resistance of plant. Aftertransformation system conducted by Agrobacterium was modified for the tomato varietyLicun, several mutants of NR gene were gotten for research of ethylene signal transductionin stress condition by transfer of antisense RNA.The role of stresses in ethylene action has been studied in tomato (Lucopersicon esculentumcv lichu) through analyzing the triple response of tomato seedlings, the expression of NRgene, cytomembrane permeability, respiration, transpiration rate, stomatal conductance,calculated co₂ and the growth and symptoms of plants.It was found that high average transfer rate is 9%-l 1% when cotyledons were planted in theculture medium with BA 2mg/L+IAA 0.2mg/L for shooting, BA 1mg/L+IAA 0.1mg/Lfor elongation of stems, BA 0.5mg/L+IAA0.1mg/L for rooting and were infected byundiluted bacteria, which were soaked by extract of potato tubers and 1mg/LIAA forstimulating them. In addition, 50mg/L Kanamycin grid is necessary from shooting torooting.The antisense mutants of NR have longer internodes and fewer branch and longer autumn;NR2 mutant grow stronger and bloom more than wild plants.There is cooperativity between Li⁺ and ethylene to plants so that the triple response oftomato seedlings, metabolism (cytomembrane permeability, respiration, transpiration rate,stomatal conductance, calculated co₂) was accelerated and stress ethylene syndrome wasshown. Li+ regulated ethylene signal transduction since it made that expression of ACC andNR gene express increased.Salicylic acid improved the elongation of hypocotyls and expression of NR gene anddecreased respiration of leaves, but it accelerated the triple response of tomato seedlings,metabolism (cytomembrane permeability, respiration, transpiration rate, stomatalconductance, calculated co₂) and stress ethylene syndrome when ethylene was added. ThemRNA of NR gene in NR mutants is fewer than wild plants in stress of salicylic acid. So,salicylic acid benefits plant resistance but the action was changed by ethylene. The plantswith antisense NR gene are stronger.IAA increased growth of hypocotyls of tomato seedling and expression of NR gene anddecreased respiration, transpiration rate, stomatal conductance. Its action is reversed byethylene. The process of IAA+ethylene resulted in a typical stress ethylene syndrome sincethe expression of NR gene was culminant.At first, ABA did not change the cytomembrane permeability but cut down respiration. Then, the stomata closed and respiration, transpiration rate decreased and leaves became chlorisis. The effects of ABA+ethylene enhanced stress ethylene syndrome. The one of reason was the NR gene expressed largely.Drought induced a stronger expression of NR gene. Drought + ethylene leaded to obvious stress ethylene syndrome.When injury symptom of tomato plants appeared by low temperature (4 °C ), the physiological index (cytomembrane permeability, respiration, transpiration rate, stomatal conductance, calculated CO2) raised but the content of NR mRNA in leaves of tomato was lower than contrast. Low temperature +ethylene made over all increase more. So ethylene causes that plant is more sensibility to low temperature.In conclusion, stress result in stress ethylene syndrome. Since stress induced expression of ACC gene and resulted in ethylene production, ethylene activated the expression of receptor gene as NR gene, which lead to signal transduction and the ethylene syndrome. The system is regulated by action of protein phosphorylation for ACC enzyme and "inhibit mode" of ethylene receptor, which are related to stress actors and 1AA.