Effects Of ABA Application On Cold-Resistance And Regulations Of The Expression For Asr1in Maize Seedling

Maize(Zea mays L.) is one of the world’s most widely grown crop area,it originated from subtropical region and as a thermophilic crop.Located in the northern temperature zone, Heilongjiang is the biggest province of maize production and exporter in China. The maize production in Heilongjiang affects not only the development of economy and society of the province, but also the overall maize industry of China.Chilling-injury during the maize growing is a main natural disaster and limiting factor for high yield in maize.The main measures to reduce the loss of commercial corn crop damage caused by the cold and frost hardy maize varieties have chosen to improve plant growth, especially in the harsh environment of the important role of cultivation and management, regulation and other chemicals in the ABA[1]. In the present study.maize were employed through pot experiment, and pretreated with Omg/L,5mg/L,15mg/L,25mg/L and35mg/L concentration of ABA before chilling stress.Research the mechanism of action that different concentrations of ABA in maize seedlings under low temperature stress.And explore the regulatory mechanism of the chilling Asrl gene expression with of exogenous ABA pretreatment,using real-time quantitative PCR.The major results were as followed.The photosystem Ⅱ (PS Ⅱ) activity centers of maize seeding leaves were damaged in the low temperature stress.Sprayingl5mg/L and25mg/L of exogenous ABA can slow down the damage to the PS Ⅱ of Maize seedlings.And the damage of PS Ⅱ were accelerated by spraying35mg/L of exogenous ABA.Photosynthetic rate (Pn),stomatal conductance (Gs),transpiration rate (Tr) levels of maize seedling leaves were decreased by five different concentrations of exogenous ABA treatment with the extension of low temperature stress.Those have the largest decline by35mg/L of exogenous ABA pretreated. This process was relieved by15mg/L and25mg/L of exogenous ABA pretreated,but the most obvious effect by15mg/L pretreatment.Both of the plasmalemma permeability and the MDA in the cells of maize seedling leaves content were increasing under low-temperature stress.Those increased least by15mg/L of exogenous ABA pretreated,and25mg/L of exogenous ABA pretreatment followed.Those increased most by35mg/L of exogenous ABA pretreated.The enzyme activities of protective enzyme system in maize seedings were highest15mg/L of exogenous ABA pretreated,and25mg/L of exogenous ABA pretreatment followed.Those were lowest by35mg/L of exogenous ABA pretreated.The activities of SOD, POD and CAT showed a change from increase to decrease. The change of SOD activities indicated a similar tendency with that of CAT activities by different concentrations of exogenous ABA pretreated with the extension of low temperature stress.Appropriate concentration of ABA treatment can enhance the synthesis of endogenous ABA in maize seedlings.Boss of the IAA,and ZR content in the leaves of maize seedings showed the trend that increase-decrease-increase by different treatments with the low temperature stress.but the GA3content decreased first and then increased.Asrl gene is expressed by the regulations of exogenous ABA,and belong to an ABA-dependent in maize.The expressions of Asrl gene are promoted significantly by spraying15mg/L and25mg/L of exogenous ABA.That can improve the cold resistance of maize seedlings by spraying5mg/L,15mg/L and25mg/L of exogenous ABA.The order of enhancement effects is that15mg/L>25mg/L>5mg/L.The cold resistance of maize was suppressed by35mg/L of exogenous ABA pretreated.