Identification And Analysis Of Genes Response To Seed Aritificial Ageing In Maize

Maize is an important cereal crop as well as industrial raw material, and seed deterioration can seriously influence its yield and quality. Until recently, however, the mechanism of seed aging has not been uncovered. In this study, Maize (Zea mays L.) cultivar (’Zhengdan958’) seeds were used as experimental materials, and seeds were treated by artificial aging treatment (AAT) (temperature:45 ℃, relative humidity:100%) to study the effect of seed viability. Then we identified genes related to seed aging response by cDNA-AFLP approach, and studied the expressional pattern of screened genes. The results are as following:1) 3-day ageing was the turnover point of seed viabilityThe results of germination and embryo viability test showed that the germination ability and embryo viability of seeds treated with 1-day ageing did not change significantly, while 3-day ageing changed drastically. The results of O2·- production rate and oxidordeuctase activity of emryo suggested that the O2·- production rate of emryo increased, while the oxidordeuctase activity of emryo decreased, and the increasing of O2·- production rate of emryo 3-days deteriorating was greatest while the decreasing of CAT activity was greatest. The results indicated that 3-day deteriorating might be the infection point of seed vigor.2) Optimization Trizol method was proper for total RNA extracted from embryo of maizeOptimization Trizol method on the basis of Trizol method, added suitable amount of PVP when grinded, increasd the extraction times, and added suitable volume of high salt solution. The detection result suggested that total RNA extracted from embryo by optimization method had the advantage of high quality, high purity and high integrity, which made it qualified for the next assay.3) Identification and analysis of genes response to seed artificial ageingThe seeds aged for 3-day were used as experimental materials, and more than 5400 transcript derived fragments (TDFs) were obtained from 212 differentially expressed TDFs (size as about 200-500 bp) screened by cDNA-AFLP approach.122 aging response relevant sequences (ARSs) were finally obtained after re-PCR, cloning and sequencing performance. BLASTX was performed and the annotated genes were classified according to GO functional annotation. These ARSs were involved in primary metabolism, secondary metabolism, protein metabolism, transcription and regulation, stress response, signal pathway, and transportation by GO functional annotation. The expression patterns of 15 genes related to seed ageing response which were involved in primary metabolism, protein metabolism, signal transduction, transcription and regulation, stress response were studied by qRT-PCR, and the result showed that different genes played different roles during the process of seed ageing.4) Possible mechanism of seed artificial ageingRespiration of seeds were stronger after seed artificial aged lead to the increasing of O2·- production rate, while the activity of oxidordeuctase decrease, and that would make an quantity accumulate of ROS. Excess ROS made injuries to membrane system, protein, nuclease and so on, lead to the decreasing of emryo vitality and the decreasing of seed vigor.