Screening And Function Identification Of The Genes Response To Alkaline Stress In Soja By DNA Chip

Salinity stress is one of the main factors which affect the growth and output of crops. It is estimated that up to 4×10⁸-9×10⁸ hectare land was salinized, which is more than three times to present agricultural land, so how to improve crops salt talerance is becoming more and more important. In north part of China, compound saline and alkali land is the main kind salinized land ,which saline and alkali always existence together. Except having stress character of neutral salinity, it also can reduce plant ability to absorb mineral elements. So it is really a more serions stress compare with neutral salt.Nowadays,it is one of most effective and direct measures to make use of salinity land by culturing salinity bear plants.Cultivated soybean origins from wild soybean,wild soybean has great resistance and is an important germplasm resources for cultivated soybean breeding. Therefore, it is very urgent to study salt-tolerance mechanism and isolate excellent genes from wild soybean for cultivated soybean improvement.At present, gene expression profiling is the most widespread type of gene chip. It can analysis different kinds of mRNA based on transcription diversity, playing a role of high flux method to find differential expression genes . By gene expression profiling, we can get more information in whole genomics level just like whole metabolism mechanism and net work of genes in genomics.Our materials was soja JLGS0001. Based on gene expression profiling to identify differential expression genes. Of course, then identify by Northern blot to confirm the result getting from gene chip.As a result, we got 5573/61171 pieces differential expression genes,which 2833 were up-regulate and 2740 were down-regulate. (1) Analyzing and classifying of up-regulate differential expression genes, and they were classed by GO function ,containing signal transduction, the expression regulation, metabolism, the growth are related, transportation and so on . (2) Homology sequence clone was used to clone SRC2 gene which differently express of 2^2.5 on gene chip based on sequence in NCBI of soybean,while material was soja JLGS0001 dealed with 150mM Na⁺ and pH=10 solution. Here RT-PCR was used.Finaly,we got a cDNA sequence with 964bp,containing whole CDS, coding 291 amino acid that had a C2 domain.(3)Gene southern blot showed that SRC2 had single copy in JLGS0001 genomics. Northern blot showed that SRC2 was osmotic stress induced gene and up- regulated by NaCl,NaCl together with Na₂CO₃,4℃treatment. Dealed with only NaCl, the expression of SRC2 mRNA reached peak at 1 hour after salt stress; Dealed with salt and alkali, the expression of SRC2 mRNA reached peak at 6 hour after stress; Dealed with cold , the expression of SRC2 mRNA reached peak at 12 hour after stress.In a word, the differential expression genes we got were useful to perform work in genomics level,also,we proved that SRC2 must be a useful gene response osmotic stress, but if we want to know exactly how it works,much more work should do next.