3000份水稻重測序資料全部公開

感覺最近接觸的生物資訊學知識越多，越對大資料時代的到來更有同感了。現在的研究者，其實很多都可以自己在家裡做了，大量的資料基本都是公開的， 但是一個人閉門造車成就真的有限，與他人交流的思想碰撞還是蠻重要的。

https://aws.amazon.com/cn/blogs/aws/new-aws-public-data-set-3000-rice-genome/
https://aws.amazon.com/cn/public-data-sets/3000-rice-genome/
https://wiki.dnanexus.com/Featured-Projects/3000-rice-genomes
這裡面列出了3000多份水稻全基因組測序資料，都共享在亞馬遜雲上面，是全基因組的雙端測序資料，共3,024個水稻資料，比對到了五種不同的水稻參考基因組上面，而且主要是用GATK來找差異基因的。
而且，資料收集者還給出了一個snp calling的標準流程！

其採用的找變異流程如下：

SNP Pipeline Commands

1. Index the reference genome using bwa index

   /software/bwa-0.7.10/bwa index /reference/japonica/reference.fa

2. Align the paired reads to reference genome using bwa mem. 
   Note: Specify the number of threads or processes to use using the -t parameter. The possible number of threads depends on the machine where the command will run.

   /software/bwa-0.7.10/bwa mem -M -t 8 /reference/japonica/reference.fa /reads/filename_1.fq.gz /reads/filename_2.fq.gz > /output/filename.sam

3. Sort SAM file and output as BAM file

   java -Xmx8g -jar /software/picard-tools-1.119/SortSam.jar INPUT=/output/filename.sam OUTPUT=/output/filename.sorted.bam VALIDATION_STRINGENCY=LENIENT CREATE_INDEX=TRUE

4. Fix mate information

   java -Xmx8g -jar /software/picard-tools-1.119/FixMateInformation.jar INPUT=/output/filename.sorted.bam OUTPUT=/output/filename.fxmt.bam SO=coordinate VALIDATION_STRINGENCY=LENIENT CREATE_INDEX=TRUE

5. Mark duplicate reads

   java -Xmx8g -jar /software/picard-tools-1.119/MarkDuplicates.jar INPUT=/output/filename.fxmt.bam OUTPUT=/output/filename.mkdup.bam METRICS_FILE=/output/filename.metrics VALIDATION_STRINGENCY=LENIENT CREATE_INDEX=TRUE MAX_FILE_HANDLES_FOR_READ_ENDS_MAP=1000

6. Add or replace read groups

   java -Xmx8g -jar /software/picard-tools-1.119/AddOrReplaceReadGroups.jar INPUT=/output/filename.mkdup.bam OUTPUT=/output/filename.addrep.bam RGID=readname PL=Illumina SM=readname CN=BGI VALIDATION_STRINGENCY=LENIENT SO=coordinate CREATE_INDEX=TRUE

7. Create index and dictionary for reference genome

   /software/samtools-1.0/samtools faidx /reference/japonica/reference.fa
   
   java -Xmx8g -jar /software/picard-tools-1.119/CreateSequenceDictionary.jar REFERENCE=/reference/japonica/reference.fa OUTPUT=/reference/reference.dict

8. Realign Target 

   java -Xmx8g -jar /software/GenomeAnalysisTK-3.2-2/GenomeAnalysisTK.jar -T RealignerTargetCreator -I /output/filename.addrep.bam -R /reference/japonica/reference.fa -o /output/filename.intervals -fixMisencodedQuals -nt 8

9. Indel Realigner

   java -Xmx8g -jar /software/GenomeAnalysisTK-3.2-2/GenomeAnalysisTK.jar -T IndelRealigner -fixMisencodedQuals -I /output/filename.addrep.bam -R /reference/japonica/reference.fa -targetIntervals /output/filename.intervals -o /output/filename.realn.bam 

10. Merge individual BAM files if there are multiple read pairs per sample

   /software/samtools-1.0/samtools merge /output/filename.merged.bam /output/*.realn.bam

11. Call SNPs using Unified Genotyper

   java -Xmx8g -jar /software/GenomeAnalysisTK-3.2-2/GenomeAnalysisTK.jar -T UnifiedGenotyper -R /reference/japonica/reference.fa -I /output/filename.merged.bam -o filename.merged.vcf -glm BOTH -mbq 20 --genotyping_mode DISCOVERY -out_mode EMIT_ALL_SITES