Identification of a RAPD marker linked to a blast resistance gene in Oryza sativa L

Marker-aided selection has received more attention in recent years. This relies on the exploitation of dose linkage between molecular markers and target gene(s). We report here a randomly amplified polymorphic DNA (RAPD) marker tightly linked to the blast resistance gene Pi-ll(t) derived from Hongjiaozhan, which confers the resistance to race ZB1 of Pyricularia oryzae Cav.

A major and stable QTL for wheat spikelet number per spike validated in different genetic backgrounds

The spikelet number per spike(SNS)contributes greatly to grain yield in wheat.Identifying various genes that control wheat SNS is vital for yield improvement.This study used a recombinant inbred line population genotyped by the Wheat55K single-nucleotide polymorphism array to identify two major and stably expressed quantitative trait loci(QTLs)for SNS.One of them(QSns.sau-2SY-2D.1)was reported previously,while the other(QSns.sau-2SY-7A)was newly detected and further analyzed in this study.QSns.sau-2SY-7A had a high LOD value ranging from 4.46 to 16.00 and explained 10.21-40.78%of the phenotypic variances.QSns.sau-2SY-7A was flanked by the markers AX-110518554 and AX-110094527 in a 4.75-cM interval on chromosome arm 7AL.The contributions and interactions of both major QTLs were further analyzed and discussed.The effect of QSns.sau-2SY-7A was successfully validated by developing a tightly linked kompetitive allele specific PCR marker in an F_(2:3) population and a panel of 101 high-generation breeding wheat lines.Furthermore,several genes including the previously reported WHEAT ORTHOLOG OF APO1(WAPO1),an ortholog of the rice gene ABERRANT PANICLE ORGANIZATION 1(APO1)related to SNS,were predicted in the interval of QSns.sau-2SY-7A.In summary,these results revealed the genetic basis of the multi-spikelet genotype of wheat line 20828 and will facilitate subsequent fine mapping and breeding utilization of the major QTLs.

Full-length transcriptome sequence and SSR marker development for genetic diversity research in yellowfin seabream Acanthopagrus latus

Yellowfin seabream Acanthopagrus latus is an important economic fish in Chinese coastal areas.Given its narrow distribution and overfishing,the genetic diversity of yellowfin seabream has been restricted for artificial breeding and reproduction.We performed full-length transcriptome sequencing and assembly of the genome of yellowfin seabream.A total of 68086 unigenes were obtained,with an N50 of 3391 bp on average length of 2933 bp.A total number of 50593 expressed sequence tags linked to simple sequence repeats(EST-SSR)were identified,among them dinucleotide repeats(40.6%)and AC/GT motifs(38.5%)were the most frequent.Of the 190 EST-SSRs for which PCR primer pairs were designed,150 primer pairs successfully amplified target loci and 15 SSRs showed high polymorphism.The alleles per locus ranged 6-50 on average of 25.3.The expected and observed heterozygosity varied from 0.632 to 0.969 and from 0.519 to 0.953,respectively.The polymorphic index content(PIC)values of each locus ranged 0.587-0.966 on average of 0.851.Among six yellowfin seabream population samples preliminarily tested for genetic diversity and differentiation,the Fangchenggang(FCG)population in Guangxi Province had the highest mean observed heterozygosity(H_(o))value(0.786),whereas the Zhangzhou(ZZ)population in Fujian Province had the lowest(0.678).The pairwise fixation index(Fst)values indicated significant population differentiation among six yellowfin seabream populations.This study provided evidence for the usefulness of the transcriptomic resource information and EST-SSR markers for natural resource conservation,population genetics,and breeding studies of yellowfin seabream in South China.