Polymorphism Analysis Of GmFT2a In Different Soybean Varieties And Screening Of Its Transcription Factor

Soybean [Glycine max （L.） Merr] is a typical short-day crop, and its growth and development isstrictly regulated by photoperiod and temperature conditions. Since soybean is sensitive tophoto-thermal regimes and there are broad diversity among genotypes, a given individual soybeanvariety usually adapts to only a narrow range of ecological region. It is imperative to improve theadaptability of soybean to environmental factors by using biological tools. In recent years, the molecularbiological studies in Arabidopsis thaliana showed that Flowering Locus T （FT） encodes florigen andplays a key role as an integrator in the flowering pathways of plants. In soybean, the homologous genesof FT also function as similar ways. The previous studies in our laboratory confirmed that GmFT2a, anFT homologue in soybean, is essential both in flowering induction and maintenance in soybean and thisgene may have important value in improving soybean adaptability. In the current study, we selected aset of soybean varieties, which showed distributed to different Maturity Groups, to investigate thesequence polymorphism of GmFT2a among soybean varieties and its relationship with photoperiodsensitivity. The results are summarized as follows.1. Photoperiod response diversified among soybean varieties of different maturity groups61soybean varieties of different Maturity Groups were exposed under different photoperiodtreatments （short day or SD of12h/12h, natural light, long day or LD of16h/8h）. The duration fromemergence （VE） to first bloom （R1） was recorded and statistical analysis for difference ofphotoperiodic responses of tested varieties was conducted. The results showed that the photoperiodsensitivity of soybean varieties followed a continuous distribution, and the photoperiod sensitivityincreased with lowering latitudes of their origins, and increased with the increase of maturity Groups.2. Relationship between GmFT2a sequence polymorphism and Maturity Group diversityAfter cloning GmFT2a by polymerase chain reaction （PCR） from tested varieties, we analyzedthe genomic sequences GmFT2a in28soybean varieties and the coding region sequence GmFT2a in6soybean varieties, in order to study the single nucleotide polymorphisms （SNPs） and its relationshipwith varied photoperiod responses and Maturity Group of different soybean varieties. The analysis ofthe genome sequences of28soybean varieties showed that there was1223bp, which includes twointrons and three exons, from exon1to exon3. No insertion or deletion sequence was found in theabove genomic sequence of28varieties and there was no nucleotide difference in the coding region of6soybean varieties. Since the SNPs existed in different varieties, it can not been drawn that the aboveSNPs were associated with maturity of soybean varieties.3. Screening transcriptional factors binding to GmFT2a cis-elements by yeast one-hybrid methodUsing yeast one-hybrid method, we obtained a transcriptional factor GmMYB173which may bindto GmFT2a cis-elements. The phylogenetic tree analysis with MAGE5method showed thatGmMYB173has similarity of92%with GmMYB176which is in the same evolutionary branch,followed by MYB14in Arachis hypogaea, MYB173in Phaseolus vulgaris, and MYB2in Medicagotruncatula, which share common conserved regions with GmMYB173. q-PCR analysis indicated that GmMYB173expressed higher under SD than under LD treatments and the expression level increasedalong with the growth of plants under LD treatment in two varieties with absolute different photoperiodsensitivity. It was speculated that under LD treatment, the enhanced expression of GmMYB173mayalleviate the LD inhibition on reproductive development of soybean.