Abstract: For further study on the molecular mechanism and interaction model of SVP and FLC
protein homologous dimerization in flowering control in Brassica juncea Coss.（mustard），the selfinteractions
of SVP and FLC were detected by the yeast two-hybrid system. The yeast stains of
pGADT7SVP or pGADT7SVP2–5 could mate with pGBKT7SVP，which grew on selective agar plates
QDO/X/A（SD/-Ade/-His/-Leu/-Trp/X-α-Gal/AbA）with blue stains. However，Y187-pGADT7SVP1 and
Y2HGold-pGBKT7SVP could not mate into zygote diploids to grow on selective plates DO/X/A. The
results showed that SVP or SVP2–5 truncated forms could act with SVP itself to combine and form
homodimers. K domain of SVP was the key amino acid region to independently mediate and determine the
homologous dimerization. MI-domain of SVP alone could not induce the self-interactions of SVP，but
enhance the strength of homologous interactions. However，C-domain of SVP could weaken the protein
self-interaction strength. The yeast stains of pGBKT7FLC2–5 and pGADT7FLC could mate into zygotes
and grew on selective agar plates QDO/X/A with blue stains. The DNA-BD and AD were brought into
proximity to activate transcription of four independent reporter genes（AUR1-C，HIS3，ADE2，MEL1）.
FLC2–5 truncated forms and FLC protein could act with each other to form homodimers. It also indicated
that K domain of FLC may play an important role in mediating the FLC homodimers. However，I-domain
of FLC could strengthen the protein self-interactions. Alignment analysis of K domain sequence showed
that K domain was consist of three subdomains（K1，K2 and K3）and formed three ? helixes. Nine high
conservative amino acids existed in K domain. Leucine zippers，protein interaction motifs，lied in K
domain.

Key words: Brassica juncea, truncated forms, SVP, FLC, yeast two-hybrid system