Anthocyanin is an important pigment that affects plant color and nutritional quality.  MYBs play an important role in plant anthocyanin synthesis and accumulation.  However, the regulatory function of MYB transcription factors in anthocyanin synthesis in flax flowers is still unclear.  In this study, 402 MYB transcription factors were identified in the flax genome.  These MYB members are unevenly distributed on 15 chromosomes.  The R2R3-LuMYB members were divided into 32 phylogenetic subfamilies.  qRT-PCR analysis showed that seven R2R3-LuMYB genes in the adjacent subfamily of the evolutionary tree had similar expression patterns, among which LuMYB216 was highly expressed in the petals of different colors.  Moreover, gene editing of LuMYB216 in flax showed that the petal color, anther color and seed coat color of mutant plants were significantly lighter than those of wild-type plants, and the anthocyanin content of lumyb216 mutant plants was significantly reduced.  Correlation analysis indicated that LuMYB216 was significantly positively correlated with the upstream regulator bHLH30.  This study systematically analyzed the MYB gene family in flax, laying a foundation for studying the regulation of LuMYB216 in flax flower anthocyanin synthesis.

Bacillus subtilis strain NCD-2 is an excellent biocontrol agent for plant soil-borne diseases, and the lipopeptide fengycin is one of the active antifungal compounds in strain NCD-2.  The regulator phoP and its sensor kinase PhoR compose a two-component system in B. subtilis.  In this study, the phoR- and phoP-knockout mutants were constructed by in-frame deletion and the role of PhoR/phoP on the production of fengycin was determined.  Inactivation of phoR or phoP in  B. subtilis decreased its inhibition ability against Botrytis cinerea growth in vitro compared to the strain NCD-2 wild type.  The lipopeptides were extracted from strain NCD-2 wild type and its mutant strains by hydrochloric acid precipitate, and the lipopeptides from phoR-null mutant or phoP-null mutant almost lost the inhibition ability against B. cinerea growth compared to the lipopeptides from strain NCD-2 wild type.  Fast protein liquid chromatography (FPLC) analysis of the lipopeptides showed that inactivation of phoR or phoP genes reduced the production of fengycin by strain NCD-2.  The fengycin production abilities were compared for bacteria under low-phosphate medium (LPM) and high-phosphate medium (HPM), respectively.  Results indicated that the regulation of fengycin production by the PhoR/PhoP two-component system occurred in LPM but not in HPM.  Reverse transcriptional-PCR confirmed that the fengycin synthetase gene fenC was positively regulated by phoP when cultured in LPM.  All of these characteristics could be partially restored by complementation of intact phoR or phoP gene in the mutant.  These data indicated that the PhoR/PhoP two-component system greatly regulated fengycin production and antifungal ability in B. subtilis NCD-2 mainly under low-phosphate conditions.

Setosphaeria turcica, an essential phytopathogenic fungus, is the primary cause of serious yield losses in corn; however,
its pathogenic mechanism is poorly understood. We cloned STK2, a newly discovered mitogen-activated protein kinase gene with a deduced amino acid sequence that is 96% identical to MAK2 from Phaeosphaeria nodorum, 56% identical to
KSS1 and 57% identical to FUS3 from Saccharomyces cerevisiae. To deduce Stk2 function in S. turcica and to identify the
genetic relationship between STK2 and KSS1/FUS3 from S. cerevisiae, a restructured vector containing the open reading
frame of STK2 was transformed into a fus3/kss1 double deletion mutant of S. cerevisiae. The results show that the STK2
complementary strain clearly formed pseudohyphae and ascospores, and the strain grew on the surface of the medium after
rinsing with sterile water and the characteristics of the complementary strain was the same as the wild-type strain. Moreover,
STK2 complemented the function of KSS1 in filamentation and invasive growth, as well as the mating behavior of FUS3 in
S. cerevisiae, however, its exact functions in S. turcica will be studied in the future research.