Transcription factor OsWRKY11 induces rice heading at low concentrations but inhibits rice heading at high concentrations

The heading date of rice is a crucial agronomic characteristic that influences its adaptability to different regions and its productivity potential.Despite the involvement of WRKY transcription factors in various biological processes related to development,the precise mechanisms through which these transcription factors regulate the heading date in rice have not been well elucidated.The present study identified OsWRKY11 as a WRKY transcription factor which exhibits a pivotal function in the regulation of the heading date in rice through a comprehensive screening of a clustered regularly interspaced palindromic repeats(CRISPR)-CRISPR-associated nuclease 9 mutant library that specifically targets the WRKY genes in rice.The heading date of oswrky11 mutant plants and OsWRKY11-overexpressing plants was delayed compared with that of the wild-type plants under short-day and long-day conditions.Mechanistic investigation revealed that OsWRKY11 exerts dual effects on transcriptional promotion and suppression through direct and indirect DNA binding,respectively.Under normal conditions,OsWRKY11 facilitates flowering by directly inducing the expression of OsMADS14 and OsMADS15.The presence of elevated levels of OsWRKY11 protein promote formation of a ternary protein complex involving OsWRKY11,Heading date 1(Hd1),and Days to heading date 8(DTH8),and this complex then suppresses the expression of Ehd1,which leads to a delay in the heading date.Subsequent investigation revealed that a mild drought condition resulted in a modest increase in OsWRKY11 expression,promoting heading.Conversely,under severe drought conditions,a significant upregulation of OsWRKY11 led to the suppression of Ehd1 expression,ultimately causing a delay in heading date.Our findings uncover a previously unacknowledged mechanism through which the transcription factor OsWRKY11 exerts a dual impact on the heading date by directly and indirectly binding to the promoters of target genes.

Arabidopsis WRKY Transcription Factors WRKY12 and WRKY13 Oppositely Regulate Flowering under Short-Day Conditions

In plants, photoperiod is an important cue for determining flowering. The floral transition in Arabidopsis thaliana is earlier under long-day （LD） than under short-day （SD） conditions. Flowering of Arabidopsis plants under SD conditions is mainly regulated by the plant hormone gibberellin （GA）. Here, we report two WRKY transcription factors function oppositely in controlling flowering time under SD conditions. Phenotypic analysis showed that disruption of WRKY12 caused a delay in flowering, while loss of WRKY13 function promoted flowering. WRKY12 and WRKY13 displayed negatively correlated expression profiles and function successively to regulate flowering. Molecular and genetic analyses demonstrated that FRUITFULL （FUL） is a direct downstream target gene of WRKY12 and WRKY13. Interestingly, we found that DELLA proteins GIBBERELLIN INSENSITIVE （GAI） and RGA-LIKE1 （RGL1） interacted with WRKY12 and WRKY13, and their interactions interfered with the transcriptional activity of the WRKY12 and WRKY13. Further studies suggested thatWRKY12 and WRKY13 partly mediated the effect of GA3 on controlling flowering time. Taken together, our results indicate that WRKY12 and WRKY13 oppositely modulate flower- ing time under SD conditions, which at least partially involves the action of GA.

The bHLH Transcription Factors MYC2, MYC3, and MYC4 Are Required for Jasmonate-Mediated Inhibition of Flowering in Arabidopsis

Dear Editor,In plants, the floral transition is flexibly controlled by various environmental conditions and endogenous developmental cues. In Arabidopsis, six major flowering pathways respond to changes in these factors （Fornara et al., 2010）. The photoperiod, vernalization, and ambient pathways monitor exogenous signals from the environment such as day length, minimum winter temperature, and ambient temperature （Fornara et al., 2010）. By contrast, the autonomous, gibberellin, and age pathways respond to endogenous cues linked to developmental status （Fornara et al., 2010）. Accumulating evidence indicates that the six flowering pathways converge in a network to regulate floral integrator genes FLOWERING LOCUS T （FT）, TWIN SISTER OF FT （TSF）, and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 （Fornara et al., 2010）.

WRKY transcription factors WRKY12 and WRKY13 interact with SPL10 to modulate age-mediated flowering

WRKY12 and WRKY13 are two WRKY transcription factors that play important roles in the control of flowering time under short-day(SD)conditions.The temporally regulated expression of WRKY12 and WRKY13 indicates that they may be involved in the age-mediated flowering pathway.However,their roles in this pathway are poorly understood.Here,we show that the transcription of WRKY12 and WRKY13 is directly regulated by SQUAMOSA PROMOTER BINDING-LIKE 10(SPLio),a transcription factor downstream of the age pathway.Binding and activation analyses revealed that SPL10 functions as a positive regulator of WRKY12 and a negative regulator of WRKY13.Further mechanistic investigation revealed that WRKY12 and WRKY13 physically interact with SPL10 and that both of them bind to the promoter of miRiy2b.Thus,the WRKY12-SPL10 and WRKY13-SPL10 interactions facilitate and inhibit SPL10 transcriptional function,respectively,to regulate miRiy2b expression.Together,our results show that WRKY12 and WRKY13 participate in the control of age-mediated flowering under SD conditions though physically interacting with SPLs and co-regulating the target gene miRi72b.

Arabidopsis VQ10 interacts with WRKY8 to modulate basal defense against Botrytis cinerea

Recent studies in Arabidopsis have revealed that some vq motif-containing proteins physically interact with WRKY transcription factors; however, their specific biological functions are still poorly understood. In this study, we confirmed the interaction between VQ1o and WRKY8, and show that VQ1o and WRKY8 formed a complex in the plant cell nucleus. Yeast two-hybrid analysis showed that the middle region of WRKY8 and the vq motif of vqlo are critical for their interaction, and that this interaction promotes the DNA-binding activity of WRKY8. Further investigation revealed that the VqlO protein was exclusively localized in the nucleus, and VQ1o was predominantly expressed in siliques, vQ1o expression was strongly responsive to the necrotrophic fungal pathogen, Botrytis cinerea and defense-relatedhormones. Phenotypic analysis showed that disruption of VQlo increased mutant plants susceptibility to the fungal pathogen B. cinerea, whereas constitutive-expres- sion of VQlo enhanced resistance to B. cinerea. Consis- tent with these findings, expression of the defenserelated PLANT DEFENSIN1.2 （PDFt2） gene was decreased in vqlo mutant plants, after B. cinerea infection, but increased in vQ1o-overexpressing transgenic plants. Taken together, our findings provide evidence that VQlo physically interacts with WRKY8 and positively regulates plant basal resistance against the necrotrophic fungal pathogen B. cinerea.