Overexpression of ZmSPL12 confers enhanced lodging resistance through transcriptional regulation of D1 in maize

• DOI: 10.1111/pbi.13787
• Publication Date: 2022-02-12T03:28:30Z
• Authors: Binbin Zhao; Miaoyun Xu; Yongping Zhao; Yaoyao Li; Hua Xu; Changyu Li; Dexing Kong; Yurong Xie; Zhigang Zheng; Baobao Wang; Haiyang Wang
• Keywords: 0303 health sciences; 03 medical and health sciences; Phenotype; Brief Communications; Zea mays

Introduction of the semi-dwarf genes (sd1 in rice, RhtB1b and RhtD1b wheat) has drastically increased lodging resistance grain yields these two important crops since 1960s, resulting so called 'Green Revolution' (Hedden, 2003). Maize (Zea mays L.) is one most widely cultivated cereal world increasing planting density an effective strategy to increase yield (Duvick, 2005). However, high could trigger shade avoidance response cause plant height ear height, prone loss. Thus, reducing plant/ear a continuous goal for maize breeders. rice or wheat are both either involved GA biosynthesis signalling. Previous studies have identified number dwarf mutants that defective signalling, such as anther ear1, plant1 (d1), dwarf3, dwarf8 dwarf9 (Lawit et al., 2010; Teng 2013). not be used breeding because pleiotropic detrimental effects, dwarfism, small size, losses. identification desirable genetic improvement maize. D1, encoding 3-oxidase (ZmGA3ox2) catalysing final step bioactive synthesis, candidate gene qPH3.1, major QTL (Teng To identify transcription factors (TFs) negatively regulate D1 expression maize, we first performed WGCNA co-expression network analysis using published transcriptomic data (Stelpflug 2016). We initially 67 TFs showing negative correlation with shoot apical meristem (SAM) internodes (cut-off value ≤ −0.8). Among them, found 10 potentially bind promoter (~3 kb upstream translation initiation site) plantpan 3.0 (Chow 2019), including ZmARF18 (Zm00001d014377), ZmSPL12 (Zm00001d015410), ZmGN1(Zm00001d007842), ZmbZIP104 (Zm00001d015421), ZmMYBR77 (Zm00001d036632), ZmbHLH128 (Zm00001d054038), ZmNAC123 (Zm00001d035084), ZmMADS73 (Zm00001d018142), ZmbHLH55 (Zm00001d012067) ZmbHLH117 (Zm00001d024783) (Figure 1a). next selected top six highest correlation, ZmARF18, ZmSPL12, ZmGN1, ZmbZIP104, ZmbHLH128, tested their binding promoter. Yeast one-hybrid assay showed only 1b). Transient strongly repressed pD1::LUC reporter 1c). Quantitative reverse PCR (RT-qPCR) revealed was mainly expressed seedling at V2 stage, SAM V8 V10 stages 1d). Subcellular localization protein exclusively localized nucleus 1e). investigate role generated Zmspl12 knockout plants CRISPR/Cas9 technology. Two independent lines (ko#1 ko#2) frame-shift mutations were phenotypic investigation. Both ko#1 ko#2 exhibited significantly higher 1f). While transgenic overexpression (ZmSPL12-OE, #499 #500) reduced compared non-transgenic control plants, degree reduction correlated levels 1g). As expected, level decreased ZmSPL12-OE 1h). Histological observation internode cells shorter than those 1i), indicating caused by cell length. Moreover, measurement stalk strength stronger 1j). confirm effect on altered levels, measured endogenous GA1, GA3, GA4 GA7 internodes. The results GAs all 1k). In addition, treatment exogenous GA3 effectively restored 1l). These support notion acts biosynthesis, thus height. test potential utility breeding, planted (#500) #500-CK under three different densities (45 000, 90 135 000 per hectare) Hainan, China 2020. had more 1m,n). enhanced (90 hectare; Figure 1o). Further, introgressed ZmSPL12-OE#500 transgene into elite parental inbred lines, Chang7-2 PH6WC, through repeated backcrossing. improved Chang7-2#500 PH6WC#500 significantly, respective original 1p,q). Together, our demonstrate mimic function confer resistance, facilitating high-density This research supported grants from National Key Research Development Program (2021YFF1000301, 2020YFE0202300), Natural Science Foundation (32022065) Hainan Yazhou Bay Seed Lab (B21HJUS01). authors declare no conflict interests. HW BW conceived designed project. BZ conducted experiments. YZ, YL, HX, DK, YX ZZ participated some CL analysed data. MX wrote manuscript. revised