No abstract

Lignin plays an important role in increasing the mechanical intensity of culm and improving lodging resistance of culm. In this study, three common buckwheat, Youqiao2 (lodging‐tolerant cultivar; YQ2), Ningqiao1 (middle lodging‐tolerant cultivar; NQ1) and Ukraine daliqiao (lodging‐susceptible cultivar; UD), were used to investigate the effects of spraying exogenous hormones uniconazole (S‐3307) or gibberellic acid (GA3) on lignin metabolism and its relation to lodging resistance in the three common buckwheat cultivars. Results showed that application of S‐3307 significantly increased lignin content and its related enzymes activities of phenylalanine ammonia‐lyase (PAL), 4‐hydroxy cinnamoyl CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POD). The major genes involved in lignin synthesis, PAL, CCR (cinnamyl CoA reductase), C4H (cinnamate4‐hydroxylase), 4CL and CCoAOMT (caffeoyl CoA O‐methyltransferase), were all upregulated expression, and COMT (catechol‐O‐methyltransferase) was downregulated. What is more, application of S‐3307 significantly improved the resistance of common buckwheat stem to lodging and increased yield. Whereas, spraying with GA3 caused opposite effect on those characteristics. These results suggested that application of exogenous S‐3307 or GA3 significantly changed the risk of lodging occurred by regulating the lignin metabolism in culms of common buckwheat.

Common buckwheat (Fagopyrum esculentum M.) belongs to the eudicot family Polygonaceae, Fagopyrum Mill, and its seeds have high nutritional value. The mechanism of seed development of common buckwheat remains unclear at the molecular level and no genes related to seed size have been identified. In this study, we performed genome-wide transcriptome sequencing and analysis using common buckwheat seeds at 5 days post anthesis (DPA) and 10 DPA from two cultivars (large-seeded and small-seeded). A total of 259,895 transcripts were assembled, resulting in 187,034 unigenes with average length of 1097 bp and N50 of 1538 bp. Based on gene expression profiles, 9127 differentially expressed genes (DEGs) were identified and analyzed in GO enrichment and KEGG analysis. In addition, genes related to seed size in the IKU pathway, ubiquitin–proteasome pathway, MAPK signaling pathway, TFs and phytohormones were identified and analyzed. AP2 and bZIP transcription factors, BR-signal and ABA were considered to be important regulators of seed size. This study provides a valuable genetic resource for future identification and functional analysis of candidate genes regulating seed size in common buckwheat and will be useful for improving seed yield in common buckwheat through molecular breeding in the future.

No abstract