This study explored the effects of abiotic stress on anthocyanin accumulation and grain weight of purple wheat (Triticum aestivum L. cv. Guizi 1). Plants were treated with five abiotic stress factors at different developmental periods of the grain, then mature grains were analysed for anthocyanin content and 1000-grain weight (TGW). Stresses included temperature (cold and heat), light (shading irradiance and continuous irradiance), drought (20 and 40 mm PEG 6000), salinity (100 and 200 mm NaCl), and wounding (four types). Of all treatments, 25% tended to increase both anthocyanin content and TGW, although only 5% reached a significant level, 27.5% decreased both, 40% increased anthocyanins but decreased TGW, and 7.5% increased TGW but decreased anthocyanins. Heat stress tended to increase anthocyanin content and decrease TGW, whereas cold stress increased anthocyanins only at 15 days post-anthesis (DPA) and decreased both traits at other times. Shading irradiance decreased anthocyanins but had little effect on TGW. Continuous irradiance increased anthocyanins and TGW at 35 DPA but decreased both at 10 DPA. The lower levels of drought (20 mm PEG 6000) and salinity (100 mm NaCl) stress tended to increase anthocyanins and decrease TGW; however, the effects of 40 mm PEG 6000 and 200 mm NaCl were different, and were period-dependent. The four types of wounds increased anthocyanins and TGW at 30 DPA, but their individual effects were different in the other four periods. The results quantified the effects of five abiotic stress factors on anthocyanin accumulation and grain weight, and provide the foundation for further study of defence-responsive molecular mechanisms of abiotic stress in purple wheat.

Background: Transcription factors, including trihelix transcription factors, play vital roles in various growth and developmental processes and in abiotic stress responses in plants. Thetrihelixgene has been systematically studied in some dicots and monocots, includingArabidopsis,tomato, chrysanthemum, soybean, wheat, corn, rice, and buckwheat. However, there are no related studies on sorghum.Results: In this study, a total of 40 sorghum trihelix (SbTH) genes were identified based on the sorghum genome, among which 34 were located in the nucleus, 5 in the chloroplast, 1 (SbTH38) in the cytoplasm, and 1 (SbTH23) in the extracellular membrane. Phylogenetic analysis of theSbTHgenes andArabidopsisand ricetrihelixgenes indicated that the genes were clustered into seven subfamilies: SIP1, GTγ, GT1, GT2, SH4, GTSb8, and orphan genes. TheSbTHgenes were located in nine chromosomes and none on chromosome 10. One pair of tandem duplication gene and seven pairs of segmental duplication genes were identified in theSbTHgene family. By qPCR, the expression of 14 SbTH members in different plant tissues and in plants exposed to six abiotic stresses at the seedling stage were quantified. Except for the leaves in which the genes were upregulated after only 2 h exposure to high temperature, the 12 SbTHgenes were significantly upregulated in the stems of sorghum seedlings after 24 h under the other abiotic stress conditions. Among the selected genes,SbTH10/37/39were significantly upregulated, whereasSbTH32was significantly downregulated under different stress conditions.Conclusions: In this study, we identified 40 trihelix genes in sorghum and found that gene duplication was the main force drivingtrihelixgene evolution in sorghum. The findings of our study serve as a basis for further investigation of the functions ofSbTHgenes and providing candidate genes for stress-resistant sorghum breeding programmes and increasing sorghum yield.

Sorghum bicolor is cultivated worldwide. Leaf spot of sorghum, which leads to leaf lesions and yield reduction, is a prevalent and serious disease in Guizhou Province, southwest China. In August 2021, new leaf spot symptoms were observed on sorghum leaves. In this study, traditional methods and modern molecular biology techniques were used to isolate and identify the pathogen. Sorghum inoculated with the isolate GY1021 resulted in reddish brown lesion that similar to symptoms observed in the field: the original isolate inoculated was reisolated and Koch’s postulates were fulfilled. Based on morphological features and phylogenetic analysis of the internal transcribed spacer (ITS) combined sequence with β-tubulin (TUB2) and translation elongation factor 1-α (TEF-1α) genes, the isolate was identified as Fusarium thapsinum (Strain accession: GY 1021; GenBank Accession: ITS (ON882046), TEF-1α (OP096445), and β-TUB (OP096446)). Then, we studied the bioactivity of various natural products and microorganisms against F. thapsinum using the dual culture experiment. Carvacrol, 2-allylphenol, honokiol, and cinnamaldehyde showed excellent antifungal activity, with EC₅₀ values of 24.19, 7.18, 46.18, and 52.81 µg/mL, respectively. The bioactivity of six antagonistic bacteria was measured using a dual culture experiment and the mycelial growth rate method. Paenibacillus polymyxa, Bacillus amyloliquefaciens and Bacillus velezensis displayed significant antifungal effects against F. thapsinum. This study provides a theoretical basis for the green control of leaf spot of sorghum.

Sorghum bicolor is cultivated worldwide. Leaf spots on sorghum, which lead to leaf lesions and impaired growth, are prevalent and severe in Guizhou Province, Southwest China. In August 2021, new leaf spot symptoms were observed on sorghum plants growing in agricultural fields. We used conventional tissue isolation methods and pathogenicity determination tests. Inoculations of sorghum with isolate 022ZW resulted in brown lesions similar to those observed under field conditions. The original inoculated isolates were reisolated and fulfilled Koch’s postulates. Based on the morphological character and phylogenetic analyses of the combined sequences of the internal transcribed spacer (ITS) region and the β-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, we identified the isolated fungus as C. fructicola. This paper is the first to report this fungus-causing disease in sorghum leaves. We studied the sensitivity of the pathogen to various phytochemicals. The sensitivity of C. fructicola to seven phytochemicals was measured using the mycelial growth rate method. Honokiol, magnolol, thymol, and carvacrol displayed good antifungal effects, with EC₅₀ (concentration for 50% of the maximal effect) values of 21.70 ± 0.81, 24.19 ± 0.49, 31.97 ± 0.51, and 31.04 ± 0.891 µg/mL, respectively. We tested the control effect of the seven phytochemicals on the anthracnose caused by C. fructicola: honokiol and magnolol displayed good field efficacy. In this study, we expand the host range of C. fructicola, providing a basis for controlling sorghum leaf diseases caused by C. fructicola.