BACKGROUND Calcium is an essential macronutrient for plant growth. Although it has been shown that exogenous Ca application can increase plant resistance to abiotic stress, little is known about its potential to enhance plant tolerance to biotic stress. Here, we investigated whether pretreatment of wheat (Triticum aestivum L.) seeds with calcium chloride (CaCl2) improves plant resistance against wheat aphid (Schizaphis graminum Rondani). The developmental time, population size, feeding behavior of aphids on plants grown from CaCl2‐ and water‐pretreated seeds, and plant defense responses to aphid attack were investigated. RESULTS Seed pretreatment with CaCl2 extended aphid development time and reduced aphid population size and feeding efficiency. In addition, the pretreatment significantly increased the concentration of Ca2+ in wheat leaves, and upregulated expression levels of TaCaM genes and callose synthase genes (TaGSL2, TaGSL8, TaGSL10, TaGSL12, TaGSL19, TaGSL22 and TaGSL23). Callose concentration in the leaves of plants grown from CaCl2‐pretreated seeds increased significantly upon aphid attack. Further, callose deposition was observed mainly in the phloem. CONCLUSION These results suggest that seed pretreatment with CaCl2 primes the plant response against wheat aphid attack, leading to modulation of callose deposition in the phloem in response to aphid attack. © 2021 Society of Chemical Industry.

Traditional soybean (Glycine max L.) breeding has improved seed yield in high-input agricultural systems, under high nitrogen (N), phosphorus (P) and potassium (K) supply. The seed yield improvements under non-P supply and the seed protein and mineral content dilution by yield improvement were evaluated in 18 soybean cultivars released from 1995 to 2016 in south-east China. Soybean varieties were grown under rainfed conditions in the field under 0 and 35kgPha−1 in four sites: Dafang and Shiqian in the growing season of 2017 and Dafang and Puding in the 2018 season. The seed yield, seed protein content and nine seed nutrition concentration were examined. Soybean seed yield increased with the year of release at rates of 5.5–6.7gm−2year−1 under 35kgPha−1 and 3.9–4.8gm−2year−1 under non-P supply in the four experiments. The increase resulted from increases in the number of filled-pods and total seed number rather than from single seed weight and number of seeds per pod. Seed protein content and seed nutrition concentration has not changed with the year of release under 0 and 35kgPha−1. Grain yield was positively correlated with the seed Fe concentration. The cultivar superiority of seed yield, seed P, Zn and Ca concentration was negatively correlated with their static stability coefficient. Traditional soybean breeding increased yield under both P and non-P supply, without affecting seed protein content and mineral concentrations. A trade-off between high seed yield and seed P, Zn and Ca concentration and their stability under different environments was shown.

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.

The belt uniform (BU) sowing pattern can improve the yield of winter wheat, but whether and how the BU sowing pattern can increase yield under different sowing densities is unknown. The field study was conducted in Guiyang (Guizhou province) during the growing season in 2017–2018, 2018–2019, and 2019–2020. Four winter wheat cultivars were used in field experiments to investigate the changes of the dry matter accumulation and partition, yield and yield components at maturity under five sowing densities (75, 150, 225, 300, and 375 plants per m2), and three sowing patterns: line and dense (LD) sowing with 33.3 cm row spacing (LDS); the belt uniform (BU) sowing with 15 cm (BUN), and 20 cm (BUW) row spacing. The BU sowing pattern significantly increases shoot dry matter and grain yield in all four winter wheat cultivars under all five sowing densities and in each growing season, particularly under the high sowing density of 300 and 375 plants m−2. Harvest index was unaffected by the different sowing densities and sowing patterns. While spike number increased, grain weight per spike decreased with the increase in sowing density. The 1000-grain weight and grain number per spike were unaffected by the sowing patterns. The variation in the shoot dry weight can explain 94% variation in grain yield and 66% variation in spike number. Allometric analysis showed that more dry matter was partitioned to the spike than to the stem and leaf. We conclude that the BU sowing pattern can increase grain yield under high sowing densities associated with a high shoot dry matter accumulation and its partition to the spike.

Sorghum is mainly used for brewing distilled liquors in China. Since grain tannins play an important role in liquor brewing, accurately understanding the relationship between grain color and tannin content can provide basis for selection standards of tannin sorghum. We resequenced a panel of 242 Chinese sorghum accessions and performed population structure and GWAS analysis to identify QTLs affecting pericarp color, testa pigment, and tannin content. Dendrogram, principal component analysis (PCA), and admixture model were used to infer population structure. Two distinct genetic sub-populations were identified according to their corresponding northern and southern geographic origin. To investigate the genetic basis of natural variation in sorghum grain color, a genome-wide association study (GWAS) with 2,760,264 SNP was conducted with multiple models (Blink, FarmCPU, GLM, and MLM). The four models identified 1090, 259, 32 and 251 SNP loci for the color of exocarp, mesocarp, testa, and tannin content, respectively. These SNPs were distributed in 440 SNP peaks. Some novel quantitative trait loci for sorghum pericarp color, testa pigments and tannin content colocalized with homologous genes in the flavonoid biosynthetic pathway from other plants, including an orthologue of maize ( Zea mays ) bz2 and homologues of Arabidopsis ( Arabidopsis thaliana ) TT2 , TT12 , and TT16 . Our investigation of the variation in grain color and tannin content in Chinese sorghum germplasm may help guide future sorghum breeding for liquor brewing.