Saccharum officinarum (sugarcane) is the fifth major cultivated crop around the world. Sugarcane rind is a promising source for anthocyanin pigments; however, limited information is available on the anthocyanin and its biosynthesis in sugarcane rinds. In this study, we have quantified 49 compounds including 6 flavonoids and 43 anthocyanins in the rind of 6 sugarcane cultivars by using LCMS/MS approach. Thirty of them were quantified for the first time in sugarcane. The 43 anthocyanins included 10 cyanidin (Cya), 11 pelargonidin (Pel), 9 peonidin (Peo), 5 malvidin (Mal), 4 delphinidin (Del), and 4 petunidin (Pet) metabolites. High contents of Cya derivatives were observed in the rind of YT71/210 (dark purple rind), such as cya-3-O-(6-O-malonyl)-glu 1283.3 µg/g and cya-3-O-glu 482.67 µg/g followed by ROC22 (red rind) 821.3 µg/g and 409 µg/g, respectively, whereas the YT93/159 (green rind) showed a minimum level of these compounds. Among six cultivars, ROC22 rind has high levels of Peo derivatives such as peo-3-O-glu (197 µg/g), peo-3-O-(6-O-malonyl)-glu (69 µg/g) and peo-3-O-(6-O-p-coumaryl)-glu (55.17 µg/g). The gene expression analysis revealed that some genes, including a MYB(t) gene, were highly associated with the color phenotype. Thus, we cloned and overexpressed the gene in Arabidopsis and found the pinkish brown color in the hypocotyl of all transgenic lines compared with the wild type. Hence, we have quantified a wide range of anthocyanins in major sugarcane cultivars, reported many new anthocyanins for the first time, and concluded that Cya and Peo derivatives are the major contributing factor of dissimilar colors in sugarcane. The finding and the verification of a novel MYB gene involved in anthocyanin biosynthesis have demonstrated that our study was very valuable for gene discovery and genetic improvement of sugarcane cultivars to harvest high anthocyanin contents.

Maize is an important cereal crop worldwide and is sensitive to abiotic stresses in fluctuant environments that seriously affect its growth, yield, and quality. The small heat shock protein (HSP20) plays a crucial role in protecting plants from abiotic stress. However, little is known about HSP20 in maize (ZmHSP20). In this study, 44 ZmHSP20s were identified, which were unequally distributed over 10 chromosomes, and 6 pairs of ZmHSP20s were tandemly presented. The gene structure of ZmHSP20s was highly conserved, with 95% (42) of the genes having no more than one intron. The analysis of the cis-element in ZmHSP20s promoter demonstrated large amounts of elements related to hormonal and abiotic stress responses, including abscisic acid (ABA), high temperature, and hypoxia. The ZmHSP20s protein had more than two conserved motifs that were predictably localized in the cytoplasm, nucleus, endoplasmic reticulum, peroxisome, mitochondria, and plasma. Phylogenetic analysis using HSP20s in Arabidopsis, rice, maize, and Solanum tuberosum indicated that ZmHSP20s were classified into 11 categories, of which each category had unique subcellular localization. Approximately 80% (35) of ZmHSP20 were upregulated under heat stress at the maize seedling stage, whereas the opposite expression profiling of 10 genes under 37 and 48 °C was detected. A total of 20 genes were randomly selected to investigate their expression under treatments of ABA, gibberellin (GA), ethylene, low temperature, drought, and waterlogging, and the results displayed that more than half of these genes were downregulated while ZmHSP20-3, ZmHSP20-7, ZmHSP20-24, and ZmHSP20-44 were upregulated under 1 h treatment of ethylene. A yeast-one-hybrid experiment was conducted to analyze the binding of four heat stress transcription factors (ZmHSFs) with eight of the ZmHSP20s promoter sequences, in which ZmHSF3, ZmHSF13, and ZmHSF17 can bind to most of these selected ZmHSP20s promoters. Our results provided a valuable resource for studying HSP20s function and offering candidates for genetic improvement under abiotic stress.

Fenlong-ridging (FL) is a recently proposed conservation tillage technology which has dramatic differences to traditional ones. Previous studies have demonstrated in many crops that FL has yield-increasing effects without additional inputs. However, little is known about the role that microbes play in mediating the growth-promoting effects of FL, which restricts its further application and improvement. Here, we characterized variation in the soil and root microbial diversity of sugarcane (GT44) under FL and traditional turn-over plough tillage (CK) by conducting 16S rRNA and ITS metabarcoding surveys. We also measured several phenotypic traits to determine sugarcane yields and analyzed the chemical properties of soil. We found that: (i) plant height (PH) and total biomass weight (TW) of sugarcane plants were 9.1% and 21.7% greater under FL than those under CK, indicating\increased biomass yield of the sugarcane in FL operation; (ii) contents of organic matter, total nitrogen, available phosphorus, and available potassium were lower in soil under FL than those under CK, which indicates the utilization of soil nutrients was greater in FL soil; (iii) FL promoted the activity of endophytic microbes in the roots, and these diverse microbial taxa might have an effect on sugarcane yield and soil chemical properties; and (iv) Sphingomonas, Rhizobium, and Paraburkholderia and Talaromyces, Didymella, and Fusarium were the top three most abundant genera of bacteria and fungi, respectively, in soil and root samples. In addition, strains from Rhizobium and Talaromyces were isolated to verify the results of the metabarcoding survey. Overall, our study provides new insights into the role of microbes in mediating the growth-promoting effects of FL. These findings could be used to further improve applications of this novel conservation tillage technology.

Lodging is one of the major constraints in attaining high yield in crop production. Major factors associated with stalk lodging involve morphological traits and anatomical features along with the chemical composition of the stem. However, little relevant research has been carried out in sorghum, particularly on the anatomical aspects. In this study, with a high-throughput procedure newly developed by our research group, the nine parameters related to stem regions and vascular bundles were generated in 58 sorghum germplasm accessions grown in two successive seasons. Correlation analysis and principal component analysis were conducted to investigate the relationship between anatomical aspects and stalk mechanical traits (breaking force, stalk strength and lodging index). It was found that most vascular parameters were positively associated with breaking force and lodging index with the correlation coefficient r varying from −0.46 to 0.64, whereas stalk strength was only associated with rind area with the r = 0.38. The germplasm resources can be divided into two contrasting categories (classes I with 23 accessions and II with 30 accessions). Compared to class II, the class I was characterized by a larger number (+40.7%) and bigger vascular bundle (+30%), thicker stem (+19.6%) and thicker rind (+36.0%) but shorter internode (plant) (−91.0%). This study provides the methodology and information for the studies of the stem anatomical parameters in crops and facilitates the selective breeding of sorghum.