The angle of tillers is crucial for shaping plant architecture, which in turn affects grain yield of rice. The formation of tiller angle is associated with the asymmetrical distribution and polar transport of auxin. However, the roles of auxin signaling in regulating tiller angle in rice remain unclear. This study identifies Oryza sativa Auxin Response Factor 5 (OsARF5) as a key regulator of tiller angle development in rice. The osarf5-1 mutant was obtained through using chemical mutagenesis. The differentially expressed genes were identified through quantitative RT-PCR and high-throughput mRNA sequencing. The interactions between OsARF5 protein and its targeted-DNAs was analyzed by chromatin immunoprecipitation and dual-luciferase reporter assays. Protein-protein interactions were assessed using yeast two-hybrid and bimolecular fluorescence complementation methods. The osarf5-1 mutation enlarges the tiller angle, weakens shoot gravitropism, and diminishes the response to auxin in rice. OsARF5 binds to the cis-acting elements in the promoters of genes related to tiller angle development and activates their expression. Genome-wide studies identify thousands of differentially expressed genes (DEGs), including auxin response genes, between wild-type and osarf5-1. Under gravistimulation, the number of DEGs in osarf5-1 decreases, indicating the involvement of OsARF5 in shoot gravitropism. The OsARF5 physically interact with three rice Indole Acetic Acid (OsIAA) repressors, forming complexes that facilitate their functions. Mutations in OsIAAs lead to a more compact plant architecture, and the expression of OsARF5-target genes is elevated in osiaa mutants, suggesting that the OsIAAs counteract OsARF5's effects on tiller angle control. OsARF5 is associated with three OsIAAs to bind to the promoter of the target genes, regulating their expression to modulate shoot gravitropism and tiller angle in rice. These findings offer new insights into the principles governing tiller angle control in rice.

Chromium is a major heavy metal pollutant that affects the health of both plants and animals. In this study, sunflower seedlings were treated with K₂Cr₇O₄ containing 50, 100, and 250 mg of pure chromium per kilogram of soil. It was found that the chromium was absorbed by the roots and transported within plant tissues to the stems and leaves. Chromium affected sunflower photosynthesis, seen in increased the Fv/Fm values as the chromium concentration rose. Metagenomic sequencing of rhizosphere microbial communities after treatment with 100 mg/kg pure chromium indicated that the rhizosphere microorganisms were resistant to chromium exposure; chromium was found to promote dopamine secretion and chromium complexation by the microorganisms. In addition, chromium was found to reduce microbial production of N₂O reductase and increase the emission of the greenhouse gas N₂O. In addressing the problem of chromium pollution in sunflower farmland, Bacillus sp. strain C8 was isolated and shown to effectively reduce soil chromium contents and chromium absorption by sunflower, thereby reducing the adverse effects of the metal. Furthermore, a gene associated with chromium resistance, LOC118480906, was identified by transcriptome sequencing of sunflower plants. In conclusion, the findings denonstrate: (1) the effect of chromium exposure on sunflower growth and development of sunflower; (2) the ecological effects of chromium exposure on sunflower farmland; (3) the regulation of soil microbes and the identification of resistance associated genes are effective ways to reduce chromium pollution.

Potato (Solanum tuberosum L.) has high nutritional value and strong adaptability and plays an extremely important role in global food security. Excessive use of nitrogen (N) fertilizer in potato production has increased costs and environmental pollution. In this study, the N use efficiency (NUE) of two potato varieties (DXY and DN310) was determined under high nitrogen conditions. The N use efficiency of DXY was relatively high. The differences between the rhizosphere microbial population groups of the two varieties were determined using the metagenomic sequencing method. The genes related to N efficiency were jointly identified using transcriptome and metabolome analyses. Significant difference was observed between the two varieties of microorganisms, leading to different rhizosphere microorganisms. Compared with DN310, the roots of DXY retained more available N and generated less NO. Additionally, DXY exhibited relatively low disease susceptibility. Combined transcriptome and metabolome analyses indicated that the differentially expressed metabolites in the two different varieties under high N conditions were mainly enriched in amino acid metabolism and sugar metabolism pathways. Using weighted gene co-expression network analysis, two genes associated with N fertilizer response were identified: PGSC0003DMG400025888 and PGSC0003DMG400017276. This study provided valuable insights into breeding potato varieties with high N efficiency.