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To overcome inadequate functional integration, irregular pits, and insufficient agricultural machinery and agronomy in tobacco seedling transplanting equipment under film, a digging transplanting integrated machine was built. The machine uses parallel four-bar mechanism. The excavation equipment uses conical spiral blades. Using the trajectory approach, the four bar mechanism's fundamental parameters can be reversed. This method meets the requirements for coordinated excavation and transplantation. Mechanical study of soil units determines upward movement characteristics. Additionally, spiral angle, spiral blade outer diameter, and spiral blade speed are quantified to affect soil movement. The range of factors is derived. Based on three factors binary regression orthogonal combination simulated optimization experiment, a discrete element analysis was performed to enhance parameters. Experimental factors optimized include a spiral angle of 19°, a spiral blade diameter of 378 mm, and a rotational speed of 258 rpm. The two optimized test indicators are: a 193 mm hole depth and 350 mm hole diameter. The improved results were verified by field validation studies using a 191 mm hole depth and 347 mm hole diameter. The simulation optimization results and field validation experiment results are very similar. This study provides a technical basis for tobacco farming concurrent drilling and transplanting research. [ABSTRACT FROM AUTHOR]

Lumazine synthase (LS) catalyzes the penultimate reaction in the multistep riboflavin biosynthesis pathway, which is involved in plant defenses. Plant defenses are often subject to synergistic effects of jasmonic acid and ethylene whereas LS is a regulator of jasmonic acid signal transduction. However, little is known about whether the enzyme contributes to defense responses. To study the role of LS in plant pathogen defenses, we generated transgenic tobacco expressing the rice (Oryza sativa) LS gene, OsLS. OsLS was cloned and found to have strong identity with its homologues in higher plants and less homology to microbial orthologues. The OsLS protein localized to chloroplasts in three OsLS-expressing transgenic tobacco (LSETT) lines characterized as enhanced in growth and defend. Compared with control plants, LSETT had higher content of both riboflavin and the cofactors flavin mononucleotide and flavin adenine dinucleotide. In LSETT, jasmonic acid and ethylene were elevated, the expression of defense-related genes was induced, levels of resistance to pathogens were enhanced, and resistance was effective to viral, bacterial, and oomycete pathogens. Extents of OsLS expression correlated with increases in flavin, jasmonic acid, and ethylene content, and correlated with increases in resistance levels, suggesting a role for OsLS in defense responses. [ABSTRACT FROM AUTHOR]

Leaf trichomes serve as a physical barrier and can also secrete antimicrobial compounds to protect plants from attacks by insects and pathogens. Besides the use of the physical and chemical mechanisms, leaf trichomes might also support plant responses by communicating the extrinsic cues to plant intrinsic signalling pathways. Here we report a role of leaf trichomes in tobacco (Nicotiana tabacum) hypersensitive cell death (HCD) induced by ParA1, an elicitin protein from a plant-pathogenic oomycete. After localized treatment with ParA1, reactive oxygen species were produced first in the leaf trichomes and then in mesophylls. Reactive oxygen species are a group of intracellular signals that are crucial for HCD to develop and for cells to undergo cell death subsequent to chromatin condensation, a hallmark of HCD. These events were impaired when the production of hydrogen peroxide (H2O2) was inhibited by catalase or a NADPH-oxidase inhibitor applied to trichomes, suggesting the importance of H2O2 in the pathway of HCD signal transduction from the trichomes to mesophylls. This pathway was no longer activated when leaf trichomes were treated with C51S, a ParA1 mutant protein defective in its interaction with N. tabacum TTG1 (NtTTG1), which is a trichome protein that binds ParA1, rather than C51S, in vitro and in trichome cells. The ParA1-NtTTG1 interaction and the HCD pathway were also abrogated when NtTTG1 was silenced in the trichomes. These observations suggest that NtTTG1 plays an essential role in HCD signal transduction from leaf trichomes to mesophylls [ABSTRACT FROM AUTHOR]