Extracellular and intracellular infection of Botryosphaeria dothidea and resistance mechanism in apple cells

Apple ring rot,which is caused by Botryosphaeria dothidea,severely affects apple production.The mechanisms employed in apple cells against B.dothidea remain unknown.In this research,the pathogen infection mode and the relationship between cell death and disease resistance in‘Fuji’/B.dothidea interaction pathosystem were investigated.By using transmission electron microscopy(TEM),our research showed that the pathogen infects apple cells both intracellularly and extracellularly.However,compared with that in immature fruit,the incidence of hyphae in the interior of mature apple fruit cells increased dramatically,suggesting that cell wall-mediated penetration resistance could be important in apple resistance against B.dothidea.TEM ultrastructural characterization identified the nuclear morphology of programmed cell death induction in both apple fruit and callus cells under B.dothidea infection.Overexpression of MdVDAC2(MDP0000271281),which encodes an outer-membrane localized anion channel protein in mitochondria,significantly promoted cell death under B.dothidea infection and simultaneously inhibited pathogen infection,suggesting that cell death represents a disease resistance mechanism in apple against B.dothidea infection.Furthermore,BdCatalase(KAF4307763),a cytochromeP450 family protein BdCYP52A4(KAF4300696),and subtilisin-domain containing proteinswere identified fromB.dothidea-secreted proteins,which suggested the potential involvement of active oxygen species and phytoalexins in combating B.dothidea infection and triggering or dampening apple resistance.Collectively,our research suggested that cell wall-mediated penetration resistance,programmed cell death machinery and microbial effector-interrelated signaling were among strategies recruited in apple to combat B.dothidea.The current research laid the foundation for further investigations into resistance mechanisms in apple.

Isolation Technology of Single Spore and Optimization of Conidia Culture Condition for Ustilaginoidea virens

The single spores were isolated from chlamydospores of Ustilaginoidea virens with three different maturities by PSA. The isolated single spores were cultured on different media at different temperatures under natural light for inducing conidia to explore the optimum isolation technique of single spore and optimum culture condition of conidia. The results showed that the successful isolating rate of single spore from yellow rice false smut balls reached 90. 00% . The sporulation quantities of isolated single spores cultured on PSD and PDB media at 22 - 29 ℃ ( variable temperature under natural light) or 28 ℃ ( constant temperature under dark condition) for 12 d were up to 6. 3 × 107 and 1. 1 × 106 spore / mL,respectively. PSA was the most effective method to isolate single spores from yellow rice false smut balls of U. virens. The optimum conidia culture condition included PSD or PDB medium,22 - 29 ℃ or 28 ℃ ,natural light and vibration culture.

组合式仿枫树子飞行器与空中分体技术

仿枫树子飞行器是一种模仿自然界枫树种子飞行原理的仿生飞行器。为提升仿枫树子飞行器的任务执行能力,设计了一种组合式仿枫树子飞行器,组合体可2、3或6个单体飞行器通过组合箱组合而成,具有地面快速拆装和空中受控分体的能力。基于叶素-动量理论完成了单体飞行器和组合体飞行器的气动建模,分析发现组合体飞行器的飞行效率相比单体飞行器提升了13.3%;完成了飞行器动力学建模和外环控制律设计,并通过六自由度飞行仿真对飞行器的典型飞行状态、空中分体过程进行了研究,结果表明飞行器具备可控飞行和空中稳定分体的能力;在实际飞行试验中,成功实现了三机组合体的空中分体。组合式设计与空中分体技术,使飞行器具备了高飞行效率和无人机集群的双重优势。