Lakshmi Nikhitha, Basha Shaik Ameer, Paramita Pal Pragya, Begum Ahil Sajeli, Vittal Ramya, Naik Saida, Devi Gali Uma, Sagar Bokka Vidya
Department of Plant Pathology, College of Agriculture, PJTSAU, Rajendranagar-500030, Hyderabad, Telangana State, India.
Department of Pharmacy, BITS-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, Hyderabad, Telangana State, India.
Chem Biodivers. 2022 Apr;19(4):e202100880. doi: 10.1002/cbdv.202100880. Epub 2022 Mar 8.
Groundnut stem rot caused by Sclerotium rolfsii is a major constraint as it affects the productivity. Although managing this disease using synthetic fungicides is a more feasible method, environmental pollution and side effects caused by them demand some safe fungicides. Seven phytochemicals piperine, quercetin, reserpine, atropine sulfate, β-sitosterol, ethyl protocatechuate and salicylic acid were initially tested against S. rolfsii under in vitro methods. All the compounds exhibited significant effects on mycelial inhibition (except atropine sulfate), sclerotial development, ooze formation, maturity, sclerotial number and germination of S. rolfsii. The more active compounds, piperine, reserpine and β-sitosterol were then evaluated under glasshouse condition by adopting various application methods (seed treatment, foliar application and micro-injection at 2000 μg/mL) on groundnut plants challenged with and without S. rolfsii. All the treatments effectively reduced the plant mortality when tested every 15 days of infection with S. rolfsii. However, the magnitude of reduction varied among the treatments, with the mortality ranging between 9.37 % and 29.68 % compared to the control (40.68 %). The piperine-microinjected plants recorded minimum mortality (3.12 %). The defense enzymes (PAL and PPO) and key end products such as phenolics (total and individual) were determined in the leaf samples collected after 24, 48 and 72 h of infection with S. rolfsii to understand the systemic resistance induction effect. An increase in PAL and PPO activity was observed in all the samples. While microinjection of β-sitosterol caused a maximum PAL induction, piperine caused a maximum PPO activity. Further, samples of piperine treated group showed higher induction of phenolic acids (86.46 μg g micro-injection) compared to β-sitosterol and reserpine groups in all the methods. When the samples were analysed (HPLC) for individual phenolic acids, maximum accumulation of various acids was observed in the samples collected after 48 h. Tannic and gallic acids were found to be accumulated in higher quantities in most of the samples. The maximum accumulation of phenolic acids was found in micro-injected samples. These results verified the reduction of mortality through the induction of defensive chemicals by the action of phytochemicals. Thus, the study recommends the use of these natural molecules for the integrated management of stem rot of groundnut after necessary field trials.
由齐整小核菌引起的花生茎腐病是影响产量的主要制约因素。尽管使用合成杀菌剂防治这种病害是一种更可行的方法，但它们造成的环境污染和副作用促使人们寻求一些安全的杀菌剂。最初采用体外方法对胡椒碱、槲皮素、利血平、硫酸阿托品、β-谷甾醇、原儿茶酸乙酯和水杨酸这七种植物化学物质进行了针对齐整小核菌的测试。所有化合物（除硫酸阿托品外）均对齐整小核菌的菌丝抑制、菌核发育、溢泌物形成、成熟度、菌核数量和萌发表现出显著影响。随后，通过对感染和未感染齐整小核菌的花生植株采用各种施用方法（种子处理、叶面喷施和2000μg/mL的微量注射），在温室条件下对活性更强的化合物胡椒碱、利血平和β-谷甾醇进行了评估。在每隔15天用齐整小核菌感染进行测试时，所有处理均有效降低了植株死亡率。然而，各处理的降低幅度有所不同，与对照（40.68%）相比，死亡率在9.37%至29.68%之间。胡椒碱微量注射的植株死亡率最低（3.12%）。在感染齐整小核菌24、48和72小时后采集的叶片样本中测定了防御酶（苯丙氨酸解氨酶和多酚氧化酶）以及关键终产物如酚类物质（总量和个体），以了解系统抗性诱导效果。在所有样本中均观察到苯丙氨酸解氨酶和多酚氧化酶活性增加。虽然β-谷甾醇微量注射引起最大的苯丙氨酸解氨酶诱导，但胡椒碱引起最大的多酚氧化酶活性。此外，在所有方法中，胡椒碱处理组的样本与β-谷甾醇和利血平组相比，显示出更高的酚酸诱导量（86.46μg g微量注射）。当对样本进行分析（高效液相色谱法）以检测单个酚酸时，在48小时后采集的样本中观察到各种酸的最大积累。在大多数样本中发现单宁酸和没食子酸积累量较高。在微量注射样本中发现酚酸的最大积累。这些结果证实了植物化学物质通过诱导防御性化学物质降低了死亡率。因此，该研究建议在进行必要的田间试验后，使用这些天然分子对花生茎腐病进行综合防治。
