Ijaz Ayesha, Mumtaz Muhammad Zahid, Wang Xiukang, Ahmad Maqshoof, Saqib Muhammad, Maqbool Hira, Zaheer Ahmad, Wang Wenqiang, Mustafa Adnan
Institute of Molecular Biology and Biotechnology, The University of Lahore, Lahore, Pakistan.
College of Life Sciences, Yan'an University, Yan'an, China.
Front Plant Sci. 2021 Nov 2;12:719504. doi: 10.3389/fpls.2021.719504. eCollection 2021.
Manganese (Mn) is an essential micronutrient for plant growth that is involved in the structure of photosynthetic proteins and enzymes. Mn deficiency is widespread mainly in dry, calcareous, and sandy soil, which leads to a significant decrease in crop yield. Mn-reducing bacteria promote the solubilization of Mn minerals, thus increasing Mn availability in soil. The present study aimed to assess the Mn solubilizing ability and plant growth-promoting potential of spp. strains for maize plants with insoluble Mn compounds. Several Mn-solubilizing bacterial (MSB) strains were isolated from the maize rhizosphere using nutrient agar media amended with 50 mM MnO. These strains were screened based on qualitative and quantitative solubilization of Mn, phosphorus, potassium, and zinc and production of ammonia. The majority of MSB strains were positive for catalase, protease, amylase, and oxidase activity, while more than 60% of tested strains were positive for lipase activity, and the production of indole-3-acetic acid and siderophores. Forty-five percent of the tested strains also showed solubilization of potassium. All the MSB strains were evaluated for their ability to promote plant growth and Mn uptake in the presence of MnO under axenic sand culture conditions. The results revealed that inoculation with MSB strains under sand culture significantly improved the growth of maize seedlings except for strains ASH7, ASH10, and ASH12. Comparatively, strains ASH6, ASH11, ASH19, ASH20, and ASH22 demonstrated a better increase in plant growth, fresh and dry biomass, and Mn uptake in roots and shoots than the other strains tested. All of these strains were identified as spp. through 16S rRNA partial gene sequencing. Maize inoculation with these selected identified MSB strains also resulted in an increase in maize growth and nutrient uptake in maize roots and shoots under soil culture conditions in the presence of native soil Mn. The current study highlights the importance of MSB strain inoculation which could be a potential bioinoculants to promote plant growth under Mn deficiency.
锰（Mn）是植物生长必需的微量营养素，参与光合蛋白和酶的结构组成。锰缺乏主要普遍存在于干旱、石灰质和沙质土壤中，这会导致作物产量显著下降。锰还原菌促进锰矿物质的溶解，从而提高土壤中锰的有效性。本研究旨在评估 spp. 菌株对含有不溶性锰化合物的玉米植株的锰溶解能力和促进植物生长的潜力。使用添加了 50 mM 二氧化锰的营养琼脂培养基从玉米根际分离出几株锰溶解细菌（MSB）菌株。基于锰、磷、钾和锌的定性和定量溶解以及氨的产生对这些菌株进行筛选。大多数 MSB 菌株过氧化氢酶、蛋白酶、淀粉酶和氧化酶活性呈阳性，而超过 60% 的测试菌株脂肪酶活性、吲哚 - 3 - 乙酸和铁载体的产生呈阳性。45% 的测试菌株还表现出钾的溶解。在无菌沙培条件下，评估了所有 MSB 菌株在存在二氧化锰的情况下促进植物生长和锰吸收的能力。结果表明，除了菌株 ASH7、ASH10 和 ASH12 外，沙培条件下接种 MSB 菌株显著改善了玉米幼苗的生长。相比之下，菌株 ASH6、ASH11、ASH19、ASH20 和 ASH22 在植物生长、鲜重和干重以及根和茎中的锰吸收方面比其他测试菌株有更好的增加。通过 16S rRNA 部分基因测序，所有这些菌株均被鉴定为 spp.。在存在天然土壤锰的土壤培养条件下，用这些选定的已鉴定 MSB 菌株接种玉米也导致玉米生长以及玉米根和茎中养分吸收的增加。当前研究突出了接种 MSB 菌株的重要性，其可能是在锰缺乏条件下促进植物生长的潜在生物接种剂。
