Hashemi Tahereh Sadat, Soltani Jalal, Samsampour Davood, Seyahooei Majeed Askari, Ghasemi Mostafa
Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Hormozgan, Bandar Abbas, Iran.
Phytopathology Section, Plant Protection Department, Bu-Ali Sina University, Agriculture Faculty, Hamedan, Iran.
Folia Microbiol (Praha). 2024 Nov 5. doi: 10.1007/s12223-024-01213-9.
Endophytes are symbionts that live in healthy plants and potentially improve the health of plant holobionts. Here, we investigated the bacterial endophyte community of Citrus reticulata grown in the northern Persian Gulf. Bacteria were isolated seasonally from healthy trees (root, stem, bark, trunk, leaf, and crown tissues) in four regions of Hormozgan province (i.e., Ahmadi, Siyahoo, Sikhoran, Roudan), a subtropical hot region in Iran. A total of 742 strains from 17 taxa, 3 phyla, and 5 orders were found, most of which belonged to Actinobacteria (Actinobacteriales) as the dominant group, followed by Firmicutes (Bacillales), Proteobacteria (Sphingomonadales, Rhizobiales), and Cyanobacteria (Synechoccales). The genera included Altererythrobacter, Arthrobacter, Bacillus, Cellulosimicrobium, Curtobacterium, Kocuria, Kytococcus, Methylopila, Mycobacterium, Nocardioides, Okiabacterium, Paracraurococcus, and Psychrobacillus. The most frequently occurring species included Psychrobacillus psychrodurans, Kytococcus schroetri, and Bacillus cereus. In addition, the overall colonization frequency and variability of endophytes were higher on the trunks. The leaves showed the lowest species variability in all sampling periods. The frequency of endophyte colonization was also higher in summer. The Shannon-Wiener (H') and Simpson indices varied with all factors, i.e., region, season, and tissue type, with the maximum in Roudan. Furthermore, 52.9% of the strains were capable of nitrogen fixation, and 70% produced antagonistic hydrogen cyanide (HCN). Thus, C. reticulata harbors a variety of bioactive bacterial endophytes that could be beneficial for host fitness in such harsh environments.
内生菌是生活在健康植物体内并可能改善植物整体健康状况的共生体。在此，我们调查了生长在波斯湾北部的网纹柑橘的细菌内生菌群落。细菌是从伊朗亚热带炎热地区霍尔木兹甘省的四个地区（即艾哈迈迪、锡亚胡、锡霍兰、鲁丹）的健康树木（根、茎、树皮、树干、叶和树冠组织）中按季节分离得到的。共发现来自17个分类单元、3个门和5个目742株菌株，其中大多数属于放线菌（放线菌目），为优势菌群，其次是厚壁菌门（芽孢杆菌目）、变形菌门（鞘脂单胞菌目、根瘤菌目）和蓝细菌（聚球藻目）。这些属包括交替赤杆菌属、节杆菌属、芽孢杆菌属、纤维微菌属、短小杆菌属、考克氏菌属、球形球菌属、甲基杆菌属、分枝杆菌属、诺卡氏菌属、奥氏杆菌属、副嗜冷球菌属和嗜冷芽孢杆菌属。最常见的物种包括嗜冷嗜冷芽孢杆菌、施氏球形球菌和蜡样芽孢杆菌。此外，内生菌在树干上的总体定殖频率和变异性更高。在所有采样期，叶片的物种变异性最低。内生菌定殖频率在夏季也更高。香农 - 维纳（H'）指数和辛普森指数随所有因素（即地区、季节和组织类型）而变化，在鲁丹地区最高。此外，52.9%的菌株能够固氮，70%的菌株产生具有拮抗作用的氰化氢（HCN）。因此，网纹柑橘含有多种具有生物活性的细菌内生菌，在如此恶劣的环境中可能对宿主健康有益。
