Murugesan Rajesh Kannan, Balakrishnan Ramkumar, Natesan Sivakumar, Jayavel Sridhar, Muthiah Ramakritinan Chockalingam
Department of Marine and Coastal Studies, School of Energy, Environment and Natural Resources, Madurai Kamaraj University, Madurai - 625021, Tamil Nadu, India.
Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai - 625021, Tamil Nadu, India.
Bioinformation. 2022 Apr 30;18(4):318-324. doi: 10.6026/97320630018318. eCollection 2022.
Coral endosymbionts act as a bio-indicator of coral ecosystem under extreme environmental conditions. The health of the coral ecosystem depends on the endosymbiont cell density of the coral hosts. Therefore, it is of interest to analyze ten coral fragments found to be under the genera Acropora, Favites, Favia, and Porites collected at various locations from Veedhalai to Mandapam, southeast coast of India during January 2019 to March 2019. The zooxanthellae cell count ranged between 4.08 (Porites sp.9) and 13.75x105 cells cm2 -1 (Favites sp.3). This indicates the health of the corals in the region. The genus (clade) level identification of endosymbionts was detected using the host excluding primers of small subunit DNA (nssrDNA). Bidirectional sequencing of 18S nrDNA gene (SSU) of all ten coral fragments show that the Veedhalai corals is associated with the genus Durusdinium (Clade D) but the corals of Mandapam is associated with the genera, Cladocopium (Clade C) and Durusdinium (Clade D). It is known that the thermal stress has negative impact on coral reef ecosystem of the world. The dominance of the genus Durusdinium in the scleractinian corals of Palk Bay may be due to frequent exposure to thermal stress. This thermotolerant endosymbionts is opportunistic. Thus, the corals of Veedhalai and Mandapam coasts, Palk Bay, India are necessarily packed with thermotolerant endosymbionts enabling conservation.
珊瑚内共生体是极端环境条件下珊瑚生态系统的生物指标。珊瑚生态系统的健康状况取决于珊瑚宿主内共生体细胞密度。因此，分析2019年1月至2019年3月期间在印度东南海岸从维德哈利到曼达帕姆不同地点采集的属于鹿角珊瑚属、蜂巢珊瑚属、扁脑珊瑚属和滨珊瑚属的10个珊瑚碎片具有重要意义。虫黄藻细胞计数范围在4.08（滨珊瑚属9号）至13.75×10⁵个细胞·平方厘米⁻¹（蜂巢珊瑚属3号）之间。这表明了该地区珊瑚的健康状况。使用小亚基DNA（nssrDNA）的宿主排除引物检测内共生体的属（分支）水平鉴定。对所有10个珊瑚碎片的18S nrDNA基因（SSU）进行双向测序表明，维德哈利的珊瑚与杜氏藻属（分支D）相关，但曼达帕姆的珊瑚与枝粒藻属（分支C）和杜氏藻属（分支D）相关。众所周知，热应激对全球珊瑚礁生态系统有负面影响。杜氏藻属在保克湾石珊瑚中的优势地位可能是由于频繁受到热应激。这种耐热内共生体具有机会性。因此，印度保克湾维德哈利和曼达帕姆海岸的珊瑚必然富含耐热内共生体，有利于保护。
