Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea.
Risk Assessment Research Center, Korea Institute of Ocean Science and Technology, Geoje, 53201, Republic of Korea.
Sci Rep. 2020 Jun 30;10(1):10653. doi: 10.1038/s41598-020-67547-9.
Different clades belonging to the cosmopolitan marine diatom Pseudo-nitzschia pungens appear to be present in different oceanic environments, however, a 'hybrid zone', where populations of different clades interbreed, has also been reported. Many studies have investigated the sexual reproduction of P. pungens, focused on morphology and life cycle, rather than the role of sexual reproduction in mixing the genomes of their parents. We carried out crossing experiments to determine the sexual compatibility/incompatibility between different clades of P. pungens, and examined the genetic polymorphism in the ITS2 region. Sexual reproduction did not occur only between clades II and III under any of experimental temperature conditions. Four offspring strains were established between clade I and III successfully. Strains established from offspring were found interbreed with other offspring strains as well as viable with their parental strains. We confirmed the hybrid sequence patterns between clades I and III and found novel sequence types including polymorphic single nucleotide polymorphisms (SNPs) in the offspring strains. Our results implicate that gene exchange and mixing between different clades are still possible, and that sexual reproduction is a significant ecological strategy to maintain the genetic diversity within this diatom species.
不同的枝系属于广布海洋硅藻菱形藻似乎存在于不同的海洋环境中，然而，也有报道称存在“杂交区”，在那里不同枝系的种群杂交。许多研究已经调查了菱形藻的有性生殖，重点是形态和生命周期，而不是有性生殖在混合其父母基因组中的作用。我们进行了杂交实验，以确定不同枝系的菱形藻之间的有性可育/不育性，并检查了 ITS2 区域的遗传多态性。在任何实验温度条件下，枝系 II 和 III 之间的有性生殖都没有发生。成功地在枝系 I 和 III 之间建立了 4 个后代菌株。从后代中建立的菌株被发现与其他后代菌株以及与其亲本菌株都能杂交。我们证实了枝系 I 和 III 之间的杂交序列模式，并在后代菌株中发现了包括多态性单核苷酸多态性（SNP）在内的新序列类型。我们的结果表明，不同枝系之间的基因交换和混合仍然是可能的，有性生殖是维持该硅藻物种内遗传多样性的重要生态策略。
