Kis-Papo Tamar, Kirzhner Valery, Wasser Solomon P, Nevo Eviatar
Institute of Evolution, University of Haifa, Mt. Carmel, Haifa 31905, Israel.
Proc Natl Acad Sci U S A. 2003 Dec 9;100(25):14970-5. doi: 10.1073/pnas.2036284100. Epub 2003 Nov 26.
We have found that genomic diversity is generally positively correlated with abiotic and biotic stress levels (1-3). However, beyond a high-threshold level of stress, the diversity declines to a few adapted genotypes. The Dead Sea is the harshest planetary hypersaline environment (340 g.liter-1 total dissolved salts, approximately 10 times sea water). Hence, the Dead Sea is an excellent natural laboratory for testing the "rise and fall" pattern of genetic diversity with stress proposed in this article. Here, we examined genomic diversity of the ascomycete fungus Aspergillus versicolor from saline, nonsaline, and hypersaline Dead Sea environments. We screened the coding and noncoding genomes of A. versicolor isolates by using >600 AFLP (amplified fragment length polymorphism) markers (equal to loci). Genomic diversity was positively correlated with stress, culminating in the Dead Sea surface but dropped drastically in 50- to 280-m-deep seawater. The genomic diversity pattern paralleled the pattern of sexual reproduction of fungal species across the same southward gradient of increasing stress in Israel. This parallel may suggest that diversity and sex are intertwined intimately according to the rise and fall pattern and adaptively selected by natural selection in fungal genome evolution. Future large-scale verification in micromycetes will define further the trajectories of diversity and sex in the rise and fall pattern.
我们发现基因组多样性通常与非生物和生物胁迫水平呈正相关（1 - 3）。然而，超过胁迫的高阈值水平后，多样性会降至少数适应的基因型。死海是地球上最恶劣的高盐环境（总溶解盐含量为340克/升，约为海水的10倍）。因此，死海是一个绝佳的天然实验室，可用于测试本文提出的遗传多样性随胁迫的“升降”模式。在此，我们研究了来自死海的盐渍、非盐渍和高盐环境中的子囊菌杂色曲霉的基因组多样性。我们使用超过600个AFLP（扩增片段长度多态性）标记（等同于基因座）筛选了杂色曲霉分离株的编码和非编码基因组。基因组多样性与胁迫呈正相关，在死海表面达到顶峰，但在50至280米深的海水中急剧下降。基因组多样性模式与以色列同一向南递增胁迫梯度上真菌物种的有性繁殖模式平行。这种平行可能表明，在真菌基因组进化中，根据升降模式，多样性和有性生殖紧密相连，并通过自然选择进行适应性选择。未来在微真菌中的大规模验证将进一步确定升降模式中多样性和有性生殖的轨迹。
