Yu Jiaojun, Wang Chaobo, Gong Xun
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, PR China.
Yunnan Key Laboratory for Wild Plant Resources, Kunming 650201, PR China.
Plant Divers. 2017 Jan 12;39(2):80-88. doi: 10.1016/j.pld.2016.11.005. eCollection 2017 Apr.
The evolution of photosynthesis is an important feature of mixotrophic plants. Previous inferences proposed that mixotrophic taxa tend to retain most genes relating to photosynthetic functions but vary in plastid gene content. However, no sequence data are available to test this hypothesis in Ericaceae. To investigate changes in plastid genomes that may result from a transition from autotrophy to mixotrophy, the plastomes of two mixotrophic plants, and , were sequenced at Illumina's Genome Analyzer and compared to the published plastome of the autotrophic plant , which also belongs to Ericaceae. The greatest discrepancy between mixotrophic and autotrophic plants was that genes for both . and . plastomes have nearly all become pseudogenes. . and . also retained all genes directly involved in photosynthesis under strong selection. The calculated rate of nonsynonymous nucleotide substitutions and synonymous substitutions of protein-coding genes (dN/dS) showed that substitution rates in shade plants were apparently higher than those in sunlight plants. The two mixotrophic plastomes were generally very similar to that of non-parasitic plants, although genes were largely pseudogenized. Photosynthesis genes under strong selection were retained in the two mixotrophs, however, with greatly increased substitution rates. Further research is needed to gain a clearer understanding of the evolution of autotrophy and mixotrophy in Ericaceae.
光合作用的进化是兼养植物的一个重要特征。先前的推断表明，兼养类群倾向于保留大多数与光合功能相关的基因，但质体基因含量有所不同。然而，在杜鹃花科中尚无序列数据可用于检验这一假设。为了研究从自养向兼养转变可能导致的质体基因组变化，对两种兼养植物[此处原文缺失两种兼养植物的具体名称]的质体基因组在Illumina基因组分析仪上进行了测序，并与同样属于杜鹃花科的自养植物[此处原文缺失自养植物的具体名称]已发表的质体基因组进行了比较。兼养植物和自养植物之间最大的差异在于[此处原文表述不明，无法准确翻译]两种[此处指代不明]的基因几乎都已成为假基因。[此处指代不明]也在强烈选择下保留了所有直接参与光合作用的基因。计算得出的蛋白质编码基因非同义核苷酸替换率和同义替换率（dN/dS）表明，阴生植物中的替换率明显高于阳生植物。尽管[此处原文表述不明，无法准确翻译]基因大多已假基因化，但这两个兼养植物的质体基因组总体上与非寄生植物的质体基因组非常相似。然而，在这两种兼养植物中，受到强烈选择的光合作用基因得以保留，但其替换率大幅增加。需要进一步研究以更清楚地了解杜鹃花科中自养和兼养的进化情况。
