芦笋两性花与雄花的碳氮比及氮化合物相关基因可变剪接的差异分析

Differences of Carbon-nitrogen Ration and Alternative Splicing of Nitrogen Compound Related Genes Between Hermaphroditic and Male Flower Buds in Asparagus officinalis L.

为探明芦笋两性花、雄花发育与碳氮比及氮化合物的关系,测定了芦笋两性花与雄花性别分化的前期、中期、后期3个时期花蕾的碳、氮化合物含量,并采用RNA-seq技术分析了6个样品中相关氮化合物基因的可变剪接及表达量的差异。结果发现,在性别分化的前期、中期,两性花蕾中含碳量低于雄花蕾,但含氮量却显著高于雄花蕾;在性别分化后期,两性花蕾中含碳量与雄花蕾相当,但含氮量仍然显著高于雄花蕾。可见,较低的碳氮比有利于两性花蕾中雌蕊的发育。RNA-seq测序及GO富集分析表明,有86个氮化合物相关基因只在两性花蕾中发生可变剪接,这些基因主要编码核糖体蛋白、MADS-box转录因子和一些酶类物质等,并且在性别分化的前期、中期,分别有52,47个基因表达量高于雄花蕾。这与两性花蕾中氮化合物含量高于雄花蕾的差异一致。综上所述,氮化合物代谢相关基因的可变剪接及较高的表达量和较低的碳氮比有利于两性花雌蕊的发育。

In order to investigate the relationship between the development of hermaphroditic and male flowers in Asparagus officinalis L. and the carbon and nitrogen compounds, the content of carbon and nitrogen compounds were determined in hermaphroditic and male flower buds of asparagus at three representative stages of early, middle and late sex determination. And the alternative splicing and expression of nitrogen compounds in six samples was analyzed by RNA-seq technique. The results showed that the carbon content of hermaphroditic flower buds was lower than that of male buds. On the contrary, the nitrogen content was significantly higher than that of male buds at the early and middle stages. At the late stage, the carbon content of hermaphroditic flower buds was equal to that of male buds, but the nitrogen content was still significantly higher than that of male buds. It was found that lower C/N was beneficial to gynoecium differentiation in hermaphroditic flower buds. Moreover, it was shown that 86 nitrogen compound metabolic related genes were alternatively spliced only in hermaphroditic flower buds by RNA-seq and GO enrichment analysis and these genes mainly encode ribosomal proteins, MADS-box transcription factors and some enzymes. At the early and middle sexual differentiation stages, there were 52 and 47 of the nitrogen compound metabolic related genes in hermaphroditic flower buds which expressing higher than those of male flower buds, respectively. This was consistent with the difference in nitrogen content between hermaphroditic and male flower buds. In conclusion, it was obviously that the alternative splice of nitrogen compound metabolic related genes and their high expression, and the lower C/N were beneficial to gynoecium differentiation in hermaphroditic flower buds.