多组学综合分析白木通自花授粉后幼果脱落机制

Multi-omics comprehensive analysis of fruitlet abscission mechanism after self-pollination of Akebia trifoliata ssp. australis

  • 摘要: 【目的】通过多组学综合分析白木通幼果在自花授粉后的脱落机制,为白木通良种繁育提供理论依据。【方法】通过人工授粉技术对白木通栽培种BMTGKAN1进行自花授粉和栽培种间授粉,授粉后第13和18 d取样,利用苯胺蓝染色法分析授粉后花粉管的萌发情况,石蜡切片技术观察授粉后胚珠发育情况,统计不同授粉处理的幼果留存率,并结合转录组和代谢组分析授粉后幼果脱落机制。【结果】自花授粉和栽培种授粉的花粉在BMTGKAN1雌蕊内萌发生长情况相似,但在受精过程中,栽培种间授粉胚珠在授粉后6 h发生核融合,自花授粉组的胚珠面积较小,未发生核融合,授粉后18 d栽培种间授粉的胚珠发育出胚乳和胚,而自花授粉胚珠未发育出胚乳和胚,出现内外珠被分离,且此时幼果留存率存在明显差异,即自花授粉后第18 d幼果留存率仅为5.92%,栽培种间授粉后第18 d幼果留存率高达86.24%。在转录和代谢水平上,栽培种间授粉与自花授粉相比,授粉后第13 d和第18 d差异表达基因(DEGs)分别为444和3646条,差异代谢物(DEMs)分别为427和412个。在相同授粉方式的比较中,自花授粉后第13 d与第18 d相比,有3305个DEGs和457个DEMs,栽培种间授粉第13 d与第18 d相比,有1123个DEGs和420个DEMs。实时荧光定量PCR检测结果与转录组数据变化趋势基本相同,说明转录组数据分析结果相对准确。在各对比组DEGs和DEMs联合分析中,至少在一个对比组中被富集到的KEGG信号通路共有162条,其中有48条在各对比组中均被富集到。植物激素信号转导通路、亚油酸代谢通路、ABC转运蛋白通路和苯丙烷生物合成通路极有可能参与调控白木通自花授粉后的幼果脱落。【结论】BMTGKAN1属于晚期自交不亲和植物,其自花授粉后13~18 d大量脱落幼果,受其体内植物激素信号转导通路、亚油酸代谢通路、ABC转运蛋白通路、苯丙烷生物合成通路调控,在种植实践中选择2个及以上花期相近的白木通栽培品种隔行交叉种植以提高坐果率。

     

    Abstract: 【Objective】In this study,multi-omics comprehensive analysis methods were used to explore the mechanism of fruitlet abscission after self-pollination of Akebia trifoliata ssp. australis,and to provide a theoretical basis for the breeding of improved varieties of A. trifoliata ssp. australis. 【Method】Self-pollination and interspecific pollination of A.trifoliata ssp. australis cultivated variety BMTGKAN1 were carried out by artificial pollination techniques. Samples were taken on the 13rd and 18th d after pollination. The pollen tube germination was analyzed by aniline blue staining method, and ovule development was observed by paraffin section technique, and the retention rate of fruitlet under different pollination treatments was calculated. The mechanism of fruitlet shedding after pollination was analyzed by transcriptome and metabolome.The germination and growth of pollen in BMTGKAN1 pisticles were similar between self-pollinated and cultivated varieties. However, during fertilization, the ovule of cultivated interspecific pollination occurred nuclear fusion at 6 h after pollination. The ovule area of self-pollination group was small, and nuclear fusion did not occur. 【Result】At 18 d after pollination,the ovules of inter-specific pollination developed endosperm and embryo,while the ovules of selfpollination developed no endosperm and embryo,and the inner and outer integuments were separated,and the fruitlet retention rate was quite different at this time. On the 18th d after pollination,the fruitlet retention rate of self-pollinated was only 5.92%,while that of cultivated species was as high as 86.24%. At the level of transcription and metabolism,compared with self-pollination,there were 444 and 3646 differential expressed genes(DEGs) and 427 and 412 differential metabolites(DEMs) on the 13rd and 18th d after pollination. In the comparison of the same pollination methods,there were 3305 DEGs and 457 DEMs on the 13rd d after self-pollination compared with the 18th d after self-pollination. There were 1123 DEGs and 420 DEMs in inter-species pollination. The results of real-time fluorescence quantitative PCR showed the same trend as the transcriptome data, indicating that the transcriptome data analysis results were relatively accurate. In the joint analysis of DEGs and DEMs in each comparison group,a total of 162 KEGG metabolic pathways were enriched in at least one comparison group,of which 48 were enriched in each comparison group. Metabolic pathways such as plant hormone signal transduction,linoleic acid metabolism,ABC transporters,and phenylpropanoid biosynthesis were likely to be involved in regulating the abscission of fruitlets after self-pollination of A. trifoliata ssp. australis. 【Conclusion】BMTGKAN1 belongs to late self-incompatibility plant, its fruitlets of A. trifoliata ssp. australis will all fall off within 13-18 d after self-pollination, and regulated by pathways of plant hormone signal transduction,linoleic acid metabolism,ABC transporters,phenylpropanoid biosynthesis. It is suggested that at least two varieties of A. trifoliata ssp. australis with similar flowering period should be selected for interlaced cross planting to improve fruit setting rate.

     

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