Gao Yadi, Hu Yuanyuan, Shen Jiayi, Meng Xuecheng, Suo Jinwei, Zhang Zuying, Song Lili, Wu Jiasheng
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin'an City, China.
Sino-Australia Plant Cell Wall Research Centre, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an City, China.
Front Plant Sci. 2021 Oct 20;12:761139. doi: 10.3389/fpls.2021.761139. eCollection 2021.
Torreya 'Merrillii' is a famous nut with great nutritional value and high medicinal value. Aril cracking is an important process for seed dispersal, which is also an indicator of seed maturation. However, the cracking mechanism of aril during the maturation stage remains largely unknown. Here, we provided a comprehensive view of the physiological and molecular levels of aril cracking in by systematically analyzing its anatomical structure, physiological parameters, and transcriptomic response during the cracking process. These results showed that the length of both epidermal and parenchymatous cell layers significantly increased from 133 to 144 days after seed protrusion (DASP), followed by a clear separation between parenchymatous cell layers and kernel, which was accompanied by a breakage between epidermal and parenchymatous cell layers. Moreover, analyses of cell wall composition showed that a significant degradation of cellular wall polysaccharides occurred during aril cracking. To examine the global gene expression changes in arils during the cracking process, the transcriptomes (96 and 141 DASP) were analyzed. KEGG pathway analysis of DEGs revealed that 4 of the top 10 enriched pathways were involved in cell wall modification and 2 pathways were related to ethylene biosynthesis and ethylene signal transduction. Furthermore, combining the analysis results of co-expression networks between different transcription factors, cell wall modification genes, and exogenous ethylene treatments suggested that the ethylene signal transcription factors ( and ) were involved in aril cracking of by regulation of and . Our findings provided new insights into the aril cracking trait in .
Torreya 'Merrillii'是一种具有很高营养价值和药用价值的著名坚果。假种皮开裂是种子传播的重要过程，也是种子成熟的一个指标。然而，假种皮在成熟阶段的开裂机制在很大程度上仍然未知。在这里，我们通过系统分析其在开裂过程中的解剖结构、生理参数和转录组反应，全面了解了Torreya 'Merrillii'假种皮开裂的生理和分子水平。这些结果表明，种子突出后133至144天（DASP），表皮和薄壁细胞层的长度均显著增加，随后薄壁细胞层与种仁之间明显分离，同时表皮和薄壁细胞层之间出现破裂。此外，细胞壁成分分析表明，在假种皮开裂过程中，细胞壁多糖发生了显著降解。为了研究假种皮在开裂过程中的全局基因表达变化，对转录组（96和141 DASP）进行了分析。对差异表达基因的KEGG通路分析表明，前10个富集通路中有4个与细胞壁修饰有关，2个通路与乙烯生物合成和乙烯信号转导有关。此外，结合不同转录因子、细胞壁修饰基因和外源乙烯处理之间的共表达网络分析结果表明，乙烯信号转录因子（ 和 ）通过调控 和 参与了Torreya 'Merrillii'的假种皮开裂。我们的研究结果为Torreya 'Merrillii'的假种皮开裂特性提供了新的见解。
