Seed Development and Embryo Culture of Endangered Abies beshanzuensis

doi:10.11983/CBB21096

Abstract

Abstract: The seed germination rate of Abies beshanzuensis is low, and the characteristics of seed development are elusive, which severely limit the natural regeneration of the population in situ. To illustrate the developmental characteris-tics of seeds and identify the main factors affecting seed development, this article aimed to study the number, weight, and microstructural characteristics of the embryo and endosperm of the seed in the female cones at different development stages, as well as the primary metabolites of the endosperm in the critical period of seed development. The results showed that July was a critical period for seed development of A. beshanzuensis. During this period, the endosperm weight increased rapidly and the carbohydrate metabolism in the endosperm was active. Anatomical and morphological analysis of the female cones showed that a large number of abnormally developed seeds appeared in cones in late July. Analysis of the primary metabolites of endosperm during the critical period showed that the content of trehalose-6-phosp-hate in the endosperm of abnormally developed seeds was significantly decreased. It was speculated that during the critical period of seed development, the decrease of trehalose-6-phosphate in the endosperm may be an important cause of abnormal seed development. Based on the characteristics of A. beshanzuensis seed development, we established the embryo culture technology for A. beshanzuensis, and generated test-tube plantlet.

Key words: Abies beshanzuensis, seed, embryo, endosperm, endangered mechanism, embryo culture

Ke Liu, Bin Liu, Lu Yuan, Hui Shuai, Yang Yang, Tingjin Wang, Deliang Chen, Xiaorong Chen, Kaibin Yang, Xiaofeng Jin, Liping Chen. Seed Development and Embryo Culture of Endangered Abies beshanzuensis[J]. Chinese Bulletin of Botany, 2021, 56(5): 573-583.

Add to citation manager EndNote|Ris|BibTeX

URL: https://www.chinbullbotany.com/EN/10.11983/CBB21096

https://www.chinbullbotany.com/EN/Y2021/V56/I5/573

Figures/Tables 7

Figure 1 Diagram of the sampling of the cones and seeds of Abies beshanzuensis

Figure 2 Morphological changes of the micropylar funnel and pollen transfer during the pollination stage of Abies beshanzuensis (A) The integument develops a stigmatic micropylar funnel (arrow); (B) The pollen (arrow) attaches to the edge of micropylar funnel; (C) The integument folds inward and the micropylar funnel is closed (arrow); (D) The pollen (arrow) enters the pollen chamber. MF: Micropylar funnel; Po: Pollen; Poc: Pollen chamber. (A)-(C) Bars=100 μm; (D) Bar=500 μm

Figure 3 The endosperm rate and embryo rate of Abies beshanzuensis cones at different developmental stages in 2019 and 2020 (A) Changes of endosperm rate of A. beshanzuensis seeds with time; (B) Changes of embryo rate of A. beshanzuensis seeds with time. Different lowercase letters indicate significant differences at 0.05 level.

Figure 4 Changes in seed, embryo and endosperm weight of Abies beshanzuensis seeds at different developmental stages in 2019 and 2020 (A) Changes in the weight of seed with time in 2019 and 2020; (B) Changes in the weight of embryo and endosperm with time in 2019; (C) Changes in the weight of embryo and endosperm with time in 2020. Different lowercase letters indicate significant differences at 0.05 level.

Figure 5 Morphology of Abies beshanzuensis seed and its embryo and endosperm during development (A) The ovule on May 25th; (B) The embryo and endosperm of type I seeds on June 25th; (C) The endosperm of type II seeds on June 25th; (D) The paraffin section of the ovule on May 25th, the pollen (top) and archegonium (bottom) are in the red box; (E) The paraffin section of type I seeds on June 25th, the embryo in the red box; (F) The paraffin section of type II seeds on June 25th; (G) The embryo and endosperm of type I seeds on July 25th; (H) The endosperm of type II seeds on July 25th; (I) The shriveled tissue of endosperm or/and embryo within type III seeds on July 25th; (J) The paraffin section of type I seeds on July 25th, the embryo in the red box; (K) The paraffin section of type II seeds on July 25th; (L) The paraffin section of type III seeds on July 25th; (M) The embryo and endosperm of type I seeds on August 25th; (N) Type III seeds on August 25th; (O) The embryo and endosperm of type I seeds on September 25th. Bars=1 000 μm. MF: Micropylar funnel; In: Integument; Em: Embryo; Es: Endosperm; Po: Pollen; FG: Female gametophyte; Re: Resinocyst; Ext: Exotesta; Ent: Endotesta; Cy: Cotyledon; Hy: Hypocotyl; Su: Suspensor system; ST: Shriveled tissue; ER: Embryo root; CC: Corrosion cavity

Figure 6 Changes of primary metabolites in endosperm of Abies beshanzuensis in June and July (A) Differential metabolites of normal endosperm in June and July; (B) The proportion of key difference metabolites in the first, fourth, and fifth models in the same change pattern in all metabolites and the proportion of the same metabolites tested in all samples; (C) Relative content of melibiose, trehalose-6-phosphate and methylmaleic acid in endosperm of A. beshanzuensis seeds in June and July. 6_NE: Normal endosperm in June; 7_NE: Normal endosperm in July; 7_AE: Abnormal endosperm in July. Different lowercase letters indicate significant differences at 0.05 level. FC: Fold change; LPC: Lysophosphatidylcholine; LPE: Lysopnosphatidylethanolamine; PC: Phosphatidylcholine

Figure 7 Changes in germination rate of embryo of Abies beshanzuensis seeds at different developmental stages (A) Embryo germination (bar=200 μm); (B) Seedlings obtained by embryo culture (bar=2 cm); (C) Changes in germination rate of embryo of A. beshanzuensis seeds at different developmental stages. Different lowercase letters indicate significant differences at 0.05 level.

References 30

[1]	樊金拴 (2007). 中国冷杉林. 北京: 中国林业出版社. pp. 104-107.
[2]	贺佳玉, 李云, 姜金仲, 曹春伟 (2008). 植物胚败育机理及其离体培养挽救技术之研究进展. 中国农学通报 24, 141-146.
[3]	姜在民, 贺学礼 (2009). 植物学. 杨凌: 西北农林科技大学出版社. pp. 297-301.
[4]	蒋志刚, 马克平 (2014). 保护生物学原理. 北京: 科学出版社. pp. 129-133.
[5]	李卫星, 崔慧, 何青松, 杨瞬博, 王莉 (2016). 裸子植物种子发育过程及基因调控研究进展. 种子 35(6), 50-56.
[6]	李晓笑, 陶翠, 王清春, 崔国发 (2012). 中国亚热带地区4种极危冷杉属植物的地理分布特征及其与气候的关系. 植物生态学报 36, 1154-1164. DOI
[7]	林金星, 胡玉熹, 吴鸿 (2013). 裸子植物花粉生物学. 北京: 科学出版社. pp. 55-180.
[8]	刘向东, 李亚娟 (2012). 植物生殖生物学研究法. 广州: 华南理工大学出版社. pp. 37-45.
[9]	盛茂银, 沈初泽, 陈祥, 田兴军 (2011). 中国濒危野生植物的资源现状与保护对策. 自然杂志 33, 149-154.
[10]	王伏雄 (1990). 银杉生物学. 北京: 科学出版社. pp. 69-72.
[11]	吴友贵, 饶龙兵, 陈德良, 周荣飞, 叶珍林 (2010). 百山祖冷杉种子的人工育苗试验. 安徽农业科学 38, 12038-12039, 12098.
[12]	徐刚标, 刘雄盛, 梁文斌 (2015). 极度濒危植物水松大孢子发生、雌配子体发育及胚形成. 林业科学 51(6), 50-62.
[13]	张美善, 刘宝 (2012). 植物胚乳发育的表观遗传学调控. 植物学报 47, 101-110. DOI
[14]	张松文 (2016). 富士响应外源GA₃和“大小年结果信号”花芽孕育的生理分子机制. 硕士论文. 杨凌: 西北农林科技大学. pp. 1-5.
[15]	Chen W, Gong L, Guo ZL, Wang WS, Zhang HY, Liu XQ, Yu SB, Xiong LZ, Luo J (2013). A novel integrated method for large-scale detection, identification, and quantification of widely targeted metabolites: application in the study of rice metabolomics. Mol Plant 6, 1769-1780. DOI PMID
[16]	Eastmond PJ, van Dijken AJH, Spielman M, Kerr A, Tissier AF, Dickinson HG, Jones JDG, Smeekens SC, Graham IA (2002). Trehalose-6-phosphate synthase 1, which catalyses the first step in trehalose synthesis, is essential for Arabidopsis embryo maturation. Plant J 29, 225-235. PMID
[17]	Fichtner F, Lunn JE (2021). The role of trehalose 6-phosphate (Tre6P) in plant metabolism and development. Annu Rev Plant Biol 72, 737-760. DOI URL
[18]	Haim D, Shalom L, Simhon Y, Shlizerman L, Kamara I, Morozov M, Albacete A, Rivero RM, Sadka A (2021). Alternate bearing in fruit trees: fruit presence induces polar auxin transport in citrus and olive stem and represses IAA release from the bud. J Exp Bot 72, 2450-2462. DOI PMID
[19]	Iwaizumi MG, Takahashi M (2012). Effects of pollen supply and quality on seed formation and maturation in Pinus densiflora. J Plant Res 125, 517-525. DOI URL
[20]	Kanehisa M, Goto S (2000). KEGG: kyoto encyclopedia of genes and genomes. Nucleic Acids Res 28, 27-30. PMID
[21]	Lauxmann MA, Annunziata MG, Brunoud G, Wahl V, Koczut A, Burgos A, Olas JJ, Maximova E, Abel C, Schlereth A, Soja AM, Bläsing OE, Lunn JE, Vernoux T, Stitt M (2016). Reproductive failure in Arabidopsis thaliana under transient carbohydrate limitation: flowers and very young siliques are jettisoned and the meristem is maintained to allow successful resumption of reproductive growth. Plant Cell Environ 39, 745-767. DOI URL
[22]	Linkies A, Graeber K, Knight C, Leubner-Metzger G (2010). The evolution of seeds. New Phytol 186, 817-831. DOI PMID
[23]	Meitzel T, Radchuk R, Mcadam EL, Thormählen I, Feil R, Munz E, Hilo A, Geigenberger P, Ross JJ, Lunn JE, Borisjuk L (2021). Trehalose 6-phosphate promotes seed filling by activating auxin biosynthesis. New Phytol 29, 1553-1565.
[24]	Owens JN, Morris SJ (1998). Factors affecting seed and cone development in Pacific silver fir ( Abies amabilis). Can J For Res 28, 1146-1163. DOI URL
[25]	Owens JN, Takaso T, Runions CJ (1998). Pollination in conifers. Trends Plant Sci 3, 479-485. DOI URL
[26]	Politi PI, Georghiou K, Arianoutsou M (2011). Reproductive biology of Abies cephalonica Loudon in Mount Aenos National Park, Cephalonia, Greece. Trees 25, 655-668. DOI URL
[27]	Shen S, Zhang L, Liang XG, Zhao X, Lin S, Qu LH, Liu YP, Gao Z, Ruan YL, Zhou SL (2018). Delayed pollination and low availability of assimilates are major factors causing maize kernel abortion. J Exp Bot 69, 1599-1613. DOI PMID
[28]	Singh H, Owens JN (1982). Sexual reproduction in grand fir ( Abies grandis). Can J Bot 60, 2197-2214. DOI URL
[29]	Wang SD, Yokosho K, Guo RZ, Whelan J, Ruan YL, Ma JF, Shou HX (2019). The soybean sugar transporter GmSWEET15 mediates sucrose export from endosperm to early embryo. Plant Physiol 180, 2133-2141. DOI URL
[30]	Yuan L, Liu ZN, Song XY, Jernstedt J, Sundaresan V (2018). The gymnosperm ortholog of the angiosperm central cell-specification gene CKI1 provides an essential clue to endosperm origin. New Phytol 218, 1685-1696. DOI PMID