New Insights of Salicylic Acid Into Stamen Abortion of Female Flowers in Tung Tree (Vernicia fordii)
New Insights of Salicylic Acid Into Stamen Abortion of Female Flowers in Tung Tree (Vernicia fordii)
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水杨酸对油桐雌花雄蕊败育的新认识
DOI：
10.3389/fgene.2019.00316
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发表时间：
2019-04-05
影响因子：
3.7
通讯作者：
Zhang, Lin
中科院分区：
文献类型：
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作者：
Liu, Meilan;Li, Wenying;Zhang, Lin
油桐（Vernicia fordii）是一种雌雄同株、雌雄异株的重要木本油料植物。油桐园雌花比例极低，导致产量低。雌花通常沿着雄蕊败育发育，否则产生不育胚珠。然而，目前对油桐雌花发育的分子基础还知之甚少。本研究通过形态学、细胞学观察、内源激素测定和RNA-seq等综合分析，探讨油桐雌花发育的分子机制。细胞学观察表明，雌花雄蕊败育属于程序性细胞死亡（PCD）类型，是由小孢子母细胞时期绒毡层退化引起的。通过RNA-seq分析，在雌花中共鉴定出1,366个差异表达基因（DEG），其中279个（20.42%）在苯丙烷类化合物合成、苯丙氨酸代谢、黄酮类化合物合成、淀粉和蔗糖代谢以及植物激素信号转导中显著富集。阶段特异性转录本鉴定检测了雌花中动态表达的重要转录调节因子基因，这些基因可能参与细胞程序死亡和花器官发育。基因表达谱分析表明，17个花药和花粉发育相关基因和37个PCD相关基因可能与SFF败育有关。进一步分析植物激素水平和共表达网络表明，水杨酸（SA）的积累可以触发油桐PCD和抑制SFF的发展。本研究为SA在调控SFF败育发育成正常雌花中的作用提供了新的见解。
Tung tree (Vernicia fordii), an economically important woody oil plant, is a monoecious and diclinous species with male and female flowers on the same inflorescence. The extremely low proportion of female flowers leads to low fruit yield in tung orchards. The female flower normally develops along with stamen abortion; otherwise sterile ovules will be produced. However, little knowledge is known about the molecular basis of the female flower development in tung tree. In this study, integrated analyses of morphological and cytological observations, endogenous phytohormone assay and RNA-seq were conducted to understand the molecular mechanism of the female flower development in tung tree. Cytological observation suggested that the abortion of stamens in female flowers (SFFs) belongs to the type of programmed cell death (PCD), which was caused by tapetum degeneration at microspore mother cell stage. A total of 1,366 differentially expressed genes (DEGs) were identified in female flowers by RNA-seq analysis, of which 279 (20.42%) DEGs were significantly enriched in phenylpropanoid biosynthesis, phenylalanine metabolism, flavonoid biosynthesis, starch and sucrose metabolism, and plant hormone signal transduction. Stage-specific transcript identification detected dynamically expressed genes of important transcription regulators in female flowers that may be involved in PCD and floral organ development. Gene expression patterns revealed that 17 anther and pollen development genes and 37 PCD-related genes might be involved in the abortion of SFF. Further analyses of phytohormone levels and co-expression networks suggested that salicylic acid (SA) accumulation could trigger PCD and inhibit the development of SFF in tung tree. This study provides new insights into the role of SA in regulating the abortion of SFF to develop normal female flowers.