摘要：
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.
通讯机构：
Key Lab of Non-wood Forest Products of State Forestry Administration, Cooperative Innovation Center of Cultivation and Utilization for Non-wood Forest Trees of Hunan Province, Central South University of Forestry and Technology, Changsha, China
通讯机构：
Central South University of Forestry and Technology/Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Changsha, China
通讯机构：
Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
摘要：
Tung tree (Vernicia fordii) is an economically important tree widely cultivated for industrial oil production in China. To better understand the molecular basis of tung tree chloroplasts, we sequenced and characterized its genome using PacBio RS II sequencing platforms. The chloroplast genome was sequenced with 161,528 bp in length, composed with one pair of inverted repeats (IRs) of 26,819 bp, which were separated by one small single copy (SSC; 18,758 bp) and one large single copy (LSC; 89,132 bp). The genome contains 114 genes, coding for 81 protein, four ribosomal RNAs and 29 transfer RNAs. An expansion with integration of an additional rps19 gene in the IR regions was identified. Compared to the chloroplast genome of Jatropha curcas, a species from the same family, the tung tree chloroplast genome is distinct with 85 single nucleotide polymorphisms (SNPs) and 82 indels. Phylogenetic analysis suggests that V. fordii is a sister species with J. curcas within the Eurosids I. The nucleotide sequence provides vital molecular information for understanding the biology of this important oil tree.
通讯机构：
Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
通讯机构：
The Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
作者机构：
[卢锟; 李泽; 龙洪旭; Lü J.-B.; 林青; 谭晓风; 张琳] Key Laboratory of Cultivation and Protection for Non- Wood Forest Trees, Ministry of Education, Cooperative Innovation Center of Cultivation and Utilization for Non-Wood Forest Trees of Hunan Province, Central South University of Forestry and Technology, Changsha, 410004, China
通讯机构：
[Tan, X.-F.] K;Key Laboratory of Cultivation and Protection for Non- Wood Forest Trees, Ministry of Education, Cooperative Innovation Center of Cultivation and Utilization for Non-Wood Forest Trees of Hunan Province, Central South University of Forestry and Technology, Changsha, China
摘要：
Fructose 1,6-bisphosphate aldolase (FBA) catalyzes the reverse cleavage of fructose-1,6-bisphosphate into dihydroxyacetone phosphate (DHAP) and 3-phosphate glyceraldehyde (G-3-P). DHAP acts as a precursor for the synthesis of glycerol, an important osmotically compatible solute under salt stress. Using rapid amplification of cDNA ends, the complete sequence of FBA1 cDNA was obtained from Camellia oleifera, a tree originated from China and notable as an important source of edible oil obtained from its seeds. Camellia oleifera FBA1 (CoFBA1) cDNA has a total length of 1,697-bp with 1,179-bp ORF, flanked by 250-bp 5′-UTR and 246-bp 3′-UTR. It was predicted to encode a 392 amino acid protein with a calculated molecular mass of 42.72 kDa and theoretical pI of 8.39. Real-time PCR analysis indicated that the CoFBA1 gene was strongly expressed in stems, weakly in roots, and induced under salt stress to a threshold before dropping at high salt concentrations (12 g L−1 NaCl). Over-expression of recombinant CoFBA1 resulted in increased tolerance to salinity in transgenic Brassica napus plants, which grew better at low salt concentrations than on media without NaCl. At all salt concentrations, the transgenic plants showed improved growth parameters (stem and root lengths and germination rates) in comparison with wild-type plants. These findings suggest that CoFBA1 plays very important roles in salt stress response, improving the survival ability of C. oleifera under salt stress conditions.
作者机构：
The Key Laboratory of Cultivation and Protection for Non-wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha 410004, China;The Key Laboratory of Nonwood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha 410004, China
通讯机构：
The Key Laboratory of Cultivation and Protection for Non-wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, China
关键词：
油桐(Vernicia fordii);转录组;脂肪酸生物合成;表达模式
摘要：
油桐是我国重要的木本油料植物,过去对油桐的研究主要集中于栽培和常规育种,与油桐种仁油脂合成相关的分子机理研究还未见报道。本研究采用转录组测序(RNA-Seq)技术,比较了油桐种子油脂合成3个不同时期的转录组,获得了大量差异表达的Unigene序列。通过GO (Gene Ontology)分类和代谢途径富集性分析将这些差异表达的Unigene归类于包含脂肪酸生物合成途径在内的128个代谢途径。随后将脂肪酸生物合成途径中的54个Unigene序列在KEGG (Kyoto Encyclopedia of Genes and Genomes)数据库中进行比对,获得了14个关键酶的同源蛋白质。本研究通过对编码这些同源蛋白质的基因在油桐种子油脂合成期的表达模式进行分析,以期为油桐油脂合成,尤其是桐酸合成机理的解析提供理论参考,并为进一步的理论研究和油桐的遗传改良提供潜在的基因资源,从而提高油桐的单位面积产量。
