Freshly harvested empress tree (Paulownia elongata) seeds have physiologic dormancy. The aim of this study was to investigate the effects of exogenous and endogenous nitric oxide (NO) on the dormancy and germination of empress tree seeds. After treatment with different concentrations of sodium nitroprusside (an NO-releasing compound) solution, the germination percentage of seeds under 12 h of continuous light was significantly greater. Seed germination percentage was promoted significantly by 10–4 M sodium nitroprusside plus cold stratification compared with seeds treated with cold stratification only. At different hours during imbibition, empress tree seeds treated with 2-(4-carboxyphenyl)-4, 4, 5, 5- tetramethylimidazoline -1-oxyl-3-oxide potassium salt (c-PTIO), NG-nitro-L-arginine methyl ester (L-NAME), and sodium tungstate showed reduced seed germination percentages. During the early hours of imbibition, c-PTIO or sodium tungstate treatment inhibited seed germination significantly. The results showed that both exogenous and endogenous NO can release empress tree seed dormancy. Endogenous NO oxide was involved in dormancy release and germination of seeds during the early stages of imbibition. Wider application of NO may be used for breaking seed dormancy in other species.
Jia Liu, Tingting Xue, and Yongbao Shen
Jia Li, Liyun Liu, Huanqi Zhou, and Meng Li
Areca (Areca catechu L.) is a tropical plant with great economic importance. In China, the fruit of areca (betel nut) is produced mainly in Hainan Province. However, the yield of betel nuts was impacted seriously by frequent water deficits in Hainan Province. Drought causes deleterious effects on the growth and development of areca plants, especially on young seedlings, which hampered the extensive planting of areca. In this study, a reagent of a superabsorbent polymer (SAP) was applied into the culture soil and we analyzed its function against drought stress when seedlings were grown under different irrigation levels. We observed that SAP application caused a significant increase in plant weight under severe drought, as well as in the maximum photochemical efficiency of PSII (Fv/Fm) and actual photochemical efficiency of PSII [Y(II)] index of chlorophyll (chl), indicating the photosynthetic efficiency of seedlings under severe drought (D) was enhanced by SAP. The antioxidant enzyme activity of areca seedlings under D was indicated to be enhanced by the increasing activity of superoxide dismutase (SOD) and peroxidase (POD), but not catalase (CAT). In addition, SAP even has slight negative effects on the growth of seedlings under adequate water. Our results provide a theoretical basis to improve the viability of areca seedlings under severe drought using SAP, which is urgently needed for the market.
Aerdake Kuwantai, Yu-jia Liu, Zong-zhe Wan, Hong-yan Liu, and Ling Wang
Mingyuan Xu, Yingwei Wang, Qianbo Wang, Shenglei Guo, Yang Liu, Jia Liu, Zhonghua Tang, and Zhenyue Wang
In this investigation, changes in growth and photosynthetic parameters were used to explain the effects of drought stress on morphology and photosynthesis of Eleutherococcus senticosus. Liquid chromatography (LC)-mass spectroscopy (MS) was used to determine the content of eleutheroside B, eleutheroside E, isofraxidin, hyperoside, rutin, and kaempferol under different drought stress conditions to explain the effects of drought stress on secondary metabolism of Eleuthero. Growth and photosynthetic physiological parameters showed that drought stress could inhibit the growth and photosynthesis of Eleuthero. The compounds studied showed the same cumulative trend in various organs of Eleuthero under different drought stress conditions, with the highest content in the moderate drought stress group and the lowest in the severe drought stress group. Among them, the content of eleutheroside B was found to be higher in the 5-year-old stem. The content of eleutheroside E was higher in the 3-year root. The content of isofraxidin was highest in the 5-year-old root. The content of hyperoside, rutin, and kaempferol were higher in the 3-year-old leaves. The results show that a wet soil environment was beneficial to growth and photosynthesis of Eleutherococcus senticosus, and moderate drought stress is conducive to the accumulation of its active ingredients.
Li Huang, Wan-zhi Ye, Ting-ting Liu, and Jia-shu Cao
Cytological features of ‘Aijiaohuang’ chinese cabbage-pak-choi (Brassica campestris ssp. chinensis) Bcajh97-01A/B genic male-sterile AB line were examined to determine phenotypic reasons for male sterility. The sterile line Bcajh97-01A was found to undergo aberrant cytokinesis during male meiosis. Transcriptional profiling of the flower buds of both fertile and sterile plants was performed at the periods preceding meiosis, at the tetrad to uninucleate pollen period, and at the binucleate to mature pollen period. Transcript-derived fragments (TDFs) from corresponding genes that were expressed in flower buds at these three different stages could be divided into nine classes. We sequenced a total of 14 new TDFs that were differentially displayed at particular pollen developmental stages, including eight genes with unknown or hypothetical functions and six genes showing significant homology with known genes. This characterization of the Bcajh97-01A genic male-sterile line allowed the identification of candidate genes underlying genic male sterility.
Yanmei Zhang, Xuelin Shen, Xiaoqin Sun, Jia Liu, Yifeng Xia, Xin Zou, and Yueyu Hang
Water chestnut (Trapa natans L.) is a group of annual, floating-leaved aquatic plants that serves as food and medical resources in many countries. However, the molecular method for distinguishing different T. natans L. resources is lacking. In this study, we detected genetic diversity of several chloroplast and nuclear genic or intergenic sequences in four varieties of T. natans and one wild type of Trapa incisa Siebold & Zuccarini to evaluate their potential as molecular markers. Our data revealed that the three chloroplast fragments (rbcL, matK, and pbsA-trnH) show no sequence difference among all tested samples. Only one nucleotide substitution is detected for the nuclear ribosomal internal transcribed spacer (ITS) in the T. natans variety Shuihongling. Four nucleotide substitutions are detected for the nuclear carotenoid isomerase (CRTISO) gene in the variety Hongxiuxie. In contrast, a total of 29 polymorphic sites are detected for a Toll and interleukin-1 receptor-nucleotide binding site–leucine rich repeat (TNL) gene in the five samples, among which six are nucleotide substitutions and the rest are insertions/deletions. The five samples could be fully distinguished from each other based on the TNL gene. To specifically authenticate ‘Heshangling’, 33 randomly amplified polymorphic DNA (RAPD) markers were adopted to amplify genomic sequences from the five samples. A pair of sequence characterized amplified region (SCAR) primers were designed based on the results of RAPD markers, which could specifically amplify one target band from all eight individuals of ‘Heshangling’, but none from any individuals of other T. natans varieties or one T. incisa. Taken together, a TNL sequence was provided in this study to distinguish four T. natans varieties and one T. incisa. Furthermore, a RAPD-SCAR marker was developed for efficient authentication of ‘Heshangling’.
De-Kun Dong, Jia-Shu Cao, Kai Shi, and Le-Cheng Liu
To investigate the genetic basis of heterosis in Brassica rapa, an F2 population was produced from the cross of B. rapa L. subsp. chinensis (L.) Hanelt and B. rapa L. subsp. rapifera Metzg. Trait performances of the F1 hybrid showed evident mid parent heterosis, which varied from 18.55% to 101.62% for the 11 traits investigated. A total of 23 main effect quantitative trait loci (QTLs) were detected for biomass and its component traits, which could explain 4.38% to 47.80% of the phenotypic variance, respectively. Sixty-five percent of these QTLs showed obvious overdominance. Epistasis analysis detected 444 two-locus interactions for the 11 traits at the threshold of P < 0.005. Some of them remained significant when more stringent threshold were set. These results suggested that overdominance and epistasis might play an important role as the genetic basis of heterosis in B. rapa.
Cai-Hong Jia, Ju-Hua Liu, Zhi-Qiang Jin, Qiu-Ju Deng, Jian-Bin Zhang, and Bi-Yu Xu
A full-length cDNA isolated from banana (Musa acuminata L. AAA group) fruit was named MaMDH, containing an open reading frame encoding 332 amino acids that represents the gene for cytoplasmic malic dehydrogenase (MDH). Sequence analysis showed that MaMDH shares high similarity with MDHs from castor bean (XP_002533463), tobacco (CAC12826), peach (AAL11502), and chickpeas (CAC10208). Real-time quantitative polymerase chain reaction (PCR) analysis of MaMDH spatial expression showed that it was expressed in all organs examined: roots, rhizomes, leaves, flowers, and fruits. The expression was the highest in flowers followed by the fruits and roots, whereas the rhizomes and leaves displayed the lowest expression levels. Real-time quantitative PCR revealed that MaMDH exhibited differential expression patterns in post-harvest banana fruits correlating with ethylene biosynthesis. In naturally ripened banana fruits, MaMDH expression was in accordance with ethylene biosynthesis. In accordance, for banana fruits treated with the ethylene analog 1-methylclopropene (1-MCP), MaMDH expression levels were inhibited and remained constant. After treatment with ethylene, MaMDH expression in banana fruits significantly increased with ethylene biosynthesis and peaked 3 days after harvest, which was 11 days earlier than that in naturally ripened banana fruits. These results suggest that MaMDH expression is induced by ethylene to regulate post-harvest banana fruits ripening.
Guang-Lian Liao, Xiao-Biao Xu, Qing Liu, Min Zhong, Chun-Hui Huang, Dong-Feng Jia, and Xue-Yan Qu
Jinyan (Actinidia eriantha × A. chinensis) is one of the gold-fleshed kiwifruit cultivars currently being promoted in south China. However, its fruit dry matter is usually less than 16%, which seriously affects fruit quality including taste and flavor. This causes a financial loss to growers: not only are the prices paid for the fruit low because of their bad reputation for quality, but some orchards have been removed. Improvement of fruit quality is essential. In this study, a method is described for squeezing and twisting flowering shoots before flowering and removing the distal vegetative parts of flowering shoots after fruit set. The effects on fruit quality were determined. The dry matter of fruit was increased by 6.6%. Fruit size also increased as did the chlorophyll a content and the chlorophyll:carotenoid ratio. The significantly increased fruit dry matter, resulting in significant increases in fruit soluble solids concentrations (P < 0.01), thereby possibly improving fruit taste. Fruit weight, fruit length, and carotenoid and ascorbic acid concentrations were significantly enhanced in comparison with controls (P < 0.01), increasing by 20%, 7%, 12%, and 19%, respectively. However, there was no significant difference in soluble sugar concentrations, titratable acid concentrations, and the reduced chlorophyll b concentrations. This research provides a practical method to increase fruit dry matter, and hence a way to allow fruit quality to reach commercial requirements for cultivars such as Jinyan, which under previous management systems had significant shortcomings in fruit flavor and taste.