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  • Author or Editor: Li Xie x
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Nanomaterials have recently been used as growth stimulants to promote the production of crops in saline-alkali through root application. However, if applied through leaves, little is known about the effect of Fe3O4 nanoparticles (NPs) on the root growth and yield, especially for medicinal crops. To fill this gap, a single factor experiment was conducted to explore the effects of Fe3O4 NPs on growth, yield, the dry matter distribution, chlorophyll content, photosynthetic characteristics, chlorophyll fluorescence parameters, and polysaccharide content of Pseudostellaria heterophylla by foliar spraying under field conditions. Fe3O4 NPs (20–50 mg·L–1) significantly promoted growth, the dry matter distribution of root and root tuber yield per unit area. Fe3O4 NPs enhanced net photosynthetic rate (P n) by increasing chlorophyll content. And Fe3O4 NPs increased the daily mean and peak value of P n, and alleviated the phenomenon of “midday depression” by improving nonstomatal limitation. Chlorophyll fluorescence parameters indicating that Fe3O4 NPs promoted the photochemical activity of PSII and alleviated photoinhibition by enhancing the photochemical use of excess excitation energy. Gray correlation analysis showed that Fe3O4 NPs enhanced the adaptability of P. heterophylla photosynthesis to high temperatures and strong light. Of note, Fe3O4 NPs enhanced the polysaccharide content of the root tuber. Phytotoxic effect was recorded at high NPs (100 mg·L–1) doses. Collectively, Fe3O4 NPs could promote performance of P. heterophylla by improving photosynthetic performance, enhancing its adaptability to the environment, and increasing the distribution ratio of photosynthates to the underground part.

Open Access

Citrus species are among the most important fruit trees in the world and have a long cultivation history. However, until now, the exact genetic origins of cultivated Citrus such as sweet orange (Citrus sinensis), lemon (C. limon), and grapefruit (C. paradisi) have remained unidentified. In the present study, amplified fragment length polymorphism (AFLP) fingerprints, nuclear internal transcribed spacer (ITS), and three plastid DNA regions (psbH – petB, trnL – trnF, and trnS - trnG) of 30 accessions of the cultivated citrus and their putative wild ancestors were analyzed in an attempt to identify their paternal and maternal origins. Molecular phylogenetic trees were constructed based on the AFLP data, and chloroplast DNA and ITS sequences using the genus Poncirus as the outgroup. Our results indicated that bergamot (C. aurantifolia) and lemon were derived from citron (C. medica) and sour orange (C. aurantium), and grapefruit was a hybrid that originated from a cross between pummelo (C. grandis) and sweet orange. Rough lemon (C. limon) was probable as a parent of rangpur lime (C. limonia) and guangxi local lemon (C. limonia). Our data also demonstrated that sweet orange and sour orange were hybrids of mandarin (C. reticulata) and pummelo, while rough lemon was a cross between citron and mandarin. For mexican lime (C. aurantifolia), our molecular data confirmed a species of Papeda to be the female parent and C. medica as the male. These findings provide new information for future study on the taxonomy, evolution, and genetic breeding of Citrus.

Free access

Selective control of creeping bentgrass (Agrostis stolonifera) is desirable when it has escaped into other turfgrasses. The objective of this study was to evaluate the influence on creeping bentgrass control from adding urea ammonium nitrate (UAN) to mesotrione plus non-ionic surfactant (NIS) spray solution, and raking to remove dead tissues of creeping bentgrass. A 2-year field study was conducted with a split-plot design, where raking was the whole plot treatment and herbicide was the sub-plot treatment. Herbicide treatments included application of mesotrione at 56 and 70 g·ha−1 singly and sequentially with 0.25% (v/v) NIS or 0.25% (v/v) NIS plus 2.5% (v/v) UAN solution. Sequential applications were made three times on a 2-week interval. Removing the dead clippings by raking improved the creeping bentgrass control from 60% to 73% averaged over rates, timings, adjuvants, and years. Adding UAN to NIS plus mesotrione improved creeping bentgrass control from 78% to 98% with three sequential applications at 70 g·ha−1.

Full access

Chinese cymbidiums (Cymbidium sp.) are important ornamental plants because of their foliage, flower shape, and fragrance. Well-known Chinese cymbidiums mainly include Cymbidium goeringii, Cymbidium faberi, Cymbidium ensifolium, Cymbidium kanran, and Cymbidium sinense. The population genetics of Chinese cymbidiums can be efficiently analyzed using small-scale marker panels with high discriminatory power. In this study, we tested several genic simple sequence repeats (SSRs) and built six genic SSR panels. The panels included several robust markers, which can rapidly assign Chinese cymbidium accessions to their source species. Fifty-three accessions of Chinese cymbidiums were analyzed using 25 markers, which exhibited polymorphism among five species. These markers were ranked according to their discriminatory scores (D scores). The program selected six markers to build an “overall” panel for all Cymbidium classifications and yielded 95.16% population assignment accuracy. Considering one species as the “critical” population and the four other species as one population, we built five genic SSR panels: C. ensifolium panel (four markers, 98.05% accuracy), C. faberi panel (six markers, 95.90% accuracy), C. goeringii panel (six markers, 95.15% accuracy), C. sinense panel (six markers, 96.35% accuracy), and C. kanran panel (five markers, 96.10% accuracy). Genetic distance matrices calculated using the “overall” panels and those derived with the 25 markers were compared. Results showed a high correlation (R = 0.807) with statistical significance (P = 0.042). Moreover, “all panels” revealed higher genetic variations among populations than “all markers.” Hence, the developed panels are suitable for efficient population classification of Chinese cymbidiums.

Free access

NAC transcription factors have been characterized in numerous plants, and the NAC gene has been shown to be involved not only in plant growth and development, but also in plant responses to abiotic and biological stresses, such as drought, high salinity, low temperature, and anaerobic/hypoxic stress. Creating an environment of anaerobic/hypoxic stress has been shown to be one of the effective storage methods for delaying the browning of fresh-cut lotus (Nelumbo nucifera) root. However, whether NAC is associated with lotus root browning under anaerobic stress has not been studied. In this study, vacuum packaging (VP; anaerobic/hypoxic stress) effectively delayed the browning of fresh-cut lotus root. The changes in the expressions of NnPAL1, NnPPOA, and NnPOD2/3 were consistent with phenylalanine aminolase, polyphenol oxidase (PPO), and peroxidase (POD) enzyme activity changes and lotus root browning. Using RNA sequencing, five NnNAC genes were isolated and studied. Transcriptional analysis indicates that the NnNAC genes showed different responses to VP. The expressions of NnNAC1/4 were inhibited by VP, which was consistent with the observed change in the degree of fresh-cut lotus root browning. However, NnNAC2 messenger RNA (mRNA) levels were upregulated, and the expressions of NnNAC3/5 showed no clear differences under different packaging scenarios. Thus, NnNAC1/4 were identified as promising candidates for further transcriptional regulation analysis in lotus root to understand more fully the molecular mechanism of browning under anaerobic/anoxic stress.

Open Access

The art of pressed flowers is a method of artistic expression involving the pressing of flowers, leaves, and other plant organs for artistic creative purposes. However, the pressing process often results in color variation of the plant material, which significantly diminishes the quality of artistic works and must be solved using appropriate techniques. During this research, phenylalanine (10 mmol⋅L−1) was used to treat the petals of postharvest Petunia flowers to investigate the impact of phenylalanine on mitigating color variation, and the effect of phenylalanine on inhibiting the color variation of Petunia petals during the pressing process was evaluated by color measurement, physicochemical indices, and gene expression level analyses. Using the CIEL*a*b* color measurements, the samples from the test group had significantly higher brightness (L*) and red coloration (a*) at the final stage (S4) than the control group. In addition, phenylalanine had a significant inhibitory effect on malondialdehyde and superoxide anion accumulations in Petunia petals during pressing and reduced the enzymatic activities of superoxide dismutase, polyphenol oxidase, and catalase. The quantitative reverse-transcription polymerase chain reaction analysis showed that the transcript levels of CHS, DFR, F3′5′H, and UFGT genes in the petals of the treatment group continued to increase during the pressing process, and the transcript levels of key genes in the anthocyanin metabolic pathway of the treated samples were higher than those of the control group at the final stage (S4). These results indicated that phenylalanine can effectively diminish the color variation of Petunia petals in the pressing process, which could serve as a theoretical basis for the development of a comprehensive technology system aimed at preserving the color of pressed horticultural plants.

Open Access

Microbial fertilizers can activate and promote nutrient absorption and help inflorescence elongation. To understand the molecular mechanisms governing grape (Vitis vinifera) inflorescence elongation after microbial fertilizer application, we comprehensively analyzed the transcriptome dynamics of ‘Summer Black’ grape inflorescence at different leaf stages. With the development of ‘Summer Black’ grape inflorescence, gibberellic acid content gradually increased and was clearly higher in the microbial fertilizer group than in the corresponding control group. In addition, the microbial fertilizer and control groups had 291, 487, 490, 287, and 323 differentially expressed genes (DEGs) at the 4-, 6-, 8-, 10-, and 12-leaf stages, respectively. Kyoto Encyclopedia of Genes and Genomes pathway annotation revealed that most upregulated DEGs were enriched in starch and sucrose metabolism pathways at the 6-, 8-, and 10-leaf stages. Weighted gene coexpression network analysis identified stage-specific expression of most DEGs. In addition, multiple transcription factors and phytohormone signaling-related genes were found at different leaf stages, including basic helix-loop-helix proteins, CCCH zinc finger proteins, gibberellin receptor GID1A, 2-glycosyl hydrolases family 16, protein TIFY, MYB transcription factors, WRKY transcription factors, and ethylene response factor, suggesting that many transcription factors play important roles in inflorescence elongation at different developmental stages. These results provide valuable insights into the dynamic transcriptomic changes of inflorescence elongation at different leaf stages.

Open Access

In the actual cultivation process, blind fertilizer application was widespread, resulting in a serious decline in the yield of Pseudostellaria heterophylla. We used the 3414 fertilizer experiment design to study the effects of combined Boron (B), Molybdenum (Mo), and Copper (Cu) on the growth indexes, diurnal changes of photosynthesis, and rapid fluorescence induction dynamics in P. heterophylla. Our results show that the optimal combination of B, Mo, and Cu simultaneously promoted the growth of underground and aboveground parts, and significantly improved the quality of single root tuber and yield per unit area. The best combination was treatment 9 (T9 = B, 1 g/L; Mo, 0.08 g/L; Cu, 0.05 g/L), and resulted in a 35.1% increase in yield per unit area compared with the control group (T1). Although the optimal combined application of microfertilizers did not change the bimodal trend of diurnal variation of photosynthesis, it effectively increased the daily average, peak, and valley values of the photosynthetic rate by alleviating the nonstomatal limitation and the photosynthetic midday depression. Pseudostellaria heterophylla leaves showed greater photochemical activity and less photoinhibition of photosystem II in T9. Major effects were that it helped protect the activity of the oxygen-evolving complex to reduce the oxidative damage of chloroplasts and prevent the dissociation of thylakoid. The microfertilizer application also enhanced the electron receiving ability of the QB and plastoquinone (PQ) electronic pools, thereby increasing the ability of electron transfer from QA to QB. The number of reaction centers per unit area was promoted notably by the fertilization treatment.

Open Access

Dendrobium officinale Kimura et Migo is a famous traditional Chinese medicinal plant. It produces various phytochemicals, particularly polysaccharides, which have nutraceutical and pharmaceutical values. To increase its biomass production and polysaccharide content, our breeding program has generated a series of polyploid cultivars through colchicine treatment of protocorm-like bodies (PLBs). The present study compared two tetraploid cultivars, 201-1-T1 and 201-1-T2, with their diploid parental cultivar, 201-1, in an established in vitro culture system. Tetraploid ‘201-1-T1’ and ‘201-1-T2’ had shorter leaves and shorter and thicker stems and roots, and they produced higher biomass compared with the diploid cultivar. The length and width of stomata significantly increased, but stomatal density decreased in tetraploid cultivars. The PLB induction rates from the stem node explants of the tetraploid cultivars were significantly higher than those of diploid. However, the PLB proliferation of tetraploids was lower than that of the diploid. The mean number of plantlets regenerated from tetraploid PLBs was also lower than that of the diploid after 4 months of culture. Polysaccharide contents in stems, leaves, and roots of 6-month-old tetraploid plantlets were significantly higher than those of diploids. The polysaccharide content in the stem of ‘201-1-T1’ was 12.70%, which was a 2-fold increase compared with the diploid cultivar. Our results showed that chromosome doubling could be a viable way of improving D. officinale in biomass and polysaccharide production.

Free access

Chinese cymbidiums are important flowering ornamental plants. Traditional propagation via seed or division cannot satisfy growers’ demand for commercialization of new cultivars, and in vitro propagation has a low micropropagation efficiency due to the browning of rhizomes. In this study, rhizomes of Cymbidium ‘14-16-13’ and ‘14-16-5’ were cultured on half-strength Murashige and Skoog (MS) medium supplemented with 6-benzyl aminopurine (BAP), NAA (α-napthaleneacetic acid), or BAP with NAA under either the dark or light. The degree of browning was read, and rhizome proliferation or sprouting (sprout numbers) was evaluated. Results showed that there was significant difference in browning grade of rhizomes between ‘14-16-13’ and ‘14-16-5’ regardless of dark and light culture. Dark culture induced rhizome proliferation but failed to induce sprouts. Light culture slightly elevated the degree of browning but induced sprouting. Among the growth regulators evaluated, BAP was more effective for sprout induction. As rhizome browning appeared to be inevitable in micropropagation of the cymbidiums, a compromise between browning and sprout production could be a realistic approach. Our study showed that rhizomes cultured on half-strength MS medium supplemented with 1.5 mg·L−1 BAP were able to produce more than 16 sprouts per vessel even though browning occurred in the rhizomes. Thus, culturing rhizomes in this medium could be a practical solution for in vitro propagation of Chinese cymbidiums.

Open Access