Physiological, biochemical and anatomical indexes were investigated for rose hardiness. It was found that bound/free water ratio, proline accumulation, photosynthetic rate, palisade/spongy tissue ratio, and lignification of winter-acclimated stems were heavily influenced by the temperature causing stem browning. Spongy cell volume and stem tenderness were inversely related to winter hardiness. Data generated from this research demonstrated that catalase stability, TTC reduction rate at 0°C, total photosynthetic rate, stem pith ray number, and leaf wax thickness are good indicators for rose hardiness to freezing temperatures. Two compound indexes were developed through the main component analysis. Based on the results obtained from 12 tested cultivars, these indexes are ideal to quantify hardiness of rose germplasm.
Mingqi Wang and Lixin Peng
Lixin Peng, Mingqi Wang and Weijian Liang
Cold tolerance/resistance of 41 hazelnut hybrid strains was investigated by evaluating electrolyte seepage velocity, recovering growth, and tissue browning for the tested cold temperatures. Results demonstrated that electrolyte seepage velocity of all tested strains was faster as temperatures dropped down. The S curve relationship was found between seepage velocity and temperature. Turning point temperature used as the half deadly injured index (LT50) was developed using a logistic equation. The mean LT50 and temperature causing tissue browning were excellent indexes to predict cold tolerance/resistance. After treated at –30 or –35 °C and then evaluated for their recovering growth, 10 cold-resistant hybrid hazelnut strains were developed. These hybrids are being tested for regional adoption and will be released as commercial cultivars.
Mingqi Wang, Lixin Peng and Banghua Wu
Based on our investigation of hazelnut germplasm and Thompson's evaluation system for European hazelnuts, an in-depth study on character description of hazelnut germplasm was conducted from 1991 to 1994. Eighty characters were evaluated for the 58 tested species. It was found that eight characters should be eliminated from Thompson's system, such as annual branch length and hair, lentical color, and serration depth. The best leaf sampling position, sample volumes for quantitative characters, and scoring standards were also determined. Therefore, an advanced evaluation system for hazelnut germplasm was developed. The advanced system is easier and simpler, and will significantly expedite systematical studies of hazelnut germplasm.
Fanjuan Meng, Ruoding Wang, Mu Peng, Chao Wang, Zhongkui Wang, Fachun Guan and Yajun Li
Inter simple sequence repeat (ISSR) were used to evaluate the genetic diversity of Kongpo Monkshood (Aconitum kongboense L.) in Motuo, Tibet Plateau. From 70 accessions of three populations, 10 out of 100 informative ISSR primers were chosen for polymorphism analysis. Percentage of polymorphic bands was 50% to 66.67% with a mean of 58.42%. The effective number of alleles (Ne) was between 1.545 (population 3) and 1.586 (population 2), and the mean value was 1.564; the Nei’s gene diversity (h) ranged from 0.315 to 0.327 with the average value of 0.320; the value of Shannon’s information index (I) ranged from 0.459 to 0.478, with the mean of 0.469. Based on molecular data, cluster analysis classified the 70 cultivars into three groups. Most accessions were related to the geographical origin and their genetic backgrounds. Bayesian structure and PCoA analysis were consistent with the dendrogram result. Based on the analysis, it will provide a reference for Kongpo Monkshood breeding purposes and contribute to identification, rational exploitation, and conservation of germplasms.
Shu’an Wang, Rutong Yang, Peng Wang, Qing Wang, Linfang Li, Ya Li and Zengfang Yin
Fachun Guan, Shiping Wang, Rongqin Li, Mu Peng and Fanjuan Meng
To analyze the evolutionary level of Prunus mira Koehne (Prunus mira Koehne Kov et. Kpst), 15 kinds of pollen grains from five altitudes were observed using a scanning electron microscope (SEM). This study demonstrates that pollen morphous P. mira has high variation; specifically, individuals from higher altitudes are much more evolved than those from lower altitudes. This is the first time the pollen morphology of P. mira has been systematically illustrated. Furthermore, 12 random amplified polymorphic DNA (RAPD) primers generated clear and repeatable bands among all individuals based on RAPD; 107 bands ranging from 200 bp to 2000 bp were generated with an average of 8.92 bands per primer. Thus, the RAPD technique proved to be a powerful tool to reveal variation on P. mira. This study provides comprehensive information for genetic diversity of P. mira from different altitudes.
Rui Zhang, Fang-Ren Peng, Dong-Liang Le, Zhuang-Zhuang Liu, Hai-Yang He, You-Wang Liang, Peng-Peng Tan, Ming-Zhuo Hao and Yong-Rong Li
Scion wood of ‘Caddo’ and ‘Desirable’ pecan (Carya illinoinensis) was grafted onto the epicotyl of 1-month-old, open-pollinated ‘Shaoxing’ pecan seedlings for evaluation as a grafting technique to reduce the time to produce grafted trees. The results showed that seedlings grafted with “base scions” had higher survival than those grafted with “terminal scions” for both ‘Caddo’ and ‘Desirable’. Also, grafting with paraffinic tape could achieve greater success rate than that with medical tape. The most ideal time to perform this grafting was late April in Nanjing, China, when pecan seedlings were about 35 days old. This study demonstrated that the technique yielded successful epicotyl grafting of >70%, and it could thus be applied in practice.
Zhuang-Zhuang Liu, Tao Chen, Fang-Ren Peng, You-Wang Liang, Peng-Peng Tan, Zheng-Hai Mo, Fan Cao, Yang-Juan Shang, Rui Zhang and Yong-Rong Li
Cytosine methylation plays important roles in regulating gene expression and modulating agronomic traits. In this study, the fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) technique was used to study variation in cytosine methylation among seven pecan (Carya illinoinensis) cultivars at four developmental stages. In addition, phenotypic variations in the leaves of these seven cultivars were investigated. Using eight primer sets, 22,796 bands and 950 sites were detected in the pecan cultivars at four stages. Variation in cytosine methylation was observed among the pecan cultivars, with total methylation levels ranging from 51.18% to 56.58% and polymorphism rates of 82.29%, 81.73%, 78.64%, and 79.09% being recorded at the four stages. Sufficiently accompanying the polymorphism data, significant differences in phenotypic traits were also observed among the pecan cultivars, suggesting that cytosine methylation may be an important factor underlying phenotypic variation. Hypermethylation was the dominant type of methylation among the four types observed, and full methylation occurred at higher levels than did hemimethylation in the pecan genomes. Cluster analysis and principal coordinate analysis (PCoA) identified Dice coefficients ranging from 0.698 to 0.778, with an average coefficient of 0.735, and the variance contribution rates of the previous three principal coordinates were 19.6%, 19.0%, and 18.2%, respectively. Among the seven pecan cultivars, four groups were clearly classified based on a Dice coefficient of 0.75 and the previous three principal coordinates. Tracing dynamic changes in methylation status across stages revealed that methylation patterns changed at a larger proportion of CCGG sites from the 30% of final fruit-size (30%-FFS) stage to the 70%-FFS stage, with general decreases in the total methylation level, the rate of polymorphism, and specific sites being observed in each cultivar. These results demonstrated that the F-MSAP technique is a powerful tool for quantitatively detecting cytosine methylation in pecan genomes and provide a new perspective for studying many important life processes in pecan.
Ya-Long Qin, Xiao-Chun Shu, Wei-Bing Zhuang, Feng Peng and Zhong Wang
Callus induction and plant regeneration play a key role in transgenic technology. Although much progress has been made with respect to eggplant, this type of research is insufficiently developed in Solanum torvum (a wild relative of eggplant), which contains a large number of resistance genes. Here, a high-efficiency regeneration system of S. torvum was established. Stem segments and leaves were cultured on Murashige and Skoog (MS) medium supplemented with 0.5–3.0 mg·L−1 6-benzyladenine (6-BA) and 0.1–0.6 mg·L−1 α-naphthaleneacetic acid (NAA). The highest callus induction ratio (100%) was produced on MS + 1.0 mg·L−1 6-BA + 0.5 mg·L−1 NAA. The combination of 0.5 mg·L−1 BA and 1.0 mg·L−1 2,4-dichlorophenoxyacetic acid in MS medium (double microelement) was the best for plant regeneration. Well-developed shoots rooted on half-strength MS medium supplemented with 0.1 mg·L−1 indole-3-acetic acid (IAA). These results will be helpful for functional verification of resistance genes from S. torvum and may be useful to those working in the field of eggplant breeding.
Changwei Shen, Yifei Ding, Xiqiong Lei, Peng Zhao, Shuo Wang, Yangchun Xu and Caixia Dong
A field experiment was conducted over three growing seasons (2012–14) to study the effect of the foliar application of different potassium (K) fertilizers [potassium phosphate monobasic (KH2PO4), potassium nitrate (KNO3), and humic acid potassium (HAK)] on the fruit growth rate, yield, and quality of ‘Kousui’ japanese pear (Pyrus pyrifola) trees. Except the first year of study, foliar application of K fertilizers generally led to an increase in the concentration of fruit total soluble sugar, titratable acidity (TA) and sweetness, along with an elevated K accumulation in leaf and fruit at maturity. In 2013 and 2014, compared with the control, KNO3 treatment led to an average 16% higher yield, and HAK led to an average 15% higher soluble solid content (SSC). Furthermore, HAK resulted in 26% higher yield in 2014. KNO3 treatment showed 19% higher leaf K concentration, 38% leaf K accumulation, and 43% fruit K accumulation in maturity than the control in 2014. Different effects were found on the concentration of specific types of sugar and organic acid, of which fructose and malate were consistently increased by the K application. With regard to the amino acids, KNO3 and HAK treatments led to a significant increase in the concentration of aspartic acid, which was 12% and 22% higher than the control, respectively. In conclusion, foliar application of KNO3 is an efficient way to increase ‘Kousui’ japanese pear fruit yield, whereas spraying HAK is an effective way to improve the fruit quality.