Loropetalum chinense var. rubrum accessions in China have not been adequately characterized for their morphological traits. Such characterization would be helpful in the development of improved cultivars and in cultivar classification. In this study, the morphological traits of 23 accessions were evaluated in spring, summer, and autumn to determine their phenotypic diversity. Cluster analysis with average distance was performed for the main traits of leaf and flower using data processing system software. The morphological investigation indicated that the number of flowering accessions and the flower number of L. chinense var. rubrum in spring were more than those in autumn. Only one accession (no. 13) yielded several flowers in summer. Some accessions had the same or similar color of leaf or flower in spring and autumn. Two accessions had the same flower color in spring and autumn, whereas others showed slightly different colors in spring and autumn. The 23 entries were grouped into four clusters in spring and five clusters in autumn based on multivariate analysis of nine classification variables. Each cluster had some specific characteristics of its own. Generally, the cluster formed first because of the similarity in leaf color. The accessions with similar flower color formed subclusters within a cluster. These accessions are an important resource for the establishment of a core collection of L. chinense var. rubrum in the world. Several accessions with good qualities were selected and should be further tested for horticultural merit.
Zhiyi Bao, Bo Chen, and Hua Zhang
Shaolan Yang, Changjie Xu, Bo Zhang, Xian Li, and Kunsong Chen
Two complementary DNA fragments encoding expansin genes Ad-EXP1 and Ad-EXP2 were isolated from ripening kiwifruit (Actinidia deliciosa cv. Bruno) by reverse transcription–polymerase chain reaction amplification using a pair of degenerate primers. The homology between these two expansin family members was 50% in nucleotide sequence and 74% in amino acid sequence. It was revealed that Ad-EXP1 and Ad-EXP2 belong to subgroups A and B of an expansin gene family respectively. However, gene expression of these two members shared similar patterns. Both were upregulated by ethylene treatment and downregulated by acetylsalicylic acid treatment. The study suggests that members of both subgroups A and B of the expansin family are involved in kiwifruit fruit ripening.
Nian Wang, Zhang Chang Qin, Jun-bo Yang, and Jing-li Zhang
Rhododendron delavayi Franch. is an important ornamental plant and often plays a role in natural hybridization with other sympatric species in Rhododendron subgenus Hymenanthes. Fifteen microsatellite loci were developed and characterized in this species. The average allele number of these microsatellites was four per locus, ranging from three to six. The ranges of expected (HE) and observed (HO) heterozygosities were 0.0365 to 0.7091 and 0.0263 to 0.9512, respectively. Cross-species amplification in R. agastum and R. decorum showed that a subset of these markers holds promise for congeneric species study. These sets of markers are potentially useful to investigate the genetic structure and gene flow of R. delavayi and other congeneric species.
Xia Qiu, Haonan Zhang, Huiyi Zhang, Changwen Duan, Bo Xiong, and Zhihui Wang
Fruit textural characteristics can affect the storage, transportation, and processing of plum (Prunus salicina Lindl) in commercial production. We analyzed 23 plum cultivars with marked differences in fruit traits. Basic physicochemical indicators and textural characteristics of the fruits were determined using puncture testing and texture profile analysis. Furthermore, through the combined application of cluster analysis and principal component analysis, the indexes were simplified to three relatively independent dimensions, comprehensively reflecting the hardness, size, and flexibility of plum fruit. Our results show a high positive correlation among textural characteristics such as hardness, springiness, gumminess, and chewiness, whereas toughness and brittleness were negatively correlated. In addition, physicochemical properties were correlated to the texture traits. The weight and size of the plum fruit were related to hardness, adhesiveness, and chewiness. The soluble solids and water content contributed to the hardness, cohesiveness, and resistance to chewing. Cluster analysis revealed three distinct clusters: Cluster I represented by ‘Meiguihong’ with high hardness and a chewable texture; Cluster II represented by ‘Siyuecui’, ‘Cuimi’, and ‘Qingcui’ with a hard and brittle texture; and Cluster III represented by ‘Jinmi’, ‘Taoli’, and ‘Oishiwase’ with a soft and tough texture. The results of this study provide a significant theoretical foundation for quality evaluation, and classification of plum fruit characteristics, thus providing insights for further breeding of plum varieties.
Zhengke Zhang, Zhaoyin Gao, Min Li, Meijiao Hu, Hui Gao, Dongping Yang, and Bo Yang
‘Tainong 1’ mango fruit were treated with hot water for 10 minutes at 55 °C and then stored at 5 °C for 3 weeks. After removal from low-temperature storage, the effects of hot water treatment (HWT) on chilling injury (CI), ripening and cell wall metabolism during storage (20 °C, 5 days) were investigated. HWT reduced the CI development of the fruit as manifested by firmer texture, external browning, and fungal lesions. A more rapid ripening process, as indicated by changes in firmness, respiration rate, and ethylene production, occurred in heated fruit after exposure to low temperature as compared with non-heated fruit. At the same time, the cell wall components in heated fruit contained more water-soluble pectin and less 1,2-cyclohexylenedinitrilotetraactic acid (CDTA)-soluble pectin than those in non-heated fruit. HWT also maintained higher polygalacturonase [enzyme classification (EC) 188.8.131.52] and β-galactosidase (EC 184.108.40.206) activities as well as lower pectin methylesterase (EC 220.127.116.11) activity. In general, the changes of ripening and cell wall metabolism parameters in the heated fruit after low-temperature storage exhibited a comparable pattern to that of non-cold-stored fruit.
Zai Q. Yang, Yong X. Li, Xiao P. Xue, Chuan R. Huang, and Bo Zhang
Wind tunnel tests were conducted in an NH-2-type wind tunnel to investigate the wind pressure coefficients and their distribution on the surfaces of a single-span plastic greenhouse and a solar greenhouse. Wind pressures at numerous points on the surfaces of the greenhouse models were simultaneously measured for various wind directions. The critical wind speeds, at which damage occurred on the surfaces of single-span plastic greenhouses and solar greenhouses, were derived. To clearly describe the wind pressure distribution on various surface zones of the greenhouses, the end surface and top surface of the plastic greenhouse and the transparent surface of the solar greenhouse were divided into nine zones, which were denoted as Zone I to Zone IX. The results were as follows: 1) At wind direction angles of 0° and 45°, the end surface of the single-span plastic greenhouse was on the windward side, and the maximum positive wind pressure coefficient was near 1. At wind direction angles of 90° and 180°, the entire end surface of the single-span plastic greenhouse was on the leeward side, and the maximum negative wind pressure coefficient was near −1. The maximum positive wind pressure on the end surface of the single-span plastic greenhouse appeared in Zone IV at a wind direction angle of 15°, whereas the maximum negative pressure appeared in Zone VIII at a wind direction angle of 105°. 2) Most of the wind pressure coefficients on the top surface of the plastic greenhouse were negative. The maximum positive and negative wind pressure coefficient on the top surface of the plastic greenhouse occurred in Zones I and II, respectively, at a wind direction angle of 60°. 3) At a wind direction angle of 0°, the distribution of wind pressure coefficient contours was steady in the middle and lower zones of the transparent surface of the solar greenhouse, and the wind pressure coefficients were positive. At a wind direction angle of 90°, the wind pressure coefficients were negative on the transparent surface of the solar greenhouse. A maximum positive wind pressure coefficient was attained at a wind direction angle of 30° in Zone IX, whereas the maximum suction force occurred in Zone VII at a wind direction angle of 135°. 4) The minimum critical wind speeds required to impair the single-span plastic greenhouse and solar greenhouse were 14.5 and 18.9 m·s−1, respectively.
Bo Zhang, Xue-Ren Yin, Ji-Yuan Shen, Kun-Song Chen, and Ian B. Ferguson
The relationship between lipoxygenase (LOX) pathway-derived volatiles and LOX gene expression was evaluated in kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa cv. Bruno] during postharvest ripening at 20 °C. The C6 aldehydes n-hexanal and (E)-2-hexenal were abundant in peel compared with flesh tissue and declined as kiwifruit ripened. Esters such as ethyl butanoate and methyl butanoate were lower in the peel than flesh and accumulated when the fruit underwent a climacteric rise in ethylene production. Total LOX activity was higher in the peel than in the flesh and increased as kiwifruit ripened. Expression of AdLox2, AdLox3, AdLox4 and AdLox6 was high in the peel, whereas AdLox1 and AdLox5 showed similar levels in the peel and flesh at the ethylene climacteric. AdLox1 and AdLox5 transcript levels increased and AdLox2, AdLox3, AdLox4 and AdLox6 levels decreased during postharvest fruit ripening. Principal component analysis showed that n-hexanal and (E)-2-hexenal were grouped with LOX genes that were downregulated as kiwifruit ripened. The possible roles of LOX genes in relation to kiwifruit volatile formation during fruit ripening are discussed.