‘Mopan’ persimmon (Diospyros kaki Thunb.) is a traditional astringent cultivar of persimmon and ‘Yoho’ persimmon (D. kaki) is a newly introduced Japanese nonastringent type of cultivar in northern China. Studies were conducted to investigate the physiological changes and expression of ripening-related genes in the postharvest process at different periods under the effects of endogenous ethylene in both cultivars. Persimmons were harvested and stored under room temperature for 20 days. An analysis of physiological changes showed significant differences between the two cultivars. Total soluble solids declined in ‘Mopan’ fruit, whereas those in ‘Yoho’ fruit increased during storage. Firmness, color, index of absorbance difference, total and soluble tannin contents, ethylene production, and respiration rates showed the same trend, but these values vary by cultivar. ‘Mopan’ fruit softened rapidly after harvest and attained edible quality in 20 days, with an increased rate of softening accompanied by increased expression of ripening-related genes. In contract, ‘Yoho’ fruit softening occurred slowly and did not soften even after 20 days, with minimal accumulation of the ripening-related genes. The information obtained from this study demonstrates that cell wall-hydrolyzing enzymes, the de-astringent process, and endogenous ethylene have critical roles in postharvest ripening, gene expression, and physiological property changes of ‘Mopan’ and ‘Yoho’ persimmon fruit during storage.
Jingjing Kou, Zhihui Zhao, Wenjiang Wang, Chuangqi Wei, Junfeng Guan, and Christopher Ference
Richard N. Arteca, Jeannette M. Arteca, Tzann-Wei Wang, and Carl D. Schlagnhaufer
The purpose of this study was to evaluate physiological, biochemical, and molecular changes that occur in unrooted Pelargonium ×hortorum cuttings during storage. Pelargonium cuttings of `Sincerity' (good shipper), `Wendy Ann' (moderate shipper) and `Snowmass' (poor shipper) were stored at 25 °C and evaluated over a 5-day period. Following removal from storage, cuttings of all cultivars exhibited steady and significant decline in photosynthesis, respiration, carbohydrate, starch, and protein over time. However, no significant differences were observed among cultivars for all of these parameters. Ethylene levels produced by `Sincerity' and `Wendy Ann' began to increase 3 days following storage; whereas, `Snowmass' showed an increase after 1 day, reaching a peak at 3 days, and then declined. When unrooted cuttings of `Snowmass' were stored for 5 days at temperatures ranging from 4 to 25 °C, it was observed that those stored at 4 °C had a significantly higher visual rating, chlorophyll content, and root and shoot weight than at higher temperatures tested. As temperature increased from 10 to 25 °C, quality of cuttings declined. Changes in gene expression of two ACC synthases and an ACC oxidase were evaluated in `Snowmass' cuttings stored at 4 and 25 °C. Correlations between ethylene and ACC levels with gene expression were observed. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Richard N. Arteca, Jeannette M. Arteca, Tzann-Wei Wang, and Carl D. Schlagnhaufer
The purpose of this study was to evaluate physiological, biochemical and molecular changes which occur in unrooted Pelargonium ×hortorum cuttings during storage. Pelargonium cuttings of `Sincerity' (good shipper), `Wendy Ann' (moderate shipper), and `Snowmass' (poor shipper) were stored at 25°C and evaluated over a 5-day period. Following removal from storage, cuttings exhibited progressive declines in photosynthesis, respiration, carbohydrate, starch and protein over time which was significant in all three cultivars, however there was little difference among the cultivars. Ethylene levels produced by `Sincerity' and `Wendy Ann' began to increase 3 days following the initiation of storage, whereas `Snowmass' showed an increase after one day reaching a peak at 3 days and was followed by a sharp decline. When unrooted cuttings of `Snowmass' were stored for a 5-day period at temperatures from 4 to 25°C, it was observed that those stored at 4°C had a significantly higher visual rating, chlorophyll content, root and shoot weight than at higher temperatures tested. The decline in quality progressively became greater from 10 to 25°C. Changes in gene expression of two ACC synthases and an ACC oxidase were evaluated in `Snowmass' cuttings which were stored at 4 and 25°C. Correlations between ethylene and ACC levels with gene expression were observed.
Xiaojuan Zong, Jiawei Wang, Li Xu, Hairong Wei, Xin Chen, Dongzi Zhu, Yue Tan, and Qingzhong Liu
Improving the poor resistance to environmental stress and the weak development of roots system in the cherry (Prunus) rootstock ‘Gisela 6’ (Prunus cerasus × Prunus canescens) is of great importance for sustainable sweet cherry (Prunus avium) production. Although a stable genetic transformation system has been developed for ‘Gisela 6’ rootstock, there is little information on the identification of genes involved in stress resistance. Using the cherry rootstock cultivar Gisela 6, we identified a total of 12 novel mitogen-activated protein kinase (MAPK) genes, designated PcMPKs. Phylogenetic analysis revealed that the PcMPKs could be divided into four groups, designated A, B, C, and D. In addition, an intron–exon structure analysis for the PcMPKs was conducted to help further understand the structure–function relationships within the cherry family. The expression profiles of PcMPKs in response to abiotic and biotic stresses were characterized using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Five PcMPKs (i.e., PcMPK4-1, PcMPK4-2, PcMPK3, PcMPK6, and PcMPK18) exhibited differential expression, and suggested their potential roles in plant responding to various stresses. This study provides the basis for further analysis on the physiological functions of PcMPKs in environmental tolerance in cherry rootstocks.
Shutian Tao, Danyang Wang, Cong Jin, Wei Sun, Xing Liu, Shaoling Zhang, Fuyong Gao, and Shahrokh Khanizadeh
Lignin is the main component of stone cells, and stone cell content is one of the crucial factors for fruit quality in chinese white pear (Pyrus ×bretschneideri). The lignin biosynthesis pathway is complex and involves many enzymatic reactions. Cinnamate-4-hydroxylase [C4H (EC.18.104.22.168)] is an essential enzyme in lignin metabolism. This study was conducted to investigate the effect of bagging on lignin metabolism during fruit development in chinese white pear. The study showed that bagging had little effect on stone cell content, lignin content, C4H activity, and C4H gene expression and that there was a positive correlation between C4H gene expression and lignin content as well as stone cell content. Moreover, a full-length complementary DNA (cDNA) encoding C4H (PbrC4H, GenBank accession number KJ577541.1) was isolated from chinese white pear fruit. The cDNA is 1515 bp long and encodes a protein of 504 amino acids. Sequence alignment suggested that the deduced protein belongs to the P450 gene family and that C4H might be located subcellularly in the cell membrane. The results indicate that bagging cannot change the lignin and stone cell content significantly and that C4H catalyzes a step in lignin biosynthesis. These findings provide certain theoretical references and practical criteria for improving the quality of chinese white pear.
Narinder P.S. Dhillon, Supannika Sanguansil, Roland Schafleitner, Yen-Wei Wang, and James D. McCreight
We report here the genetic characterization of bitter gourd (Momordica charantia) based on polymorphisms of 50 simple sequence repeat (SSR) loci in 114 accessions that included landraces, breeding lines, and commercial open-pollinated and F1 hybrid cultivars widely grown in Asia. Neighbor-joining tree analysis revealed a high level of genetic variability in the collection. The 114 accessions formed three subpopulations represented by five clusters. Distribution of accessions across the five clusters reflected their geographic origin to a large extent. South Asian accessions originating from India, Bangladesh, and Pakistan were more closely related to each other than to any other geographical group. Likewise, southeast Asian accessions that originated from Cambodia, Vietnam, Indonesia, and Philippines were grouped together. Accessions that originated from Taiwan were genetically distinct and grouped separately. A landrace from Laos was genetically close to the accessions from Thailand and genetically distinct from the rest of the accessions. White-fruited genotypes were genetically distinct from green- and dark green–fruited genotypes. Low- and medium-bitter accessions were more similar to each other than to the high-bitter genotypes. Accessions with cylindrical fruit were genetically distinct from those with spindle or elongated fruit. Commercial cultivars in each cluster were closely related, which indicated a narrowing of the bitter gourd genetic base in Asia in response to market demands for uniformity and yield. Use of diverse germplasm resources in bitter gourd breeding will help in sustainable breeding and production.
Yi-Chen Chen, Wei-Chun Chang, San-Tai Wang, and Shu-I Lin
Grafting is widely used in the commercial production of cucurbits (Cucurbitaceae) and solanaceous (Solanaceae) vegetables, but seldom in the production of cruciferous vegetables such as cabbage (Brassica oleracea Capitata group). In our study, we developed a tube grafting method for cabbage using the ‘K-Y cross’ cabbage as the scion and ‘Tsuei Jin’ chinese kale (B. oleracea Alboglabra group) as the rootstock (K-Y/TJ), and then used the K-Y/TJ grafted seedlings to identify the best healing conditions. The examined healing conditions included temperature (15, 20, or 25 °C), relative humidity (RH; 75%, 85%, or 95%), and light intensity (high light intensity, 79 to 107 μmol·m–2·s–1; low light intensity, 38.6 to 58.8 μmol·m–2·s–1; or full darkness, 0 μmol·m–2·s–1). Considering all the healing conditions, the K-Y/TJ grafted seedlings healing at 20 °C, 95% RH, and high light intensity exhibited survival rates of up to 96.7% and overall superior seedling quality. ‘K-Y cross’ cabbages were then grafted onto chinese kale rootstocks, and the head traits of all grafted plants were comparable to those of nongrafted and/or self-grafted ‘K-Y cross’ plants. ‘K-Y cross’ plants grafted on ‘Jie Lan’ chinese kale rootstocks had greater ascorbic acid and total soluble solid (TSS) contents than nongrafted and self-grafted ‘K-Y cross’ plants. Overall, this research describes a successful tube grafting method and the optimal healing conditions for grafted cabbage seedlings, which can be used as a tool to improve head quality.
Mingxiu Liu, Peng Wang, Xu Wei, Qing Liu, Xiaolin Li, Guolu Liang, and Qigao Guo
Triploid loquat (2n = 3x = 51) has stronger growth vigor and larger leaves, flowers, and fruit compared with its diploid parental plant (2n = 2x = 34), but the effects of triploidization on the contents of flavonoids and phenolics in leaves and flowers, which are the most important antioxidant compounds for pharmacological applications, have not been reported. In this report, 58 triploid loquat genotypes and seven corresponding diploid parental cultivars were used to evaluate the effects of triploidization on the contents of total flavonoids and phenolics and the antioxidant activities of leaves and flower buds. The results showed that the contents of total flavonoids and phenolics and their corresponding antioxidant activities were higher in most of the triploid loquat genotypes than their diploid parents. The antioxidant activities of leaves and flower buds were significantly correlated with the total flavonoids and phenolics contents in both diploid loquat and triploid loquat. It could be inferred that triploidization could increase the contents of flavonoids and phenolics in leaves and flower buds of loquat. Notably, the contents of total flavonoids and phenolics of leaves in triploid genotype ‘H3/24’ were the highest, reaching 212.00 mg rutin equivalent (RE)/g DW and 93.06 mg gallic acid equivalents (GAE)/g DW, respectively, which were significantly higher than those previously reported. Such a valuable trait may be stacked with other triploid traits that are already established, such as larger vegetative organs and better tolerance to various stresses, as a feasible strategy for breeding loquat cultivars with high pharmaceutical potency.
Xu-Wen Jiang, Cheng-Ran Zhang, Wei-Hua Wang, Guang-Hai Xu, and Hai-Yan Zhang
The effects of CaCl2, GA3, and H2O2 priming on Isatis indigotica Fort. seed germination characteristics, seedling growth parameters, and antioxidant enzyme activities under salt stress were investigated. NaCl had an adverse effect on the germination and seedling performance of I. indigotica. However, these three priming agents alleviated salt stress by increasing the germination percentage, improving seed vigor, accelerating germination velocity, and establishing strong seedlings. The optimal concentrations were 15 g/L for CaCl2, 0.2 g/L for GA3, and 40 mm for H2O2. Seed priming treatments enhanced the activities of antioxidant enzymes in seedlings, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), under a salt environment, which reduced the oxidative injury caused by salt. Seed priming is a promising technique that can enhance the ability of I. indigotica seed germination when salt is present.
Bingqiang Wei, Lanlan Wang, Paul W. Bosland, Gaoyuan Zhang, and Ru Zhang
A cytoplasmic male sterility (CMS) system is one of the most efficient ways to produce F1 hybrid seeds in pepper (Capsicum annuum). Restorer-of-fertility (Rf) genes are a critical component within the CMS/Rf system. The inheritance of Rf genes in pepper by joint segregation analysis was examined. The inheritance of Rf genes in the two progenies was controlled by two major additive-dominant epistatic genes and additive-dominant epistasis polygene. The two major genes had high additive effects and dominant effects. In addition, there existed significant epistatic effects between the two major genes. The major genes had high heritability in F2, BC1, and BC2 generations. Also, the fertility restorer characteristic can be selected during early generations of the breeding cycle.