Lili Song, Hai Liu, Yanli You, Yong Wang, Yueming Jiang, Changtao Li and Daryl Joyce
Ji-Yu Zhang, Zhong-Ren Guo, Rui Zhang, Yong-Rong Li, Lin Cao, You-Wang Liang and Li-Bin Huang
This study examined the ability to vegetatively propagate 1-year-old pecan (Carya illinoinensis) through the rooting of hardwood cuttings. Cuttings were treated with varying concentrations of different auxins and different combinations of media and ambient temperatures. Under different temperature conditions, all auxin treatments induced the rooting of cuttings but did not promote sprouting. The effectiveness of the induction of adventitious roots was as follows: 1-naphthalene acetic acid (NAA) > indole 3-butyric acid > indole 3-acetic acid. The base of the parent shoot treated by NAA at a concentration of 0.09%, planted in substrate with bottom heat was the most effective, with 82% rooting, 8.3 roots/cutting and root lengths of 7.3 cm. These findings suggested that auxin and substrate/air temperature differences are both indispensable in the process of adventitious roots formation in pecan. This study revealed that the propagation of hardwood cuttings derived from branches of 1-year-old pecan is possible.
Ting Min, Li-Fang Niu, Jun Xie, Yang Yi, Li-mei Wang, You-wei Ai and Hong-xun Wang
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.
Ting Min, En-chao Liu, Jun Xie, Yang Yi, Li-mei Wang, You-wei Ai and Hong-xun Wang
Ethylene response factor (ERF) genes have been involved in responses to biotic and abiotic stress, including hypoxia and anaerobic stress. Vacuum packaging (a typical anaerobic stress) is an effective storage method used to delay browning of fresh-cut lotus root (Nelumbo nucifera). In model plants, ERF genes have been identified as responsive to hypoxia. Whether ERF is associated with browning of vacuum-packaged lotus root has not been studied. The effects of vacuum packaging on browning, phenolic content, the enzyme activity of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD), and PPO, PAL, POD, and ERF genes expression in fresh-cut lotus root were studied. Downregulation of NnPAL1, NnPPOA, and NnPOD2/3 attributable to vacuum packaging coincided with increased related enzyme activities and the degree of browning of fresh-cut lotus root. The expression patterns of NnERF4/5 were consistent with the changes in NnPAL1, NnPPOA, and NnPOD2/3 gene expression. It has been proposed that NnERF4/5 could have be important regulators of fresh-cut lotus root browning, and that the relationships of NnERF4/5 and NnPAL1, NnPPOA, and NnPOD2/3 should to be studied further.
En-chao Liu, Li-fang Niu, Yang Yi, Li-mei Wang, You-wei Ai, Yun Zhao, Hong-xun Wang and Ting Min
Ethylene response factor (ERF) genes have been characterized in numerous plants, where they are associated with responses to biotic and abiotic stress. Modified atmosphere packaging (MAP) is an effective treatment to prevent lotus root browning. However, the possible relationship between ERF transcription factors and lotus root browning under MAP remains unexplored. In this study, the effects of phenol, phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) enzyme activities; and PPO, PAL, POD, and ERF gene expression on fresh-cut lotus root browning were studied with MAP. The expression pattern of ERF2/5 correlated highly with the degree of browning. It is suggested that NnERF2/5 can be used as an important candidate gene for the regulation of fresh-cut lotus root browning under MAP, and the correlation of each gene should be studied further.
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.
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.
Jaysankar De, Aswathy Sreedharan, You Li, Alan Gutierrez, Jeffrey K. Brecht, Steven A. Sargent and Keith R. Schneider
Cooling procedures used by blueberry (Vaccinium sp.) growers often may include delays up to 24 hours that can damage the fruit through rough handling and adverse temperatures, thereby potentially compromising quality and, subsequently, safety. The objectives of this experiment were to compare forced-air cooling (FAC) compared to hydrocooling without sanitizer (HW) and hydrocooling with sanitizer (HS) regarding the quality and shelf life of southern highbush blueberry [SHB (Vaccinium corymbosum)] and to determine the efficacy of these treatments for reducing Salmonella in SHB. Freshly harvested SHB that were inoculated with a five-serovar cocktail of rifampin-resistant Salmonella were rapidly chilled by FAC or hydrocooling (HW and HS) using a laboratory model system. FAC did not show any significant reduction (P > 0.05) in Salmonella or in the effects on the microbiological quality of blueberries. HW and HS reduced Salmonella by ≈2 and >4 log cfu/g SHB, respectively, on day 0. These postharvest treatments were also evaluated for their ability to help maintain fruit quality throughout a storage period of 21 days at 1 °C. Hydrocooling (both HS and HW) provided more rapid cooling than FAC. Hydrocooled blueberries showed significant weight gain (P < 0.05), whereas FAC resulted in a slight, but insignificant (P > 0.05), reduction in final weight. The results of hydrocooling, both HS and HW, shown in this study could help to extend the shelf life while maintaining or increasing the microbiological quality of fresh market blueberries. Information obtained by this study can be used for developing the best temperature management practices to maintain the postharvest safety and quality of blueberries.