The banning of synthetic fungicides for postharvest use on fruits in Canada has prompted a search for alternative control strategies for postharvest brown rot caused by Monilinia fructicola (Wint.) Honey on sweet cherry (Prunus avium L.). Thymol and carvacrol were the two most potent fungicides among the monoterpenoids tested. The brown rot incidences of M. fructicola-inoculated cherry dipped in 1000 μg·mL-1 thymol and carvacrol were 24% and 23%, respectively, compared with 81% for the control. The effects of thymol and carvacrol were not significantly enhanced by the addition of CaCl2 or CaB'y®, a foliar calcium fertilizer. Decco® 282 significantly reduced the activity of thymol. Methyl jasmonate, an elicitor of plant defense mechanisms, did not reduce brown rot by itself, and did not increase the efficacy of thymol and carvacrol when used as an additive in dipping or fumigation experiments. Thymol and carvacrol caused stem browning of cherry fruits in the fumigation experiment, however, 69% and 73%, respectively, of the browning was prevented when methyl jasmonate was used as a co-fumigant. Chemical names used: 5-methyl-2-(1-methylethyl)phenol (thymol); 2-methyl-5-(1-methylethyl)phenol (carvacrol); methyl 3-oxo-2-(2-pentenyl)cyclopentane acetate (methyl jasmonate).
Xiaohong Wang, Bishun Ye, Xiangpeng Kang, Ting Zhou and Tongfei Lai
Tomato (Solanum lycopersicum) fruit ripening is a complex genetic trait correlating with notable fruit phenotypic, physiologic, and biochemical changes. Transcription factors (TFs) play crucial roles during this process. LeHB-1, an HD-zip homeobox protein, is a ripening-related TF and acts as an important regulator of fruit ripening. However, the detailed biochemical and molecular basis of LeHB-1 on tomato fruit ripening is unclear. In the current study, the biologic functions of LeHB-1 were determined by a potato virus X (PVX)-mediated gene-silencing approach. The results indicate that PVX-induced LeHB-1 silencing in tomato could decrease pigment accumulation and delay fruit ripening. Compared with controls, nonripening flesh retains a greater pH value and a lesser anthocyanin content. By evaluating expression levels of genes related to tomato fruit ripening, we inferred that LeHB-1 located at the downstream of LeMADS-RIN-mediated regulatory network. In addition, LeHB-1 silencing mainly disturbed phytoene desaturation and isomerization, and led to a decrease in trans-lycopene accumulation, but did not influence flavonoid biosynthesis directly in tomato fruit. The findings provide a theoretical foundation for illustrating the biologic functions of LeHB-1 in tomato fruit ripening and quality.
Huixia Li, Zhujun Chen, Ting Zhou, Yan Liu, Sajjad Raza and Jianbin Zhou
The interaction between potassium (K) and magnesium (Mg) in plants has been intensively studied. However, the responses of different tomato (Solanum lycopersicum L.) cultivars to high K levels at low temperatures remained unclear. Herein, a complete randomized hydroponic experiment was conducted to evaluate the effects of temperature (25 °C day/18 °C night vs. 15 °C day/8 °C night) and K concentrations (156 mg·L−1 vs. 468 mg·L−1) on the growth and Mg nutrition of tomato cultivars Gailiangmaofen (MF) and Jinpeng No. 1 (JP). Compared with the control temperature (25 °C day/18 °C night), the low temperature decreased total biomass, shoot biomass, and Mg uptake in shoot by 17.3%, 24.1%, and 11.8%, respectively; however, the root/shoot ratio was increased. High K had no significant effect on plant growth or biomass compared with the control K concentration (156 mg·L−1); however, Mg concentrations and uptake in shoot were significantly lower under high-K treatment. Significant difference was observed for K uptake, but not for Mg uptake, between the two cultivars. There was no significant interaction between temperature and high K on Mg uptake of tomato, so a combined stress of low temperature and high K further inhibited Mg uptake and transport. Low temperature and high K increased the risk of Mg deficiency in tomato.
Xianqin Qiu, Hao Zhang, Hongying Jian, Qigang Wang, Ningning Zhou, Huijun Yan, Ting Zhang and Kaixue Tang
Roses are one of the economically most important groups of ornamental plants. The internal transcribed spacers (ITS) of the nuclear ribosomal DNA and the chloroplast gene matK were used to investigate the genetic diversity and genetic relationships among Rosa germplasm including 39 wild species, 21 old garden roses, and 29 modern cultivars. Three dendrograms based on ITS and matK clustering data indicated that 1) 39 wild genotypes were consistent with their classification into botanical sections with only a few exceptions; 2) most of the wild genotypes were separated from rose cultivars. However, three sections, Synstylae, Chinenses, and Rosa, that contributed to the modern roses generally gathered together with almost all old garden and modern roses on the molecular level; and 3) the relationships between cultivated roses as inferred by ITS and matK sequences do not correlate with horticultural groups. Results demonstrated that both sequence techniques can contribute to clarifying the genetic relationships of rose accessions and germplasm conservation to enhance the ornamental and economic value of rose.
Xi Shan, Heng Zhou, Ting Sang, Sheng Shu, Jin Sun and Shirong Guo
We investigated the effects of exogenous spermidine (Spd) on the carbohydrate, nitrogen (N), and endogenous polyamine status of tomato (Solanum lycopersicum) seedlings exposed to high-temperature stress [38/28 °C (day/night)]. High-temperature stress reduced the contents of pyruvate and succinate and inhibited plant growth. The application of exogenous Spd alleviated the inhibition of plant growth induced by high temperature, and also led to an increase in pyruvate, citrate, and succinate levels. High temperature markedly increased the NH4 +-N content and reduced the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate dehydrogenase (GDH). Spd significantly alleviated the negative effects on NH4 +-N assimilation induced by high-temperature stress. Moreover, Spd significantly increased the activities of NR and GDH in the high-temperature-stressed tomato leaves. In contrast, Spd application to high-temperature-stressed plant leaves counteracted high-temperature-induced mRNA expression changes in N metabolism. Spd significantly upregulated the transcriptional levels of NR, nitrite reductase, GS, GDH, and glutamate synthase (GOGAT). In addition, exogenous Spd significantly increased endogenous polyamines. These results suggest that Spd could improve carbohydrate and N status through regulating the gene expression and activity of key enzymes for N metabolism, thus confers the tolerance to high temperature on tomato seedlings.
Ting Zhou, Hao Jiang, Donglin Zhang, Junjun Fan, Long Zhang, Guibin Wang, Wangxiang Zhang and Fuliang Cao
Junjun Fan, Wangxiang Zhang, Donglin Zhang, Ting Zhou, Hao Jiang, Guibin Wang and Fuliang Cao
Chenping Zhou, Ruiting Chen, Yaqiang Sun, He Wang, Yi Wang, Ting Wu, Xinzhong Zhang, Xuefeng Xu and Zhenhai Han
Bridge grafting is widely applied in trunk-wounded apple trees. In this study, we carried out semigirdling and ring girdling on the trunk of ‘Nagafu 2’/Malus baccata (L.) Borkh apple trees to simulate trunk injury. We then bridge grafted a M9 self-rooted rootstock on the injured trunks to study the effects of bridge grafting on flowering, fruit-set, tree vigor, and fruit characteristics in ‘Nagafu 2’ apple. The results showed that both semigirdling and ring girdling due to the large wounded area caused significant decrease in flowering, fruit-set, and tree vigor (estimated by measuring leaf area, leaf gas exchange, tree height, and shoot growth); in addition, ring girdling increased flesh and peel firmness. However, bridge grafting of M9 self-rooted rootstock on semigirdling and girdling apple trees resulted in partial recovery of tree vigor (leaf area and photosynthesis) and maintaining the reduction of vegetative growth, thereby increasing flowering, fruit-set, yield, fruit weight, and peel firmness.