Ximan Kong’s research while affiliated with Shenyang Agricultural University and other places

Contemporary climatic stress seriously affects rice production. Unfortunately, long-term domestication and improvement modified the phytohormones network to achieve the production needs of cultivated rice, thus leading to a decrease in adaptation. Here, we identify a 14-3-3 protein-coding gene OsGF14h in weedy rice that confers anaerobic germination and anaerobic seedling development tolerance. OsGF14h acts as a signal switch to balance ABA signaling and GA biosynthesis by interacting with the transcription factors OsHOX3 and OsVP1, thereby boosting the seeding rate from 13.5% to 60.5% for anaerobic sensitive variety under flooded direct-seeded conditions. Meanwhile, OsGF14h co-inheritance with the Rc (red pericarp gene) promotes divergence between temperate japonica cultivated rice and temperate japonica weedy rice through artificial and natural selection. Our study retrieves a superior allele that has been lost during modern japonica rice improvement and provides a fine-tuning tool to improve flood adaptation for elite rice varieties. Waterlogging tolerance is important in direct seeding rice cultivation practice. Here, the authors identify a 14-3-3 protein-coding gene OsGF14h in weedy rice that confers anaerobic germination and anaerobic seedling development tolerance by balancing ABA signaling and GA biosynthesis.

Leaf yellowing has become an important limiting factor for harvested pak choi, affecting its commodity quality and market value. Our previous results showed that in stay-green pak choi, nye, an SGR mutant likely prolongs its shelf life. To uncover the mechanism of the SGR mutation underlying extended shelf life, nye and its near isogenic line (nye-) harboring the SGR allele were used to conduct the postharvest analysis. Compared with nye-, nye exhibited delayed leaf yellowing and weight loss, prolonged shelf life, and maintained high –a* value and Fv/Fm during shelf life. High chlorophyll content and integral membrane structure were observed in nye, which likely contributed to delayed postharvest yellowing. The membrane integrity of nye was well maintained, manifested as a low level of electrolyte leakage and malondialdehyde (MDA). The increased accumulation of phospholipids and glycolipids, high degree of fatty acid unsaturation, and downregulated activities and gene expression of lipoxygenase （LOX）and phospholipase D （PLD）proved that less severe membrane lipid metabolism occurred in nye. These factors may be the key to delaying postharvest yellowing and extending shelf life. Our findings will contribute to the development of a new method to delay postharvest yellowing and maintain the shelf life and commercial value of leafy vegetables by using the SGR gene.

The fine structure of amylopectin affects rice quality; in particular, the amylopectin chain length distribution (ACLD) in milled rice differs between subspecies of Oryza sativa L. However, the correlation between ACLD and quality trait factors, and the genetic basis of ACLD phenotypic variation, are still unknown. Here, the correlations of ACLD with cooking and eating quality and with the rapid viscosity analysis (RVA) index were studied using chromosome segment substitution lines (CSSLs). Clear variations in ACLD were observed in introgression lines: introgression of indica segments of chromosome 3 and 7 increased the proportion of amylopectin Fa, and another segment of chromosome 3 reduced the proportion of amylopectin Fb2. A segment of chromosome 11 decreased the proportion of amylopectin Fa but increased that of Fb3. Correlation analysis with the RVA index further showed that the breakdown viscosity (BDV) was negatively correlated with the proportion of amylopectin Fb1, Fb2, and Fb3 chains, and positively correlated with Fa. Consistency viscosity (CSV) values were negatively correlated with the proportion of amylopectin Fb1, Fb2, and Fb3 chains. We thus clarified the quality trait factors determined by variation in ACLD, and provide key information for pyramiding inter-subspecific genetic superiority in molecular design breeding for rice quality.

The change of lipid metabolism is a key point of blueberry fruit after refrigeration. This study was conducted to evaluate the effects of intermittent warming (IW) of “DuKe” blueberry fruit on its shelf life at 20 ± 0.5°C following 30 days of refrigeration. IW-treated fruit showed higher contents of phosphatidylcholine, linoleic acid, and oleic acid but lower contents of phosphatidic acid and palmitic acid compared to controls. Protective effects on the cell membrane were also reflected as inhibition of the activity of phospholipase D and lipoxygenase. The blueberry fruit showed a lower decay and pitting incidence with higher firmness than control. Interestingly, IW increased C-repeat binding transcription factor gene expression, which can induce the expression of genes related to hypothermia tolerance in plant cells at low temperature. These results indicate that IW can prevent damage to the membrane lipids, which occurs by senescence at a low temperature of blueberry fruit.

Chilling injury (CI) restricts the quality and shelf life of bell pepper fruits; reducing these CI-induced detrimental effects is therefore of high economic and agricultural relevance. Here, we investigated the effects of trisodium phosphate (TSP), salicylic acid (SA), and TSP + SA treatments on pepper fruits under cold stress at 4℃ for 25 d. Combined TSP + SA treatment performed an optimal effect. Specifically, TSP + SA treatment enhanced fatty-acid desaturation efficiency, as indicated by the increased expression of key fatty acid desaturase genes, and higher content of unsaturated fatty acids. Meanwhile, TSP + SA treatment inhibited the CI-induced membrane damage, manifested as lower electrolyte leakage and malondialdehyde content. Furthermore, low field-nuclear magnetic resonance and proline content also revealed that TSP + SA treatment mitigated CI through enhancing water retention in pepper fruits. Collectively, our results may shed new light on optimizing the low-temperature storage conditions of post-harvest peppers.

The effects of methyl jasmonate (MeJA) treatment on membrane lipid metabolism of green bell pepper during cold storage was studied. The results showed that the chilling injury (CI) index, electrolyte leakage, malondialdehyde (MDA) content, phospholipase D (PLD) activity and gene expression of green bell pepper treated with MeJA were lower than those of the control fruit. MeJA treatment was able to maintain a higher level of ascorbic acid (VC) content, higher levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) and lower levels of digalactosyldiacylglycerol (DGDG), phosphatidic acid (PA), digalactosyldiacylglycerol/monogalactosyldiacylglycerol (DGDG/MGDG) and PC/PE compared to control fruit. In addition, MeJA treatment can also increase the proline content of green bell pepper fruit. Therefore, the reason that MeJA can improve the cold resistance of green bell pepper fruit may be attributed by the decreased expression and activity of PLD gene. The degradation of membrane lipid was delayed, and the content of proline increased, thereby maintaining cell membrane stability.

Refrigeration is used to retard senescence and extend the storage life of ‘Nanguo’ pears, but fruits subjected to long-term refrigeration are prone to pericarp browning during subsequent shelf life. To uncover the potential effects of membrane lipid changes during fruit pericarp browning, changes in fruit appearance and cell ultrastructure were observed after different storage durations. Membrane lipid content as well as the activity and gene expression of enzymes involved in membrane lipid metabolism and membrane stability were analyzed. Results showed that long-term refrigeration increased the activity and expression of PLD, LOX, lipase, and membrane stability-related genes that promoted membrane lipid degradation and peroxidation, reduced membrane lipid unsaturation, and led to severe browning. Overall, membrane instability induced by disordered membrane lipid metabolism under low temperature stress may account for pericarp browning of cold stored ‘Nanguo’ pears.

Low-temperature storage is the primary postharvest method employed to maintain fruit quality and commercial value. However, pitting can develop during refrigeration, especially during the shelf life. In this study, a membrane lipidomic approach was employed to analyze the potential relationship between pitting and membrane lipid metabolism during post-cold-storage shelf life. We also determined the changes in ultrastructure and water distribution by low-field nuclear magnetic resonance (LF-NMR) and assessed the permeability of membrane, membrane lipid peroxidation, proline and malondialdehyde contents, and the activity and gene expression of phospholipase D and lipoxygenase, which are involved in membrane lipid metabolism. The results indicated that the changes in blueberry phospholipids during storage could be caused by cold stress. Furthermore, dehydration is a manifestation of chilling injury. Finally, the significant increase in electrolyte leakage, content of malondialdehyde and proline, and activity of phospholipase D and lipoxygenase in chilled blueberry also indicated that membrane lipid metabolism plays an important role in cold stress response.

Bell peppers are susceptible to chilling injury (CI). To uncover the metabolism of membrane lipid fatty acids (FAs) accompanying CI, a gas chromatography-mass spectrometry (GC-MS)-based approach was used to quantitatively profile major membrane lipid FAs in bell peppers. RT-qPCR was performed to investigate the expression of the key genes that regulate the synthesis of unsaturated FAs. Additionally, we used microstructural, organoleptic, and physicochemical investigations to monitor the primary physiological metabolism of bell peppers. The study revealed that CI symptoms mostly resulted from the destabilization of the cytomembrane, which was induced by decreasing FA desaturation. Moreover, three times lower level of the double bond index in chilled fruits, than the control, further proved that membrane FA unsaturation can be considered a key factor during CI. In conclusion, this study revealed that the metabolism of membrane lipid FAs is involved in responses to CI.

Bell peppers are vulnerable to low temperature (below 7 °C) and subject to chilling injury (CI). To elucidate the relationship between cell membrane lipid composition and CI, a membrane lipidomic approach was carried out. In addition, we performed microstructural analysis and low-field nuclear magnetic resonance to better understand CI. We also monitored primary physiological metabolism parameters to explain lipidomics. Our study indicated that cellular structure damage was more serious at 4 °C, mostly represented by plasmalemma damage and plastid degradation. Membrane lipidomic data analysis reveals MGDG, PC, PE and PA as crucial biomarkers during CI. Furthermore, the significant increase in proline, electrolyte leakage and phospholipase D in chilled fruits also proved that membrane lipid metabolism is involved in the response to low temperature stress. To our knowledge, this study is the first attempt to describe the CI mechanisms in bell peppers based on membrane lipidomics.