Genomic basis of the distinct biosynthesis of ß-glucogallin, a biochemical marker for hydrolyzable tannin production, in three oak species.

Hydrolyzable tannins (HTs), predominant polyphenols in oaks, are widely used in grape wine aging, feed additives, and human healthcare. However, the limited availability of a high-quality reference genome of oaks greatly hampered the recognition of the mechanism of HT biosynthesis. Here, high-quality reference genomes of three Asian oak species (Quercus variabilis, Quercus aliena, and Quercus dentata) that have different HT contents were generated. Multi-omics studies were carried out to identify key genes regulating HT biosynthesis. In vitro enzyme activity assay was also conducted. Dual-luciferase and yeast one-hybrid assays were used to reveal the transcriptional regulation. Our results revealed that ß-glucogallin was a biochemical marker for HT production in the cupules of the three Asian oaks. UGT84A13 was confirmed as the key enzyme for ß-glucogallin biosynthesis. The differential expression of UGT84A13, rather than enzyme activity, was the main reason for different ß-glucogallin and HT accumulation. Notably, sequence variations in UGT84A13 promoters led to different trans-activating activities of WRKY32/59, explaining the different expression patterns of UGT84A13 among the three species. Our findings provide three high-quality new reference genomes for oak trees and give new insights into different transcriptional regulation for understanding ß-glucogallin and HT biosynthesis in closely related oak species.

PpyABF3 recruits the COMPASS-like complex to regulate bud dormancy maintenance via integrating ABA signaling and GA catabolism.

Bud dormancy is essential for perennial trees that survive the cold winters and to flower on time in the following spring. Histone modifications have been reported to be involved in the control of the dormancy cycle and DAM/SVPs are considered targets. However, how the histone modification marks are added to the specific gene loci during bud dormancy cycle is still unknown. Using yeast-two hybrid library screening and co-immunoprecipitation assays, we found that PpyABF3, a key protein regulating bud dormancy, recruits Complex of Proteins Associated with Set1-like complex via interacting with PpyWDR5a, which increases the H3K4me3 deposition at DAM4 locus. Chromatin immunoprecipitation-quantitative polymerase chain reaction showed that PpyGA2OX1 was downstream gene of PpyABF3 and it was also activated by H3K4me3 deposition. Silencing of GA2OX1 in pear calli and pear buds resulted in a similar phenotype with silencing of ABF3. Furthermore, overexpression of PpyWDR5a increased H3K4me3 levels at DAM4 and GA2OX1 loci and inhibited the growth of pear calli, whereas silencing of PpyWDR5a in pear buds resulted in a higher bud-break percentage. Our findings provide new insights into how H3K4me3 marks are added to dormancy-related genes in perennial woody plants and reveal a novel mechanism by which ABF3 integrates abscisic acid signaling and gibberellic acid catabolism during bud dormancy maintenance.

Anthocyanin Biosynthesis Associated with Natural Variation in Autumn Leaf Coloration in Quercus aliena Accessions.

Quercus aliena is an economically important tree species and one of the dominant native oak species in China. Although its leaves typically turn yellow in autumn, we observed natural variants with red leaves. It is important to understand the mechanisms involved in leaf color variation in this species. Therefore, we compared a Q. aliena tree with yellow leaves and three variants with red leaves at different stages of senescence in order to determine the causes of natural variation. We found that the accumulation of anthocyanins such as cyanidin 3-O-glucoside and cyanidin 3-O-sambubiglycoside had a significant effect on leaf coloration. Gene expression analysis showed upregulation of almost all genes encoding enzymes involved in anthocyanin synthesis in the red-leaved variants during the early and main discoloration stages of senescence. These findings are consistent with the accumulation of anthocyanin in red variants. Furthermore, the variants showed significantly higher expression of transcription factors associated with anthocyanin synthesis, such as those encoded by genes QaMYB1 and QaMYB3. Our findings provide new insights into the physiological and molecular mechanisms involved in autumn leaf coloration in Q. aliena, as well as provide genetic resources for further development and cultivation of valuable ornamental variants of this species.

The role of radiotherapy in the treatment of sinonasal undifferentiated carcinoma: A population-based analysis.

BACKGROUND: Sinonasal undifferentiated carcinoma (SNUC) is a rare, aggressive disease with ambiguous management and poor prognosis. This study aimed to evaluate the role of radiation therapy (RT) and explore the optimal treatment sequence. METHODS: Retrospective analysis of survival trends of 410 SNUC patients between 1973 and 2015. RESULTS: The 5-year cancer-specific survival (CSS) rate (45.1%) and overall survival (OS) rates (38.1%) were reported in the 84-month median follow-up. Radiotherapy was a prognosticator for improving CSS (hazard ratio [HR] = 0.425, 95% confidence interval [CI]: 0.299-0.603, p = 0.000) and OS (HR = 0.415, 95% CI: 0.303-0.570, p = 0.000), either with surgery (p = 0.000) or without surgery (p = 0.000). However, in a combined therapy of surgery and RT, preoperative and postoperative RT (5-year OS rates were 47.1% and 45.6%, respectively, p = 0.486) were not significantly different. CONCLUSIONS: Radiotherapy plays a key role in improving SNUC survival rates. No significant difference in survival rates was observed in preoperative and postoperative RT treatment.

For a Colorful Life: Recent Advances in Anthocyanin Biosynthesis during Leaf Senescence.

Leaf senescence is the last stage of leaf development, and it is accompanied by a leaf color change. In some species, anthocyanins are accumulated during leaf senescence, which are vital indicators for both ornamental and commercial value. Therefore, it is essential to understand the molecular mechanism of anthocyanin accumulation during leaf senescence, which would provide new insight into autumn coloration and molecular breeding for more colorful plants. Anthocyanin accumulation is a surprisingly complex process, and significant advances have been made in the past decades. In this review, we focused on leaf coloration during senescence. We emphatically discussed several networks linked to genetic, hormonal, environmental, and nutritional factors in regulating anthocyanin accumulation during leaf senescence. This paper aims to provide a regulatory model for leaf coloration and to put forward some prospects for future development.

Melatonin-mediated low-temperature tolerance of cucumber seedlings requires Ca2+/CPKs signaling pathway.

Melatonin (Mel) is recognized as a prominent plant growth regulator. This study investigated the alleviating effect of Mel pretreatment on growth inhibition caused by low-temperature (LT) stress (10 °C/6 °C) in cucumber seedlings and explored the role of the Ca2+/Calcium-dependent protein kinases (CPKs) signaling pathway in Mel-regulated LT tolerance. The main results are as follows: compared to LT treatment alone, 100 µM Mel increased both the content of Ca2+ (highest about 42.01%) and the expression levels of Ca2+ transporter and cyclic nucleotide-gated channel (CNGC) genes under LT. Similarly, Mel enhanced the content of CPKs (highest about 27.49%) and the expression levels of CPKs family genes in cucumber leaves under LT. Additionally, pretreatment with 100 µM Mel for three days strengthened the antioxidant defense and photosynthesis of seedlings under LT. Genes in the ICE-CBF-COR pathway and the MAPK cascade were upregulated by Mel, with maximum upregulations reaching approximately 2.5-fold and 1.9-fold, respectively, thus conferring LT tolerance to cucumber seedlings. However, the above beneficial effects of Mel were weakened by co-treatment with calcium signaling blockers (LaCl3 or EGTA) or CPKs inhibitors (TFP or W-7), suggesting that the Ca2+/CPKs pathway is involved in the Mel-mediated regulation of LT tolerance. In conclusion, this study revealed that Mel can alleviate growth inhibition in cucumber seedlings under LT stress and demonstrated that the Ca2+/CPKs signaling pathway is crucial for the Mel-mediated enhancement of LT tolerance. The findings hold promise for providing theoretical insights into the application of Mel in agricultural production and for investigating its underlying mechanisms of action.

Characteristic of epicotyl dormancy and its hormonal regulation in Chinese cork oak (Quercus variabilis).

Emergence heterogeneity caused by epicotyl dormancy contributes to variations in seedling quality during large-scale breeding. However, the mechanism of epicotyl dormancy release remains obscure. We first categorized the emergence stages of Chinese cork oak (Quercus variabilis) using the BBCH-scale. Subsequently, we identified the key stage of the epicotyl dormancy process. Our findings indicated that cold stratification significantly released epicotyl dormancy by increasing the levels of gibberellic acid 3 (GA3) and GA4. Genes associated with GA biosynthesis and signaling also exhibited altered expression patterns. Inhibition of GA biosynthesis by paclobutrazol (PAC) treatment severely inhibited emergence, with no effect on seed germination. Different concentrations (50 µM, 100 µM, and 200 µM) of GA3 and GA4+7 treatments of germinated seeds demonstrated that both can promote the emergence, with GA4 exhibiting a more pronounced effect. In conclusion, this study provides valuable insights into the characterization of epicotyl dormancy in Chinese cork oak and highlights the critical role of GA biosynthesis in seedling emergence. These findings serve as a basis for further investigations on epicotyl dormancy and advancing large-scale breeding techniques.

Target of rapamycin coordinates auxin are involved in exogenous melatonin regulated low temperature tolerance in cucumber seedlings.

Low temperature (LT) is an important environmental factor affecting the growth and yield of plants. Melatonin (MT) can effectively enhance the LT tolerance of cucumber. This study found that LT stress induced the expression of Comt1 (caffeic acid O-methyltransferase 1), with the highest expression being about 2-times that of the control. Meanwhile, the content of MT was found to be roughly 63.16% of that in the control samples. Compared with LT treatment alone, exogenous MT pretreatment upregulated the expression levels of TOR (Target of rapamycin), PIN1 (Pin-formed 1), and YUC4 (YUCCA 4), with maximum upregulations reaching approximately 66.67%, 79.32%, and 42.86%, respectively. These results suggest that MT may modulate the tolerance of cucumber seedlings to LT stress by regulating the expression of TOR, PIN1, and YUC4. In addition, co-treatment with AZD-8055 (a TOR inhibitor) or NPA (N-1-naphthylphthalamic acid, an auxin polar transport inhibitor) and MT attenuated MT-induced resistance to LT stress, leading to higher levels of reactive oxygen species (ROS), reduced antioxidant defense capacity, and increased damage to the membrane system in cucumber seedlings. Concurrently, the content of osmoregulatory substances and the photosynthesis decreased. These results demonstrate that both TOR and auxin were required for MT to alleviate LT-induced damage in cucumber. In summary, the present study demonstrates that TOR and auxin signaling synergistically contribute to alleviating LT damage in cucumber seedlings by exogenous MT. These findings help us understand the function of MT and provide insights into the regulatory network of MT that regulates the LT tolerance of plants.

Identification and expression analysis of MAPK cascade gene family in foxtail millet (Setaria italica).

The mitogen-activated protein kinase (MAPK) cascade pathway is a highly conserved plant cell signaling pathway that plays an important role in plant growth and development and stress response. Currently, MAPK cascade genes have been identified and reported in a variety of plants including Arabidopsis thaliana, Oryza sativa, and Triticum aestivum, but have not been identified in foxtail millet (Setaria italica). In this study, a total of 93 MAPK cascade genes, including 15 SiMAPKs, 10 SiMAPKKs and 68 SiMAPKKKs genes, were identified by genome-wide analysis of foxtail millet, and these genes were distributed on nine chromosomes of foxtail millet. Using phylogenetic analysis, we divided the SiMAPKs and SiMAPKKs into four subgroups, respectively, and the SiMAPKKKs into three subgroups (Raf, ZIK, and MEKK). Whole-genome duplication analysis revealed that there are 14 duplication pairs in the MAPK cascade family in foxtail millet, and they are expanded by segmental replication events. Results from quantitative real-time PCR (qRT-PCR) revealed that the expression levels of most SiMAPKs and SiMAPKKs were changed under both exogenous hormone and abiotic stress treatments, with SiMAPK3 and SiMAPKK4-2 being induced under almost all treatments, while the expression of SiMAPKK5 was repressed. In a nutshell, this study will shed some light on the evolution of MAPK cascade genes and the functional mechanisms underlying MAPK cascade genes in response to hormonal and abiotic stress signaling pathways in foxtail millet (Setaria italica).

Involvement of NO and Ca2+ in the enhancement of cold tolerance induced by melatonin in winter turnip rape (Brassica rapa L.).

As a multifunctional phytohormone, melatonin (Mel) plays pivotal roles in plant responses to multiple stresses. However, its mechanism of action remains elusive. In the present study, we evaluated the role of NO and Ca2+ signaling in Mel enhanced cold tolerance in winter turnip rape. The results showed that the NO content and concentration of intracellular free Ca2+ ([Ca2+]cyt) increased by 35.42% and 30.87%, respectively, in the leaves of rape seedlings exposed to cold stress. Compared with those of the seedlings in cold stress alone, the NO content and concentration of [Ca2+]cyt in rape seedlings pretreated with Mel increased further. In addition, the Mel-mediated improvement of cold tolerance was inhibited by L-NAME (a NO synthase inhibitor), tungstate (a nitrate reductase inhibitor), LaCl3 (a Ca2+ channel blocker), and EGTA (a Ca2+ chelator), and this finding was mainly reflected in the increase in ROS content and the decrease in osmoregulatory capacity, photosynthetic efficiency and antioxidant enzyme activities, and expression levels of antioxidant enzyme genes. These findings suggest that NO and Ca2+ are necessary for Mel to improve cold tolerance and function synergistically downstream of Mel. Notably, the co-treatment of Mel with L-NAME, tungstate, LaCl3, or EGTA also inhibited the Mel-induced expression of MAPK3/6 under cold stress. In conclusion, NO and Ca2+ are involved in the enhancement of cold tolerance induced by Mel through activating the MAPK cascades in rape seedlings, and a crosstalk may exist between NO and Ca2+ signaling.