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.
Oriental melon (Cucumis melo var. makuwa Makino) is a fruit with distinctive characteristics that is grown in Fuzhou, China. Fusarium wilt disease management remains a major challenge in the production of this fruit. Here, we performed seven field trials at four locations in Fuzhou, Fujian Province, China, to evaluate the control of fusarium wilt and yield of Oriental melons grafted on two Cucurbita rootstocks [Shengyan Tianzhen (SYTZ) and Nanzhen No. 1 (NZ1)]. During the growing seasons of 2008 to 2011, Oriental melons grafted on SYTZ and NZ1 exhibited dramatically reduced incidences of fusarium wilt disease and increased yields compared with nongrafted Oriental melons. Disease was only recorded in Trial 3 at Hongwei (2009), where plants grafted on SYTZ and NZ1 exhibited 1.05% and 1.1% infection, respectively. In the other six field trials, wilting was not observed at all. In comparison, the incidence of the disease in nongrafted Oriental melons ranged from 45.0% to 100.0%. The use of Cucurbita rootstocks improved the qualitative and quantitative carotenoid profiles, increasing lutein levels (12.7 and 10.8 μg·g−1 of fresh weight, respectively) and ζ-carotene and phytofluene amounts in fruit samples from SYTZ- and NZ1-grafted plants. In particular, the Liyu/NZ1 combination significantly increased β-carotene content ≈4-fold compared with nongrafted samples. In conclusion, Cucurbita rootstocks provided acceptable protection of Oriental melon cv. Liyu against fusarium wilt and improved the productivity and quality of fruits.
The database of grape transcription factors (DGTF) is a plant transcription factor (TF) database comprehensively collecting and annotating grape (Vitis L.) TF. The DGTF contains 1423 putative grape TF in 57 families. These TF were identified from the predicted wine grape (Vitis vinifera L.) proteins from the grape genome sequencing project by means of a domain search. The DGTF provides detailed annotations for individual members of each TF family, including sequence feature, domain architecture, expression information, and orthologs in other plants. Cross-links to other public databases make its annotations more extensive. In addition, some other transcriptional regulators were also included in the DGTF. It contains 202 transcriptional regulators in 10 families.