Abstract
BackgroundFulvic acid (FA) is a kind of plant growth regulator, which can promote plant growth, play an important role in fighting against drought, improve plant stress resistance, increase production and improve quality. However, the function of FA in tea plants during drought stress remain largely unknown.ResultsHere, we examined the effects of 0.1 g/L FA on genes and metabolites in tea plants at different periods of drought stress using transcriptomics and metabolomics profiles. Totally, 30,702 genes and 892 metabolites were identified. Compared with controlled groups, 604 and 3331 differentially expressed metabolite genes (DEGs) were found in FA-treated tea plants at 4 days and 8 days under drought stress, respectively; 54 and 125 differentially expressed metabolites (DEMs) were also found at two time points, respectively. Bioinformatics analysis showed that DEGs and DEMs participated in diverse biological processes such as ascorbate metabolism (GME, AO, ALDH and L-ascorbate), glutathione metabolism (GST, G6PDH, glutathione reduced form and CYS-GYL), and flavonoids biosynthesis (C4H, CHS, F3’5’H, F3H, kaempferol, quercetin and myricetin). Moreover, the results of co-expression analysis showed that the interactions of identified DEGs and DEMs diversely involved in ascorbate metabolism, glutathione metabolism, and flavonoids biosynthesis, indicating that FA may be involved in the regulation of these processes during drought stress.ConclusionThe results indicated that FA enhanced the drought tolerance of tea plants by (i) enhancement of the ascorbate metabolism, (ii) improvement of the glutathione metabolism, as well as (iii) promotion of the flavonoids biosynthesis that significantly improved the antioxidant defense of tea plants during drought stress. This study not only confirmed the main strategies of FA to protect tea plants from drought stress, but also deepened the understanding of the complex molecular mechanism of FA to deal with tea plants to better avoid drought damage.
Highlights
Fulvic acid (FA) is a kind of plant growth regulator, which can promote plant growth, play an important role in fighting against drought, improve plant stress resistance, increase production and improve quality
The Relative water content (LWC), Chlorophyll content (CC), Relative electrolyte conductivity (ELC) and Reactive oxygen species (ROS) in FA-treated tea plants changed significantly at 4 days of drought stress compared with controlled groups (Fig. 1b)
The results showed that the FA could modulate the co-expression of differentially expressed metabolite genes (DEGs) and differentially expressed metabolites (DEMs) related to ascorbate metabolism, glutathione metabolism and flavonoids biosynthesis during drought stress
Summary
Fulvic acid (FA) is a kind of plant growth regulator, which can promote plant growth, play an important role in fighting against drought, improve plant stress resistance, increase production and improve quality. Tea plants are often exposed to drought stress, which has profound effects on tea yield and quality [1]. With the shortage of water resources, the drought has become a main disturbance for tea production in fields, resulting in reduction of yield by around 14–40% in different cultivation areas every year [2, 3]. Catechins, caffeine, theanine and some free amino acids in tea would be significantly reduced under drought stress, resulting in a serious decline in tea quality [4]. Exploring the response mechanisms of tea plants to drought stress is essential for developing and breeding new drought-resistant varieties
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