Transcriptome analysis of gibberellins and abscisic acid during the flooding response in Fokienia hodginsii

Deciphering the effect of phytohormones on the phyllosphere microbiota of Eucommia ulmoides

Phytohormones are key signals mediating plant-microbe molecular communication. However, their roles in driving phyllosphere microbiota assembly remain unclear. Here, high throughput target assays for 12 phytohormones and microbial amplicon sequencing techniques were used to reveal the effects of hormone components on phyllosphere microbiota of Eucommia ulmoides. Most of the phytohormone components in old leaves were lower than in tender leaves, such as indole-3-acetic acid (IAA), salicylic acid (SA), and jasmonic acid (JA), but the phyllosphere microbial community diversity in the older leaves was significantly higher than in the tender leaves, with more complex and aggregated microbial cooccurrence network. The E. ulmoides phyllosphere microbiota at tender and older leaf stage were dominated by the same dominant taxa at the phylum level, with Ascomycota and Basidiomycota as the main fungal taxa and Actinobacteriota, Bacteroidota, Firmicutes and Proteobacteria as the main bacterial taxa. FUNGuild and FAPROTAX functional predictions revealed that the high abundance functional groups of the E. ulmoides phyllosphere microbes were similar at tender and old leaf stages, with fungal functions mainly involving in plant pathogen, undefined saprotroph and endophyte, and bacterial functions mainly involving in chemoheterotrophy, fermentation and aerobic_chemoheterotrophy. Additionally, mantel test and variance partitioning analysis showed that IAA and N6-(delta 2-isopentenyl)-adenine (IP) were key phytohormones impacting the E. ulmoides phyllosphere microbiota, and their effects were largely interdependent. Our results improve the understanding of composition, diversity, function and influencing factors of phyllosphere microbiota, which might provide cue for sustainable agriculture and forestry management via precise regulation of the phyllosphere microbiota.

The Role of Aquaporins in Plant Growth under Conditions of Oxygen Deficiency

Plants frequently experience hypoxia due to flooding caused by intensive rainfall or irrigation, when they are partially or completely submerged under a layer of water. In the latter case, some resistant plants implement a hypoxia avoidance strategy by accelerating shoot elongation, which allows lifting their leaves above the water surface. This strategy is achieved due to increased water uptake by shoot cells through water channels (aquaporins, AQPs). It remains a puzzle how an increased flow of water through aquaporins into the cells of submerged shoots can be achieved, while it is well known that hypoxia inhibits the activity of aquaporins. In this review, we summarize the literature data on the mechanisms that are likely to compensate for the decline in aquaporin activity under hypoxic conditions, providing increased water entry into cells and accelerated shoot elongation. These mechanisms include changes in the expression of genes encoding aquaporins, as well as processes that occur at the post-transcriptional level. We also discuss the involvement of hormones, whose concentration changes in submerged plants, in the control of aquaporin activity.