Organisms with three or more complete sets of chromosomes are designated as polyploids. Polyploidy serves as a crucial pathway in biological evolution and enriches species diversity, which is demonstrated to have significant advantages in coping with both biotic stressors (such as diseases and pests) and abiotic stressors (like extreme temperatures, drought, and salinity), particularly in the context of ongoing global climate deterioration, increased agrochemical use, and industrialization. Polyploid cultivars have been developed to achieve higher yields and improved product quality. Numerous studies have shown that polyploids exhibit substantial enhancements in cell size and structure, physiological and biochemical traits, gene expression, and epigenetic modifications compared to their diploid counterparts. However, some research also suggested that increased stress tolerance might not always be associated with polyploidy. Therefore, a more comprehensive and detailed investigation is essential to complete the underlying stress tolerance mechanisms of polyploids. Thus, this review summarizes the mechanism of polyploid formation, the polyploid biochemical tolerance mechanism of abiotic and biotic stressors, and molecular regulatory networks that confer polyploidy stress tolerance, which can shed light on the theoretical foundation for future research.

Clubroot is an infectious root disease caused by Plasmodiophora brassicae in Brassica crops, which can cause immeasurable losses. We analyzed integrative transcriptome, small RNAs, degradome, and phytohormone comprehensively to explore the infection mechanism of P. brassicae. In this study, root samples of Brassica rapa resistant line material BrT24 (R-line) and susceptible line material Y510-9 (S-line) were collected at four different time points for cytological, transcriptome, miRNA, and degradome analyses. We found the critical period of disease resistance and infection were at 0–3 DAI (days after inoculation) and 9–20 DAI, respectively. Based on our finding, we further analyzed the data of 9 DAI vs. 20 DAI of S-line and predicted the key genes ARF8, NAC1, NAC4, TCP10, SPL14, REV, and AtHB, which were related to clubroot disease development and regulating disease resistance mechanisms. These genes are mainly related to auxin, cytokinin, jasmonic acid, and ethylene cycles. We proposed a regulatory model of plant hormones under the mRNA–miRNA regulation in the critical period of P. brassicae infection by using the present data of the integrative transcriptome, small RNAs, degradome, and phytohormone with our previously published results. Our integrative analysis provided new insights into the regulation relationship of miRNAs and plant hormones during the process of disease infection with P. brassicae.

Arundo donax is widely used as an ornamental plant in landscape gardening because of its adaptability to varying degrees of waterlogged conditions. However, to date, little information is available about the adaptive mechanism of A. donax under waterlogging stress. The results showed that long-term mild waterlogging efficiently induced the formation of adventitious roots (ARs) and further promoted root aerenchyma development, and that the activity of antioxidant enzymes (SOD, POD, and CAT) in Ars also was greatly enhanced after waterlogging. At the transcriptomic level, the expression of genes related to apoptosis, the regulation of cell division, ethylene biosynthesis, alginate synthesis, auxin signaling pathways, and anaerobic respiration was mostly up-regulated after the occurrence of waterlogging stress but genes involved in the abscisic acid signaling pathways were partly down-regulated, which indicated a preferential and favorable transcriptional response in regulating adventitious root development. Taken together, this study definitely advances our knowledge of the morphological, physiological, and transcriptomic responses of A. donax under waterlogging stress and sheds new lights on its adaptive mechanisms.

Drought can seriously hinder the growth of plants, resulting in reduced crop yield and quality. At present, the tolerance of DEAD-box helicases (DHC) to abiotic stresses, such as drought, high salinity, low temperature, and high temperature, has been confirmed in a variety of plants; therefore, using DEAD-box helicases to develop stress-resistant plants has great application prospects. In this study, Brassica rapa was used as a model to explore the response of the BrDHC1 gene to drought stress by creating RNA interference and overexpressing lines in B. rapa. The mechanism of BrDHC1 involved in drought resistance was revealed by the analysis of morphological characteristics, physiological indicators, and expression analysis of related stress response genes. The results showed that the overexpression of the BrDHC1 gene was more conducive to enhancing the resilience of plants under drought stress in B. rapa. Taken together, these results confirmed BrDHC1 as a newly identified DEAD-box helicase gene that could actively regulate plant growth and development under drought stress in B. rapa.