Phytohormone crosstalk is crucial for plant defenses against pathogens and insects in which salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) play key roles. These low molecular mass signals critically trigger and modulate plant resistance against biotrophic as well as necrotrophic pathogens through a complex signaling network that even involves participation of other hormones. Crosstalk among SA, JA and ET is mediated by different molecular players, considered as integral part of these crosscommunicating signal transduction pathways. Recent progress has revealed that the positive versus negative interactions among those pathways ultimately enable a plant to fine-tune its defense against specific aggressors. On the other hand, pathogens have evolved strategies to manipulate the signaling network to their favour in order to intensify virulence on host plant. Here we review recent advances and current knowledge on the role of classical primary defense hormones SA, JA and ET as well as their synergistic and antagonistic interaction in plant disease and immune responses. Crosstalk with other hormones such as abscisic acid, auxin, brassinosteroids, cytokinins and melatonin is also discussed mainly in plant disease resistance. In addition to our keen focus on hormonal crosstalk, this review also highlights potential implication of positive and negative regulatory interactions for developing an efficient disease management strategy through manipulation of hormone signaling in plant.

Background: Pueraria is a dry root commonly used in Traditional Chinese Medicine or as food and fodder, and tuberous root expansion is an important agronomic characteristic that influences its yield. However, no specific genes regulating tuberous root expansion in Pueraria have been identified. Therefore, we aimed to explore the expansion mechanism of Pueraria at six developmental stages (P1–P6), by profiling the tuberous roots of an annual local variety “Gange No.1” harvested at 105, 135, 165, 195, 225, and 255 days after transplanting. Results: Observations of the tuberous root phenotype and cell microstructural morphology revealed that the P3 stage was a critical boundary point in the expansion process, which was preceded by a thickening diameter and yield gain rapidly of the tuberous roots, and followed by longitudinal elongation at both ends. A total of 17,441 differentially expressed genes (DEGs) were identified by comparing the P1 stage (unexpanded) against the P2–P6 stages (expanded) using transcriptome sequencing; 386 differential genes were shared across the six developmental stages. KEGG pathway enrichment analysis showed that the DEGs shared by P1 and P2–P6 stages were mainly involved in pathways related to the “cell wall and cell cycle”, “plant hormone signal transduction”, “sucrose and starch metabolism”, and “transcription factor (TF)”. The finding is consistent with the physiological data collected on changes in sugar, starch, and hormone contents. In addition, TFs including bHLHs, AP2s, ERFs, MYBs, WRKYs, and bZIPs were involved in cell differentiation, division, and expansion, which may relate to tuberous root expansion. The combination of KEGG and trend analyses revealed six essential candidate genes involved in tuberous root expansion; of them, CDC48, ARF, and EXP genes were significantly upregulated during tuberous root expansion while INV, EXT, and XTH genes were significantly downregulated. Conclusion: Our findings provide new insights into the complex mechanisms of tuberous root expansion in Pueraria and candidate target genes, which can aid in increasing Pueraria yield.

Autophagy is an important degradation pathway that maintains cellular homeostasis in living organisms and plays a key role in plant fitness and immunity. To date, more than 30 autophagy-related genes (ATGs) have been identified in model plants such as Arabidopsis. However, autophagy in Chinese cabbage, the largest cultivated vegetable crop in China, has scarcely been studied. We identified 64 Chinese cabbage autophagy-associated genes, named BrATGs, at the genome-wide level. The majority of the BrATGs were highly conserved over a long evolutionary period, and the expression patterns indicated that BrATGs were most highly expressed in the healing tissues and flowers. Furthermore, BrATGs responded to the stresses of the heavy metal Cd, drought, salt, and low and high temperatures to varying degrees. Among them, BrATG8c/8j was specifically induced in response to drastic temperature changes; BrATG4c was upregulated only in response to drought and salt stress; and BrATG8f/10/VTI12C was highly expressed only in response to Cd stress. This work will advance the understanding of the molecular mechanisms underlying the abiotic stress response in Chinese cabbage.

Pueraria is a dry root commonly used in Traditional Chinese Medicine or as food and fodder, and tuberous root expansion is an important agronomic characteristic that influences its yield. However, current research has identified no specific genes regulating tuberous root expansion in Pueraria. Therefore, we aimed to explore the expansion mechanism of Pueraria at six developmental stages (P1–P6), by profiling the tuberous roots of an annual local variety “Gange No.1” harvested at 105, 135, 165, 195, 225, and 255 days after transplanting. Observations of the tuberous root phenotype and cell microstructural morphology revealed that the P3 stage was a critical boundary point in the expansion process, which was preceded by diameter thickening and yield gain rapidly of the tuberous roots, and followed by longitudinal elongation at both ends. A total of 17,441 differentially expressed genes (DEGs) were identified by comparing the P1 stage (unexpanded)against the P2–P6 stages (expanded) using transcriptome sequencing; 386 differential genes were shared across the six developmental stages. KEGG pathway enrichment analysis showed that the DEGs shared by P1 and P2–P6 stages were mainly involved in processes related to the “cell wall and cell cycle”, “plant hormone signal transduction”, and “sucrose and starch metabolism”. This finding is consistent with the physiological data collected on changes in sugar and hormone contents for Pueraria. The combination of KEGG and trend analyses revealed six essential candidate genes involved in tuberous root expansion; of them, CDC48, ARF, and EXP genes were significantly upregulated during tuberous root expansion while the INV, EXT, and XTH genes were significantly downregulated. These findings provide insights into the complex mechanisms of tuberous root expansion in Pueraria and candidate target genes, which can aid in increasing Pueraria yield.