OsAPX1 Positively Contributes to Rice Blast Resistance.

Ascorbate peroxidases (APXs) maintain cellular reactive oxygen species (ROS) homeostasis through their peroxidase activity. Here, we report that OsAPX1 also promotes ROS production such that a delicate cellular ROS homeostasis is achieved temporally after Magnaporthe oryzae infection. OsAPX1 specifically induces ROS production through increasing respiratory burst oxidase homologs (OsRBOHs) expression and can be inhibited by DPI, a ROS inhibitor. The time-course experiment data show that the simultaneous induction of OsAPX1 and OsRBOHs leads to ROS accumulation at an early stage; whereas a more durable expression of OsAPX1 leads to ROS scavenging at a later stage. By the temporal switching between ROS inducer and eliminator, OsAPX1 triggers an instant ROS burst upon M. oryzae infection and then a timely elimination of ROS toxicity. We find that OsAPX1 is under the control of the miR172a-OsIDS1 regulatory module. OsAPX1 also affects salicylic acid (SA) synthesis and signaling, which contribute to blast resistance. In conclusion, we show that OsAPX1 is a key factor that connects the upstream gene silencing and transcription regulatory routes with the downstream phytohormone and redox pathway, which provides an insight into the sophisticated regulatory network of rice innate immunity.

Analyzing Differentially Expressed Genes and Pathways Associated with Pistil Abortion in Japanese Apricot via RNA-Seq.

Reproduction is a critical stage in the flower development process, and its failure causes serious problems affecting fruit quality and yield. Pistil abortion is one of the main factors in unsuccessful reproduction and occurs in many fruit plants. In Japanese apricot, the problem of pistil abortion is very common and affects fruit quality and plant yield; however, its molecular mechanism is not clearly understood. Therefore, in the current study, we used RNA-Seq to identify the differentially expressed genes (DEGs) and pathways actively involved in pistil abortion. A total of 3882 differentially expressed genes were found after cutoff and pairwise comparison analysis. According to KEGG pathway analysis, plant hormone signaling transduction and metabolic pathways were found most significantly enriched in this study. A total of 60 transcription factor families such as MADS-box, NAC and TCP showed their role in this process. RT-qPCR assays confirmed that the expression levels were consistent with RNA-Seq results. This study provides an alternative to be considered for further studies and understanding of pistil abortion processes in Japanese apricot, and it provides a reference related to this issue for other deciduous fruit crops.