Oxidative burst causes loss of tapetal Ubisch body and male sterility in rice

We identified the nup1 mutant rice that exhibited specific male sterility due to the absence of Ubisch body formation and pollen grain production. We cloned the causal gene and demonstrated that NUP1, a class III peroxidase predominantly expressed in the anther wall, mediated ROS scavenging. The loss-of-function of NUP1 resulted in ROS burst in anthers, which disrupted the oxidation-reduction process and carbohydrate and lipid metabolisms, and thereby led to loss of tapetal Ubisch bodies and ultimately resulted in male sterility in rice. Our study expands the understanding of the molecular mechanisms by which ROS homeostasis regulates cell metabolism, tapetal Ubisch body formation and male fertility in plants. Anthers at stages of 10 (S10) and 11 (S11) from wild-type and nup1 mutant were collected with three biological replicates. Total RNA was isolated and used for poly(A) RNA isolation with oligo(dT) beads, and were then used for RNA-seq library construction using the NEBNext Ultra RNA Library Prep Kit for Illumina (New England Biolabs), based on the manufacturer’s instructions. RNA-seq libraries were sequenced (paired-end 150-bp) on an Illumina NovaSeq 6000 platform at Novogene, China. After quality control and adapter trimming, reads were mapped to the Oryza sativa v.7.0 genome sequences (MSU Rice Genome Annotation Project) using Hisat2 (Kim et al., 2019). Gene expression level quantification and differential expression analysis (FDR < 0.01, FC > 2) were conducted using Cufflinks (Trapnell et al., 2010).