OsDCL3b affects grain yield and quality in rice.

KEY MESSAGE: We reported that knockdown of OsDCL3b decreased grain yield but increased grain quality in rice, which is helpful for molecular breeding in crops. Multiple DICER-LIKE (DCL) genes usually exist and show diverse biochemical and phenotypic functions in land plants. In rice, the biochemical function of OsDCL3b is known to process 24-nucleotide panicle phased small RNAs, however, its phenotypic functions are unclear. Here we reported that knockdown of OsDCL3b led to reduced pollen fertility, seed setting rate, and decreased grain yield but increased grain quality in rice. To reveal the molecular mechanism of the above phenomena, extracted RNAs from rice panicles of the wild type (WT) and OsDCL3b-RNAi line S6-1 were analyzed by deep sequencing. It showed that knockdown of OsDCL3b affected the biogenesis of both 21- and 24-nucleotide small RNAs including miRNAs and phased small RNAs. Using RNA-seq, 644 up- and 530 down-regulated mRNA genes were identified in panicles of line S6-1, and 550 and 273 differentially spliced genes with various alternative splicing (AS) events were observed in panicles of line S6-1 and WT, respectively, suggesting that OsDCL3b involved in influencing the transcript levels of mRNA genes and the AS events in rice panicles. Thus, our results show that knockdown of OsDCL3b will affect the biogenesis of small RNAs, which is involved in regulating the transcription of mRNA genes, and consequently influence the grain yield and quality in rice.

Expression and function analysis of a rice OsHSP40 gene under salt stress.

Heat shock proteins (HSPs) play essential roles in both plant growth and abiotic stress tolerance. In rice, OsHSP40 was recently reported to regulate programmed cell death (PCD) of suspension cells under high temperature. However, the expression and functions of OsHSP40 under normal growth or other abiotic stress conditions is still unknown. We reported the expression and function of a rice OsHSP40 gene under salt stress. Homologous proteins of OsHSP40 were collected from the NCBI database and constructed the neighbor-joining (NJ) phylogenetic tree. The expression pattern of OsHSP40 was detected by qRT-PCR under NaCl (150 mM) treatment. Then, identified a rice T-DNA insertion mutant oshsp40. At last, we compared and analyzed the phenotypes of oshsp40 and wild type under salt stress. OsHSP40 was a constitutively expressed small HSP (sHSP) gene and was close related to other plant sHSPs. Moreover, the expression of OsHSP40 was regulated by salt, varying across time points and tissues. Furthermore, the growth of T-DNA insertion mutant of OsHSP40 (designated as oshsp40) was suppressed by NaCl (150 mM) compared with that of the WT at seedling stage. Detailed measurement showed root and shoot length of the oshsp40 seedlings were significantly shorter than those of the WT seedlings under NaCl stress. In addition, the pot experiment results revealed that seedlings of oshsp40 withered more seriously compared with those of WT after NaCl treatment and recovery, and that survival rate and fresh weight of oshsp40 seedlings were significantly reduced. Taken together, these data suggested that OsHSP40 had multiple functions in rice normal growth and abiotic stress tolerance.

Towards a global phylogeny of freshwater mussels (Bivalvia: Unionida): Species delimitation of Chinese taxa, mitochondrial phylogenomics, and diversification patterns.

The Yangtze River Basin in China is one of the global hotspots of freshwater mussel (order Unionida) diversity with 68 nominal species. Few studies have tested the validity of these nominal species. Some taxa from the Yangtze unionid fauna have not been adequately examined using molecular data and well-positioned phylogenetically with respect to the global Unionida. We evaluated species boundaries of Chinese freshwater mussels, and disentangled their phylogenetic relationships within the context of the global freshwater mussels based on the multi-locus data and complete mitochondrial genomes. Moreover, we produced the time-calibrated phylogeny of Unionida and explored patterns of diversification. COI barcode data suggested the existence of 41 phylogenetic distinct species from our sampled 40 nominal taxa inhabiting the middle and lower reaches of the Yangtze River. Maximum likelihood and Bayesian inference analyses on three loci (COI, 16S, and 28S) and complete mitochondrial genomes showed that the subfamily Unioninae sensu stricto was paraphyletic, and the subfamily Anodontinae should be subsumed under Unioninae. In addition, we described two new tribes (Aculamprotulini tribe nov. and Lepidodesmini tribe nov.) in the subfamily Unioninae and one new genus (Parvasolenaiagen. nov.) in the subfamily Gonideinae. Molecular dating analysis suggested freshwater mussels diversified at 346.1 Mya (HPD = 286.6-409.9). The global diversification rate for Unionida was estimated to be 0.025 species/Myr. Our study found only a single well-supported rate shift in Unionida diversification, occurring at the base of the subfamily Ambleminae. The evolution of active host-attraction may have triggered the burst of speciation in Ambleminae, and the environment and geography of the Mississippi River Basin likely sustained this radiation.

RNA interference mediated pten knock-down inhibit the formation of polycystic ovary.

Pten (phosphatase and tensin homolog deleted on chromosome 10), a kind of tumor suppressor gene, plays important roles in female reproductive system. But its expression and roles in the formation of polycystic ovaries are yet to be known. In this study, we constructed a rat model of PCOS using norethindrone and HCG injections and found the expressions of pten mRNA and PTEN protein increased significantly in the polycystic ovary tissue by immunohistochemistry, RT-PCR, and western blot. Furthermore, the results showed that in vivo ovaries could be effectively transfected by lentiviral vectors through the ovarian microinjection method and indicated that pten shRNA may inhibit the formation of polycystic ovaries by pten down-regulation. Our study provides new information regarding the role of PTEN in female reproductive disorders, such as polycystic ovary syndrome.