The complete chloroplast genome sequence of Salvia chienii E.Peter, 1936 (Lamiaceae).

Salvia chienii E.Peter is a medicinal herb mainly distributed in Huangshan Mountain of Anhui province, China. In this study, the first complete chloroplast genome of S. chienii was sequenced and assembled. The genome length was 151,530 bp and encoded 143 genes (91 protein-coding genes, eight rRNA genes, and 37 tRNA genes). The phylogenomic analysis showed that S. chienii was closely related to S. miltiorrhiza. Further evolutionary studies of the genus Salvia could benefit from the complete chloroplast genome of S. chienii present in this study.

RNAi-directed down-regulation of RSV results in increased resistance in rice (Oryza sativa L.).

Rice stripe disease (RSD), caused by rice stripe virus (RSV), is a serious disease in temperate rice-growing areas. We have created an RNAi construct containing coat protein gene (CP) and disease specific protein gene (SP) sequences from RSV. The RNAi construct was transformed into two susceptible japonica varieties, Suyunuo and Guanglingxiangjing, to develop resistance against RSD. The homozygous progeny of rice plants in the T(5) and T(7) generations containing RNAi constructs, after self-fertilization were strongly resistant to viral infection. RT-PCR indicated that viral replication of SP and CP in the transgenic plants was significantly inhibited. There were no obvious morphological or developmental differences between the transgenic and wild-type plants from seedling stage to maturity. The excellent agronomic traits of these two varieties, such as high yield and good quality were maintained. Suppression of virus genes using RNAi is therefore a practical and effective strategy for controlling viral infection in crops.

The complete chloroplast genome of Salvia liguliloba Y. Z. Sun (Lamiaceae).

Salvia liguliloba Y. Z. Sun is a plant species endemic to the Tianmu Mountains. In this study, we assembled the complete chloroplast genome of S. liguliloba. The chloroplast genome of S. liguliloba was 151,490 bp with quadripartite structure in length, which contained 124 encoded genes, including 79 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. Our phylogenetic analysis result based on 54 chloroplast genomes revealed that S. liguliloba was closely related to S. miltiorrhiza according to the current sampling extent in Lamiaceae.

Characterization of complete chloroplast genome of Salvia honania L. H. Bailey (Lamiaceae).

Salvia honania L. H. Bailey is an endemic species, mainly distributed in Henan and Hubei provinces in China. The first complete chloroplast genome of Salvia honania was sequenced and assembled in this study. The genome is 151,559 bp in length and contains 132 encoded genes in total, including 87 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. The phylogenomic analysis showed that Salvia honania was closely related to Salvia meiliensis according the current sampling extent.

Natural Variations in SLG7 Regulate Grain Shape in Rice.

Rice (Oryza sativa) grain shape, which is controlled by quantitative trait loci (QTL), has a strong effect on yield production and quality. However, the molecular basis for grain development remains largely unknown. In this study, we identified a novel QTL, Slender grain on chromosome 7 (SLG7), that is responsible for grain shape, using backcross introgression lines derived from 9311 and Azucena. The SLG7 allele from Azucena produces longer and thinner grains, although it has no influence on grain weight and yield production. SLG7 encodes a protein homologous to LONGIFOLIA 1 and LONGIFOLIA 2, both of which increase organ length in Arabidopsis. SLG7 is constitutively expressed in various tissues in rice, and the SLG7 protein is located in plasma membrane. Morphological and cellular analyses suggested that SLG7 produces slender grains by longitudinally increasing cell length, while transversely decreasing cell width, which is independent from cell division. Our findings show that the functions of SLG7 family members are conserved across monocots and dicots and that the SLG7 allele could be applied in breeding to modify rice grain appearance.

Mutation of the light-induced yellow leaf 1 gene, which encodes a geranylgeranyl reductase, affects chlorophyll biosynthesis and light sensitivity in rice.

Chlorophylls (Chls) are crucial for capturing light energy for photosynthesis. Although several genes responsible for Chl biosynthesis were characterized in rice (Oryza sativa), the genetic properties of the hydrogenating enzyme involved in the final step of Chl synthesis remain unknown. In this study, we characterized a rice light-induced yellow leaf 1-1 (lyl1-1) mutant that is hypersensitive to high-light and defective in the Chl synthesis. Light-shading experiment suggested that the yellowing of lyl1-1 is light-induced. Map-based cloning of LYL1 revealed that it encodes a geranylgeranyl reductase. The mutation of LYL1 led to the majority of Chl molecules are conjugated with an unsaturated geranylgeraniol side chain. LYL1 is the firstly defined gene involved in the reduction step from Chl-geranylgeranylated (Chl(GG)) and geranylgeranyl pyrophosphate (GGPP) to Chl-phytol (Chl(Phy)) and phytyl pyrophosphate (PPP) in rice. LYL1 can be induced by light and suppressed by darkness which is consistent with its potential biological functions. Additionally, the lyl1-1 mutant suffered from severe photooxidative damage and displayed a drastic reduction in the levels of α-tocopherol and photosynthetic proteins. We concluded that LYL1 also plays an important role in response to high-light in rice.