The complete mitochondrial genome of Zelkova schneideriana Hand-Mazz (Ulmaceae) and phylogenetic analysis.

Zelkova schneideriana Hand-Mazz is a second-class key protected wild plant in China. Here, the complete mitochondrial genome of Zelkova schneideriana Hand-Mazz was sequenced using Nanopore Sequel and Illumina NovaSeq platform. The mitochondrial genome was assembled into three circular-mapping molecules with the genome sizes of 154,640 bp, 192,388 bp and 146,907 bp, including 36 protein-coding genes, 19 tRNA genes, and 3 rRNA genes. Phylogenetic analysis indicated that Zelkova schneideriana Hand-Mazz is close with Hemiptelea davidii, a species in same Ulmaceae Mirb.

Complete mitochondrial genome of Hemiptelea davidii (Ulmaceae) and phylogenetic analysis.

Hemiptelea davidii (Hance) Planch is a potential valuable forest tree in arid sandy environments. Here, the complete mitochondrial genome of H. davidii was assembled using a combination of the PacBio Sequel data and the Illumina Hiseq data. The mitochondrial genome is 460,941 bp in length, including 37 protein-coding genes, 19 tRNA genes, and three rRNA genes. The GC content of the whole mitochondrial genome is 44.84%. Phylogenetic analyses indicated that H. davidii is close with Cannabis and Morus species.

[Virus resistance in transgenic watermelon plants containing a WMV-2 coat protein gene].

Virus disease is a major cause that affects the quality and output of watermelon which is an important fruit in summer. So it is really urgent to develop disease resistance plants. But it takes a long time to breed such plants in conventional ways, and it is very difficult to get ideal result. With the development of plant genetic engineering, new ways have been found to breed plants with disease resistance. By using plant transgenic technique, much progress was been made in plant improvement. There are many successful cases of transgenic plants against corresponding virus disease through transferring coat protein gene. This paper reports the results of inheritance, segregation, expression of WMV-2 coat protein gene in inbred transgenic watermelon and its resistance to virus. Through PCR analysis of inbred plants, we found WMV-2 coat protein gene in the genome of progeny R1 separated with 3:1. After successive selection and identification of 4 generations, 8 transgenic pure lines with almost the same agronomic traits were obtained from 3 independent transformants of T7, T11 and T32. The result of Western blotting shows all 3 different transgenic lines of R4T7-1, R4T11-3 and R4T32-7 can produce coat protein. Disease resistance experiment on transgenic plants with WMV-2 shows that, compared with the control groups, transgenic plants can delay the disease infection and reduce the incidence and the symptoms of virus disease. And the transgenic line R4T32-7 expressed high resistance to infection by WMV-2, which lays a foundation for breeding of disease resistant varieties through plant transgenic technique.

[Genetic analysis and molecular tagging of a gene for non-palea in rice].

The mutants involved in the development of floral organ are good material for understanding the molecular genetic mechanisms of floral development. A rice mutant, that lacks palea in its florets, was derived from a spontaneous mutation in an indica line, SAR III-93-369. Genetic analyses in three F2 populations from the mutant crossed with three rice varieties, Sheng 47, N625 and CDR22, respectively, showed that the mutant trait is controlled by a single recessive gene. In the F2 population from npa-1/Sheng47 the gene for the non-palea trait was mapped between two restriction fragment length polymorphism markers, C498 and RZ450, with distances of 7.5 cM and 2.4 cM, respectively. The tagged recessive non-palea gene is temporarily designated npa-1.

[Identification of molecular markers associated with rice root traits by correlation coefficient analysis].

After growing in nutrient solution for 10 days, 84 rice varieties were harvested and measured in maximum root length (MRL) and root dry weight (RDW) separately. Twenty-seven of them were selected as representative variety for correlated fragments screening with amplified fragment length polymorphism (AFLP) technique. After surveying with 15 pairs of AFLP primers, 7 fragments from 4 pairs of primers were identified having significant correlation with MRL or/and RDW based on correlation coefficient analysis. One of them, "T3P3f", was cloned and sequenced, and its specific primers (Z336) were designed for the regular PCR amplication. Further analysis in 84 rice varieties revealed that correlation coefficient between Z336 and MRL was -0.193, much closer to the significant level of 5%; as between Z336 and RDW was -0.391, over the significant level of 1%. For the trait expression, Z336 could explain the root trait difference of 3.7% for MRL and 15.3% for RDW, respectively. The result shows the marker Z336 might tightly link with a QTL that has the negative relation with RDW expression. With a double haploid (DH) population from a cross of ZYQ8 and JX17, Z336 was finally anchored on rice chromosome 11 with a linked marker of 9.4 cM.