楠木在成都平原区园林绿化中的应用

1楠木的特性及价值1.1楠木的特性楠木为亚热带树种,具有典型的地带性,幼树较耐荫,长大后喜光,深根性,有较强的萌蘖力,喜温暖湿润气候,不耐寒冷,生长的土壤主要是紫色砂叶岩与石灰岩风化而成的黄壤;最适合在土层深厚、肥沃,富含腐殖质,排水良好的中性或微酸性冲积土或壤质土上生长。生长缓慢,主要分布于贵州东北部、西部及四川盆地西部的海拔1000m以下的阔叶林中,其中以四川平原尤为普遍,现我国长江以南各地的温暖湿润地区均有种植。楠木天然分布稀少,具有较强的抗氟化氢的能力,是国家二级珍稀濒危保护植物。

Map-based cloning of a recessive gene v_1 for virescent leaf expression in cotton(Gossypium spp.)

Background： Virescence, as a recognizable phenotype available for research on chloroplast development and in the early development stage of cotton, is not only photosynthesis but also for heterosis exploitation in cotton Methods： In current study, for fine mapping of virescent-1 （V1） in cotton, three populations with a total of 5 678 individuals were constructed using T582 which has the virescent trait. Tobacco rattle virus, TRV1 and TRV2 （pYL156）, were used as vectors for the virus-induced gene silencing （VlGS） assay. Results： The V1 gene was fine-mapped to a 20 kb interval on chromosome 20 of tetraploid cotton. We identified only one candidate gene with four single nucleotide polymorphisms between parents, among which the single nucleotide polymorphism at the position of 1 082 base pair caused the change of amino acid residue from Arg （3-79） to Lys （]-582）. The relative expression of the candidate gene in virescent plants was extensively lower than that in normal plants. Nullification of the gene by VlGS significantly turned the green leaf of normal cotton plants into yellow. We named this candidate gene as GhRVL. Conclusions： This study will facilitate the further research on virescent formation, and will be useful for breeding of hybrid cottons.

The rice OsV4 encoding a novel pentatricopeptide repeat protein is required for chloroplast development during the early leaf stage under cold stress

Pentatricopeptide repeat （PPR） proteins, charac- terized by tandem arrays of a 35 amino acid motif, have been suggested to play central and broad roles in modulating the expression of organelle genes in plants. However, the molecular mechanisms of most rice PPR genes remains unclear. In this paper, we isolated and characterized a temperature-conditional virescent mutant, OsV4, in rice （Oryza sativa cultivar Jiahual （WT, japonica rice variety））. The mutant displays albino phenotype and abnormal chloroplasts at the three leaf stage, which gradually turns green after the four leaf stage at a low temperature （20℃）. But the mutant always develops green leaves and well-developed chloroplasts at a high temperature （32℃）. Genetic and molecular analyses uncovered that OsV4 encodes a novel chloroplast-targeted PPR protein including four PPR motifs. Further investigations show that the mutant phenotype is associated with changes in chlorophyll content and chloroplast development. The OsV4 transcripts only accumulate to high levels in young leaves, indicating that its expression is tissue-specific. In addition, transcript levels of some ribosomal components and plastid- encoded polymerase-dependent genes are dramatically re- duced in the albino mutants grown at 20℃. These findings suggest that OsV4 plays an important role during early chloroplast development under cold stress in rice.

Selection and Characterization of a Novel Photoperiod-Sensitive Male Sterile Line in Upland Cotton

Upland cotton （Gossypium hirsutum L.） shows strong heterosis. However, heterosis is not widely utilized owing to the high cost of hybrid seed production. Creation of a photoperiod-sensitive genetic male sterile line could substantially reduce the cost of hybrid seed production in upland cotton. Such a mutant with virescent marker was found by space mutation in near-earth orbit and its traits had been stable after 4 years of selection in Anyang and Sanya, China. This mutant was fertile with an 11-12.5 h photoperiod when the temperature was higher than 21.5 ℃ and was sterile with a 13-14.5 h photoperiod. Genetic analysis indicated that both traits were controlled by a single recessive gene or two closely linked genes. Also, the cytological observations and transcriptome profiling analysis showed that the degradation of pollen grain cytoplasm should be the primary reason why the mutant line were male sterile under long-day conditions.

Characterization and Molecular Mapping of a New Virescent Mutant in Rice

Plant leaves play a significant role in photosynthesis. Normal chloroplast development is critical for plant growth and yield performance. Defect of the chlorophyll in chloroplasts may cause abnormal leaf colors, such as yellow, white, or stripe. Chloroplasts have their own genomes encoding for about 100 genes that are essential for plastid protein synthesis and photosynthesis （Kanno and Hirai, 1993; Sato et al., 1999）. Moreover, over 3000 proteins encoded by plant nuclear genomes target to the chloroplasts and participate in the chloroplast development and/or photosynthesis. Hitherto, a number of plant genes, which encode for enzymes involved in chlorophyll biosynthetic pathways,

Convertibility of Virescent Rice Associated With the Small Subunit of Ribulose-1, 5-Bisphosphate Carboxylase/Oxygenase

Virescent rice is a type of non-lethal chlorophyll deficient mutant generated by natural mutation, genetically known as mutation of nuclear genes. Under normal growing conditions, virescent rices can develop from white seedlings to green seedlings through a half-white stage (white leaves with green strips) and therefore possess the convertibility. This differs definitely from the lethal albino mutant of rice, such as those derived from anther culture. It has been known that the generation of albino pollen plants is due to