To introgress the good fiber quality and yield from Gossypium barbadense into a commercial Upland cotton variety, a high-density simple sequence repeat (SSR) genetic linkage map was developed from a BC1 F1 population of Gossypium hirsutum × Gossypium barbadense. The map comprised 2,292 loci and covered 5115.16 centiMorgan (cM) of the cotton AD genome, with an average marker interval of 2.23 cM. Of the marker order for 1,577 common loci on this new map, 90.36% agrees well with the marker order on the D genome sequence genetic map. Compared with five published high-density SSR genetic maps, 53.14% of marker loci were newly discovered in this map. Twenty-six quantitative trait loci (QTLs) for lint percentage (LP) were identified on nine chromosomes. Nine stable or common QTLs could be used for marker-assisted selection. Fifty percent of the QTLs were from G. barbadense and increased LP by 1.07%-2.41%. These results indicated that the map could be used for screening chromosome substitution segments from G. barbadense in the Upland cotton background, identifying QTLs or genes from G. barbadense, and further developing the gene pyramiding effect for improving fiber yield and quality.

No abstract

No abstract

A field replacement experiment was used to study the interspecific interaction among three perennial grasses (Elymus nutans, Festuca sinensis and Festuca ovina) that are distributed widely on the east Qinghai-Tibetan plateau. The experiment consisted of four different species mixtures at four seeding densities and two fertilizer levels. Aboveground biomass, relative yield and complementary effect were determined from harvested shoot dry weights. The results showed that above-ground biomass was greater in all species mixtures than in monocultures. The difference between the observed and expected relative yield was greater than zero in all mixtures for E. nutans and was greater than zero in the F. sinensis/F. ovina mixture, but was below zero in all other mixtures for F. sinensis, and was below zero in all mixtures for F. ovina. The complementary effect was more negative across all seeding densities except at a seeding density of 400 seeds/m 2 , and was negative across all mixtures except the F. sinensis/F. ovina mixture. In addition, fertilization had an insignificant impact on the relative yield, but a significant impact on the complementary effect. Fertilization enhanced negative interspecific interaction among the species.

Low temperature plasma (LTP) exerted beneficial effects on seed germination and crop growth. With application of LTP on seed germination of Platycodon grandiflorum, germination indexes and physiological parameters and transcriptome profile were investigated in this experiment. The results showed the seed germination rate and germinating potential of Platycodon grandiflorum in LTP increased by 24.7% and 30.7% comparing to CK respectively (p < 0.05). The SOD and CAT activity of the seed sprouts increased by 26.78% and 12.41% comparing to CK. Transcriptome results showed that 14342 up-regulated and 4366 down-regulated different expressing genes (DEGs) at LTP and CK. A considerable number of DEGs related to the plant hormone signal transduction, peroxisome, oxidative phosphorylation, starch and surose in response to low temperature plasma were identified in this study. The transcriptomic gene expression profiles present a valuable genomic tool to the molecular mechanisms of Platycodon grandiflorum seed germination underlying low temperature plasma. which can provide theoretical basis and practical guidance for cultivation and planting of Platycodon grandiflorum.

Avocado is an economically important crop and widely cultivated in the tropical and subtropical regions of China, whereas little is known about its genetic diversification. Twenty-six EST-SSR markers were developed based on avocado EST sequences. Molecular characterization was applied to assess the genetic relationships among different accessions. In total, nine gSSRs and nine EST-SSRs were selected to illuminate the genetic relationships within the 92 samples. Diversity parameters associated to the selected markers indicated the relatively low genetic diversity and a certain degree of inbreeding in the 92 avocado accessions. Clustering method and principal coordinate analysis clearly distinguished the accessions in accordance to the botanical races and geographic regions by molecular characterization. Moreover, the botanical race or hybrids of some unknown race accessions from different geographic origins could be determined based on known genotypes in the same cluster.

Plant ribosomes contain four specialized ribonucleic acids, the 5S, 5.8S, 18S, and 25S rRNAs. Maturation of the latter three rRNAs requires cooperative processing of a single transcript by several endonucleases and exonucleases at specific sites. In maize (Zea mays), the exact nucleases and components required for rRNA processing remain poorly understood. Here, we characterized a conserved RNA 3′-terminal phosphate cyclase (RCL)-like protein, RCL1, that functions in 18S rRNA maturation. RCL1 is highly expressed in the embryo and endosperm during early seed development. Loss of RCL1 function resulted in lethality due to aborted embryo cell differentiation. We also observed pleiotropic defects in the rcl1 endosperm, including abnormal basal transfer cell layer growth and aleurone cell identity, and reduced storage reserve accumulation. The rcl1 seeds had lower levels of mature 18S rRNA and the related precursors were altered in abundance compared with wild type. Analysis of transcript levels and protein accumulation in rcl1 revealed that the observed lower levels of zein and starch synthesis enzymes mainly resulted from effects at the transcriptional and translational levels, respectively. These results demonstrate that RCL1-mediated 18S pre-rRNA processing is essential for ribosome function and messenger RNA translation during maize seed development.

No abstract