Species Of Panicoideae Research Articles

Domestication-associated PHYTOCHROME C is a flowering time repressor and a key factor determining Setaria as a short-day plant.

Phytochromes play vital roles in the regulation of flowering time, but little is known in Panicoideae species, especially the C4 model Setaria. Here, genomic variations of PHYTOCHROME C (PHYC) between wild and cultivated Setaria gene pools were analysed and three SiphyC mutants were identified. The function of SiPHYC was verified by CRISPR-Cas9 approach and transcriptome sequencing. Furthermore, efficiency of indoor cultivation of SiphyC mutants were systematically evaluated. An extreme purified selection of PHYC was detected in wild to cultivated domestication process of Setaria. SiphyC mutants and knockout transgenic plants showed an early heading date and a loss of response to short-day photoperiod. Furthermore, variable expression of SiFTa, SiMADS14 and SiMADS15 might be responsible for promoting flowering of SiphyC mutants. Moreover, SiphyC mutant was four times that of the indoor plot ratio of wild-type and produced over 200 seeds within 45 d per individual. Our results suggest that domestication-associated SiPHYC repressed flowering and determined Setaria as a short-day plant, and SiphyC mutants possess the potential for creating efficient indoor cultivation system suitable for research on Setaria as a model, and either for maize or sorghum as well.

Complete Chloroplast Genome Sequence of Broomcorn Millet (Panicum miliaceum L.) and Comparative Analysis with Other Panicoideae Species

Broomcorn millet (Panicum miliaceum L.) is one of the earliest domesticated cereals worldwide, holding significant agricultural, historical, and evolutionary importance. However, our genomic knowledge of it is rather limited at present, hampering further genetic and evolutionary studies. Here, we sequenced and assembled the chloroplast genome (cp) of broomcorn millet and compared it with five other Panicoideae species. Results showed that the cp genome of broomcorn millet was 139,826 bp in size, with a typical quadripartite structure. In total, 108 genes were annotated and 18 genes were duplicated in the IR (inverted region) region, which was similar to other Panicoideae species. Comparative analysis showed a rather conserved genome structure between them, with three common regions. Furthermore, RNA editing, codon usage, and expansion of the IR, as well as simple sequence repeat (SSR) elements, were systematically investigated and 13 potential DNA markers were developed for Panicoideae species identification. Finally, phylogenetic analysis implied that broomcorn millet was a sister species to Panicum virgatum within the tribe Paniceae, and supported a monophyly of the Panicoideae. This study has reported for the first time the genome organization, gene content, and structural features of the chloroplast genome of broomcorn millet, which provides valuable information for genetic and evolutionary studies in the genus Panicum and beyond.

The relationship between past vegetation type and fire frequency in western Japan inferred from phytolith and charcoal records in cumulative soils

Phytolith and macrocharcoal records in cumulative soils were compared in five areas in western Japan, including two sites on the Tonomine Plateau where we examined those records. Past vegetation types, as represented by the compositions of phytolith assemblages, are closely related to macrocharcoal fluxes, regardless of age, suggesting that in Japan, fluxes in cumulative soils could be an indicator of fire frequency. On the Tonomine Plateau, phytolith and charcoal records indicate that, in the middle and late Holocene (at least 5000 to ∼1000 years ago), Sasa and Panicoideae species in a temperate climate. At least for approximately the last 600 years the Japanese pampas (Miscanthus sinensis) grassland has undergone annual burning. The results from the Tonomine Plateau site of this study and from four other sites suggest that macrocharcoal fluxes in cumulative soils of >10 particles·cm−2 y−1 indicate a high frequency of fires, resulting in the dominance of Andropogoneae species. Dominance of Pleioblastus species under the influence of fire was observed in soils with a charcoal flux of 2–10 particles·cm−2 y−1, suggesting that the species flourished under a moderate frequency of fire (possibly every several years or more). In soils with a charcoal flux of less than ∼1 particles·cm−2 y−1, there was no influence of fire on vegetation, and Sasa and Pleioblastus species flourished where the vegetation type was determined primarily by the climatic conditions. These findings indicate that macrocharcoal fluxes and phytolith assemblages exhibit a consistent relationship that is independent of age, and that macrocharcoal fluxes are linked to fire frequency, thus suggesting that the frequency of fire has determined the vegetation type in these areas. Therefore, phytolith and charcoal records in cumulative soils provide a context for quantitatively understanding the influence of fire on vegetation patterns in the past.

Water relations traits of C4 grasses depend on phylogenetic lineage, photosynthetic pathway, and habitat water availability.

The repeated evolution of C4 photosynthesis in independent lineages has resulted in distinct biogeographical distributions in different phylogenetic lineages and the variants of C4 photosynthesis. However, most previous studies have only considered C3/C4 differences without considering phylogeny, C4 subtype, or habitat characteristics. We hypothesized that independent lineages of C4 grasses have structural and physiological traits that adapt them to environments with differing water availability. We measured 40 traits of 33 species from two major C4 grass lineages in a common glasshouse environment. Chloridoideae species were shorter, with narrower and longer leaves, smaller but denser stomata, and faster curling leaves than Panicoideae species, but overall differences in leaf hydraulic and gas exchange traits between the two lineages were weak. Chloridoideae species had two different ways to reach higher drought resistance potential than Panicoideae; NAD-ME species used water saving, whereas PCK species used osmotic adjustment. These patterns could be explained by the interactions of lineage×C4 subtype and lineage×habitat water availability in affected traits. Specifically, phylogeny tended to have a stronger influence on structural traits, and C4 subtype had more important effects on physiological traits. Although hydraulic traits did not differ consistently between lineages, they showed strong covariation and relationships with leaf structure. Thus, phylogenetic lineage, photosynthetic pathway, and adaptation to habitat water availability act together to influence the leaf water relations traits of C4 grasses. This work expands our understanding of ecophysiology in major C4 grass lineages, with implications for explaining their regional and global distributions in relation to climate.

The Taxonomic Significance of the Ability of Grass 'Seed' to Germinate under Waterlogged Conditions

Summary. Results of experiments with grass 'seed' germination are reported and briefly discussed. It has long been known that whereas the 'seed' (in the sense of that which is customarily sown) of some grass species will germinate under water, those of others will not (Morinaga 1926). Accordingly, it was decided to determine, for a sample of grass species, whether the capacity of their seeds to germinate under unaerated, still water was related to their taxonomic position within the family. Two 1 litre beakers were filled to a depth of 10 cm with tap water and air bubbled through one but not the other. All experiments were carried out at ambient temperatures with natural lighting. Samples of 50 'seed' were tested for their capacities to germinate in each of the two environments. Germination was regarded as having taken place when either or both the coleoptile and radicle emerged. The seedlings were then discarded. The results of testing 59 species are summarized in Table 1 where suppression indicates that percentage germination is statistically less (5% level) in still than in aerated water. Where germination percentages were low failure to germinate in still water was regarded as suppression. Though the results are of little physiological interest as the conditions of the tests were not rigorously controlled, they appear to have some taxonomic value. Of the 12 genera in which more than one species was tested, the germination percentage in still water was similar to that in the aerated for 6 (Bothriochloa, Cenchrus, Chloris, Digitaria, Eragrostis, and Panicum); was much less in 3 (Avena, Bromus and Sorghum) and was more in Sporobolus. Germination response was variable in Phalaris and Aristida with the germination of one species being suppressed and the other not. Furthermore, it can be seen from Table 1 that as with genera there is a reasonable constancy of germination behaviour between species in the same subfamily other than for species of the Pooideae and Arundinoideae. The majority of species of Panicoideae germinate as readily in still as aerated water and for no species of the Chloridoideae or Bambusoideae was germination inhibited in still as compared to aerated water. The results presented above are in accord with those of El-Aish & Brown (1958) who showed that reduced oxygen tension adversely affected the germination of species of Pooideae but not Panicoideae. Though the two sets of data are not strictly comparable they suggest that within the Gramineae there may be two respiration pathways with close taxonomic association just as with the C3 and C4 pathways of photosynthesis.

種子でんぷん粒とイネ科の系統分類

1. Starch grains of endosperm of 766 grass species belonging to 244 genera have been examined. The starch grains are divided into four types. Type 1 represents simple grains which are broadly elliptic, elliptic-round, or rarely reniform. Starch grains of Type 2 are also simple, but they are hexagonal, pentagonal, round, or rarely rectangular. In Type 3, both simple and compound grains are included in the same seed. In Type 4, only compound grains are found throughout the endosperm.2. Type 1 is found only in Triticeae, Bromus and Brachypodium. Type 2 is observed in most species of Panicoideae, some members of Eragrostoideae, Arundinoideae and Bambusoideae and Brachyelytrum of Festucoideae. Some species of Panicoideae, Eragrostoideae and Arundinoideae have shown Type 3. Type 4 is most common in grasses, and is found in many species of Festucoideae, Eragrostoideae and Oryzoideae, and in some species of Panicoideae, Arundinoideae, and Bambusoideae.3. Systematic significance of starch grains has been discussed. The differences between Types 2, 3 and 4 may be of minor value, as all of these types are sometimes found in species of the same genus. The difference between Type 1 and Type 4 seems to be systematically significant. According to the habitual division of the starch grains of grass endosperm into two types, simple and compound, the starch features can not be rightly used in the systematics.