Study On Biological Feature Of Brachypodium Distachyon L., A New Model Plant Of Grasses And Cloning Of Partial Gene Of Ramosa 2

Brachypodium distachyon (L.) Beauv (Bd21) is one of the Pooideae grasses, commonly known as Purple False Brome, for short Brachypodium distachyon. It is a annual temperate grass plant, originated from the Middle East, North Africa, Asia and Europe and distributes widely. Bd21 is one genotype of the Brachpodium distachyon (L.)Beauv, it is quite similar to Arabidopsis thaliana in stature, an individual size, less chromosome, smaller genome, less than 15% repetitive sequences, low levels of methylation, the rich genetic resources, high planting density, a short growth cycle, self-propagation and simple growth conditions, and easy to be transformed. It has main characters of grasses, for example, the sensitivity to pathogens, caryopsis and so as to meet the requirements for a good model grass. Therefore, the Brachypodium distachyon can serve as a good supplement for rice and Arabidopsis, and it is a promising new type of grass model plant. In this paper, the study of two aspects was as follows:Study on biological feature of Brachypodium distachyon L. Brachypodium distachyon Bd21 growth characteristics and morphology development were observed by using of soil culture method in three conditions of light, LD(the long daylight period of 16 hours light and 8 hours dark), SD(the short daylight period of 8 hours light and 16 hours of darkness), and FD(full a day 24-hour light), a temperature of 23℃±2℃, light intensity for 5μmol.m m-2.s-1. The results showed that the growth of plants under the different culture conditions were very different, such as the flowering time of plants, the plant height, number of leaf at stage of flowering, total leaf, height of mature plant, panicle branch, number of branch, number of grain and distribution of the root system. The earliest flowering time plants, 28 d, appeared under FD condition, then plants under SD and LD. The plants with largest number of panicle branches, branch and grains appeared under LD. The plants with the most width of root distribution, about 12cm, also appeared under LD, then SD and FD. By observing the growth of the three conditions it could be confirmed that Brachypodium distachyon Bd21 belongs obviously to LD plant. Bd21 exhibits characteristics of branch spike, differing from the other grass plants.Clone of gene of ramosa2. Ramosa2 is a gene that controls feature of panicle branches. In order to study on branch characteristic of Brachypodium distachyon, ramosa2 was cloned. According to the conservative sequence of ramosa2 in maize, sorghum, rice, barley and wheat, primers were designed. By using the Brachypodium distachyon Bd21 genomic DNA as a template, and about 850bp of four gene fragments, Bd21-1, Bd21-2, Bd21-3 and Bd21-4 were cloned by PCR. The similarity of the four fragments is 99.9%. Sequence alignment showed that it was 59.1～62.0%homological with ramosa2 gene in wheat (Triticum aestivum), barley(Hordeum vulgare), maize(Zea mays), sorghum(Sorghum bicolor) and rice(Oryza sativa). At the same time, this study was cloned four gene fragments, which may be the first gene of LBD family transcription factor of Brachypodium distachyon (LBD transcription factor is specific to higher plants in a new gene family, has been cloned based on several LBD gene function studies, that genes involved in the higher plants LBD lateral organ development). The role of ramosa2 in the formation of branch needs to be further studied.