Studies On Biological And Agronomic Traits Of Gu (Zizania Latifolia)

Zizania is one of genera with the closest relationship to Oiyza genus in the grass family and the only genus which distributed discontinuously between Eurasia and North America in the tribe Oryzeae. Gu (Zizania latifolia) was an important cereal in Chinese history (one of six important cereals in Zhou Dynasty), but it now has disappeared. Another species in Zizania genus, Zizania palustris, has been domesticated as a commercial cereal crop in North America in last century. However, no effort has been done in genetic improvement or domestication of Chinese Gu to date. As a part of our effort to recover the ancient Chinese cereal, in this study, the genetic resources of wild and semi-domesticated Gu had been collected and researched on biological characteristics and agronomic traits. The main results are as follows:1.9accessions of wild and semi-domesticated Gu material were totally collected in Huzhou City, Zhejiang Province and5accessions in Wuhan City, Hubei province. We got two accessions of semi-domesticated Gu material, Jiayou1and Geshanl, whose compact-type and stem stout is distinct from other wild Gu material. Further more, the chromosome number and genome size of collected Gu was examined separately by two diffident ways. In addition, the main agronomic traits of two semi-domesticated Gu (Jiayou1and Geshan1) were investigated including flowering time, inflorescence structure, seed phenotype and germination rate.2. The results of modified carbol fuchsin stain and fluorescent in situ hybridization (FISH) showed that chromosome number of Gu was2n=34, which was different from that of Z. palustris (2n=30). Gu’s genome size estimated by flow cytometer (FCM) and K-mer analysis was about600Mb, which was much smaller than that of Z. palustris (860Mb).3. The flowering period of Jiayou1usually happened in one month from the middle of September to October, which was about15days earlier than wild Gu and10days later than Geshan1. The ratio of pistillate to staminate flowers is about1:1.8and an inflorescence ideograms of Gu was first drawn. The kilo-grain mass of brown Gu was about12.7g with9.7mm of length and1.48mm width of brown seeds, which were smaller than Z. palustris. Furthermore, the regular arrangement of starch granules was found in the Gu seed by scanning electron micrographs (SEM). The germination rate of Jiayou1seeds could reach62.9%with an improved seed treatment method.In sumary, the semi-domesticated Gu, which has a compact plant architecture and normal flowering, provide an important genetic material for the domestication of Gu, although other target traits such as seed shattering need to be improved in future. The ancient crop and its domestication should been given more attention, and more efforts should be taken on artificial mutation breeding.