The rhizospheric microbiome becomes more diverse with maize domestication and genetic improvement

Domestication and genetic improvement of maize improve yield and stress tolerance due to changes in morphological and physiological properties, which likely alter rhizosphere microbial diversity. Understanding how the evolution of maize germplasm impacts its rhizobacterial traits during the growth stage is important for optimizing plant-microbe associations and obtaining yield gain in domesticated germplasms. In this study, a total of nine accessions representing domestication and subsequent genetic improvement were selected. We then sequenced the plant DNA and rhizobacterial DNA of teosinte, landraces and inbred lines at the seedling, flowering and maturity stages in a field trial. Moreover, the soil chemical properties were determined at the respective stages to explore the associations of soil characteristics with bacterial community structures. The results showed that domestication and genetic improvement increased the rhizobacterial diversity and substantially altered the rhizobacterial community composition. The core microbiome in the rhizosphere differed among germplasm groups. The co-occurrence network analysis demonstrated that the modularity in the bacterial network of the inbred lines was greater than those of teosinte and the landraces. In conclusion, the increased diversity of the rhizobacterial community with domestication and genetic improvement may improve maize resilience to biotic stresses and soil nutrient availability to plants.

Chloroplast DNA Underwent Independent Selection from Nuclear Genes during Soybean Domestication and Improvement

The chloroplast is one of the most important organs in plants because of its essential role in photosynthesis.Studies have shown that the chloroplast was once a free-living cyanobacteria and was integrated into the host species through endosymbiosis（Goksoyr.1967）.after which a large number of its genes had been donated to the host nuclear genome（Heins and Soll, 1998）.

Domestication and improvement of cotton:From tree cotton to American upland cotton and to the world's largest fiber crop

Subject Code:C06With the supports by the National Natural Science Foundation of China,collaborative studies by the research groups led by Prof.Zhang Tianzhen(张天真)from Nanjing Agricultural University,presently Zhejiang University,Prof.Du Xiongming from the Institute of Cotton Research(ICR),Chinese

Gene duplication drove the loss of awn in sorghum.

Loss of the awn in some cereals including sorghum is a key transition during cereal domestication or improvement that has facilitated grain harvest and storage.The genetic basis for the loss of awn in sorghum during domestication or improvement remains unknown.Here,we identified a transcription factor gene awn1 encoding an ALOG domain,which is responsible for awn loss during sorghum domestication or improvement.awn1 arose from a gene duplication from chromosome 10 that translocated to chromosome 3,recruiting a new promoter from the neighbouring intergenic region filled with"noncoding DNA",and recreating the first exon and intron.The awn1 acquires high expr`ession after duplication and represses the elongation of awns in domesticated sorghum.Comparative mapping revealed a high collinearity at awn1 paralog locus on chromosome 10 across cereals and awn growth and development was successfully reactivated on the rice spikelet by inactivating rice awn1 orthologue.Further RNA-seq and DAP-seq revealed that as a transcription repressor,AWN1 directly bound to the motif in the regulatory regions from three MADS genes related to flower development and two genes DL and LKS2 for the development of awn,downregulated the expressions of these genes,and then repressed the elongation of awn.The preexistence of regulatory elements in the neighbouring intergenic region of awn1 before domestication signified that noncoding DNA may serve as a treasure trove for evolution during adaptation to a changing world.Our results supported that gene duplication can promptly drive the evolution of gene regulatory network.