Lodging-Resistance Breeding of Platycodon grandiflorus Using Distant Hybridization

The distant hybridization was used in lodging-resistance breeding of Platycodon grandiflorus. The parents were Platycodon grandiflorus (♀) and Campanula medium (♂). 187 seeds of F1 were harvested by using the inter-generic hybridization in 2009 and 2010, 2 repeat, and 88 normal plants were obtained. The characteristics of leaves, stems and branches were the same as female for F1 generation, F2 generation, backcross generation and S1 generation, and there were some different characteristics with female which were flower colors, branching habit and plant height. A lodging-resistance plant was selected in F1, which was about 75 cm high, deep pink flower color and developed lateral branches. The DNA groups of each generation were separated by 1% agarose gel electrophoresis and there were not significant differences. Among the each generation many flower colors and forms were obtained.

Transcriptomic and metabolomic analysis provides insights into lignin biosynthesis and accumulation and differences in lodging resistance in hybrid wheat

The use of hybrid wheat is one way to improve the yield in the future.However,greater plant heights increase lodging risk to some extent.In this study,two hybrid combinations with differences in lodging resistance were used to analyze the stem-related traits during the filling stage,and to investigate the mechanism of the difference in lodging resistance by analyzing lignin synthesis of the basal second internode(BSI).The stem-related traits such as the breaking strength,stem pole substantial degree(SPSD),and rind penetration strength(RPS),as well as the lignin content of the lodging-resistant combination(LRC),were significantly higher than those of the lodgingsensitive combination(LSC).The phenylpropanoid biosynthesis pathway was significantly and simultaneously enriched according to the transcriptomics and metabolomics analysis at the later filling stage.A total of 35 critical regulatory genes involved in the phenylpropanoid pathway were identified.Moreover,42%of the identified genes were significantly and differentially expressed at the later grain-filling stage between the two combinations,among which more than 80%were strongly up-regulated at that stage in the LRC compared with LSC.On the contrary,the LRC displayed lower contents of lignin intermediate metabolites than the LSC.These results suggested that the key to the lodging resistance formation of LRC is largely the higher lignin synthesis at the later grain-filling stage.Finally,breeding strategies for synergistically improving plant height and lodging resistance of hybrid wheat were put forward by comparing the LRC with the conventional wheat applied in large areas.