Recently, Journal of Experimental Botany published the article titled “Combining high-throughput micro-CT-RGB phenotyping and genome-wide association study to dissect the genetic architecture of tiller growth in rice” from HZAU plant phenomics team, with Prof. Yang Wanneng as corresponding author and Doctoral students Wu Di and Guo Zilong as co-first authors. The team independently developed a high-throughput micro-CT-RGB imaging system to screen the dynamic process of rice growth at tillering stages, and revealed the genetic structure of the process, thus playing an important role in rice genetic improvement.
Rice is one of the staple crops in China. Selecting plants with the ideal tiller structure, particularly in terms of tiller angle and number, is a key issue in boosting rice yield. With the rapid development of functional genomics and molecular breeding, it is urgent to improve the capacity of quickly detecting thousands of rice materials. The traditional methods of determining cereal tiller traits tend to be destructive, labor intensive, and time consuming, so how to improve the methods become a bottleneck restricting the development of functional genomics and rice breeding.
In response to these problems, HZAU plant phenomics team has developed a high-throughput micro-CT-RGB imaging system, and they obtain high resolution (up to 30 μm) tiller images and 75 phenotypic traits. Based on acceleration technologies such as GPU, about 310 rice plants can be detected per day. In addition, by using self-designed image analysis algorithm with high throughput, the team can obtain a large number of new traits which couldn’t be done before, such as tiller area, average tiller angle, tiller area growth rate and so on. Through modeling and analysis, it was found that there was a more significant correlation between tiller area and yield of rice compared with tiller number.
In this study, the team extracted 739 traits from 234 rice accessions at nine time points. A total of 402 significantly associated loci were identified by genome-wide association study, including a major locus associated with tiller angle, TAC1. Furthermore, the team found two loci containing associations with both vigor-related traits identified by high-throughput micro-CT-RGB imaging and yield. The superior alleles would be beneficial for breeding for high yield and dense planting. Interestingly, the team also found that the 234 indica rice materials with higher tiller senescence had a lower yield and low scores for drought resistance. If the angular change first intensifies and then eases, the yield was usually slightly higher.
The work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, the Fundamental Research Funds for the Central Universities, and the UK Biotechnology and Biological Sciences Research Council. In addition, the technology has been conferred a Chinese invention patent in Nov, 2018 (non-destructive measuring device and method for tiller traits of rice based on micro-CT, 201510899754X), and has good market prospects.