High yield is one of the important goals of crop breeding research. Increasing crop population planting density is an important way to increase yield under the condition of limited arable land area. However, under high-density planting conditions, due to the mutual shading of plants, the light intensity in the canopy will be insufficient, and photosynthesis will be affected, showing shade-avoidance syndrome( SAS). The main characteristics of SAS include hypocotyl elongation, increase of stem length, thinning of stem, decrease of branch number, early flowering and accelerated senescence, which will significantly reduce the crop yield. Therefore, mining high-density planting tolerant germplasm and studying its mechanism will provide material resources and theoretical support for high-yield breeding.
A research paper entitled “Genetic and transcriptome analyses reveal the candidate genes and pathways involved in the inactive shade-avoidance response enabling high-density planting of soybean” by the soybean center of Institute of Cereal and Oil Crops of HAAFS was published online in the Frontiers in Plant Science. Jidou 17, a soybean variety with high yield, stable yield and wide adaptability, was released by the soybean center. It shows inactive SAS( iSAS) and good shade tolerance under high-density planting or weak light and other shade conditions. In order to explore the high-density planting tolerant genes and analyze their regulatory mechanisms, using the RIL population constructed by varieties of Jidou 17 and Jidou 12, and combining with haplotype analysis, this study located the shade-tolerance locus qSAR1 to a 554 Kb interval on chromosome 10, containing a total of 44 genes. According to the results of previous studies, 4 of the genes were found to be closely related to SAS. The combined RNA-seq analysis of 48 samples of selected near-isogenic lines and their parents under high and low light conditions showed that the differentially expressed genes were mainly enriched in the biological progress such as “proteasomal protein catabolic process” and “proteasome-mediated ubiquitin-dependent protein catabolic process”, etc. Some genes related to high-density planting tolerance were found by expression trend analysis. This study laid a foundation for cloning shade-tolerant gene and further analyzing its shade-tolerant mechanism and breeding application.
Postdoctoral fellow ZHAO Jing, associate researcher SHI Xiaolei of Institute of Cereal and Oil Crops of HAAFS, and associate professor CHEN Lei of College of Life Sciences, Yantai University, are the co-first authors. Researcher ZHANG Mengchen, YAN Long and YANG Chunyan are the corresponding authors. This research was supported by the National Natural Science Foundation of China, the National Soybean Industry Technology System and Hebei Natural Science Innovation Team, etc.
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