摘要
Tillering contributes to grain yield and plant architecture and therefore is an agronomically important trait in sorghum （Sorghum bicolor）. Here, we identified and functionally characterized a mutant of the Non- dormant Axillary Bud 1 （NAB1） gene from an ethyl methanesulfonate-mutagenized sorghum population. The nab1 mutants have increased tillering and reduced plant height. Map-based cloning revealed that NAB~ encodes a carotenoid-cleavage dioxygenase 7 （CCDT） orthologous to rice COryza sativa） HIGH-TILLERING DWARF1/ DWARF^7 and Arabidopsis thaliana MORE AXILLARY BRANCHING 3. NAB1 is primarily expressed in axillary nodes and tiller bases and NAB1 localizes to chloroplasts. The nab1 mutation causes outgrowth of basal axillary buds; removing these non-dormant basal axillary buds restoredthe wild-type phenotype. The tillering of nab1 plants was completely suppressed by exogenous application of the synthetic strigolactone analog GR24. Moreover, the nab1 plants had no detectable strigolactones and displayed stronger polar auxin transport than wild-type plants. Finally, RNA-seq showed that the expression of genes involved in multiple processes, including auxin-related genes, was significantly altered in nab1. These results suggest that NAB1 functions in strigolactone biosynthesis and the regulation of shoot branching via an interaction with auxin transport.
Tillering contributes to grain yield and plant architecture and therefore is an agronomically important trait in sorghum （Sorghum bicolor）. Here, we identified and functionally characterized a mutant of the Non- dormant Axillary Bud 1 （NAB1） gene from an ethyl methanesulfonate-mutagenized sorghum population. The nab1 mutants have increased tillering and reduced plant height. Map-based cloning revealed that NAB~ encodes a carotenoid-cleavage dioxygenase 7 （CCDT） orthologous to rice COryza sativa） HIGH-TILLERING DWARF1/ DWARF^7 and Arabidopsis thaliana MORE AXILLARY BRANCHING 3. NAB1 is primarily expressed in axillary nodes and tiller bases and NAB1 localizes to chloroplasts. The nab1 mutation causes outgrowth of basal axillary buds; removing these non-dormant basal axillary buds restoredthe wild-type phenotype. The tillering of nab1 plants was completely suppressed by exogenous application of the synthetic strigolactone analog GR24. Moreover, the nab1 plants had no detectable strigolactones and displayed stronger polar auxin transport than wild-type plants. Finally, RNA-seq showed that the expression of genes involved in multiple processes, including auxin-related genes, was significantly altered in nab1. These results suggest that NAB1 functions in strigolactone biosynthesis and the regulation of shoot branching via an interaction with auxin transport.
基金
funded by grants from the National Natural Science Foundation of China(31461143023 and 31471570)
the Ministry of Science and Technology of the People’s Republic of China(2015BAD15B03)to Hai-Chun Jing
