Abstract:

To provide a theoretical basis for the utilization of imidazolinone resistant foxtail millet breeding, the safe dose and maximum dose of imidazolinone herbicide applied in foxtail millet were investigated, and the resistance genes to imidazolinone were preliminarily mapped. The resistant material ‘An 5158’ and sensitive material ‘Yugu 9’ were used as the research objects. The seeds and seedlings of foxtail millet were sprayed with different concentrations of imidazolinone, and the parents and BC1 populations were sprayed with 250 mL/hm ², combined with transcriptome analysis to complete the primary mapping of resistance genes to imidazolinone. The results showed that only 14% seeds of sensitive material ‘Yugu 9’ could germinate, but could not survive at the concentration of 250 mL/hm ², while the germination and survival rate of resistant material ‘An 5158’ were not affected. On the 7 ^th day of spraying, the stress response physiological indexes (SOD, POD, CAT, MDA) of the sensitive material ‘Yugu 9’ seedlings showed significant changes at 250 mL/hm ², and the difference was significant among different spraying days, while these indexes of resistance material ‘An 5158’ began to show a similar trend at 450 mL/hm ². When the parents and BC1 populations were sprayed with imidazolinone (250 mL/hm²), the mortality rate of the backcross generations was about 50%, which was in line with the rule of complete dominant inheritance. Based on transcriptome sequencing analysis, the resistance genes to imidazolinone herbicide of foxtail millet were located in the range of 6.8-30.8 Mb on the short arm of the 1st chromosome, and there were 9 candidate genes in this region. Herein, the safe dose of imidazolinone herbicide was determined to be 250 mL/hm² in foxtail millet, and the complete dominant inheritance rule was verified. The preliminary mapping of the candidate genes related to imidazolinone resistance was completed, which could provide a theoretical basis for molecular assisted breeding of herbicide resistance.

Key words: foxtail millet, imidazolidinone, herbicide resistance, gene mapping, molecular assisted breeding