Changes of Endogenous Hormone Content in Resistant and Susceptible Near-isogenic lines of Rice after Infection with Xanthomonas oryzae pv.oryzicola

【Objective】The objective was to study the changes of endogenous hormone content during the interaction between rice resistance, susceptible near-isogenic lines and pathogenic bacteria of Xanthomonas oryzae pv.oryzicola （Xooc）to provide theoretical basis for the study of the resistance mechanism of bacterial leaf streak.【Method】Using rice resistant and susceptible near isogenic lines（LR19 and LS19）as materials, the treatment groups were inoculated by pricking with pathogenic bacteria of Xooc, while the control groups were inoculated with sterilized water. At 0, 24, 48 and 96 h after inoculation, the leaves of rice at the tillering stage were taken as samples to analyzed the changes in the content of salicylic acid（SA）, jasmonic acid（JA）, ethylene（ETH）, gibberellin（GA）and zeatin（ZT）.【Result】After inoculation, the average contents of SA, ETH and ZT in the treatment groups of LR19 were 8.32 μg/mL 220.06 nmol/L and 5.56 pmol/ L, respectively, while those in the control groups were 8.31 μg/mL 250.86 nmol/L and 6.4 pmol/L, respectively. The average contents of SA, ETH and ZT in the treatment groups of LS19 were 6.57 μg/mL, 128.35 nmol/L and 4.37 pmol/L, respectively, while those in the control groups were 6.27 μg/mL, 134.7 nmol/L and 4.96 pmol/L, respectively. For these three hormones, there were no significant differences between the treatment and control groups of both lines, but the contents in resistant material were always higher than those in susceptible material. After inoculation, the average contents of JA and GA in the treatment groups of LR19 were 2 316.0 pmol/L and 63.81 pmol/L, respectively, while those in the control groups were 1 174.33 pmol/L and 75.19 pmol/L, respectively. The average contents of JA and GA in the treatment groups of LS19 were 3 043.08 pmol/L and 83.20 pmol/ L, respectively, while those in the control groups were 971.83 pmol/L and 66.27 pmol/L, respectively. For these two hormones, there were significant differences between the treatment and control groups of both lines, and the contents in resistant material were lower than those in susceptible material.【Conclusion】The contents of hormones SA, ETH and ZT in the resistant near isogenic lines were higher than those in the susceptible near-isogenic lines. Infection with Xooc induced the changes of JA and GA contents in both lines, which may be related to the BLS resistance.