Two rice maintaining lines with different drought tolerances, viz., Jin 23B （tolerant） and Zhenshan 97B （sensitive）, were used to study the oxidative stress and soluble sugar in rice anthers and pollen viability under drought stress during flowering stage. Higher antioxidant enzyme activities and lower malonaldehyde （MDA） content in rice anthers were observed in Jin 23B than in Zhenshan 97B under drought stress. Further, a great increase in the content of soluble sugar in rice anthers of Jin 23B was observed across the whole drought exposure, while Zhenshan 97B showed significant decrease in soluble sugar during 9-12 d after drought stress （DADS）. Accordingly, a marked decline of pollen fertility and activity, pollen numbers in an anther and pollen numbers on a stigma was observed in Zhenshan 97B, whereas little difference was found in Jin 23B. Thus, we suggest that pollen abortion caused by drought stress may be related with the reciprocity between oxidative stress and soluble sugar content in rice anthers.
FU Guan-fu SONG Jian XIONG Jie LI Yu-rong CHEN Hui-zhe LE Ming-kai TAO Long-xing
Two rice genotypes with different drought tolerance, namely Jin 23B （drought tolerant） and Zhenshan 97B （drought sensitive）, were used to study the antioxidant enzyme activities, soluble sugar and starch contents in spikelets, pistil water potential and pollen number on a stigma under water-deficit stress at the flowering stage, which were involved in the spikelet sterility. Compared with respective controls, drought stress induced more serious decreases of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） activities and more significant increase of malonaldehyde （MDA） content in spikekets of Zhenshan 97B than in Jin 23B on 9 and 12 days after water stress （DAWS）. The soluble sugar and starch contents increased significantly in spikelets of Jin 23B, but decreased significantly in spikelets of Zhenshan 97B during 9-12 DAWS. The pistil maintained higher water potential in Jin 23B than in Zhenshan 97B during 3-6 DAWS and 9-12 DAWS. In addition, water stress induced more significant decrease in the pollen number on a stigma as well as the percentage of unfilled grains in Zhenshan 97B than in Jin 23B. Thus, it is suggested that water stress induced spikelet sterility by damaging antioxidant enzyme activities, reducing carbohydrate content in spikelets and decreasing pistil water potential at the flowering stage in rice.
Fu Guan-fuSONG JianLI Yu-rongYUE Ming-kaiXIONG JieTAO Long-xing
