耐旱杂草稻幼苗光合系统对干旱胁迫的响应

Responses of the photosynthetic system of drought-tolerance weedy rice to drought stress at the seedling stage

干旱胁迫是影响水稻生产最重要的非生物胁迫因子之一。杂草稻具有较强的抗非生物胁迫的能力,是栽培稻遗传改良的重要种质资源。以1份耐旱杂草稻HEB07-2、1份普通杂草稻WR04-6和栽培稻巴西陆稻(iapar9)和越富(yuefu)为材料,研究了杂草稻和栽培稻光合系统、叶温及水分利用效率对干旱胁迫的响应差异。结果表明:PEG模拟干旱胁迫72 h后,旱敏感品种越富总叶绿素含量显著降低,而杂草稻HEB07-2叶绿素含量上升,WR04-6和iapar9总叶绿素含量无显著变化。干旱胁迫期间,供试材料初始荧光(Fo)上升,最大荧光(Fm)下降,旱敏感品种越富上升幅度最大,而HEB07-2的Fo和Fm上升和下降时间较其他试材晚,说明其受伤害时间延后。干旱胁迫使供试材料净光合速率、气孔导度下降,旱敏感品种越富下降幅度最大,HEB07-2最小。利用红外热像仪测定群体温度变化发现,越富和WR04-6在干旱胁迫下叶温显著上升,而HEB07-2和巴西陆稻叶温无显著变化。

Drought is the most important abiotic stress constraint responsible for reducing yield in most rice-producing areas. Weedy rice is considered an important germplasm resource for rice improvement, because it has many useful genes conferring abiotic stress tolerance. The objective of this study was to elucidate the different drought-stress responses of drought-tolerance weedy rice （HEB07-2）, common weedy rice （WR04-6）, upland rice （iapar9）, and drought-sensitive cultivated rice （yuefu） , with respect to the photosystem, leaf temperature, and water use efficiency after 5, 24, or 72 h of treatment. The results show that 72 h of drought stress has almost no effect on the total chlorophyll content of iapar9 orWR04-6, but reduced the chlorophyll content of the drought-sensitive variety, and increased the chlorophyll content of HEB07- 2. Maximum fluorescence （ Fm ） and maximum quantum efficiency （ Fv/Fm ） were both reduced in plants exposed to drought, whereas the initial fluorescence （Fo ） was elevated. Our analysis indicated that under drought conditions, photosystem I1 was damaged, with the injury to the drought-sensitive variety yuefu being much more serious than that incurred by the drought-tolerance weedy rice HEB07-2. The start time of Foincreased and that of Fmdecreased, being later in HEB07-2 than in other genotypes. This indicates that HEB07-2 was injured later than others. The photosynthetic rate and stomatal conductance decreased with increased drought, but the change occurred more slowly in weedy rice HEB07-2 than in the cuhivar yuefu. Plant population temperature changes were measured using an infrared camera, with the leaf temperature of yuefu and WR04-6 increasing significantly under drought stress, while that of HEB07-2 and the upland rice cuhivar iapar9 did not change significantly. Under drought stress, the malondialdehyde （MDA） content of yuefu increased much more than that of other genotypes. MDA content of HEB07-2 increased the least, indicating that it experienced less severe injury. The results indicate that HEB07-2 and iapar9 were the most drought-tolerant, and yuefu was the least drought-tolerant. In conclusion, the variation among the weedy rice and cultivated rice cuhivars tested suggests that there are valuable genetic resources for improving the drought-tolerance of rice.