大气CO2浓度升高对不同类型水稻灌浆期有机物合成与分配的影响

为明确不同类型水稻对高浓度CO2的响应差异,应用先进的FACE(Free air CO_2 enrichment)试验平台,以粳稻(Japonica)武运粳21(WYJ21)和籼稻(Indica)扬稻6(YD6)为试材,研究灌浆期两种类型水稻体内有机物含量的变化。与对照相比,WYJ21籽粒中直链和支链淀粉含量在FACE处理下略有增加,YD6籽粒中直链淀粉含量在完熟期显著高于对照8.9%;WYJ21籽粒中α淀粉酶、β淀粉酶活性变化不显著,YD6籽粒中β淀粉酶活性在完熟期显著低于对照28.1%;WYJ21籽粒蔗糖含量在乳熟期高于对照11.5%,YD6籽粒中蔗糖含量在蜡熟期低于对照14.4%,WYJ21和YD6茎中蔗糖含量分别在蜡熟和乳熟期显著下降。FACE下两水稻品种茎中蔗糖合成酶(SS)活性变化自乳熟至完熟期呈现先降后升的趋势,且均在中后期达到显著水平,WYJ21在灌浆前期茎中磷酸蔗糖合成酶(SPS)活性显著增加,YD6茎中SPS活性在灌浆后期显著增加;FACE处理降低了两水稻茎中蛋白质含量,其中WYJ21茎中蛋白质含量在蜡熟期显著下降38.5%,YD6茎中蛋白质含量在蜡熟和完熟期分别下降33.9%和60.5%。CO_2、时期、品种对水稻茎中蔗糖含量、SS和SPS活性的影响达到显著水平;CO_2、时期、品种以及它们的交互作用显著影响直链和支链淀粉含量、α与β淀粉酶活性以及蛋白质含量。上述结果表明,不同类型水稻在不同灌浆时期对高浓度CO_2的响应程度不同,籼稻YD6的响应程度要大于粳稻WYJ21。

Synthesis and distribution of organic substances in different types of rice during filling stage under elevated atmospheric CO2 condition

Elevated atmospheric CO2 concentration(CO2])may enhance carbonhydrate content but decrease protein concentrations in plants. Here a field experiment was conducted to examine the effects of CO2 enrichment on synthesis and distribution of organic substances in two different types of rice, Wuyunjing 21(WYJ21, Japonica)and Yangdao6(YD6, Indica)under Free-air CO2 enrichment(FACE)con-ditions in China. Compared with the control, amylose and amylopectin content in grains of WYJ21 was increased slightly under CO2 enrich-ment, whereas the amylase content in YD6 grains significantly increased by 8.9%. Meanwhile, theβ-amylose activity in grains of YD6 un-der FACE was significantly decreased by 28.1%at post-filling stage, while no significant changes inα-amylose andβ-amylose were ob-served in WYJ21. The sucrose content in grains was 11.5%higher at milk stage in WYJ21, but 14.4%lower at ripening stage in YD6 than the control check, respectively. Meanwhile, the sucrose content in stems of WYJ21 and YD6 under FACE was significantly reduced at ripen-ing stage and milk stage, respectively. In addition, the sucrose synthetase(SS)activity of stems in both rice types was significantly increased at post-filling stage. FACE increased the sucrose phosphate synthase(SPS)activity of stems in WYJ21 at pre-filling stage and increased that of YD6 at post-filling stage. On the other hand, FACE decreased the protein content in stems of WYJ21 by 38.5%at ripening stage and by 33.9%and 60.5%in YD6 at ripening stage and full ripe stage, respectively. Statistical analysis showed that CO2, stages and cultivars sig-nificantly affected the sucrose content and SS and SPS activities in stems. CO2, stage, cultivar and/or their interactions significantly affect the amylose and amylopectin content,α-amylose andβ-amylose activity, and protein content. All these results demonstrated that different re-sponses were detected in different types of rice to elevated CO2] during the filling stage. Rice YD6 had greater CO2 responses to some extent than WYJ21.