Drought-Stimulated Activity of Plasma Membrane Nicotinamide Adenine Dinucleotide Phosphate Oxidase and Its Catalytic Properties in Rice

The activity of plasma membrane （PM） nicotinamide adenine dinucleotide phosphate （NADPH） oxidase and its catalytic properties in rice was investigated under drought stress conditions. Drought stress led to decreased leaf relative water content （RWC） and, as a result of drought-induced oxidative stress, the activities of antioxidant enzymes increased significantly. More interestingly, the intensity of applied water stress was correlated with increased production of H2O2 and O2^- and elevated activity of PM NADPH oxidase, a key enzyme of reactive oxygen species generation in plants. Histochemical analyses also revealed increased H2O2 and O2^- production in drought-stressed leaves. Application of diphenylene iodonium （DPI）, an inhibitor of PM NADPH oxidase, did not alleviate drought-induced production of H2O2 and O2^-. Catalysis experiments indicated that the rice PM NADPH oxidase was partially fiavin-dependent. The pH and temperature optima for this enzyme were 9.8 and 40 ℃, respectively. In addition, drought stress enhanced the activity under alkaline pH and high temperature conditions. These results suggest that a complex regulatory mechanism, associated with the NADPH oxidase-H2O2 system, is involved in the response of rice to drought stress.

水稻穗内不同粒位间的矿质营养变化差异及其与籽粒植酸含量的关系(英文)

研究目的:阐明水稻穗内不同粒位间的主要矿质营养元素和植酸含量差异、粒位分布特点及其与品种穗型间的联系。创新要点:将水稻品种的穗型变化与稻米营养品质结合起来,从水稻穗粒结构角度,对同一稻穗内不同籽粒间的主要矿质营养元素与植酸含量差异、粒位分布特点及其与水稻品种穗型间的相互关系进行了较系统的探讨分析。研究方法:以典型的直立穗型和弯穗型粳稻品种为材料,通过对两类水稻品种在相同栽培条件下籽粒矿质营养元素和植酸含量的测定分析,并依据水稻籽粒在稻穗上的着生部位,将同一稻穗内的不同籽粒划分为六个粒位,比较分析了两类品种同一稻穗内不同部位间矿质营养元素和植酸含量的差异变化及其粒位分布特点。重要结论:水稻穗型虽然与品种间的籽粒矿质营养元素和植酸含量高低没有直接关系,但对其穗内不同籽粒间的主要矿质营养元素和植酸含量存在着较大影响;与稻穗中下部的弱势粒相比,同一稻穗内着生在稻穗上中部的强势粒通常具有相对较高的锌、铁矿质元素含量,而籽粒植酸含量和植酸/锌(铁)摩尔比则有所降低,稻米营养品质也相对较好;不同矿质营养元素相比,粒位效应对铁矿质营养的影响作用要略大于对钙和锌营养元素含量。