蛋白质N-糖基化在拟南芥生长周期中的变化规律及去糖基化对根发育的影响

蛋白质N-糖基化修饰在植物生长发育中发挥重要作用。为探究蛋白质N-糖基化在拟南芥(Arabidopsis thaliana)整个生长周期中的变化规律以及去N-糖基化对拟南芥生根发育的影响,通过N-糖链酶解和HPLC与MALDI-TOF-MS分析解析了不同生长时期的拟南芥Col-0植株的N-糖链组成(结构和含量)变化。以...     

Growth and Development, and Auxin Polar Transport in Higher Plants under Microgravity Conditions in Space: BRIC-AUX on STS-95 Space Experiment

Received 13 September 1999/ Accepted in revised form 12 October 1999     

Comparison of Leaf Plastochron Index and Allometric Analyses of Tooth Development in Arabidopsis thaliana

Abstract Two methods of analyses were used to investigate tooth development in serrate (se) mutant and wild-type Columbia-1 (Col-1) Arabidopsis thaliana leaves. There were almost twice as many teeth with deeper sinuses and two orders of toothing on the margins of serrate compared with Columbia-1 leaves. The main objective of this study was to test three hypotheses relative to the source of polymorphism in tooth development: (i) Teeth share similar growth rates and initial sizes, but the deeper teeth are initiated earlier in leaf development. (ii) Teeth share similar timing of initiation and growth rates, but the deeper teeth have a larger initial size. (iii) Teeth share similar timing of initiation and initial sizes, but the deeper teeth have a faster growth rate. Leaf plastochron index (LPI) was used as the time variable for leaf development. Results showed teeth in se were initiated at −27 LPI, 15 plastochrons earlier than those of Col-1. Serrate leaf expansion was biphasic, with the early phase expanding at half the relative plastochron rate of the later phase, which equaled the constant relative expansion rate of Col-1 leaves. Allometric analyses of tooth development obscured the interactions between time of tooth and leaf initiation and the early phase of leaf expansion characteristic of serrate leaves and teeth. Timing of developmental events that allometric analysis obscured can be readily detected with the LPI as a developmental index. Received 25 January 2000; accepted 17 March 2000     

Arabidopsis thaliana plastidial methionine sulfoxide reductases B,MSRBs, account for most leaf peptide MSR activity and are essential for growth under environmental constraints through a role in the preservation of photosystem antennae

Methionine oxidation to methionine sulfoxide (MetSO) is reversed by two types of methionine sulfoxide reductases (MSRs), A and B, specific to MetSO S‐ and R‐diastereomers, respectively. Two MSRB isoforms, MSRB1 and MSRB2, are present in chloroplasts of Arabidopsis thaliana. To assess their physiological role, we characterized Arabidopsis mutants knockout for the expression of MSRB1, MSRB2 or both genes. Measurements of MSR activity in leaf extracts revealed that the two plastidial MSRB enzymes account for the major part of leaf peptide MSR capacity. Under standard conditions of light and temperature, plants lacking one or both plastidial MSRBs do not exhibit any phenotype, regarding growth and development. In contrast, we observed that the concomitant absence of both proteins results in a reduced growth for plants cultivated under high light or low temperature. In contrast, double mutant lines restored for MSRB2 expression display no phenotype. Under environmental constraints, the MetSO level in leaf proteins is higher in plants lacking both plastidial MSRBs than in Wt plants. The absence of plastidial MSRBs is associated with an increased chlorophyll a/b ratio, a reduced content of Lhca1 and Lhcb1 proteins and an impaired photosynthetic performance. Finally, we show that MSRBs are able to use as substrates, oxidized cpSRP43 and cpSRP54, the two main components involved in the targeting of Lhc proteins to the thylakoids. We propose that plastidial MSRBs fulfil an essential function in maintaining vegetative growth of plants during environmental constraints, through a role in the preservation of photosynthetic antennae.     

Effects of Natural and Synthetic Auxins on the Gravitropic Growth Habit of Roots in Two Auxin-Resistant Mutants of Arabidopsis, axr1 and axr4: Evidence for Defects in the Auxin Influx Mechanism of axr4

Arabidopsis thaliana, axr4 , was restored by the addition of 30–300 nM 1-naphthaleneacetic acid (NAA) to the growth medium. Neither indole-3-acetic acid (IAA) nor 2,4-dichlorophenoxyacetic acid (2,4-D) showed such an effect. Growth of axr4 roots was resistant to IAA and 2,4-D, but not at all to NAA. The differential effects of the three auxins suggest that the defects of axr4 result from a lower auxin influx into its cells. The partially agravitropic growth habit of axr1 roots, which was less severe than that of axr4 roots, was only slightly affected by the three auxins in the growth medium at concentrations up to 300 nM; growth of axr1 roots was resistant to all three of the auxins. These results suggest that the lesion of axr1 mutants is different from that of axr4. Received 9 June 1999/ Accepted in revised form 16 August 1999     

不同通气条件下硫代硫酸银对马铃薯试管苗生长和抗氧化酶活性的影响

以二倍体马铃薯试管苗为试材,研究不同通气条件下乙烯生理拮抗剂硫代硫酸银(STS)对试管苗生长和抗氧化酶活性影响的结果表明:通气条件下培养的试管苗茎高降低,叶面积和叶绿素含量增加,培养基中附加STS的效果更为明显,无论在通气还是不通气条件下,培养基中加STS的试管苗茎高降低,叶面积和叶绿素含量增加,均达极显著水平.通气和培养基中加STS的试管苗中丙二醛(MDA)含量下降。通气条件下超氧化物歧化酶(要SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性提高;培养基中加STS的试管苗中SOD活性提高,POD和CAT活性下降。