Wiciarz Monika, Gubernator Beata, Kruk Jerzy, Niewiadomska Ewa
Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Kraków, Poland.
Physiol Plant. 2015 Mar;153(3):467-76. doi: 10.1111/ppl.12248. Epub 2014 Aug 5.
In order to find some basis of salinity resistance in the chloroplastic metabolism, a halophytic Thellungiella salsuginea was compared with glycophytic Arabidopsis thaliana. In control T.s. plants the increased ratios of chlorophyll a/b and of fluorescence emission at 77 K (F730 /F685 ) were documented, in comparison to A.t.. This was accompanied by a higher YII and lower NPQ (non-photochemical quenching) values, and by a more active PSI (photosystem I). Another prominent feature of the photosynthetic electron transport (PET) in T.s. was the intensive production of H2 O2 from PQ (plastoquinone) pool. Salinity treatment (0.15 and 0.30 M NaCl for A.t. and T.s., respectively) led to a decrease in ratios of chl a/b and F730 /F685 . In A.t., a salinity-driven enhancement of YII and NPQ was found, in association with the stimulation of H2 O2 production from PQ pool. In contrast, in salinity-treated T.s., these variables were similar as in controls. The intensive H2 O2 generation was accompanied by a high activity of PTOX (plastid terminal oxidase), whilst inhibition of this enzyme led to an increased H2 O2 formation. It is hypothesized, that the intensive H2 O2 generation from PQ pool might be an important element of stress preparedness in Thellungiella plants. In control T.s. plants, a higher activation state of carboxylase ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) was also documented in concert with the attachment of Rubisco activase (RCA) to the thylakoid membranes. It is supposed, that a closer contact of RCA with PSI in T.s. enables a more efficient Rubisco activation than in A.t.
为了探寻叶绿体代谢中耐盐性的某些依据,将盐生植物盐芥与甜土植物拟南芥进行了比较。与拟南芥相比,在对照盐芥植株中,叶绿素a/b比值以及77K时的荧光发射比值(F730/F685)有所增加。这伴随着更高的YII值和更低的NPQ(非光化学猝灭)值,以及更活跃的PSI(光系统I)。盐芥光合电子传递(PET)的另一个显著特征是从质体醌(PQ)库中大量产生H2O2。盐处理(拟南芥和盐芥分别用0.15M和0.30M NaCl)导致chl a/b和F730/F685比值下降。在拟南芥中,发现盐胁迫驱动YII和NPQ增强,同时伴随着从PQ库中产生H2O2的刺激。相反,在盐处理的盐芥中,这些变量与对照相似。大量H2O2的产生伴随着质体末端氧化酶(PTOX)的高活性,而抑制该酶会导致H2O2形成增加。据推测,从PQ库中大量产生H2O2可能是盐芥植物应激准备的一个重要因素。在对照盐芥植株中,还记录到1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco,EC 4.1.1.39)羧化酶的更高活化状态,这与Rubisco活化酶(RCA)附着在类囊体膜上有关。据推测,盐芥中RCA与PSI的更紧密接触使得Rubisco活化比拟南芥更有效。