Effect of mitochondrial genome rearrangement on respiratory activity, photosynthesis, photorespiration and energy status of MSC16 cucumber (Cucumis sativus) mutant

Abstract

The effects of changes in mitochondrial DNA in cucumber (Cucumis sativus L.) mosaic mutant (MSC16) on respiration, photosynthesis and photorespiration were analyzed under non-stressed conditions. Decreased respiratory capacity of complex I in MSC16 mitochondria was indicated by lower respiration rates of intact mitochondria with malate and by rotenone-inhibited NADH or malate oxidation in the presence of alamethicin. Moreover, blue native PAGE indicated decreased intensity of protein bands of respiratory chain complex I in MSC16 leaves. Concerning the redox state, complex I impairment could be compensated to some extent by increased external NADH dehydrogenases (ND(ex)NADH) and alternative oxidase (AOX) capacity, the latter presenting differential expression in the light and in the dark. Although MSC16 mitochondria have a higher AOX protein level and an increased capacity, the AOX activity measured in the dark conditions by oxygen discrimination technique is similar to that in wild-type (WT) plants. Photosynthesis induction by light followed different patterns in WT and MSC16, suggesting changes in feedback chloroplast DeltapH caused by different adenylate levels. At steady-state, net photosynthesis was only slightly impaired in MSC16 mutants, while photorespiration rate (PR) was significantly increased. This was the result of large decreases in both stomatal and mesophyll conductance to CO2, which resulted in a lower CO2 concentration in the chloroplasts. The observed changes on CO2 diffusion caused by mitochondrial mutations open a whole new view of interaction between organelle metabolism and whole tissue physiology. The sum of all the described changes in photosynthetic and respiratory metabolism resulted in a lower ATP availability and a slower plant growth.

Plasma membrane-generated ROS and their possible contribution to leaf cell growth of cucumber (Cucumis sativus) MSC16 mitochondrial mutant

“…In addition to earlier described effects of mitochondrial mutation on MSC16 leaf carbon and energy metabolism which may affect growth (Juszczuk et al 2007;Szal et al 2009Szal et al , 2010, our data indicate also the possible involvement of apoplastic ROS. ROS level in the apoplast is the result of the activities of plasma membrane-located NADPH oxidases (Low and Merida 1996;Lamb and Dixon 1997) and cell wall-located peroxidases (Wojtaszek 1997).…”

“…It was reported earlier (Malepszy et al 1996;Juszczuk et al 2007) that MSC16 mutant plants have a considerably slower growth rate and deformed leaves comparing to WT. Cross section of leaves showed that in the mesophyll tissue of MSC16 the area of one cell is often 50-100% greater than of comparable WT leaf cells (Fig.…”

“…The MSC16 line has marked phenotypic changes, including a slower growth rate and a leaf mosaic pattern with chlorotic patches (Malepszy et al 1996). The mitochondrial genome rearrangement in cucumber MSC16 results in a decreased leaf ATP concentration, changes in nucleotides distribution (Szal et al 2008) and changes in respiratory chain activity, including lower Complex I capacity, increased activities of external NADH dehydrogenases (NDex), higher alternative oxidase (AOX) capacity and protein level (Juszczuk et al 2007;Juszczuk and Rychter 2009). Cytochemical detection revealed an increased abundance of H 2 O 2 in the mitochondrial membrane and decreased H 2 O 2 content in the apoplast of mesophyll cells in MSC16 leaves (Szal et al 2009).…”

Complete Mitochondrial Complex I Deficiency Induces an Up-Regulation of Respiratory Fluxes That Is Abolished by Traces of Functional Complex I

“…In plants, several complex I mutants have been reported (Gutierres et al, 1999;Karpova and Newton, 1999;Brangeon et al, 2000;Perales et al, 2005;de Longevialle et al, 2007;Juszczuk et al, 2007;Meyer et al, 2009;Haïli et al, 2013). Most of these show delayed growth, but unlike in H. sapiens, the absence of complex I does not cause premature death, possibly due to the presence of bypasses for complex I.…”

Changes in the OXPHOS system in leaf and root mitochondria of Arabidopsis thaliana subjected to long-term sulphur deficiency

“…4a, c, d). Tobacco CMSII and A. thaliana frostbite1 mitochondrial mutants that lack Complex I, and cucumber MSC16 mutant with lower level of Complex I, display the compensation of Complex I by additional type II NAD(P)H dehydrogenases (Juszczuk et al 2007;Garmier et al 2008;Juszczuk and Rychter 2009;Podgórska et al 2015). The increased capacity of ND in/ex NADH in root mitochondria of S-deficient bean and A. thaliana and in Fe-deficient cucumber may be responsible for rapid adjustment of respiration during prolonged macro-or micronutrient deficiency (Vigani and Zocchi 2010;Juszczuk and Ostaszewska 2011;Ostaszewska et al 2014).…”