NOA1 Functions in a Temperature-Dependent Manner to Regulate Chlorophyll Biosynthesis and Rubisco Formation in Rice

Abstract

NITRIC OXIDE-ASSOCIATED1 (NOA1) encodes a circularly permuted GTPase (cGTPase) known to be essential for ribosome assembly in plants. While the reduced chlorophyll and Rubisco phenotypes were formerly noticed in both NOA1-supressed rice and Arabidopsis, a detailed insight is still necessary. In this study, by using RNAi transgenic rice, we further demonstrate that NOA1 functions in a temperature-dependent manner to regulate chlorophyll and Rubisco levels. When plants were grown at 30°C, the chlorophyll and Rubisco levels in OsNOA1-silenced plants were only slightly lower than those in WT. However, at 22°C, the silenced plants accumulated far less chlorophyll and Rubisco than WT. It was further revealed that the regulation of chlorophyll and Rubisco occurs at the anabolic level. Etiolated WT seedlings restored chlorophyll and Rubisco accumulations readily once returned to light, at either 30°C or 15°C. Etiolated OsNOA1-silenced plants accumulated chlorophyll and Rubisco to normal levels only at 30°C, and lost this ability at low temperature. On the other hand, de-etiolated OsNOA1-silenced seedlings maintained similar levels of chlorophyll and Rubisco as WT, even after being shifted to 15°C for various times. Further expression analyses identified several candidate genes, including OsPorA (NADPH: protochlorophyllide oxidoreductase A), OsrbcL (Rubisco large subunit), OsRALyase (Ribosomal RNA apurinic site specific lyase) and OsPuf4 (RNA-binding protein of the Puf family), which may be involved in OsNOA1-regulated chlorophyll biosynthesis and Rubisco formation. Overall, our results suggest OsNOA1 functions in a temperature-dependent manner to regulate chlorophyll biosynthesis, Rubisco formation and plastid development in rice.

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“…The noe1 mutant accumulated more NO than its wild-type plant [16]. On the contrary, the noa1 mutant with defect in NO synthesis-associated protein1 (NOA1) reduced NO biosynthesis [15]. Genetic mutants with altered endogenous NO levels provide a powerful tool for dissecting the physiological function of NO in plants [9,17].…”

“…Rice seeds (Oryza sativa L.) were first sterilized in 5% sodium hypochlorite solution for 15 min, followed by rinsing thoroughly with sterilized water and germinated on moist filter paper at 35 • C for 48 h. The germinated seeds were transferred to a hydroponic culture containing Kimura B nutrient solution as described previously [15]. Seedlings were grown in an environmentally-controlled growth chamber with a 14 h/27 • C day and a 10 h/25 • C night regime, a light intensity of 400 mol m −2 s −1 photosynthetically active radiation, and relative humidity of about 70%.…”

“…The NOE1 mutant obtained from a large T-DNA-tagged population by genetic screening accumulated more NO than its wild-type plants [16]. The noa1 mutant with defect in NO synthesis-associated protein1 (NOA1) was generated via RNA interference [15]. The reduced NO production has been observed in noa1 mutant plants [16,17].…”

“…Biomass was measured after drying at 70 • C for 48 h and was recorded by weighing individual seedling. Total chlorophyll (Chl) content in rice shoot was determined according to the method of Yang et al [15].…”

Effects of changes in micro-weather conditions on structural features, total protein and carbohydrate content in leaves of the Atlantic rain forest tree golden trumpet (Tabebuia chrysotricha)

“…Low daytime temperature may inhibit photosynthesis (Pyl et al, 2012), once it can significantly affect Rubisco content, whereas, changes in light irradiance have been shown not to significantly affect it (Yang et al, 2011). Although exposure of plants such as rice to cold temperatures has been shown to reduce Rubisco synthesis (Hahn and Walbot, 1989), in plant shrub as Aucuba japonica, Rubisco content is increased from summer to the highest values in winter and/or early spring (Muller et al, 2011).…”