Chlorophyll (Chl) b is a ubiquitous accessory pigment in land plants, green algae, and prochlorophytes. This pigment is synthesized from Chl a by chlorophyllide a oxygenase and plays a key role in adaptation to various environments. This study characterizes a rice mutant, pale green leaf (pgl), and isolates the gene PGL by using a map-based cloning approach. PGL, encoding chlorophyllide a oxygenase 1, is mainly expressed in the chlorenchyma and activated in the light-dependent Chl synthesis process. Compared with wild-type plants, pgl exhibits a lower Chl content with a reduced and disorderly thylakoid ultrastructure, which decreases the photosynthesis rate and results in reduced grain yield and quality. In addition, pgl exhibits premature senescence in both natural and dark-induced conditions and more severe Chl degradation and reactive oxygen species accumulation than does the wild-type. Moreover, pgl is sensitive to heat stress.
Chilling stress is one of the main abiotic factors affecting rice growth and yield. In rice, chlorophyllide oxygenase encoded by is responsible for converting chlorophyllide to chlorophyllide , playing a crucial role in photosynthesis and thus rice growth. However, little is known about the function of in chilling stress responses.
Unlabelled: Chlorophyll is synthesized from chlorophyllide , catalyzed by chlorophyllide oxygenase (). To examine whether reduced chlorophyll content regulates chlorophyll (Chl) synthesis and photosynthesis, we raised transgenic tobacco plants with antisense expression, which had lower chlorophyll content and, thus, higher Chl / ratio. Further, these plants had (i) lower chlorophyll and total Chl content, whether they were grown under low or high light; (ii) decreased steady-state levels of chlorophyll biosynthetic intermediates, due, perhaps, to a feedback-controlled reduction in enzyme expressions/activities; (iii) reduced electron transport rates in their intact leaves, and reduced Photosystem (PS) I, PS II and whole chain electron transport activities in their isolated thylakoids; (iv) decreased carbon assimilation in plants grown under low or high light.
Department of Horticultural Sciences, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, USA.
Anthocyanins are a class of natural pigments that accumulate transiently or permanently in plant tissues, often in response to abiotic and biotic stresses. They play a photoprotective role by attenuating the irradiance incident on the photochemical apparatus and quenching oxyradicals through their powerful anti-oxidative function. The objective of the current study is to understand the impact of introducing mybA1 () in 'Hamlin' sweet orange trees on various aspects, including photosynthetic performance, pigment composition, and gene expression related to photosynthesis and light harvesting.
The chlorophyllide a oxygenase (CAO) plays a crucial role in the biosynthesis of chlorophyll b (Chl b). In the moss Physcomitrium patens (P. patens), two distinct gene copies, PpCAO1 and PpCAO2, are present.
