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Gu J.-W.,Zhengzhou University | Gu J.-W.,Shandong Academy of Agricultural Sciences | Liu J.,Shandong Academy of Agricultural Sciences | Xue Y.-J.,Shandong Academy of Agricultural Sciences | And 3 more authors.
Rice Science

Phytochrome family mainly senses red and far-red light to regulate a range of developmental processes throughout the life cycle of plants. Rice phytochrome gene family is composed of three members known as PHYA, PHYB and PHYC. It has been elucidated that individual phytochromes display both unique and overlapping roles in rice photomorphogenesis by characterization of all rice phytochrome mutants including single mutants, all combinations of double mutants as well as triple mutants. Based on the published data and authors' ongoing studies, current knowledge of rice phytochrome functions in regulating seedling de-etiolation, root gravitropic response and elongation, plant architecture, flowering time and fertility is summarized. Additionally, the important issues in the field of rice phytochromes are proposed. © 2011 China National Rice Research Institute. Source

Liu J.,Shandong Normal University | Liu J.,Shandong Academy of Agricultural Sciences | Zhang F.,CAS Institute of Genetics and Developmental Biology | Zhou J.,Shandong Academy of Agricultural Sciences | And 5 more authors.
Plant Molecular Biology

We report that phytochrome B (phyB) mutants exhibit improved drought tolerance compared to wild type (WT) rice (Oryza sativa L. cv. Nipponbare). To understand the underlying mechanism by which phyB regulates drought tolerance, we analyzed root growth and water loss from the leaves of phyB mutants. The root system showed no significant difference between the phyB mutants and WT, suggesting that improved drought tolerance has little relation to root growth. However, phyB mutants exhibited reduced total leaf area per plant, which was probably due to a reduction in the total number of cells per leaf caused by enhanced expression of Orysa;KRP1 and Orysa;KRP4 (encoding inhibitors of cyclin-dependent kinase complex activity) in the phyB mutants. In addition, the developed leaves of phyB mutants displayed larger epidermal cells than WT leaves, resulting in reduced stomatal density. phyB deficiency promoted the expression of both putative ERECTA family genes and EXPANSIN family genes involved in cell expansion in leaves, thus causing greater epidermal cell expansion in the phyB mutants. Reduced stomatal density resulted in reduced transpiration per unit leaf area in the phyB mutants. Considering all these findings, we propose that phyB deficiency causes both reduced total leaf area and reduced transpiration per unit leaf area, which explains the reduced water loss and improved drought tolerance of phyB mutants. © 2011 Springer Science+Business Media B.V. Source

Xie X.-Z.,Shandong Academy of Agricultural Sciences | Xie X.-Z.,Laboratory of Crop Genetic Improvement and Biotechnology | Xue Y.-J.,Shandong Academy of Agricultural Sciences | Xue Y.-J.,Shanxi Agricultural University | And 6 more authors.
Molecular Plant

Old leaves of wild-type rice plants (Oryza sativa L. cv. Nipponbare) are more resistant to blast fungus (Magnaporthe grisea) than new leaves. In contrast, both old and new leaves of the rice phytochrome triple mutant (phyAphyBphyC) are susceptible to blast fungus. We demonstrate that pathogenesis-related class 1 (PR1) proteins are rapidly and strongly induced during M. grisea infection and following exogenous jasmonate (JA) or salicylic acid (SA) exposure in the old leaves, but not in the new leaves of the wild-type. In contrast, the accumulation of PR1 proteins was significantly attenuated in old and new leaves of the phyAphyBphyC mutant. These results suggest that phytochromes are required for the induction of PR1 proteins in rice. Basal transcription levels of PR1a and PR1b were substantially higher in the wild-type as compared to the phyAphyBphyC mutant, suggesting that phytochromes also are required for basal expression of PR1 genes. Moreover, the transcript levels of genes known to function in SA-or JA-dependent defense pathways were regulated by leaf age and functional phytochromes. Taken together, our findings demonstrate that phytochromes are required in rice for age-related resistance to M. grisea and may indirectly increase PR1 gene expression by regulating SA-and JA-dependent defense pathways. © 2011 The Author. Source

Zhang C.,Shandong Academy of Agricultural Sciences | Zhang C.,Shandong University of Technology | Zhang F.,CAS Institute of Genetics and Developmental Biology | Zhou J.,Shandong Academy of Agricultural Sciences | And 7 more authors.
Plant Cell Reports

Tandem zinc finger proteins (TZFs) in plants are involved in gene regulation, developmental responses, and hormone-mediated environmental responses in Arabidopsis. However, little information about the functions of the TZF family in monocots has been reported. Here, we investigated a cytoplasmic TZF protein, OsTZF1, which is involved in photomorphogenesis and ABA responses in rice seedlings. The OsTZF1 gene was expressed at relatively high levels in leaves and shoots, although its transcripts were detected in various organs. Red light (R)-and far-red light (FR)-mediated repression of OsTZF1 gene expression was attributed to phytochrome B (phyB) and phytochrome C (phyC), respectively. In addition, OsTZF1 expression was regulated by salt, PEG, and ABA. Overexpression of OsTZF1 caused a long leaf sheath relative to wild type (WT) under R and FR, suggesting that OsTZF1 probably acts as a negative regulator of photomorphogenesis in rice seedlings. Moreover, ABA-induced growth inhibition of rice seedlings was marked in the OsTZF1-overexpression lines compared with WT, suggesting the positive regulation of OsTZF1 to ABA responses. Genome-wide expression analysis further revealed that OsTZF1 also functions in other hormone or stress responses. Our findings supply new evidence on the functions of monocot TZF proteins in phytochrome-mediated light and hormone responses. Key message OsTZF1 encodes a cytoplasm-localized tandem zinc finger protein and is regulated by both ABA and phytochrome-mediated light signaling. OsTZF1 functions in phytochrome-mediated light and ABA responses in rice. © 2012 Springer-Verlag. Source

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