PREFACE

Cell Research, 15(8) August 2005

Editor's Preface

Lu LIANG, M.D., Ph.D., Associate Editor-in-Chief, Cell Research

Federal Institute of Technology (ETH) Zurich, Institute of Plant Sciences, Plant Biochemistry & Physiology Group, Experimental Station Eschikon 33, CH-8315 Lindau, Switzerland.

E-Mail: lu.liang@ipw.biol.ethz.ch

In this special issue of Plant Cell Biology, we present research performed on model plants of Arabidopsis thaliana, tobacco, rice, Lotus japonicus, papaya, and orchid to address plant cellular signaling mechanisms and plant development.

The physiological function of Arabidopsis cAMP in response to pathogen infection is examined by Dr. Wei Hua WU and colleagues. They observed elevated cAMP level in Arabidopsis plants attacked by pathogenic fungi V. dahliae and plants injected with Verticillium toxins. Application of cAMP analogue 8-Br-AMP strongly induced the expression of pathogenesis-related protein 1 gene (PR1) and plant resistance to diseases in a salicylic acid (SA) dependent manner, thus placing cAMP upstream of SA in plant-defense signaling pathway. Involvement of OsWRKY03, an Arabidopsis AtWRKY29/22 homolog in rice defense signaling pathway is analyzed by Dr. Cheng Cai CHU and colleagues. They showed that in OsWRKY03 overexpression transgenic rice pathogenesis-related genes including OsNPR1, OsPR1b, ZB8 and POX22.3 were upregulated.

Ca²⁺ is an important biological signal for plant survival and development. Dr. Ying Tang LU and colleagues investigate the biochemical characteristics of a tobacco calcium-dependent protein kinase, NtCPK5, a new member of CPKs superfamily. They have shown that NtCPK5 is a plasma membrane localized protein and thus a putative sensor of Ca²⁺ singling. The N-terminal acylation sites of NtCPK5 are required for the protein localization. It will be interesting to see the functional importance of the membrane localization domain of NtCPK5 in plants in the future. The function of a plant specific G-box Interacting Protein 1 (GIP1) in enhancement of the DNA binding activity of transcription factor the G-box Binding factor (GBF) has been carefully characterized by Dr. Robert J. FERL and colleagues. They suggest that GIP1 is a potent nuclear chaperone through promoting protein folding and preventing protein aggregation.

Transcription factor LEAFY (LFY) in Arabidopsis plays an important role in flower development by transducing flower timing signals to downstream floral homeotic genes and is considered as one of the floral pathway integrators. Dr. Ray MING and colleagues cloned LFY homolog, PFL in papaya and proposed that PFL might play a similar role in papaya flower development as LFY did in Arabidopsis. Papaya is a plant unique in its three sex forms of male, female, and hermaphrodite. PFL transcript however does not show preferential expression in individual sex forms although the protein might express differently. By using cDNA-RAPD and cDNA suppression subtractive hybridization methods, Dr. Fure Chyi CHEN and colleagues have studied genes differentially expressed in flower buds of Phalaenopsis orchids from the wild type and the peloric mutant. Except of transcripts derived from cymbidium mosaic virus most of the transcripts differentially expressed have unknown function. Interestingly, a portion of transcripts enriched in wild type flower bud compared to that in peloric mutant contributes to genes involved in epigenetic regulation such as DNA methylation, chromatin remodeling, suggesting the involvement of epigenetic in orchid flower development. To study plant leave development, Dr. Da LUO and colleagues isolated Arabidopsis PHANTASTICA orthologs in Lotus japonicus, LjPHANa and LjPHANb and further analyzed the expression of LjPHANa and LjPHANb in mutants of reduced leaflets1 (rel1) and reduced leaflets3 (rel3) that showed altered adaxial-abaxial patterning.

Selection of quality crops to meet special needs is one of the research focuses for plant scientists. Dr. Jian Min WAN and colleagues by using SSR analysis have located the mutation in W3660, a rice mutant containing low glutelin and thus a good source for patients suffering from diabetes and kidney failure, to chromosome 2 between SSR2-001/SSR2-004 and RM1358. They further showed that GluB5 gene included in between SSR2-001/SSR2-004 was specifically reduced and thus identified a new rice mutant with low glutelin content. Dr. Ji Zeng JIA and colleagues have put efforts to analyze rye ω-secalin gene family in wheat 1BL/1RS translocation Lankao 906 that shows privilege in disease resistance but poor quality in bread making. They isolated a few ω-secalin genes and showed that these genes were actively expressed in developing seeds of Lankao 906, which might be the cause of the defects of Lankao 906 in bread processing. Tomato FER is responsible for iron uptake. Dr. Hong Qing Ling and colleagues have shown that Arabidopsis AtbHLH29 is fully functional in tomato and can complement tomato T3238fer mutant phenotype and thus a truly functional homolog of tomato FER.

Finally, Dr. Long MAO and colleagues have analyzed rice miR395 gene family from evolution level. They provide a nice model of miR395 gene duplications through evolution. Dr. Min NI gives a thorough review on light signaling pathways, which will surely be appreciated by the people in the field.