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Very long-chain fatty acids (VLCFAs) are essential precursors of membrane lipids, such as phospholipids and sphingolipids, cuticular waxes, suberins, and Brassica seed oils. The first step of VLCFA synthesis is mediated by 3-ketoacyl-CoA synthase (KCS), which catalyzes the condensation of a C2 unit from malonyl-CoA to acyl-CoA. In the present study, we investigated the role of KCS4 in pollen tube and root growth. KCS4 was predominantly expressed in shoot and root apical meristems, leaf veins, mature and germinated pollen grains, and developing embryos. The fluorescent signals of KCS4 fused with enhanced yellow fluorescent protein (KCS4:eYFP) were detected in the endoplasmic reticulum of tobacco epidermis. KCS4 disruption inhibited pollen tube elongation and root growth, whereas KCS4 promoter-driven KCS4 expression rescued the growth-retarded phenotype to wild type (WT) in kcs4 complementation lines. Root growth assay of WT and kcs4 lines treated with metazachlor and mefluidide, which are specific KCS inhibitors, and fatty acid analysis of their roots and seeds revealed that KCS4 is involved in the elongation of longer than C24 VLCFAs, which are essential for root and pollen tube growth.

The FCA gene, which is a component of the autonomous pathway that regulates flowering time, is an important example of how alternative processing can control plant development. We have previously characterized the FCA homolog, OsFCA, from a japonica-type rice cultivar and demonstrated that the polyadenylation site within intron 3, which can generate non-functional FCA-β, was conserved in rice. In this study, we detected five alternatively processed variants of OsFCA pre-mRNA, four of which were equivalents of FCA-α, -β, -γ, and -δ, in japonica-type Korean rice cultivars. The fifth transcript, referred to as OsFCA-ɛ, was similar to OsFCA-γ, except a part of the OsFCA intron 16 was retained. Unlike the FCA-γ protein, the OsFCA-γ protein contains a glycine-rich region at its N-terminus. We detected the OsFCA transcripts missing the region encoding the glycine-rich domain in the indica-type rice, but not in the japonica-type rice. We also found that the OsFCA-δ and OsFCA-ɛ transcripts were expressed in almost all of the different tissue types examined. Taken together, these results indicate that the alternative processing of the OsFCA transcript is more complex than its Arabidopsis counterpart.

Transcription factors (TFs) are the key regulators of gene expression and play crucial roles during plant growth and development. A novel TF family, containing one or two BSD domains in a variety of organisms ranging from prokaryotes to human, was newly identified by computational analysis. In this study, one Arabidopsis gene encoding the BSD domain, designated as AtBSD1, was characterized. The AtBSD1 transcript was expressed in all Arabidopsis tissues tested. The expression level of the AtBSD1 transcripts was not controlled by exogenous application of abiotic stresses and plant hormones. When the AtBSD1::GFP construct under the control of the CaMV35S promoter was introduced into onion epidermal cells, a GFP signal was detected in the nucleus. A transcriptional activity assay of the AtBSD1 protein in yeast revealed that the AtBSD1 protein functions as a transcriptional activator, and the N-terminal region (1–204 amino acids) of the AtBSD1 protein contains a transcriptional activation domain. These results suggest that Arabidopsis genes encoding the BSD1 domain might be classified as a novel transcription factor family.

Functional characterization of the fatty acid desaturase genes and seed-specific promoters is prerequisite for altering the unsaturated fatty acid content of oilseeds by genetic manipulation. The ω-6 fatty acid desaturase (FAD2) and ω-3 fatty acid desaturase (FAD3) catalyze extra-plastidial desaturation of oleic acid to linoleic acid and linoleic acid to linolenic acid, respectively. These are major constituents in seed storage oils. Here, we report the complementation of a perilla linoleic acid desaturase (PrFAD3) cDNA under the seed-specific sesame FAD2 (SeFAD2) promoter in the Arabidopsis fad3 mutant. PrFAD3 is functionally active and the SeFAD2 promoter is applicable for modifying fatty acid composition in developing seeds. Transient expression of the GUS gene under that promoter in the developing seeds and leaves of sesame, soybean, and corn via microprojectile bombardment indicated that the SeFAD2 promoter likely will be useful for altering the seed phenotypes of dicot and monocot crops.

Rice lipid transfer protein(LTP) genes belong to a complex multigene family and are differentially regulated. The organ specificity of expression for the different classes of riceLTP gene Subfamily I was investigated here.LTPC1 (Class I) was highly expressed in flowers and stems, whileLTPC2 (Class II) showed higher expression in leaves and stems.LTPC3 (Class III) showed higher expression in stems, whereas corresponding mRNA was barely detected in leaves. Treatment of 3-wk-old plants with ABA induced the expression ofLTPC1 andLTPC3 after 1 d. Expression of all threeLTP isoforms was induced in response to salicylic acid. Because some of these genes are reportedly induced by pathogens, we also investigated whether they might be responsive to infection byMagnaporthe grisea. Transcripts ofLTPC1 started to accumulate in the leaves at 8 h after incompatible inoculation, reaching a maximum level at 48 h. In contrast, the response was much slower and weaker after compatible inoculation.

To investigate the signal transduction pathway of cytokinin, we incubated seven-day-old maize leaves in distilled water with or without 0.1 mM benzylaminopurine (BAP). Several gene fragments were either induced or repressed by this exogenous treatment, and were then isolated by differential display-polymerase chain reaction (DD-PCR). One fragment (IBC4) had significant sequence homology with the N-terminal portion of the chloroplast ATP synthase IV subunit gene (atpl) of higher plants. After the stimulated expression of IBC4 by BAP was confirmed using orthern blot hybridization, we isolated the full-length gene, including 1BC4, from the chloroplast genome. We verified it as anatpl gene, using BLAST search analysis. Thisatpl gene, designated asZm- atpl (Zea mays- atpl), is 744 nucleotides long and encodes 247 amino adds. Its deduced amino acid sequence does not vary among maize cultivars, and it shares >90% identity with theatpl genes fromOryza sativa, Triticum aestivum, Nkotiana tabacum, Spinacia oleracea, andPisum sativum. We also confirmed, by northern blot analysis, that expression ofZm- atpl transcripts was significantly stimulated by the exogenous application of BAP.