Identification of Hinesol as a Chlorophyll-Preserving Substance

A chlorophyll-preserving substance was isolated from rhizomesof Atractylodes lancea DC. and identified as (—)-hinesolon the basis of spectroscopic data. Hinesol at more than 0.22DIH was effective for preserving chlorophyll of oat (Avena sativaL. cv Victory) leaves in the dark with 40 to 50% of the initialchlorophyll content being retained at 2.2 mM. However, hinesolstimulated chlorophyll loss with light exposure and at 4.5 mMcaused complete bleaching when measured 4 days after treatment. ¹Dedicated to the memory of the late Professor Joji Ashida. (Received December 9, 1982; Accepted April 22, 1983)     

Monoclonal Antibodies Specific for Non-Derivatized Gibberellins I. Preparation of Monoclonal Antibodies against GA4 and Their Use in Immunoaffinity Column Chromatography

Cell lines producing monoclonal antibodies specific for non-derivatizedgibberellins (GAs) were prepared from spleen cells of a mouseimmunized with an immunogen that carried 16-substituted GA₄as a hapten. The conditions for association and dissociationof antibody-hapten complexes were examined to determine themost effective procedure for immunoaffinity chromatography.The final procedure adopted was proven to be very effectiveby its application to the analysis of GAs in the anthers ofrice and immature seeds of Phaseolus vulgaris ⁴Present address: Department of Agricultural Chemistry, UtsunomiyaUniversity, Mine-machi 350, Utsunomiya, 321 Japan (Received August 8, 1990; Accepted March 7, 1991)     

Eu-Chlorella large subunit rDNA sequences and group I introns in ribosomal DNA of the paramecian symbiotic alga NC64A

Although the examination of large subunit ribosomal RNA genes (LSU rDNA) is advanced in phylogenetic studies, no corresponding sequence data from trebouxiophytes have been published, with the exception of ‘Chlorella’ellipsoidea Gerneck. We determined the LSU rDNA sequence of Chlorella vulgaris Beijerinck and of the symbiotic alga of green paramecium, Chlorella sp. NC64A. A total of 59 nucleotide substitutions were found in the LSU rDNA of the two species, which are disproportionately distributed. Primarily, 65% of the substitutions were encountered in the first 800 bp of the alignment. This segment apparently has evolved eight times faster than the complete SSU rDNA sequence, making it a good candidate for a phylogenetic marker and giving a resolution level intermediate between small subunit (SSU) rDNA and internal transcribed spacers. Green algae are known as a group I intron‐rich group along with rhodophytes and fungi. NC64A is particularly rich in the introns; five introns were newly identified from the LSU rDNA sequence, which we named Cnc.L200, Cnc.L1688, Cnc.L1926, Cnc.L2184 and Cnc.L2437, following the insertion positions. In the present study we analyzed these introns with three others (Cnc.S943, Cnc.S1367 and Cnc.S1512) that had already been found in NC64A SSU rDNA. Secondary structure modeling placed these introns in the group I intron family, with four introns belonging to subgroup C1 and the other four introns belonging to subgroup E. Five of the intron insertion positions are unique to the paramecian symbiont, which may indicate relatively recent events of intron infections that includes transpositions. Intron phylogeny showed unprecedented relationships; four Cnc. IC1 introns made a clade with some green algal introns with insertions at nine different positions, whereas four Cnc. IE introns made a clade with the S651 intron (Chlorella sp. AN 1–3), which lay as a sister to the S516 insertion position subfamily.     

Isolation of two new gibberellins from immature seeds of Canavalia

Summary Two new gibberellins, Canavalia gibberellin-I (CG-I) and Canavalia gebberellin-II (CG-II), were isolated from immature seeds of sword bean, Canavalia gladiata DC. The molecular formulas C₁₉H₂₂O₇ and C₁₉H₂₂O₆, were assigned to CG-I and CG-II, respectively, on the basis of high resolution mass, infrared and NMR spectra. The growth-promoting effects of CG-I and CG-II on dwarf maize mutants d ₁ and d ₅, rice seedlings and dwarf peas, Progress No. 5, are reported.     

Changes in Endogenous Ribosyl-trans-zeatin and IAA Levels in Relation to the Proliferation of Tobacco Crown Gall Cells

Changes in the contents of major endogenous plant hormones intobacco crown gall cells, namely IAA and ribosyl-trans-zeatin,during cell growth were examined using HPLC and ¹⁴C-labeledplant hormones. The content of IAA was high at the early logarithmicstage, while that of ribosyl-trans-zeatin was high at the middlelogarithmic stage. This suggests that cell growth is affectedfirst by IAA, then by ribosyl-trans-zeatin. ³ Present address: Department of Agricultural Chemistry, TottoriUniversity, Koyama, Tottori 680, Japan (Received July 13, 1981; Accepted September 11, 1981)     

The MIXTA-like Transcription factor MYB16 is a major regulator of cuticle formation in vegetative organs

Cuticle secreted on the surface of the epidermis of aerial organs protects plants from the external environment. We recently found that Arabidopsis MIXTA-like R2R3-MYB family members MYB16 and MYB106 regulate cuticle formation in reproductive organs and trichomes. However, the artificial miRNA (amiRNA)-mediated knockdown plants showed no clear phenotypic abnormality in vegetative tissues. In this study, we used RNA interference (RNAi) targeting MYB16 to produce plants with reduced expression of both MYB16 and MYB106. The rosette leaves of RNAi plants showed more severe permeable cuticle phenotypes than the myb106 mutants expressing the MYB16 amiRNA in the previous study. The RNAi plants also showed reduced expression of cuticle biosynthesis genes LACERATA and ECERIFERUM1. By contrast, expression of a gain-of-function MYB16 construct induced over-accumulation of waxy substances on leaves. These results suggest that MYB16 functions as a major regulator of cuticle formation in vegetative organs, in addition to its effect in reproductive organs and trichomes.