Involvement of gibberellins in expression of a cysteine proteinase (SH-EP) in cotyledons of Vigna mungo seedlings.

The expression of a papain-type proteinase, designated SH-EP, in cotyledons of Vigna mungo seedlings has been shown to require some factors in the embryonic axes. Gibberellin A1 (GA(1)) and GA(20) were identified by GC-MS in embryonic axes of V. mungo seedlings. The level of accumulation of SH-EP in cotyledons of V. mungo seedlings was greatly reduced by treatment of the seeds with uniconazole-P, an inhibitor for GA biosynthesis. The reduced level of accumulation of SH-EP in cotyledons by uniconazole-P was recovered by exogenous application of GA(1) and GA(20) to the seedlings.     

Notes on the boletes of Japan 1. Four new species of the genus Boletus from central Honshu,Japan

Four new species of Boletus are fully described and illustrated from central Honshu, Japan: (1) B. panniformis (Section Calopodes) produces a typically felted and scabrous pileus, bitter flesh, a finely reticulate, red stipe, and occurs in subalpine, coniferous forests; (2) B. ventricosus (Section Appendiculati) forms a usually ventricose or subbulbous stipe, yellow to greyish orange, extremely short tubes, often pluriseptate, broadly clavate to doliform caulocystidia, and occurs in lowland, mixed forests; (3) B. cepaeodoratus (Section Appendiculati) possesses a pinkish red pileus, a usually finely reticulate stipe, relatively short tubes, and occurs in lowland, mixed forest; (4) B. viscidipellis (Section Luridi) yields a hairy, viscid pileus, intensely cyanescent flesh, and occurs in lowland, mixed forests.     

Control of ciliary orientation through cAMP-dependent phosphorylation of axonemal proteins in paramecium caudatum

Ciliary reorientations in response to cAMP do not take place after a brief digestion with trypsin in ciliated cortical sheets from Triton-glycerol-extracted Paramecium. In this study, we examined the effects of tryptic digestion on the cAMP-dependent phosphorylation of axonemal proteins to clarify the relationship between phosphorylation and ciliary reorientation. As reported for Paramecium tetraurelia, cAMP stimulated phosphorylations of the 29 kDa and 65 kDa axonemal polypeptides also in Paramecium caudatum. After a brief digestion of axonemes by trypsin, none of the cAMP-dependent phosphorylations occurred. On the other hand, the 29 kDa polypeptide still remained to be labeled after a brief digestion of axonemes that had previously been labeled with (32)P in the presence of cAMP, which indicates that this brief digestion breaks down endogenous cAMP-dependent protein kinases but not phosphorylated proteins. This must be the reason that trypsin-treated cilia on the sheets cannot reorient towards the posterior part of the cell. Our results indicate that cAMP regulates not only the beat frequency but also the ciliary orientation via phosphorylation of dynein subunits in Paramecium.     

Development of Endopeptidase Activity in Cotyledons of Vigna mungo Seedlings: Effects of Exogenously Applied End-Products and Plant Hormones

The development of endopeptidase activity in cotyledons of Vignamungo seedlings was examined after application of exogenousamino acids, sugars and plant hormones. The endopeptidase activityin the cotyledons fell when germinating seeds were allowed toabsorb a solution of amino acids at high concentrations, andit was postulated that this effect might have been caused inpart by osmotic stress and in part by end-product repression.Protein immunoblotting with an antiserum against SH-EP, themajor cysteine endopeptidase occurring in the cotyledons, showedthat sugars and amino acids at high concentrations also delayedthe post-translational processing of SH-EP intermediates. Endopeptidaseactivity equivalent to nearly twice that in controls was observedwhen GA₃ was applied at 10 to 100 µM to cotyledons thathad been detached from the embryonic axis. In addition, naphthaleneaceticacid at 1 to 100 µM, kinetin at 1 to 10 µM and jasmonicacid at 1 to 10 µM also increased the activity to a limitedextent. Results of pulse-chase experiments suggested that theeffect of GA₁ on the endopeptidase activity in the detachedcotyledons was attributable to suppression of the degradationof the enzyme. Protein immunoblotting revealed the presenceof 34-kOa and 35-kDa intermediates of SH-EP in addition to previouslyreported 36-kDa and 43-kDa intermediates. (Received June 26, 1995; Accepted October 16, 1995)     

Isolation of norbergenin from Saxifraga stolonifera

Norbergenin, a C-glucoside, was isolated from Saxifraga stolonifera and its structure assigned as 2β-d-glucopyranosylgallic acid °-lactone.     

Studies onC-glycosides in higher plants

The intracellular distribution of bergenin and related compounds was examined in mesophyll cell protoplasts ofSaxifraga stolonifera. Vacuoles ofS. stolonifera leaves contained 46% to 55% of the bergenin and related compounds. It was also noted that 50% of the gallic acid was located in chloroplasts. From the results obtained it was concluded that bergenin and norbergenin were primarily localized in the vacuoles, but gallic acid was distributed equally in vacuoles and chloroplasts.     

Synthesis and Turnover of {alpha}-Amylase in Cotyledons of Germinating Vigna mungo Seeds: Effects of Exogenously Applied End-Products and Plant Hormones

Pulse-chase experiments indicated that the higher levels ofa-amylase in detached and incubated cotyledons of Vigna mungothan those in cotyledons attached to the embryonic axis weredue to both faster synthesis and slower degradation of the enzymein the detached cotyledons than in the attached cotyledons.Levels of a-amylase in the cotyledons were examined in termsof possible effects of end-products and the effects of exogenouslyapplied plant hormones and growth regulators. Levels of a-amylaseactivity and content were reduced by high concentrations ofglucose and sucrose, and it is suggested that this effect wascaused mostly by osmotic stress and partly by end-product repression.The level of a-amylase was nearly twice that in controls after1 to 10µM GA₃ had been applied to the cotyledons. In addition,0.1 mM kinetin, 0.1 mM 2,4-D and 0.1 to 0.S mM naphthaleneaceticacid also increased the level by 34% to 66% as compared to thecontrol. ABA and uniconazole both prevented the synthesis ofa-amylase. (Received July 4, 1994; Accepted November 14, 1994)     

Studies onC-glycosides in higher plants

The biosynthesis of bergenin and arbutin in the organs ofSaxifraga stolonifera has been studied by tracer techniques. Among the organs tested, the leaves showed the highest incorporation of label fromd-glucose-U-¹⁴C into bergenin and arbutin under continuous light, although every organ is more or less able to synthesize both glucosides. The incorporation rate into bergenin was higher in the young leaves, whereas the synthesis of arbutin became active in the mature leaves. The fact that the addition of unlabeled gallic acid enhanced the incorporation of label into bergenin suggests that gallic acid may be a likely glucosyl acceptor in bergenin biosynthesis.     

Studies onC-glycosides in higher plants

Sixteen species including 1 variety and 1 form from 9 genera belonging to Saxifragaceae were examined for bergenin content. Bergenin was found only in Saxifragoideae, no bergenin being present in Hydrangeoideae and Ribesioideae. The amount of bergenin was shown to range from 0.1 to 1 mg per g fresh weight, depending on the organs tested, and the highest amounts were usually observed in rhizomes. The contents of bergenin in a leaf ofSaxifraga stolonifera increased continuously with the leaf expansion, while the level on a fresh weight basis remained constant during the leaf growth.