EFFECTS OF NUCLEIC ACID- AND PROTEIN-ANTIMETABOLITES ON FROND AND FLOWER PRODUCTION IN LEMNA GIBBA G3

Frond and flower production in a long-day duckweed, Lemna gibbaG3, grown under continuous illumination in the presence or absenceof varied concentrations of 5-fluorodeoxyuridine, 5-fluorouracill,2- thiouracil, 8-azaguanine or ethionine and/or correspondingmetabolite, i.e., thymidine, orotic acid, uracil, guanine ormethionine, have been investigated. From the results obtained,the presumptive flows of vegetative and reproductive informationfrom gene DNA to protein have been associated with frond andflower initiation in the duckweed meristem, respectively. (Received September 3, 1964; )     

EFFECTS OF EXOGENOUS AMINO ACIDS ON THE FLOWER AND FROND PRODUCTION IN DUCKWEED, LEMNA GIBBA G3

1. Twenty usual amino acids examined were shown to be dividedinto two groups with respect to their actions on the flowerformation (A) and frond multiplication (B) in a long-day duckweed,L. gibba G3. Amino acids of the first group (e.g., arginine)inhibited A without preventing B, and those of the second group(e.g., lysine) inhibited both A and B. The inhibition of flowerformation was always the greatest when amino acid was appliedat the induction period. 2. The floral inhibition by arginine applied at the inductionperiod was partially or wholly reversed by the simultaneousaddition of other amino acid (especially lysine) or by one additionallong day. The inhibitions by lysine, however, were not reversedby arginine. 3. It was discussed that the terminal step(s) of photoperiodicinduction process might depend largely on the relative in vivoconcentrations of amino acids. (Received January 28, 1964; )     

多胺与激动素对稀脉浮萍离体叶状体衰老的影响

多胺与ＫＴ 都可抑制暗诱导衰老的稀脉浮萍（Ｌｅｍ ｎａ ａｅｑｕｉｎｏｃｔｉａｌｉｓ）离体叶状体的叶绿素损失,且多胺的作用大于ＫＴ。ＫＴ 还显著抑制蛋白质的损失与蛋白酶活性的上升,而多胺对此却无大的影响。０．０５ ｍ ｍ ｏｌ／Ｌ的甲基乙二醛二脒基－腙（ＭＧＢＧ）轻微促进叶绿素和蛋白质的损失。０．０５ ｍ ｍ ｏｌ／Ｌ的ＫＴ 可抑制衰老过程中腐胺（Ｐｕｔ）的上升和亚精胺（Ｓｐｄ）的下降,而对精胺（Ｓｐｍ ）无明显影响。在稀脉浮萍中,精氨酸脱羧酶（ＡＤＣ）活性占优势。ＫＴ 可轻微促进ＡＤＣ 活性,而对鸟氨酸脱羧酶（ＯＤＣ）和Ｓ－腺苷甲硫氨酸脱羧酶（ＳＡＭＤＣ）活性无显著影响。讨论了多胺与细胞分裂素在抑制植物叶片衰老过程中作用途径的可能关系     

LIGHT- AND DARK-GROWTH IN LONG-DAY DUCKWEED, LEMNA GIBBA G3, AS AFFECTED BY KINETIN

Under short-day conditions the growth or the production of fronds in Lemna gibba G3 was stimulated by KIN (10^–5 M);the longer the nyctoperiod, the greater the stimulation was.Under long-day conditions KIN was slightly inhibitory for thefirst 2 days, but promotive thereafter. IAA (10^–5 M) reversedthe growth inhibition by KIN in long-days, and DCA (10^–4to 10^–6 M) and also CA (10^–4 to 10^–6 M), althoughless effectively, cancelled the growth promotion by KIN in short-days.DCA (10^–5 M) little altered the KIN inhibition in thefirst 2 days of light culture, nevertheless it alleviated strikinglythe KIN promotion in the subsequent illuminated days. These and relevant findings explained the above-described promotionand inhibition by KIN of the duckweed growth in terms of invivo level of a cofactor (probably auxin) which may be underthe regulative influence of photoperiodic conditions given.Moreover, some bearing of the above conclusion on floweringmechanism in this long-day duck-weed was suggested. (Received September 12, 1966; )     

FURTHER STUDIES ON THE ACTION OF FREE AMINO ACIDS ON FLOWERING OF DUCKWEED, LEMNA GIBBA G3

1. The maximum inhibition of flowering of a long-day duckweed,L. gibba G3, occurred when amino acid was added to the culturemedium on the third long-day. Lysine could reverse the inhibitionnon-specifically.
2. When the concentration ratio of endogenousarginine to endogenouslysine was under 10, the flowering processesprogressed normally,and the flower production decreased withthe increase of theratio from 10 to 20.
3. These and relevantfindings support our previous conclusionthat in vivo free aminoacids may contribute in establishingintracellular state determiningwhether certain essential reaction(s)involved inflowering processescan proceed normally or not.

( Accepted February 15, 1965)     

THE RHYTHMICAL CHANGE IN SENSITIVITY OF A LONG-DAY DUCKWEED, LEMNA GIBBA G3, TO DARK-BREAK

1. Effect of varied lengths of darkness given before continuousillumination, and that of dark-break of continuous light asa function of the time of its application, on the flower formationin a long-day duckweed, Lemna gibba G3, were studied. The results obtained suggested a rhythmic change in sensitivityto darkness, i.e., a cycle of 36 hr-period consisting of 12hr of sensitivity and the following 24 hr of insensitivity.The inhibition by darkness (12–36 hr) given before thestart of, or by dark-break (12, 24 hr) inserted in, the inductionperiod involved an extension of the induction period, but nota slow-down of the rate of flower formation. The dark-breakgiven after the induction period, however, suppressed the rateof flower production in proportion to the length of the darkness. 2. The inhibition of flowering by darkness given in the darksensitivephase was cancelled by a relatively brief light period insertedin the darkness. 3. Relation between the rhythm and the length of induction periodwas discussed. (Received August 13, 1965; )     

CHANGE IN SENSITIVITY TO DARK BREAK AND ITS RELATION TO FLORAL INDUCTION IN LONG-DAY DUCKWEED, LEMNA GIBBA G3

Change in dark-sensitivity of a long-day duckweed, Lemna, gibbaG3, under varied photoperiodic conditions was studied. When photoperiod shorter than 12 hr was given to phase I (thefirst half of the first cycle) or a short-day was given as thefirst cycle, the sensitive system to light .interruption appearedin phase II (the second half of the first cycle), and the inhibitionof flowering caused by darkened phase III (the first half ofthe second cycle) could be alleviated by light interruptiongiven to darkened phase III. In other words, the phase in whichthe sensitive system was most active was different from thephase in which this system actually worked. This system couldalso enhance the function of the light period given to the firsthalf of the next cycle. Probably owing to this mechanism, thelong-day plant can flower when the nyctoperiod of short-dayregime to which the plant is subjected is interrupted by light. (Received July 3, 1967; )     

EFFECTS OF GROWTH SUBSTANCES ON EXCISED FLORAL BUDS OF AQUILEGIA

Buds at various stages of development were grown for 3 weeks on solid media containing coconut milk, minerals, vitamins, sucrose, and varying quantities of gibberellic acid, indoleacetic acid, and kinetin. The best average growth was obtained on media containing GA at 2.0 mg/liter, IAA at 1.0 mg/liter, and kinetin at 0.05 mg/liter. When results were compared for buds explanted at very young stages and at older stages, however, young buds attained better average growth on media with 0.5 mg/liter of IAA. Evidence is presented for interaction between IAA and kinetin. With buds explanted at young stages, as the kinetin concentration was increased, optimum growth occurred on media with increasing concentrations of IAA. With older buds, on the other hand, as the kinetin concentration was increased, optimum growth occurred on decreasing concentrations of IAA. Bud growth was compared on media with growth substances sterilized by autoclaving with growth on similar media with these substances filter-sterilized. Better growth occurred generally on the media with filter-sterilized ingredients. A long-range objective of this research is the development of a system that would make possible quantitative measurements of floral development in vitro.     

TWO LIGHT REACTIONS IN THE PHOTOPERIODIC CONTROL OF FLOWERING OF LEMNA PERPUSILLA AND L. GIBBA

The effects of light quality on the photoperiodic control inthe flowering of a SD duckweed, Lemna perpusilla strain 6746,and a LD duckweed, L. gibba strain G3, were investigated withspecial reference to the interaction between R and B or FR lights. In the diurnal alternation of R or G light and dark periods,L. perpusilla responded as a SDP, but in that of B or FR lightit was almost daylength-indifferent. On the other hand, L. gibbaresponded as a LDP under B, R or FR light, although the criticallight length was altered by the light quality. In the diurnal alternation of R and B or FR light periods containingno dark period, L. perpusilla flowered with the shortening ofthe optimal and critical R light lengths, compared with theplant exposed to that of R light and dark period. The floweringresponse of L. gibba to the R light length showed double peaks,that is, the first peak at the R duration less than 9 hours,and the second at the R duration longer than 9 hours. The firstpeak corresponds to the optimal R light length in L. perpusilla. Under the CL with a mixture of R and B or FR lights, the floweringand frond production were influenced by the intensity ratioof two light given. In both plants, the optimal ratio of B toR or FR to R for the flowering was always greater than thatfor the frond production. It is suggested that the B or FR light interacts with the Rlight in the photoperiodic process in the plants and this interactionbetween the R and B or FR lights should be of importance forobtaining a better understanding of photoperiodism. (Received August 28, 1965; )     

EFFECTS OF PLANT GROWTH SUBSTANCES ON IN VITRO FIBER DEVELOPMENT FROM UNFERTILIZED COTTON OVULES

Fertilization of cotton ovules was prevented by removal of styles and stamens on the morning of anthesis. Forty-eight hr later ovaries were harvested and ovules were aseptically transferred to liquid culture medium supplemented with various plant growth substances. In the absence of phytohormones, ovules browned and failed to increase in size or produce fibers. Indoleacetic acid and gibberellic acid provided for ovule growth and fiber development. Kinetin provided for ovule growth only. The ovule's capacity for indoleacetic acid- or gibberellic acid-stimulation of fiber development was reduced by high concentrations of kinetin or abscisic acid. Low concentrations of kinetin partially reversed the inhibitory effect of abscisic acid.     

褪黑素对内蒙阿白山羊在非生绒季节促绒生长及绒产量的影响

用简易的外科手术在阿白山羊梳绒后的非长绒季节，给羊体颈部皮下埋植一种含褪黑素的胶囊试验，经５周后受试羊群长出了新绒，对照群则未见新绒生长。在８月下旬天然生绒季节快下到时，试验组羊绒已长至近３公分；而对照群才开始生绒，但绒长不足１分分。表明含上述激素胶囊促绒生长首次成功。翌年对上述羊群跟踪检测结果：受试羊群个体产绒量的特级（≥４５０克／头）率。提高为５０－６８．４％，与对照群（３５％）相比，提高１５