摘要:

Attempts were made to obtain bacteria‐free plants ofPsychotria punctatafrom tissue cultures. Stem explants and callus derived from them were induced to form roots but failed to form buds on Linsmaier and Skoog medium and 96 chemical modifications of it, including most of those known to induce bud formation in other species. Roots formed with ample IAA (2 mg/liter or more) and a low kinetin concentration (0.25 or 0.50 mg/liter). Adenine inhibited root formation in these media, but tyrosine did not. Tyrosine did lower the percentage of calluses commencing growth. When enzyme‐hydrolyzed lactalbumin (1.3 g/liter), kinetin (0.5 mg/liter) and IAA (5 mg/liter) were added to Linsmaier and Skoog medium modified by decreasing inorganic nitrogen and increasing inorganic phosphate, callus grew at the fastest rate observed (increasing threefold in fresh weight in three weeks) and formed numerous roots. This was adopted as the stock callus medium. Casein hydrolysates also stimulated growth but less so than lactalbumin hydrolysate. When lactalbumin hydrolysate or a casein hydrolysate lacking tryptophan was supplied, growth occurred without added auxin if sufficient cytokinin was added. Cytokinin was required at unusually high concentration and was tolerated at still higher concentration. Formation, elongation, and branching of roots persisted on a saturated solution of BA which inhibited callus growth about 70 % and delayed callus senescence. Light caused earlier callus senescence after growth had ceased but did not affect callus growth or root formation. Light‐induced senescence was prevented by a high cytokinin concentration.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10066.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Translocation of photosynthates was found to occur when blades ofNereocystiswere illuminated in the presence of C14bicarbonates. Rates of translocation averaging 37 cm/hr in the laboratory were observed. Samples from the epidermis, cortex, and medulla of the stipes of plants with blades exposed to tracer showed that the radioactivity in organic compounds was confined to medulla where sieve filaments occurred. Girdle preparations of blades, interrupting the mucilage ducts and leaving the blade medulla intact, allowed translocation to take place. These data indicate that conduction of photosynthate takes place in the medulla. Similarities between the anatomy of algal sieve filaments and angiosperm sieve tubes, coupled with the continuity of the sieve filaments from blade medulla to stipe medulla suggested indirectly that the sieve filaments were conducting elements. Further support of this hypothesis was provided from collections of radioactive exudate from cells in the medulla of the lower stipe that were continuous with the sieve filaments. Tracer applied to the blades was partially recovered as organic material in a clear fluid that collected inside the pneumatocyst. Continued accumulation of radioactivity in this fluid was dependent on living blades; fluid with low specific activity that did not increase during the experiment accumulated slowly if blades were killed with ethanol after an exposure to tracer. It is possible that the system that produced the stipe fluid was part of (or a side effect of) the system responsible for maintaining volume in the conducting system. It may also provide an alternate route (other than the sieve filaments) for delivery of photosynthates to the base of the plant. Carbon‐14 applied to blade tips as bicarbonate was recovered in part as radioactive mannitol in the translocation stream.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10067.x

出版商:Wiley    

年代:1972

数据来源: WILEY

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10068.x

出版商:Wiley    

年代:1972

数据来源: WILEY

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10053.x

出版商:Wiley    

年代:1972

数据来源: WILEY