Ribosomes in incompatible pollen tubes in the Solanaceae

Some members of the Solanaceae have a self‐incompatibility mechanism preventing self‐fertilization. Stylar ribonucleases (S‐RNases) are responsible for growth inhibition of self‐pollen tubes. A prevalent model postulates that the S‐RNases act as intracellular cytotoxins that degrade ribosomal RNA, and possibly also messenger RNA, in the incompatible pollen tubes. Since ribosomes and polysomes are easily noticed with the electron microscope, it should be possible to confirm disintegration of these structures. However, our inspection by electron microscopy revealed the presence of ribosomes and polysomes in pollen tubes formed after self‐pollination of the self‐sterile species Brugmansia (Datura) suaveolens and Nicotiana alata . There was no decrease over time in the number of bound ribosomes per unit of rough endoplasmic reticulum (RER) membrane. The results indicate that the inhibition of tube growth is not due to a general degradation of ribosomal and messenger RNA. Therefore, the substrate for S‐RNases presumably is very specific.     

Comparison of the primary structure of the large and small subunits of fraction I protein from solanaceae plants and other families

Large and small subunits of fraction I proteins from five plants (tobacco, paprika, tomato, eggplant and potato) of the family Solanaceae were isolated, and the triptic peptides of these subunits were compared after separation by ion exchange column chromatography. Using tobacco as the standard for comparison, 4 (paprika), 5 (tomato), 3 (eggplant) and 8 (potato) out of 27 resolved large subunit peptides were found to be different. On the other hand, 2 (paprika), 3 (tomato), 2 (eggplant) and 7 (potato) out of 15 clearly resolved peptides were found to be different from tobacco in the case of small subunit. These differences were appreciably bigger than those found for different species of the genus Nicotiana to which tobacco belongs. The tryptic peptides of more distantly related plants from tobacco (comfrey, spinach and rape) differed more than those of Solanaceae in either large or small subunit.     

Biosynthesis of ticloidine in Physalis peruviana

The aerial parts and roots of Physalis peruviana (Cape Gooseberry) have been shown to contain tigloidine (3β-tigloyloxytropane) and 3α-tigloyloxytropane. The tiglic acid moiety of these alkaloids is derived from l-iSoleucine.     

Glutathione in conditioned media of tobacco suspension cultures

Conditioned media of suspension cultures of Nicotiana tabacum var. Samsun contain 0.15-0.20 mmol/l glutathione. These concentrations correspond closely to the intracellular content of glutathione and represent about three to four times the amount of glutathione needed to maintain the intracellular level of glutathione. In contrast to the GSH:GSSG ratio inside the cells, the amount of GSSG in the media rises to 20% of the GSH content.     

The effect of temperature on adenosine diphosphate glucose pyrophosphorylase from Solanum tuberosum

A partially purified extract of adenosine diphosphate glucose pyrophosphorylase has been prepared from Solanum tuberosum. The effect of temperature on the initial rate of reaction has been determined in the presence and absence of activator. The results are discussed in relation to the sweetening of potatoes at 2°.     

Pectolytic enzyme activity from Nicotiana tabacum pollen

Ungerminated pollen of Nicotiana tabacum contains a pectolytic enzyme which has its optimal activity between pH 5.5 and 6.5. Pectic lyase was not detected.     

The black nightshades (Solatium section Solatium) of the Indian subcontinent

Material of Solanum section Solanum from India and Pakistan is assignable to three species: a diploid, S. americanum; a tetraploid, S. villosum; and a hexaploid, S. nigrum. These species are distinguished by slight but consistent differences and a key is included to facilitate their identification. None of the members of section Solanum appears to be a weed of significant agronomic importance in this area, except in a few localized areas.     

The glycoalkaloids of Solanum demissum

Two glycoalkaloids previously unreported in Solanum demissum have been isolated and identified as commersonine and neotomatine.     

Phenolic glycosides from Solanum glaucophyllum: A new quercetin triglycoside containing D- apiose

Eight phenolic glycosides have been isolated from the leaves of S. glaucophyllum, one of them being quercetin-3-O-(2^G-β-D-apiosylrutinoside).