A survey of cultivated heirloom tomato varieties identifies four new mutant alleles at the green-flesh locus

The process of crop domestication occurs through the selection and subsequent propagation of novel alleles that improve traits of interest. Cultivated tomato (Solanum lycopersicum), particularly heirloom varieties, exhibit a wide range of variation in fruit size, shape and color. The green-flesh mutant of tomato possesses a stay-green phenotype resulting in fruits that ripen to a red-brown color, due to the retention of chlorophyll and the simultaneous accumulation of lycopene. The recent identification of the GREEN-FLESH gene provides a molecular tool with which to investigate the origin of a subset of cultivated tomato varieties that resemble the green-flesh mutant. Sequence analysis of the GF locus from 26 varieties revealed the existence of four previously unidentified null alleles. This study illustrates the potential of cultivated tomato varieties, including heritage cultivars, heirlooms, and land races, for uncovering new alleles in genes of interest.     

Effects of prostaglandins E-2 and F-2 alpha on the metabolism of [U-14C]glucose by mouse morulae-early blastocysts in vitro

During 5-h culture in the presence of radioactive glucose, PGE-2 (10 micrograms/ml) significantly inhibited incorporation of glucose into the acid-soluble glycogen pool. PGE-2 at 1 and 10 micrograms/ml and PGF-2 alpha at 1 microgram but not 10 micrograms/ml stimulated incorporation of glucose into non-glycogen macromolecules during culture. However, the utilization of acid-soluble glycogen and other biochemical pools was not affected by the presence of PGs in the medium during 24-h chase culture of pulse-labelled embryos. Carbon dioxide production was significantly suppressed in the presence of PGs but accumulation of lactate was not affected. The results indicate that PGE-2 and PGF-2 alpha, in physiological concentrations, directly influence the metabolism of glucose by preimplantation embryos.     

Floral Induction in Wolffia microscopica by Salicylic Acid and Related Compounds under Non-inductive Long Days

Flowering in Wolffia microscopica, a short-day plant, couldbe induced with salicylic acid (SA), under long days. Aspirin,benzoic acid and salicylaldoxime were also effective for inductionof flowering in this duckweed. Amonsgt these, SA is the mosteffective compound, as it could induce flowering even at 10^–7M. Flowering was further enhanced when Wolffia fronds were subjectedto short days, in the presence of SA. However, SA neither showedany effect on flowering ofW. microscopica in the absence ofEDTA in the nutrient medium, nor could it, by itself, supporteven the vegetative growth. The probable mechanism of actionof SA has also been discussed. It appears that the effect cannotbe due simply to chelation of metal ions and perhaps the salicylmoiety itself exerts a specific effect. (Received March 15, 1983; Accepted May 6, 1983)     

Molecular cloning and expression of a xylanase gene from Cellulomonas sp. into Escherichia coli

Summary The xylanase gene of Cellulomonas sp. NCIM 2353 was cloned in pUC 18 and selected by growth on xylan as the sole carbon source. The functional clone harboured the recombinant plasmid with an insert of 1.42 kbp, as determined by restriction mapping and Southern hydridization. The clone secreted a xylanase of 45 000 mol. wt. as determined by Western blot analysis using specific antixylanase antibodies. The DNA insert carried the full structural gene along with its promoter and possibly regulatory sequences, since xylanase activity in the clone Cs11 was inducible by xylan. Offprint requests to: D. N. Deobagkar     

High Frequency Divisions in Leaf Base Protoplasts of Wheat (Triticum aestivum L.)

Protoplasts were isolated from the basal meristematic region of leaves from 6-day-old seedlings of wheat (Triticum aestivum). Protoplasts divided when cultured on MS medium (as agarose beads) in presence of nurse tissue. Donor seedlings when grown on BAP-supplemented MS medium were found to be considerably superior for protoplast isolation and culture than when grown on MS basal medium, in terms of protoplast viability, cell wall formation and cell division frequency. In addition, reduction of ammonium content of the culture medium, together with a dark Incubation, led to a high protoplast division frequency of about 70%. Microcolonies of 10-to 12-celled stages were obtained in Triticum aestivum, varieties HD 2329, HD 2285, Kalyan Sona, Arjun and CPAN 1676.     

Speed Breeding Opportunities and Challenges for Crop Improvement

Journal of Plant Growth Regulation - Crop improvement in light of the rapidly changing climate and the increasing human population continues to be one of the primary concerns for researchers across...     

Computer aided study of the interaction of thyroid hormone receptor with DNA.

Interaction of the first zinc finger from human thyroid hormone receptor (finger) with hexanucleotide duplex d(AGGTCA).d(TGACCT) from thyroid regulatory element has been studied by molecular mechanics simulation technique. The structure of the finger as well as its complex with DNA is optimized using constrain of tetrahedral coordination of the zinc ion to Cys sulphurs. The finger is stabilized by series of H--bonds (5 in backbone, 2 in side chains and 2 between backbone and side chains). The complex is stabilized by H-bonds between side chains of Tyr 11, His 12, Tyr 13 and Arg 14 with G2, G3 and G8. DNA is in B form. H--bonding network within DNA is preserved. Opposite strand P-P and Cl'-Cl' distances are changed slightly. There is a systematic change in the backbone torsional angles and sugar pucker. Also, there is an evidence of protein-induced conformational change in DNA.     

EhCoactosin Stabilizes Actin Filaments in the Protist Parasite Entamoeba histolytica

Entamoeba histolytica is a protist parasite that is the causative agent of amoebiasis, and is a highly motile organism. The motility is essential for its survival and pathogenesis, and a dynamic actin cytoskeleton is required for this process. EhCoactosin, an actin-binding protein of the ADF/cofilin family, participates in actin dynamics, and here we report our studies of this protein using both structural and functional approaches. The X-ray crystal structure of EhCoactosin resembles that of human coactosin-like protein, with major differences in the distribution of surface charges and the orientation of terminal regions. According to in vitro binding assays, full-length EhCoactosin binds both F- and G-actin. Instead of acting to depolymerize or severe F-actin, EhCoactosin directly stabilizes the polymer. When EhCoactosin was visualized in E. histolytica cells using either confocal imaging or total internal reflectance microscopy, it was found to colocalize with F-actin at phagocytic cups. Over-expression of this protein stabilized F-actin and inhibited the phagocytic process. EhCoactosin appears to be an unusual type of coactosin involved in E. histolytica actin dynamics.