Improving hybrid seed production in corn with glyphosate-mediated male sterility.

BACKGROUND: Hybrid corn varieties exhibit benefits associated with heterosis and account for most of the corn acreage in the USA. Hybrid seed corn is produced by crossing a female parent which is male-sterile and therefore incapable of self-pollination with a male parent as the pollen donor. The majority of hybrid seed corn is produced by mechanical detasseling which involves physically removing the tassel, a process that is laborious and costly. RESULTS: Glyphosate-resistant corn was developed via expression of a glyphosate insensitive 5-enolpyruvyl-shikimate 3-phosphate synthase enzyme (CP4-EPSPS). Experimentation with molecular expression elements resulted in selective reduction of CP4-EPSPS expression in male reproductive tissues. The resulting plant demonstrated sterile tassel following glyphosate application with little to no injury to the rest of the plant. Using (14)C-glyphosate as a marker, we also examined the translocation of glyphosate to the tassel via spray application in a track sprayer to simulate field application. The results allowed optimization of spray parameters such as dose, spray timing and target to maximize tassel delivery of glyphosate for efficient sterilization. CONCLUSION: The Roundup hybridization system (RHS) is a novel process for hybrid seed production based on glyphosate-mediated male sterility. RHS replaces mechanical detasseling with glyphosate spray and greatly simplifies the process of hybrid seed corn production.

The control of Asian rust by glyphosate in glyphosate-resistant soybeans.

BACKGROUND: Glyphosate is a widely used broad-spectrum herbicide. Recent studies in glyphosate-resistant (GR) crops have shown that, in addition to its herbicidal activity, glyphosate exhibits activity against fungi, thereby providing disease control benefits. In GR wheat, glyphosate has shown both preventive and curative activities against Puccinia striiformis f. sp. tritici (Erikss) CO Johnston and Puccinia triticina Erikss, which cause stripe and leaf rusts respectively. RESULTS: Laboratory studies confirmed earlier observations that glyphosate has activity against Phakopsora pachyrhizi Syd & P Syd which causes Asian soybean rust (ASR) in GR soybeans. The results showed that glyphosate at rates between 0.84 and 1.68 kg ha(-1) delayed the onset of ASR in GR soybeans. However, field trials conducted in Argentina and Brazil under natural infestations showed variable ASR control from application of glyphosate in GR soybeans. Further field studies are ongoing to define the activity of glyphosate against ASR. CONCLUSIONS: These results demonstrate the disease control activities of glyphosate against rust diseases in GR wheat and GR soybeans.

Glyphosate inhibits rust diseases in glyphosate-resistant wheat and soybean.

Glyphosate is a broad-spectrum herbicide used for the control of weeds in glyphosate-resistant crops. Glyphosate inhibits 5-enolpyruvyl shikimate 3-phosphate synthase, a key enzyme in the synthesis of aromatic amino acids in plants, fungi, and bacteria. Studies with glyphosate-resistant wheat have shown that glyphosate provided both preventive and curative activities against Puccinia striiformis f. sp. tritici and Puccinia triticina, which cause stripe and leaf rusts, respectively, in wheat. Growth-chamber studies demonstrated wheat rust control at multiple plant growth stages with a glyphosate spray dose typically recommended for weed control. Rust control was absent in formulation controls without glyphosate, dependent on systemic glyphosate concentrations in leaf tissues, and not mediated through induction of four common systemic acquired resistance genes. A field test with endemic stripe rust inoculum confirmed the activities of glyphosate pre- and postinfestation. Preliminary greenhouse studies also demonstrated that application of glyphosate in glyphosate-resistant soybeans suppressed Asian soybean rust, caused by Phakopsora pachyrhizi.

Ackee poisoning: relationship to vomiting sickness (abstract only)

The toxic effect of Hypoglycin A, a polypeptide isolated from the ackee, on animals is presented. The outstanding features are vomiting, drowsiness,coma and death, accompanied by hypo-glycaemia and low level glycogen. These findings resemble those observed in some cases of so-called "vomiting sickness" of Jamaica. Animal experiments have also shown that rats fed with a low protein high carbohydrate "Jamaican diet" were more sensitive to Hypoglycin A than rats on a normal diet. The significance of these experiments will be discussed. The final proof that "vomiting sickness" could be due to ackee poisoning would be to identify the ackee toxin from the "vomiting sickness" patients by chemical, biochemical and biological methods. (AU)

The effects of hypoglycin-A on thyroid activity (abstract only)

The effects of hypoglycin-A (L-a-amino-á-methylene cyclopropane propprionic acid) the active principle of the fruit blighia sapida, ("ackee"), on the thyroid function of the rat have been studied. At the end of twenty-four hours hypoglycin-A (5-40 mg/kg. body weight) depressed the level of the protein bound iodine (PBI) in the plasma. With doses of hypoglycin-A in the range of 5-10 mg/kg body weight, there is some increase in the urinary excretion of radioactive iodine (131I), while larger doses (20-40 mg/kg) definitely decreased the urinary excretion of 131I. It is assumed the at hypoglycin-A acts on the thyroid function like sodium salycylate in causing an acute decrease in the level of the PBI, and like thiouracil, by causing a decrease deiodination by the liver and the thyroid gland. In a time course study, the effect of hypoglycin-A, 10 mg/kg on injected 131I, there appear to be two active metabolic components of hypoglycin-A, which cause depression of the uptake 131I by the thyroid, kidney and liver, one having an effect within one hour, the other acting four hours after administration. The effect of hypoglycin-A on thyroid function appears not to be specific, but a part of its general antimetabolic action (AU)

In vitro effects of catachol amines on the vas deferens of guinea pigs

Adrenaline and Noradrenaline both caused a contraction of the vas deferens. However, adrenaline was a more potent stimulant than noradrenaline. Isoprenaline by itself had no effect on the vas deferens, but it modified the stimulatory effect of subsequent administered adrenaline and noradrenaline. In small doses isoprenaline lessened and in large doses it potentiated the stimulating effect of the other two amines, the degree of inhibition by isoprenaline being greater on noradrenaline than on adrenaline. It was suggested that isoprenaline acted by inhibiting alpha adrenergic receptors in small concentrations, stimulating them in large concentrations and not by stimulating Beta receptors as is presently believed (AU)

Critical staining of pancreatic alpha granules with phosphotungstic acid hematoxylin

Mammalian pancreatic alpha granules were differentially stained with phosphotungstic acid haematoxylin. Paraffin sections were dewaxed and hydrated, oxidised 5-40 sec in freshly prepared 0.3 percent KMnO4 acidified with 0.3 percent (w/v) H2SO4, decolourised in 4 percent potassium metabisulphite, mordanted 20 min to 2 hr in 4 percent iron alum, stained in phosphotungstic acid haematoxylin 16-48 hr, rinsed in 95 percent ethanol until no stain runs from the tissue, dehydrated in absolute ethanol, cleared in xylene, and covered in synthetic resin. Advantages of this procedure are: (1) consistent, reproducible staining; (2) applicability to all the common laboratory mammals and man; (3) wide latitude at each stage, permitting its use as a routine method; and (4) superior visualization of alpha granules, due to suppression of background staining and absence of glare. For fixation, formalin-acetic or Bouin's solution is recommended (AU)

Pharmacological screening of Jamaican medicinal plants

The pharmacological screening of local medicinal plants began in 1958. The results of the first fifty-five plants screened have already been published. The results of the next sixty-one plants screened were briefly summarized (AU)

Simple hypotensive and hypertensive principles from some West Indian medicinal plants

Examination of those plant extracts which were previously found (Feng and others, 1962) to have transient depressor activity has led to the isolation of gamma-aminobutyric acid, from the leaves of Artocarpus incisa L. and Piper amalago L. and to the demonstration by paper chromatography of its presence of several extracts. Extracts showing pressor activity were also examined and tyramine has been isolated from Phoradendron wattii Kr. and Urb. and dopamine has been shown by paper chromatography to be present in Piper amalago L. and Stachytarpheta jamaicensis Vahl(AU)

Pharmacological screening of some West Indian medicinal plants

A systematic pharmacological examination has been made of 55 Jamaican plants, most of which have a local reputation as medicinals. A number of interesting, but no outstanding, activities were observed. The results are tabulated (AU)