Shoot

About: Shoot is a research topic. Over the lifetime, 32188 publications have been published within this topic receiving 693348 citations.

Polycomb repression of flowering during early plant development.

Abstract: All plants flower late in their life cycle. For example, in Arabidopsis, the shoot undergoes a transition and produces reproductive flowers after the adult phase of vegetative growth. Much is known about genetic and environmental processes that control flowering time in mature plants. However, little is understood about the mechanisms that prevent plants from flowering much earlier during embryo and seedling development. Arabidopsis embryonic flower (emf1 and emf2) mutants flower soon after germination, suggesting that a floral repression mechanism is established in wild-type plants that prevents flowering until maturity. Here, we show that polycomb group proteins play a central role in repressing flowering early in the plant life cycle. We found that mutations in the Fertilization Independent Endosperm (FIE) polycomb gene caused the seedling shoot to produce flower-like structures and organs. Flower-like structures were also generated from the hypocotyl and root, organs not associated with reproduction. Expression of floral induction and homeotic genes was derepressed in mutant embryos and seedlings. These results suggest that FIE-mediated polycomb complexes are an essential component of a floral repression mechanism established early during plant development.

Effects of Drought Stress on Soluble Proteins in two Maize Varieties

Abstract: Drought stress was generated by PEG 6000. Water potentials were: zero as the control, and -0.15, -0.49, -1.03, and -1.76 MPa as treatments. After 24-h treatment the total soluble protein content of 2 maize (Zea mays L.) cultivars (704 and 301) was determined and SDS-PAGE gel electrophoresis in the first dimension was performed. By decreasing water potentials, total soluble protein content first increased, and then decreased in the roots and leaves of both varieties. The decrease in total soluble protein content in the roots of both varieties was equal, but in the leaves of cv. 301 it was greater than in cv. 704. In drought conditions the decrease in root and shoot fresh weight in cv. 704 was greater than in cv. 301. With water potential -1.76 MPa, the accumulation of dehydrin-like 38, 50, 57, and 65 KDa M.W. root proteins and 15, 17, 20, 27, 30, 37, 54, and 59 KDa M.W. leaf proteins increased. However, the expression of 15, 19, and 27 KDa M.W. root proteins, and 22 KDa M.W. leaf protein was induced in both varieties. The accumulation of dehydrin-like proteins in the roots and leaves of cv. 704 was higher than in cv. 301. There was no relationship between protein changes and drought tolerance.

Leaf tissue remaining after cutting and regrowth in perennial ryegrass

Abstract: When one or two leaves were removed out of the three or sometimes four present on each tiller of five genotypes of perennial ryegrass grown in nutrient solution, it was found that the relative growth rate (RGR) was not much less than that of untreated plants. The removal of lower leaves had no effect on RGR. Removal of all leaf blades depressed RGR. It is suggested that the results obtained indicate that the plant has the capacity to compensate for loss of leaf tissue by increased activity in the remaining leaves. Leaf appearance rate and tiller production were found to be the attributes most sensitive to the defoliation treatments imposed, and the degree to which leaf appearance rates were affected by defoliation was found to be a good indicator of the regrowth capacity of the different genotypes. Evidence was obtained linking high regrowth potential with high relative increases in the proportion of plant material allocated to new shoot growth.