Shoot

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

Expression of tomato salicylic acid (SA)-responsive pathogenesis-related genes in Mi-1-mediated and SA-induced resistance to root-knot nematodes.

Abstract: Summary The expression pattern of pathogenesis-related genes PR-1, PR-2 and PR-5, considered as markers for salicylic acid (SA)-dependent systemic acquired resistance (SAR), was examined in the roots and shoots of tomato plants pre-treated with SA and subsequently infected with root-knot nematodes (RKNs) (Meloidogyne incognita). PR-1 was up-regulated in both roots and shoots of SA-treated plants, whereas the expression of PR-5 was enhanced only in roots. The over-expression of PR-1 in the whole plant occurred as soon as 1 day after SA treatment. Up-regulation of the PR-1 gene was considered to be the main marker of SAR elicitation. One day after treatment, plants were inoculated with active juveniles (J2s) of M. incognita. The number of J2s that entered the roots and started to develop was significantly lower in SA-treated than in untreated plants at 5 and 15 days after inoculation. The expression pattern of PR-1, PR-2 and PR-5 was also examined in the roots and shoots of susceptible and Mi-1-carrying resistant tomato plants infected by RKNs. Nematode infection produced a down-regulation of PR genes in both roots and shoots of SA-treated and untreated plants, and in roots of Mi-carrying resistant plants. Moreover, in resistant infected plants, PR gene expression, in particular PR-1 gene expression, was highly induced in shoots. Thus, nematode infection was demonstrated to elicit SAR in shoots of resistant plants. The data presented in this study show that the repression of host defence SA signalling is associated with the successful development of RKNs, and that SA exogenously added as a soil drench is able to trigger a SAR-like response to RKNs in tomato.

Improvement of seed yields under boron-limiting conditions through overexpression of BOR1, a boron transporter for xylem loading, in Arabidopsis thaliana.

Abstract: Soil fertilization is a common practice in modern agriculture, undertaken to prevent nutrient deficiency in crops. However, fertilization is costly and causes environmental pollution. The cultivation of plants that tolerate low nutrient supplies may circumvent this problem. Here, we report the generation of Arabidopsis thaliana plants that tolerate boron (B)-deficient conditions due to the overexpression of BOR1, an efflux B transporter that is required for efficient xylem loading of B. In several independently generated transgenic plants expressing BOR1 or BOR1-GFP under the control of the cauliflower mosaic virus 35S RNA promoter, root-to-shoot translocation of B was enhanced and shoot growth was greater under B-limiting conditions compared with wild-type plants. In addition, the transgenic plants showed increased translocation of B, especially to the shoot apex, and set seed normally under B-limiting conditions, under which wild-type plants failed to set seed. This study therefore reports plants that show improved seed yields compared with wild-type under nutrient-deficient conditions as a result of increased production of an essential mineral nutrient transporter.

Studies of flowering behaviour in Eucalyptus regnans F. Muell.

Abstract: The buds of Eucalyptus regnans are protected by an operculine involucre for 12 months and develop as exposed umbels for a further 15-17 months. The flowering period is about 3 months but the extreme range is from late February to early July at elevations of 600-750 m. Flowers remain open for 1-2 weeks. Older trees tend to flower later than younger trees on the same site. Pollination is probably effected chiefly by insects and birds. Flowering abundance follows a 2-year cycle with a tendency for heavier production every fourth year, but this pattern may be interrupted by severe insect attack on young shoots. Considerable losses occur at all stages of development owing to abscission, and to damage by gall and other insects. Quantitative estimates of flowering from litter trays indicate that the flower production of good years may be 25-65 times as great as in poor years. The mature forest produced 2.15-15.5 times as many flowers as the pole stage trees, and 1.5-10 times as many as the spar stage forest. Estimates of the fruit set following the late autumn flowering of 1954 indicate that that of the mature forest was 1.6 times as great as that in the spar stage forest and 3.5 times as great as that in the pole stage forest. The corresponding relative flower abundance in these forests was 1.5 and 3.8 respectively. However, the percentage of Rowers setting fruit from the early autumn flowering of 1956 was very much lower. Most capsules abscind or dehisce or fall attached to twigs within 3 years of their maturity. The quantitative estimate of flowering and fruit set permits seed crops from heavy flowering to be forecast a few years ahead of seed fall.