Forest growth is an important factor both economically and ecologically, and it follows a predictable trend with age. Generally, growth accelerates as canopies develop in young forests and declines substantially soon after maximum leaf area is attained. The causes of this decline are multiple and may be linked to age- or size-related processes, or both. Our objective was to determine the relati...

Twigs of Salix species are candidates for cryopreservation procedures because they become tolerant of freezing temperatures during mid-winter. We examined several variables in developing a two-step cryopreservation procedure for sections from these twigs. Samples of Salix triandra cooled to -30 or -35 degree C and then transferred to the vapor phase over liquid nitrogen gave the greatest percen...

Huanglongbing (HLB) is a highly destructive, fast-spreading disease of citrus, causing substantial economic losses to the citrus industry worldwide. Nutrient levels and their cellular distribution patterns in stems and leaves of grapefruit were analysed after graft-inoculation with lemon scions containing 'Candidatus Liberibacter asiaticus' (Las), the heat-tolerant Asian type of the HLB bacteri...

The remarkably low alkaloid content of whole tobacco shoots grown as scions on rootstocks of lowalkaloid species has been recorded by many investigators (cf. Dawson (5), James (8), and Mothes (10) for reviews). Although the data of Tso and Jeffrey (14) appeared to be in contradiction, the disagreement has since been resolved (see below). Solt (13) demonstrated that low alkaloid content in this ...

We investigated the effect of target mRNA level on grafting-transmitted gene silencing in tomato plants by using a strong ACC oxidase 1 (ACO1) silencer as the stock and transgenic ACO1 overexpressers as scions. Manifestation of graft transmission of sense gene silencing required a high initial level of target mRNA in the scion. A relatively high level of siRNA, similar to that in the strong ACO...

In order to separate the effects of size and meristem maturation on age-related changes in shoot growth behaviour, a reciprocal grafting experiment was conducted involving juvenile (J), mid-age (MA) and old-growth (OG) red spruce (Picea rubens Sarg.) trees as both scion donors and rootstock. The effects of rootstock and scion age on vegetative growth, foliar morphology and reproductive developm...

Movement-deficient potato virus X (PVX) mutants tagged with the green fluorescent protein were used to investigate the role of the coat protein (CP) and triple gene block (TGB) proteins in virus movement. Mutants lacking either a functional CP or TGB were restricted to single epidermal cells. Microinjection of dextran probes into cells infected with the mutants showed that an increase in the pl...