Studies on dwarfing mechanisms of dwarf rootstocks

在苗期对砧木矮化能力进行准确的评价，可以加快矮化砧木育种计划的进展。本研究的目的是确定来自矮化砧木的愈伤组织是否像田间表现所预期的那样，在离体条件下限制了来自接穗品种的另一个愈伤组织的生长。愈伤组织来源于桃和李的芽。这些愈伤组织生长在接穗砧木位置，在它们之间放置滤纸。砧木位置的桃愈伤组织，即与培养基接触的桃愈伤组织，在粳稻愈伤组织下生长的重量比在桃愈伤组织下生长的重量小。在桃的愈伤组织上生长时，接穗位置的粳稻愈伤组织重量较大。在接穗位置的桃愈伤组织在桃和粳稻愈伤组织上生长得同样好。在另一个实验中，将桃愈伤组织转移到培养基中，在培养基中先培养粳稻愈伤组织一周，然后去除。桃愈伤组织在先前用粳稻培养的培养基上重量较轻。桃愈伤组织的预孵育对日本伪善愈伤组织的生长没有影响。当桃与金盏花的愈伤组织不接触放置在相邻位置时，其中一种愈伤组织不影响相邻愈伤组织的生长，金盏花的酚含量高于桃，但桃愈伤组织的生长与金盏花和金盏花本身的酚含量无关。结果表明，利用组织培养技术可以评价粳稻砧木的矮化能力，矮化是由粳稻释放的某些化合物引起的。

Accurate evaluation of the dwarfing ability of rootstocks at the seedling stage permits faster progress in breeding programs for the dwarf rootstocks. The objective of this study was to determine whether callus from a dwarfing rootstock restricted growth of another callus from a scion cultivar in vitro as would be expected from a field performance. Calli were derived from shoots of peach and Prunus japonica Thunb. These calli were grown in scion-stock position, placing filter paper between them. Peach callus in the stock position, i.e. grown in contact with the media, weighed less when grown under P.japonica callus than when grown under peach callus. P.japonica callus in the scion position weighed more when grown on peach callus. Peach callus in the scion position grew equally well on either peach or P.japonica callus. In another experiment, peach callus was transferred into the media where P.japonica callus was previously incubated for one week and then removed. Peach callus weighed less on the media previously incubated with P.japonica. Preincubation of peach callus did not affect growth of P.japanica callus. When peach and P.japonica calli were placed in the adjacent position without contact, one kind of callus did not affect growth of callus adjacent to it.P.japonica contained nore phenols than peach, but growth of peach callus was independent of phenol contents of P.japonica and itself. The results suggest that dwarfing ability of rootstocks couldbe evaluated by tissue culture techniques and that dwarfing is caused by some compounds released from P.japonica.