Influence of metabolic stress on the inheritance of cell determination in the moss, Pottia intermedia

Epigenetically-determined apogamy in aposporous regenerants of the moss Pottia intermedia persists during vegetative propagation, the capacity of apogamy being inherited by individual aposporous protonemal cells. To test Bauer-Lazarenko's proposal that stable apogamy in mosses may be due to some self-replicating cytoplasmic factor, the effects of different metabolic stress treatments on the expression of apogamy have been tested. Chronic metabolic stress caused by long-term growth of autotrophic aposporous protonema on mineral medium with 0.25% of casamino acids and on Murashiga-Skoog (MS) medium with sucrose and phytohormones, as well as by transitory action of high kinetin concentration, have a much stronger influence on the expression of apogamy, than short-term stress treatments with RNase and Pb(2+). Apogamy has been found to be lost stably, after prolonged growth on MS medium containing kinetin and ABA. The proposal that the capacity for apogamy is related to the release of aposporous protonemal cells from a putative factor for apogamy is discussed.     

百合未授粉子房离体培养胚胎形成及植株再生

未受精子房离体培养是诱导雌核产生单倍体的技术之一。以1个野生种和3个杂种系共7个百合(Lilium)基因型为实验材料, 探讨了基础培养基、花蕾取样时期和外源激素等因素对百合未授粉子房离体培养胚胎形成的影响。结果表明, CBM、MS和BDS三种基础培养基均可诱导百合未授粉子房胚胎形成, 但以BDS培养基诱导效果最佳; 开花前1天的花蕾较适于百合未授粉子房离体培养; 2 mg·L^-1 2,4-D + 2 mg·L^-1 6-BA和2 mg·L^-1 2,4-D + 2 mg·L^-1 KT两种外源激素配方均适用于百合未授粉子房离体培养诱导胚胎形成。在培养过程中, 大多数胚性胚珠中只含有1个胚胎, 位于珠孔端、合子端或极核处, 少数胚性胚珠中含有双胚胎。通过百合未授粉子房离体培养, 从5个基因型材料中共获得146株再生植株。采用根尖染色体计数法对其中的62株进行了倍性测定, 其中43株与母体植株染色体倍性不同。     

Cytokinins antagonize the jasmonates action on the regulation of potato (Solanum tuberosum) tuber formation in vitro

Cucurbita pepo L. (squash, pumpkin) is a highly polymorphic vegetable species of major importance. Our study characterized a spectrum of C. pepo germplasm for the ability to regenerate in vitro by direct organogenesis from cotyledon explants. Cultivars tested included both cultivated subspecies, texana and pepo, and nearly all of their respective cultivar-groups. Direct shoot regeneration occurred in all accessions, and was generally high (56–94%), with a single exception of 22% (‘Bolognese’). There was no significant difference between the percentage regeneration of the two subspecies. Shoot regeneration per responding explant was uniform (1.2–1.6 shoots per explant). Only ‘True French’ produced statistically more shoots (3.9 per explant) than other accessions. The morphology of regeneration varied. Most cultivars produced long shoots, often fasciated, amid a few small buds. Some subspecies pepo cultivars (Beirut, Yugoslavia 7, Ma’yan and True French) produced short, massive, hollow shoots, sometimes accompanied by shoots that were more normal. Two subspecies texana cultivars (Creamy Straightneck and Small Bicolor) produced single (sometimes double) shoots without other buds. The production of chimeric (mixoploid) regenerants varied and there was a tendency to regenerate chimeric plants from the widest-fruited accessions (i.e. lowest length-to-width ratio) in each subspecies. Subspecies pepo Pumpkin Group ‘Tondo di Nizza’ showed significantly greater production of chimeric regenerants. In comparison with the great range of variation observed in fruit shape, the variation of in vitro responses (mostly less than 2-fold in regeneration and shoot production) was less than expected.