Dendrobium orchids carrying antisense ACC oxidase: small changes in flower morphology and a delay of bud abortion, flower senescence, and abscission of flowers.

Four Dendrobium Sonia 'Earsakul' lines were generated by insertion of one, two or three antisense copies of a Carica papaya gene encoding 1-aminocyclopropane-1-carboxylic acid oxidase (CpACO). Whole vegetative plants of the transgenic lines showed about 50% of the basal ethylene production rate, while the increase in ethylene production in floral buds during opening and open flowers prior to visible senescence was delayed. Detailed analysis of more than 100 parameters in flowering plants showed no effect of antisense ACO on plant morphology and coloration, except for shorter length and width of some of the sepals and petals.

Time course of programmed cell death, which included autophagic features, in hybrid tobacco cells expressing hybrid lethality.

PCD with features of vacuolar cell death including autophagy-related features were detected in hybrid tobacco cells, and detailed time course of features of vacuolar cell death were established. A type of interspecific Nicotiana hybrid, Nicotiana suaveolens × N. tabacum exhibits temperature-sensitive lethality.

Vesicles between plasma membrane and cell wall prior to visible senescence of Iris and Dendrobium flowers.

Cut Iris flowers (Iris x hollandica, cv. Blue Magic) show visible senescence about two days after full opening. Epidermal cells of the outer tepals collapse due to programmed cell death (PCD).

Expression of expansin genes in the pulp and the dehiscence zone of ripening durian (Durio zibethinus) fruit.

Durian (Durio zibethinus) fruit was harvested at the commercially mature stage and stored at 25°C. Durian fruit have 3-5 longitudinal dehiscence zones (DZs) in the peel, which are up to 40cm long and 2cm thick in large fruit. Dehiscence started a week after harvest, was hastened by exogenous ethylene, and delayed by 1-methylcyclopropene (1-MCP), showing that it is regulated by endogenous ethylene.

Two abscission zones proximal to Lansium domesticum fruit: one more sensitive to exogenous ethylene than the other.

Longkong (Lansium domesticum) fruit grows in bunches and is also sold as bunches. Individual fruit can separate from the bunch both before and after commercial harvest. The fruit has two separation sites.

Carotenoids in durian fruit pulp during growth and postharvest ripening.

Durian (Durio zibethinus) cvs. Chanee and Monthong fruit were severed from the tree during 14 day intervals, from 10 weeks after anthesis until commercial maturity. We determined the pulp (i.

Macroautophagy and microautophagy in relation to vacuole formation in mesophyll cells of Dendrobium tepals.

Prior to flower opening, mesophyll cells at the vascular bundles of Dendrobium tepals showed a large increase in vacuolar volume, partially at the expense of the cytoplasm. Electron micrographs indicated that this increase in vacuolar volume was mainly due to vacuole fusion. Macroautophagous structures typical of plant cells were observed.

Ethylene and pollination decrease transcript abundance of an ethylene receptor gene in Dendrobium petals.

We studied the expression of a gene encoding an ethylene receptor, called Ethylene Response Sensor 1 (Den-ERS1), in the petals of Dendrobium orchid flowers. Transcripts accumulated during the young floral bud stage and declined by the time the flowers had been open for several days. Pollination or exposure to exogenous ethylene resulted in earlier flower senescence, an increase in ethylene production and a lower Den-ERS1 transcript abundance.

Crystalloids in apparent autophagic plastids: remnants of plastids or peroxisomes?

Plant macroautophagy is carried out by autophagosome-type organelles. Recent evidence suggests that plastids also can carry out macroautophagy. The double membrane at the surface of plastids apparently invaginates, forming an intraplastidial space.

Pollination increases ethylene production in Lilium hybrida cv. Brindisi flowers but does not affect the time to tepal senescence or tepal abscission.

In many species, pollination induces a rapid increase in ethylene production, which induces early petal senescence, petal abscission, or flower closure. Cross-pollination in Lilium hybrida cv. Brindisi resulted in a small increase in flower ethylene production.

Pollinia-borne chemicals that induce early postpollination effects in Dendrobium flowers move rapidly into agar blocks and include ACC and compounds with auxin activity.

The early visible effects of pollination in orchids are likely due to pollinia-borne chemicals. In Dendrobium we tested whether such compounds were water soluble and would diffuse in solid-aqueous phase, and determined both 1-aminocyclopropane-1-carboxylic acid (ACC) concentrations and auxin activity. Following pollination, the flower peduncle showed epinastic movement, followed by yellowing of the flower lip, flower senescence and ovary growth.

Lipid globules on the plastid surface in Iris tepal epidermis cells during tepal maturation and senescence.

Epidermis cells in the outer tepals of Iris flowers (Iris×hollandica, cv. Blue Magic) start programmed cell death (PCD) prior to floral opening. The tepals show visible senescence symptoms three days after full opening.

Flower opening and closure: an update.

This review is an update of a 2003 review (Journal of Experimental Botany 54,1801-1812) by the same corresponding author. Many examples of flower opening have been recorded using time-lapse photography, showing its velocity and the required elongation growth. Ethylene regulates flower opening, together with at least gibberellins and auxin.

Expression of an AtNAP gene homolog in senescing morning glory (Ipomoea nil) petals of two cultivars with a different flower life span.

AtNAP, a NAC family transcription factor, has been shown to promote leaf senescence in Arabidopsis. We isolated an AtNAP homolog in morning glory (Ipomoea nil), designated InNAP, and investigated its expression during petal senescence. We used two cultivars, one showing a normal short flower life span (cv.

Length of the dark period affects flower opening and the expression of circadian-clock associated genes as well as xyloglucan endotransglucosylase/hydrolase genes in petals of morning glory (Ipomoea nil).

We isolated differentially expressed and dark-responsive genes during flower development and opening in petals of morning glory. Flower opening usually depends on petal expansion and is regulated by both genetic and environmental factors. Flower opening in morning glory (Ipomoea nil) is controlled by the dark/light regime just prior to opening.

Classical macroautophagy in Lobivia rauschii (Cactaceae) and possible plastidial autophagy in Tillandsia albida (Bromeliaceae) tapetum cells.

The tapetum in anthers is a tissue that undergoes programmed cell death (PCD) during the production of pollen. We observed two types of autophagy prior to cell death. In Lobivia rauschii (Cactaceae), tapetum cells showed plant-type autophagosomes-autolysosomes, which have been found previously exclusively in root meristem cells.

Ultrastructure of autophagy in plant cells: a review.

Just as with yeasts and animal cells, plant cells show several types of autophagy. Microautophagy is the uptake of cellular constituents by the vacuolar membrane. Although microautophagy seems frequent in plants it is not yet fully proven to occur.

Amorphous areas in the cytoplasm of Dendrobium tepal cells: production through organelle degradation and destruction through macroautophagy?

In Dendrobium flowers some tepal mesophyll cells showed cytoplasmic areas devoid of large organelles. Such amorphous areas comprised up to about 40% of the cross-section of a cell. The areas were not bound by a membrane.

Opening of Iris flowers is regulated by endogenous auxins.

Flower opening in Iris (Iris×hollandica) requires elongation of the pedicel and ovary. This moves the floral bud upwards, thereby allowing the tepals to move laterally. Flower opening is requires with elongation of the pedicel and ovary.

Delay of iris flower senescence by cytokinins and jasmonates.

It is not known whether tepal senescence in Iris flowers is regulated by hormones. We applied hormones and hormone inhibitors to cut flowers and isolated tepals of Iris × hollandica cv. Blue Magic.

Endogenous ethylene does not regulate opening of unstressed Iris flowers but strongly inhibits it in water-stressed flowers.

The floral buds of Iris flowers (Iris x hollandica) are enclosed by two sheath leaves. Flower opening depends on lifting the flower up to a position whereby the tepals can move laterally. This upward movement is carried out by elongation of the subtending pedicel and ovary.

Classes of programmed cell death in plants, compared to those in animals.

Relatively little is known about programmed cell death (PCD) in plants. It is nonetheless suggested here that tonoplast rupture and the subsequent rapid destruction of the cytoplasm can distinguish two large PCD classes. One class, which is here called 'autolytic', shows this feature, whilst the second class (called 'non-autolytic') can include tonoplast rupture but does not show the rapid cytoplasm clearance.

Do plastids in Dendrobium cv. Lucky Duan petals function similar to autophagosomes and autolysosomes?

In animal cells a double-membrane-bound structure, the autophagosome, encloses a portion of the cytoplasm. The encapsulated material becomes digested after fusion of the autophagosome with a vesicle containing lytic enzymes. The autophagosome is then termed autolysosome.