Physiological Aspects of Parasitism in Mistletoes (<i>Arceuthobium</i> and <i>Phoradendron</i>). II. The Photosynthetic Capacity of Mistletoe

Hull, Richard T.; Leonard, O. A.

doi:10.1104/pp.39.6.1008

Cited by 65 publications

(27 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Following the early work of Hull and Leonard (7,8), Ehleringer, Schulze and co-workers (5,18) have shed light on the principles underlying diversion of host resources to xylem-tapping mistletoes. A common feature is that mistletoe leaves have a Tn' in excess of that of their host, thus favoring the flux of resources to the parasite.…”

mentioning

confidence: 99%

Gas Exchange Characteristics of the Sorghum-Striga Host-Parasite Association

Press¹,

Tuohy²,

Stewart³

1987

Plant Physiol.

View full text Add to dashboard Cite

Gas exchange characteristics are reported for both members of the sorghum-Striga host-parasite association. Both Striga hermonthica (Del.) Benth and Striga asiatica (L.) Kuntze had transpiration rates considerably in excess of those of sorghum (Sorghum bicolor (L.) Moench, cv CSH1). Stomatal conductance in both Striga spp. showed little response to periods of darkness and moderate water stress. Low rtes of net CO2 fixation and high rates of dark respiration led to no net daily (24 hours) C gan, and Striga would appear to be reliant on its host for photosynthate. Infection of sorghum plants with either S. hermoxthica or S. asiatica reduced host photosynthetic capacity. Infected sorghum plants were also more prone to water stress, but reduced rates of CO2 fixation could not be accounted for in terms of lower stomatal conductance. Lower stomatal conductances were associated with an increase in water use efficiency (WUE) in uninfected sorghum; however, Strigainfected sorghum plants had lower WUE than those of uninfected plants.We suggest that Striga exerts a specific effect on processes affecting C acquisition in sorghum leaves. The water relations of S. hennonthica and S. asiatica are not characteristic of plants growing in semiarid environments and are more likely to reflect the nature of the parasitic life-style. Despite transfer of water and solutes from host to parasite, the reduction in C fixation observed in infected sorghum plants appears to be the major determinant of growth reductions observed in sorghum supportng Striga Parasitic angiosperms rely on one or more neighboring plants (the host) either partially or totally for the acquisition of water, inorganic and organic solutes. Transfer is achieved via the haustorium, which may be located either above ground (e.g. green leafy mistletoes) or below ground (e.g. Striga) and links the Striga hermonthica and Striga asiatica (Scrophulariaceae) are parasitic on members of the Gramineae. They are the most serious cause of yield reduction in sorghum in the rainfed semiarid tropics (3). Their low photosynthetic activity compared to autotrophic Scrophulariaceae (12,19) coupled with the reduction in productivity of host plants (1), suggests a dependence on host photosynthate. In addition, Striga has only a vestigial root system, making independent uptake of water and inorganic solutes unlikely.In comparison with autotrophic Scrophulariaceae, Striga has a high Tn and poor stomatal control (19) and may have mechanisms in common with the mistletoes for the withdrawal of host transport fluids.In this paper we compare the C and H20 relations of sorghum and Striga, and consider: (a) the extent to which Striga is reliant on host photosynthate, (b) the effects of parasitism on host C acquisition, (c) the extent to which Striga employs a high Tn for the diversion of host water and solutes, and (d) the consequences of an additional water sink on the water status of the host. MATERIALS AND METHODSPlant Material and Growth Conditions. Sorghum (Sorghum bicolor (L.) M...

show abstract

mentioning

confidence: 99%

Gas Exchange Characteristics of the Sorghum-Striga Host-Parasite Association

Press¹,

Tuohy²,

Stewart³

1987

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…Carbohydrate storage in the dwarf mistletoe endophytic system before thinning could reduce dependence of mistletoe on resources from the host tree supplied after thinning. Early studies suggested that carbohydrate acquired by dwarf mistletoes from host xylem sap accumulated primarily in the endophytic system (Rediske and Shea 1961;Hull and Leonard 1964b). However, more recent evidence from A. oxycedri indicated accumulation of most compounds, including carbohydrates, in the aerial shoots of dwarf mistletoe with little accumulation in the endophytic system (Rey et al 1991).…”

Section: Discussionmentioning

confidence: 96%

“…The dwarf mistletoes are similar to the leafy mistletoes of the Loranthaceae and other families because they acquire all of their water and nutrients from their hosts (Fisher 1983;Lamont 1983). However, dwarf mistletoes differ from many other types of mistletoe because they are essentially leafless and are more heterotrophic (Hull and Leonard 1964b;Miller and Tocher 1975;Logan et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Host physiological condition regulates parasitic plant performance: Arceuthobium vaginatum subsp. cryptopodum on Pinus ponderosa

2005

View full text Add to dashboard Cite

Much research has focused on effects of plant parasites on host-plant physiology and growth, but little is known about effects of host physiological condition on parasite growth. Using the parasitic dwarf mistletoe Arceuthobium vaginatum subsp. cryptopodum (Viscaceae) and its host Pinus ponderosa, we investigated whether changes in host physiological condition influenced mistletoe shoot development in northern Arizona forests. We conducted two studies in two consecutive years and used forest thinning (i.e., competitive release) to manipulate host physiological condition. We removed dwarf mistletoe shoots in April, before the onset of the growing season, and measured the amount of regrowth in the first season after forest thinning (Study I: n=38 trees; Study II: n=35 trees). Thinning increased tree uptake of water and carbon in both studies, but had no effect on leaf N concentration or delta13C. Mistletoe shoot growth was greater on trees with high uptake of water and carbon in thinned stands than trees with low uptake in unthinned stands. These findings show that increased resource uptake by host trees increases resources to these heterotrophic dwarf mistletoes, and links mistletoe performance to changes in host physiological condition.

show abstract

“…Chlorophyll concentrations are low in some taxa like Arceuthobium and Tristerix aphyllus; in at least some leafy mistletoes, in contrast, the concentration of leaf chlorophyll appears to be roughly the same as that of the host (Hull and Leonard 1964b). The question of photosynthesis in mistletoes, however, must be seen in relation to the intake of water and nutrients from the host.…”

Section: Haustoria In Santalalesmentioning

confidence: 95%