Jasmonic acid induced resistance in grapevines to a root and leaf feeder

We investigated the effects of induced resistance to the folivore Pacific spider mite, Tetranychus pacificus McGregor (Acari: Tetranychidae), as well as the root-feeding grape phylloxera Daktulosphaira vitifoliae (Fitch) (Homoptera: Phylloxeridae) in grapevines using exogenous applications of the natural plant inducer, jasmonic acid. Foliar jasmonic acid application at concentrations that caused no phytotoxicity significantly reduced the performance of both herbivores. There were less than half as many eggs produced by spider mites feeding on the induced leaves compared with control grapevine leaves. Induction reduced the numbers of phylloxera eggs and nymphal instars by approximately threefold and twofold, respectively, on induced compared with control grapevine roots. The negative demographic effects of jasmonic acid application appeared to be caused by changes in fecundity for the Pacific spider mite, and possibly changes in development rate and fecundity for grape phylloxera.     

Seasonality of herbivory and communication between individuals of sagebrush

Seasonal changes in herbivore numbers and in plant defenses are well known to influence plant–herbivore interactions. Some plant defenses are induced in response to herbivore attack or cues correlated with risk of attack although seasonal variation in these defenses is relatively poorly known. We previously reported that sagebrush becomes more resistant to its herbivores when neighboring plants have been experimentally clipped with scissors. In this study we asked whether herbivory to leaves of sagebrush varied seasonally and whether there was seasonal variation in natural levels of damage when neighbors were clipped. We found that sagebrush accumulated most chewing damage early in the season, soon after the spring flush of new leaves. This damage was caused by generalist grasshoppers, deer, specialist caterpillars, beetles, gall makers, and other less common herbivores. Sagebrush showed no evidence of preferentially abscising leaves that had been experimentally clipped. Experimental clipping by Trirhabda pilosa beetle larvae caused neighbors to accumulate less herbivore damage later that season, similar to results in which clipping was done with scissors. Induced resistance caused by experimentally clipping a neighbor was affected by season; plants with neighbors clipped in May accumulated less damage throughout the season relative to plants with unclipped neighbors or neighbors clipped later in the summer. We found a correlation between seasonal herbivore pressure, damage accumulated by plants, and induced responses to experimentally clipping neighbors. The causal mechanisms responsible for this correlation are unknown although a strong seasonal effect was clear.     

Microbial Transport, Survival, and Succession in a Sequence of Buried Sediments

Abstract Two chronosequences of unsaturated, buried loess sediments, ranging in age from <10,000 years to >1 million years, were investigated to reconstruct patterns of microbial ecological succession that have occurred since sediment burial. The relative importance of microbial transport and survival to succession was inferred from sediment ages, porewater ages, patterns of abundance (measured by direct counts, counts of culturable cells, and total phospholipid fatty acids), activities (measured by radiotracer and enzyme assays), and community composition (measured by phospholipid fatty acid patterns and Biolog substrate usage). Core samples were collected at two sites 40 km apart in the Palouse region of eastern Washington State, near the towns of Washtucna and Winona. The Washtucna site was flooded multiple times during the Pleistocene by glacial outburst floods; the Winona site elevation is above flood stage. Sediments at the Washtucna site were collected from near surface to 14.9 m depth, where the sediment age was approximately 250 ka and the porewater age was 3700 years; sample intervals at the Winona site ranged from near surface to 38 m (sediment age: approximately 1 Ma; porewater age: 1200 years). Microbial abundance and activities declined with depth at both sites; however, even the deepest, oldest sediments showed evidence of viable microorganisms. Same-age sediments had equal quantities of microorganisms, but different community types. Differences in community makeup between the two sites can be attributed to differences in groundwater recharge and paleoflooding. Estimates of the microbial community age can be constrained by porewater and sediment ages. In the shallower sediments (<9 m at Washtucna, <12 m at Winona), the microbial communities are likely similar in age to the groundwater; thus, microbial succession has been influenced by recent transport of microorganisms from the surface. In the deeper sediments, the populations may be considerably older than the porewater ages, since microbial transport is severely restricted in unsaturated sediments. This is particularly true at the Winona site, which was never flooded.     

Effects of herbivory and plant conditioning on the population dynamics of spider mites

Plants vary in their resistance to tetranychid spider mites, and this can have profound effects on spider-mite population dynamics. Such variation can be attributable to many factors. In this review, however, we focus on how previous or concurrent feeding by phytophagous hervivores influences expression of plant resistance to spider mites.Induced resistance is a change in the host plant in response to extrinsic stimuli, resulting in reduced host suitability for the population growth of spider mites. We begin our review by summarizing the different ways in which spider mites and plants interact to produce induced resistance-like phenomena. We then discuss a number of hypotheses which address the mechanisms underlying induced resistance and end by suggesting agricultural applications. Although the potential use of induced resistance to manage spider mites is apparent, progress in this area will depend on a better understanding of the mechanisms involved and their associated costs and benefits to the plant.     

Associational resistance for mule’s ears with sagebrush neighbors

Many examples of associational resistance have been reported, in which a plant’s neighbors reduce the rate of damage by herbivores that it experiences. Despite 30 years of interest and hundreds of examples of associational resistance, we still know very little about how plants avoid their herbivores. This lack of mechanistic understanding prevents us from predicting when or where associational resistance will be important or might affect species’ distributions. I demonstrate here that the plant neighborhoods that surrounded focal mule’s ears (Wyethia mollis) individuals affected the damage they received. In particular, distance between a focal mule’s ears individual and its nearest sagebrush neighbor (Artemisia tridentata) was a good predictor of how much leaf area the mule’s ears would lose to herbivores over 2 years. Mule’s ears close to sagebrush suffered less loss than those with more distant nearest sagebrush neighbors. Mule’s ears with near sagebrush neighbors suffered half the leaf loss as mule’s ears with sagebrush experimentally removed. This associational resistance was probably not caused by sagebrush attracting or increasing populations of predators of generalist herbivores. Sagebrush is known to emit chemicals that are feeding deterrents to generalist grasshoppers and these deterrents were probably involved here. Volatile chemicals emitted by damaged sagebrush have been found to induce resistance in neighboring plants of several species. However, I found no evidence for such eavesdropping here as mule’s ears gained associational resistance from sagebrush neighbors whether or not those sagebrush neighbors had been experimentally damaged. Understanding the mechanisms responsible for associational resistance is critical to predicting where and when it will be important.     

Prolonged exposure is required for communication in sagebrush

Volatile communication allows plants to coordinate systemic induced resistance against herbivores. The mechanisms responsible and nature of the cues remain poorly understood. It is unknown how plants distinguish between reliable cues and misinformation. Previous experiments in which clipped sagebrush branches were bagged suggested that cues are emitted or remain active for up to 3 days. We conducted experiments using plastic bags to block emission of cues at various times following experimental clipping. We also collected headspace volatiles from clipped and unclipped branches for 1 h, transferred those volatiles to assay branches, and incubated the assays for either 1 or 6 h. We found that assay branches that received volatile cues for less than 1 h following clipping of neighbors failed to induce resistance. Assay branches that received volatile cues for more than 1 h experienced reduced herbivory throughout the season. Branches incubated for 6 h with volatiles that had been collected during the first hour following clipping showed induced resistance. These results indicate that sagebrush must receive cues for an extended time (>1 h) before responding; they suggest that the duration of cue reception is an important and overlooked process in communication allowing plants to avoid unreliable, ephemeral cues.     

Self-recognition affects plant communication and defense

Animals have the ability to distinguish self from non-self, which has allowed them to evolve immune systems and, in some instances, to act preferentially towards individuals that are genetically identical or related. Self-recognition is less well known for plants, although recent work indicates that physically connected roots recognize self and reduce competitive interactions. Sagebrush uses volatile cues emitted by clipped branches of self or different neighbours to increase resistance to herbivory. Here, we show that plants that received volatile cues from genetically identical cuttings accumulated less natural damage than plants that received cues from non-self cuttings. Volatile communication is required to coordinate systemic processes such as induced resistance and plants respond more effectively to self than non-self cues. This self/non-self discrimination did not require physical contact and is a necessary first step towards possible kin recognition and kin selection.     

Utilization of nosylepimines of 1,6-anhydro-beta-D-hexopyranoses for the preparation of halogenated aminosaccharides

The aziridine ring cleavage of N-nosylepimines 3 and 7 having d-allo and d-manno configurations with halides led regioselectively to N-o-nitrobenzenesulfonylated 2-halo-3-amino- and 3-halo-2-amino-2,3-dideoxy derivatives of 1,6-anhydro-β-d-glucopyranose 8-14 in 59-81% yields. Removal of o-nitrobenzenesulfonyl protecting group with benzenethiol afforded aminosaccharides, which were converted into more stable hydrochlorides 15-18.     

Biallelic IgH rearrangements in patients with indolent lymphoproliferative disorders: molecular and practical implications

We report a group of patients (pts) with indolent lymphoproliferative disorder who had both alleles for the immunoglobulin heavy chain genes rearranged (biIgH). This group of 17 pts consisted of 9 small lymphocytic lymphomas (SLL) and 8 chronic lymphocytic leukemia (CLL). The polymerase chain reaction (PCR) amplification of clonal immunoglobulin heavy (IgH) rearrangement using the complementarity determining region III (CDRIII) constantly retrieved two distinct bands in all PCR informative samples of those pts. To rule out biclonality, we evaluated samples by fluorescein activated cell sorting (FACS) analysis and sequenced the PCR products. We were able to obtain both IgH sequences from 12 patients. FACS suggested biclonality in one case, which also correlated with sequencing results as both IgH rearrangements were in-frame. Recently, we reported a patient who sustained transformation into an aggressive disease after biIgH was detected in the setting of monoclonal disease (Cerny et al., 2003b, Haematologica 88(05):ECR15 B.). We decided to compare clinical characteristics and prognosis of 17 pts with biIgH and 37 pts with monoIgH rearrangements. Although we found some minor differences in disease characteristics between both groups, these did not translate into a significantly different overall survival. Our findings suggest that true biclonal cases of CLL are rare.     

Consequences of variation in flowering phenology for seed head herbivory and reproductive success in Erigeron glaucus (Compositae)

Summary We examined the relationship between flowering phenology, reproductive success (seed production only), and seed head herbivory for 20 similarly sized clones of Erigeron glaucus growing at Bodega Bay Reserve, northern California, USA. Although clones tended to reach peak flowering on the same date, they differed in the proportion of their total flowers produced around that date (flowering synchrony). Clones also differed in the number and density of flower heads presented at any one time to pollinators and herbivores (floral display). Both of these characteristics had consequences for herbivory and plant reproductive success. The proportion of flower heads damaged by insect herbivores was greater for clones that concentrated flowering activity during the main flowering period for the population as a whole (high synchrony) compared to clones that spread flowering out temporally. The primary reason for this result was that clones with low flowering synchrony produced a significant proportion of their flower heads during the fall and therefore, escaped attack by the tephritid fly, Tephritis ovatipennis. Clones with intermediate synchrony had lower seed success (total number of viable seeds produced over the year) than clones with either low or high synchrony. The proportion of flower heads damaged by insect herbivores and number of tephritid flies reared from flower heads were both negatively correlated to floral display while seed head mass and germination rates were positively related to display. Thus, clones which produced dense floral displays were favored both in terms of reduced herbivory and increased successful seed production.