MdWRKY75e enhances resistance to Alternaria alternata in Malus domestica

The Alternaria alternata apple pathotype adversely affects apple (Malus domestica Borkh.) cultivation. However, the molecular mechanisms underlying enhanced resistance to this pathogen in apple remain poorly understood. We have previously reported that MdWRKY75 expression is upregulated by A. alternata infection in ‘Sushuai’ apples. In this study, we discovered that overexpression of MdWRKY75e increased the resistance of transgenic apple lines to A. alternata infection, whereas silencing this gene enhanced susceptibility to A. alternata infection. Furthermore, we found that MdWRKY75e directly binds to the MdLAC7 promoter to regulate the biosynthesis of laccase and increase the biosynthesis of lignin during A. alternata infection. Moreover, the thickening of the cell wall enhanced the mechanical defense capabilities of apple. In addition, we found that jasmonic acid remarkably induced MdWRKY75e expression, and its levels in transgenic apple lines were elevated. These results indicate that MdWRKY75e confers resistance to the A. alternata apple pathotype mainly via the jasmonic acid pathway and that pathogenesis-related genes and antioxidant-related enzyme activity are involved in the disease resistance of MdWRKY75e transgenic plants. In conclusion, our findings provide insights into the importance of MdWRKY75e for resistance to A. alternata infection in apples.

Modelling and Manufacturing of Progressive die for Mechanical Press Operations

A progressive die is a type of die in which multiple operations performed in a single stroke, which was mostly used in sheet metal operations. The working process of sheet metal is widely used in all manufacturing industries such as mechanical, defense and automotive etc. The key advantage of metal working process involves enhancement of production rate and cost reduction. This paper is aimed to develop a multi-functional die which can perform simultaneously both punching and blanking operations in one stroke. The present work is mainly focused on modeling and manufacturing of the die components, where PRO-E was used for modelling and FANUC controlled CNC machine was used to execute and prepared part program.

Are extrafloral nectaries efficient against herbivores? Herbivory and plant defenses in contrasting tropical species

Aims Plants have limited resources for defenses and species that invest in biotic defenses might exhibit leaves that invest less in other types of defenses. We have investigated whether plants that have few mechanical defenses, but have extrafloral nectaries (EFNs) patrolled by ants, are less prone to herbivory, compared with plants without EFNs that have tougher leaves. Methods Data from the literature were extracted to examine the reported levels of herbivory in plants with or without EFNs. In a savanna vegetation in southern Brazil, field data were collected in leaves from six tropical species and herbivory and specific leaf area (SLA) levels were measured. We further evaluated differences in herbivory and SLA among species and between plants with or without EFNs. In order to test the relationship between herbivory and leaf toughness we regressed average herbivory and average SLA per plant. Important Findings Plants exhibited variable levels of leaf damage, but plants without ant defenses experienced the highest levels of leaf area loss to herbivory. Levels of mechanical defenses were also variable among the plant species. Plants without EFNs were tougher, exhibiting lower values of SLA. Although plants without EFNs had more sclerophyllous leaves, this mechanical defense was not sufficient to impair and/or reduce herbivore feeding, suggesting that the biotic defenses performed by patrolling ants might be more effective than investment in mechanical defenses associated with leaf palatability.

Asteraceae Paradox: Chemical and Mechanical Protection of Taraxacum Pollen

Excessive pollen harvesting by bees can compromise the reproductive success of plants. Plants have therefore evolved different morphological structures and floral cues to narrow the spectrum of pollen feeding visitors. Among “filtering” mechanisms, the chemical and mechanical protection of pollen might shape bee-flower interactions and restrict pollen exploitation to a specific suite of visitors such as observed in Asteraceae. Asteraceae pollen is indeed only occasionally exploited by generalist bee species but plentifully foraged by specialist ones (i.e., Asteraceae paradox). During our bioassays, we observed that micro-colonies of generalist bumblebee (Bombus terrestris L.) feeding on Taraxacum pollen (Asteraceae) reduced their pollen collection and offspring production. Bees also experienced physiological effects of possible defenses in the form of digestive damage. Overall, our results suggest the existence of an effective chemical defense in Asteraceae pollen, while the hypothesis of a mechanical defense appeared more unlikely. Pre- and post-ingestive effects of such chemical defenses (i.e., nutrient deficit or presence of toxic compounds), as well as their role in the shaping of bee-flower interactions, are discussed. Our results strongly suggest that pollen chemical traits may act as drivers of plant selection by bees and partly explain why Asteraceae pollen is rare in generalist bee diets.

Pod and seed defensive coloration (camouflage and mimicry) in the genus Pisum

The small genusPisumis composed of two annual species,P.fulvumand the domesticated peaP.sativum. The domesticated pea has two main wild-type taxa:P.elatiusandP.humile. Members of the genusPisumare not well defended from herbivory by high levels of toxins like the seeds of many other legume species. We studied the color patterns in the pods and seeds of these three wild taxa (P.fulvum,P.elatiusandP.humile) in order to examine their potential for defensive coloration (camouflage and Batesian mimicry). All three taxa are polymorphic concerning pod and seed coloration. The mature pods of many individuals ofP.humileandP.elatiusmimic aposematic caterpillars, but some are plain green. The pods of some individuals ofP.elatiushave a zigzag or straight red marking along them that resembles the conspicuous dorsal markings of the local common venomous viper, potentially mimicking it. The pods of many individuals ofP.fulvumhave dark blotches that when compared to such patterns in animals, potentially function as camouflage. The seeds of all three species are camouflaged by either: (1) color matching with that of soil (especiallyP.fulvumandP.elatius), (2) disruptive coloration (especiallyP.humile), (3) variability in seed-coat color that may undermine the use of search images by visually oriented granivores that look for cryptic seeds (all taxa). The mature pods ofP.fulvumare also defended in many inflorescences by degenerated flowers that develop into sharp thorns. It seems that this species is still in the process of evolving this mechanical defense as the response to millennia of strong grazing pressure.

Associations of Two Ecologically Significant Social Insect Taxa in the Litter of an Amazonian Rainforest: Is There a Relationship between Ant and Termite Species Richness?

In spite of the ecological dominance of Neotropical ants and termites, little is understood about how their interactions influence their species richness and distribution. We surveyed ground-dwelling termite and ant species in a primary rainforest in Ecuador and analyzed ecological correlates of diversity. Termite richness was positively correlated with ant richness and abundance of twig-nesting ants. We found no evidence of competition for twigs between termites and ants. No ecological factors were correlated with termite diversity although elevation and twig and log abundance influenced ant diversity. When ant richness was compared to the richness of termites employing different predator defenses, a positive correlation was found with soldierless termites, but not genera employing chemical or mechanical defense. Our results suggest that multiple ecological factors influence ant and termite diversity, and that ant predation on termites may have a greater effect than competition between ant and termites for nest sites and food sources.

Water content and reserve allocation patterns within the bulb of the perennial geophyte red squill (Liliaceae) in relation to the Mediterranean climate

The patterns of water content and reserve allocation in the bulb parts of red squill ( Urginea maritima (L.) Baker) and the plant’s adaptive strategy to Mediterranean climate (Crete, Greece) were investigated. The different bulb parts serve varying ecological functions in terms of their resources and their importance for these functions. The basal plate is the active centre, developing one or two apical meristems and roots in autumn, as well as the flowering bud in late summer. The middle of the bulb (approximately the third bulb scale) stores the resources and the tunics (the outer covering structures) that provide mechanical defense. The water content and reserve allocation patterns synchronize the plant’s phenological development with the seasonality of the Mediterranean climate. The adaptive strategies are based on the development of a deciduous semisubterranean life form primarily for the avoidance of drought, herbivores, and other environmental hazards, as well as nutrient shortage. The presence of cells containing lipids, polysaccharides, raphides, water, mucilage, bufadienolides, the presence of sclerenchyma, the tightly packed epidermis, and the presence of the tunics facilitate this.