Expression of Arabidopsis Bax Inhibitor‐1 in transgenic sugarcane confers drought tolerance

The sustainability of global crop production is critically dependent on improving tolerance of crop plants to various types of environmental stress. Thus, identification of genes that confer stress tolerance in crops has become a top priority especially in view of expected changes in global climatic patterns. Drought stress is one of the abiotic stresses that can result in dramatic loss of crop productivity. In this work, we show that transgenic expression of a highly conserved cell death suppressor, Bax Inhibitor‐1 from Arabidopsis thaliana (AtBI‐1), can confer increased tolerance of sugarcane plants to long‐term (>20 days) water stress conditions. This robust trait is correlated with an increased tolerance of the transgenic sugarcane plants, especially in the roots, to induction of endoplasmic reticulum (ER) stress by the protein glycosylation inhibitor tunicamycin. Our findings suggest that suppression of ER stress in C₄ grasses, which include important crops such as sorghum and maize, can be an effective means of conferring improved tolerance to long‐term water deficit. This result could potentially lead to improved resilience and yield of major crops in the world.     

GEITLERINEMA SPECIES (OSCILLATORIALES,CYANOBACTERIA) REVEALED BY CELLULAR MORPHOLOGY,ULTRASTRUCTURE, AND DNA SEQUENCING1

Geitlerinema amphibium (C. Agardh ex Gomont) Anagn. and G. unigranulatum (Rama N. Singh) Komárek et M. T. P. Azevedo are morphologically close species with characteristics frequently overlapping. Ten strains of Geitlerinema (six of G. amphibium and four of G. unigranulatum) were analyzed by DNA sequencing and transmission electronic and optical microscopy. Among the investigated strains, the two species were not separated with respect to cellular dimensions, and cellular width was the most varying characteristic. The number and localization of granules, as well as other ultrastructural characteristics, did not provide a means to discriminate between the two species. The two species were not separated either by geography or environment. These results were further corroborated by the analysis of the cpcB‐cpcA intergenic spacer (PC‐IGS) sequences. Given the fact that morphology is very uniform, plus the coexistence of these populations in the same habitat, it would be nearly impossible to distinguish between them in nature. On the other hand, two of the analyzed strains were distinct from all others based on the PC‐IGS sequences, in spite of their morphological similarity. PC‐IGS sequences indicate that these two strains could be a different species of Geitlerinema. Using morphology, cell ultrastructure, and PC‐IGS sequences, it is not possible to distinguish G. amphibium and G. unigranulatum. Therefore, they should be treated as one species, G. unigranulatum as a synonym of G. amphibium.     

Variability in reproductive traits in Jatropha curcas L. accessions during early developmental stages under warm subtropical conditions

Variability in floral, fruit, and seed characteristics, and oil content of 15 accession of Jatropha curcas during early development were assessed during two flowering periods in south Florida subtropical climate. The two flowering periods had leaf flushing in March. Field evaluation using 18 quantitative traits showed significant variation among accessions. The number of female flowers and female : male flower ratio ranged from 1 to 15 and 1 : 8.8 to 1 : 67.8, respectively. Fruit set by natural pollination was 89 and 66% during the first (1st) and second (2nd) flowering periods, respectively. A higher number of female‐type inflorescences were observed during summer. There were significant differences in seed traits, except for number of seeds per fruit. Accession TREC 31 had the highest individual seed dry weight and 100‐seed weight (0.83 g and 79.7 g, respectively). The oil content varied from 19.30% to 35.62%. Seed dry weight had positive correlation with seed fresh weight, seed length, seed thickness, seed width, and 100‐seed weight, but negative correlation with oil content. Based on the cluster analysis using 15 morphological traits, jatropha accessions were grouped into five main clusters and accessions from different geographic regions grouped together in a cluster. Principal component analyses (PCA) revealed morphological variation. The first three components explained 73.5% of the total variation and seed dry weight, 100‐seed weight, total flowers per inflorescence, male flowers per inflorescence and fruit set can be used to distinguish accessions. The PCA also indicated that flowering traits were more influenced by seed origin while seed traits were affected by flowering spans. Although evaluations were performed in plants during the juvenile phase, accessions TREC 31 and TREC 55 had superior averages for almost all characters evaluated. These results provide a preliminary assessment of the high variability in jatropha accessions evaluated and their potential for use in breeding and genetic improvement programs.     

Worker demography in a large-colony,swarm-founding wasp

Neotropical swarm-founding wasps build nests enclosed in a covering envelope, which makes it difficult to count individual births and deaths. Thus, knowledge of worker demography is very limited for swarm-founding species compared with that for independent-founding species. In this study, we explored the worker demography of the swarm-founding wasp Polybia paulista, the colony size of which usually exceeds several thousand adults. We considered each wasp colony as an open-population and estimated the survival probability, recruitment rate, and population size of workers using the developments of the Cormack–Jolly–Seber model. We found that capture probability varied considerably among the workers, probably due to age polyethism and/or task specialization. The daily survival rate of workers was high (around 0.97) throughout the season and was not related to the phase of colony development. On the other hand, the recruitment rate ranged from 0 to 0.37, suggesting that worker production was substantially less important than worker survival in determining worker population fluctuations. When we compared survival rates among worker groups of one colony, the mean daily survival rate was lower for founding workers than for progeny workers and tended to be higher in progeny workers that emerged in winter. These differences in survivorship patterns among worker cohorts would be related to worker foraging activity and/or level of parasitism.     

Quick and accurate detection of Sclerotinia sclerotiorum and Phomopsis spp. in soybean seeds using qPCR and seed‐soaking method

Seed‐borne pathogenic fungi can cause serious damage to soybean crops by reducing the germination, vigour and emergence of the seeds. Special attention should be paid to pathogen detection in seeds to prevent its introduction in disease‐free areas. Considering the importance of rapid and successful diagnosis of seed‐borne pathogenic fungi in soybeans, this study evaluated a method to detect Sclerotinia sclerotiorum and Phomopsis spp. in seeds using quantitative polymerase chain reaction (qPCR). Naturally infested samples were subjected to detection using qPCR and blotter test, and the findings were compared. Using soybean seeds soaked in water, both pathogens were detected at an infestation level up a 0.0625% (one infected seed out of 1,599 healthy seeds) by qPCR. This technique allowed the detection of 300 fg of S. sclerotiorum and 30 fg of Phomopsis spp. DNA in the seed samples. Phomopsis spp. was detected in 40.7% of the evaluated seed batches (81 batches) and S. sclerotiorum was detected in 32.1% of the evaluated batches, although most of the seeds had low infestation levels. It was up to 28.5 times more efficient to use qPCR rather than blotter test to detect pathogens with a low incidence of occurrence in soybean seeds. If routinely used to test healthy seeds, qPCR would contribute to reducing soybean losses due to diseases as well as decreasing the costs required to control those diseases.     

The acceptance rate of young wasps by alien colonies depends on colony developmental stages in the swarm-founding wasp, Polybia paulista von ihering (Hymenoptera: Vespidae)

In social insects, newly emerged individuals learn the colony-specific chemical label from their natal comb shortly after their emergence. These labels help to identify each individual's colony of origin and are used as a recognition template against which individuals can discriminate nestmates from non-nestmates. Our previous studies with Polybia paulista von Ihering support this general pattern, and the acceptance rate of young female and male wasps decreased as a function of their age. Our study also showed in P. paulista that more than 90% of newly emerged female wasps might be accepted by conspecific unrelated colonies. However, it has not been investigated whether the acceptance rate of newly emerged female wasps depends on colony developmental stage of recipient colonies. We introduced newly emerged female wasps of P. paulista into different colony developmental stags of recipient colonies, i.e., worker-producing and male-producing colonies. We found that the acceptance rate of newly emerged female wasps by alien colonies was pretty lower by male-producing colonies than worker-producing colonies. This is the first study to show that the acceptance rate of young female wasps depends on stages of recipient colonies.     

Taxonomic investigation using DNA fingerprinting in Geitlerinema species (Oscillatoriales, Cyanobacteria)

The taxonomic study of 14 strains of Geitlerinema amphibium (Ag. ex Gom.) Anagnostidis and Geitlerinema unigranulatum (R.N. Singh) Komárek and Azevedo, coming from several localities was undertaken. Use was made of morphological data and molecular data were obtained by means of the DNA fingerprinting technique using highly iterated palindrome (HIP1) sequences. The employed morphological characteristics were those used for species taxonomic identification belonging to the Geitlerinema genus, namely, cell dimensions, shape of the apical cell, motility, number and localization of cyanophycin granules in the cell. The two species revealed as polymorphic were discriminated only by means of the average cellular diameters. In spite of this, minima and maxima values of the cellular diameters overlapped. It was found from molecular analysis that a high genetic diversity and the formation of two clusters consisted of G. amphibium and G. unigranulatum, plus a sole strain keeping itself isolated from the remaining. Also, these clusters were not related to the geographic location; they encompassed strains from water bodies distant from each other by as much as 3500 km, or Brazilian and Spanish strains. Molecular and morphological data support the possibility that G. unigranulatum could be considered a synonym for G. amphibium. HIP1 fingerprinting is a powerful tool for the study of genetic of cyanobacteria closely related taxa. This study points to the necessity of using other than morphological data in the taxonomic revision of cyanobacteria, as well as in the proposition of new taxons.     

Antioxidative responses and morpho-anatomical adaptations to waterlogging in Sesbania virgata

Sesbania virgata (Leguminosae) is tolerant of long periods of soil inundation. However, its morphological adaptations to anoxia and its response to possible damage from oxidative stress are still unknown. Here, we provide new information that helps to explain the ability of S. virgata plants to grow in flooded environments. Plants containing six expanded leaves were placed in masonry tanks and were subjected to the following conditions: control (well watered), soil waterlogging (water to the setup level of 1 cm above the soil surface—roots and parts of the stems flooded), and complete submergence (whole plant flooded). Plants exposed to flooding (soil waterlogging and complete submergence) significantly increased their production of hydrogen peroxide (H₂O₂), indicating the extent of oxidative injury posed by stress conditions. We demonstrate that plants exposed to flooding develop an efficient scavenger of ROS (generated during stress) in the roots through the coordinated action of nonenzymatic ascorbic acid (Asc) and dehydroascorbate (DHA) as well as the enzymatic antioxidants superoxide dismutase (SOD), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) that are present in the tissues. Moreover, we observed the development of morpho-anatomical structures such as adventitious roots, lenticels, and cracks in the stem of plants under soil waterlogging. The secondary root of plants under soil waterlogging showed a thinner cortex and larger number of elements of small diameter vessels. Numerous aerenchymas were observed in the newly formed in the adventitious roots. We conclude that these antioxidative responses and morpho-anatomical adaptations in the roots are part of a suite of adaptations that allow S. virgata plants to survive long periods of flooding, notably under waterlogged conditions.