Diversity of fungal pathogens associated with loquat and development of novel virulence scales

Loquat [Eriobotrya japonica (Thunb.) Lindl.] is an important fruit crop in Pakistan; however, a constant decline in its production is noted due biotic and abiotic stresses, particularly disease infestation. Fungal pathogens are the major disease-causing agents; therefore, their identification is necessary for devising management options. This study explored Taxila, Wah-Cantt, Tret, Chatar, Murree, Kalar-Kahar, Choa-Saidan-Shah and Khan-Pur districts in the Punjab and Khyber Paktoon Khawa (KPK) provinces of Pakistan to explore the diversity of fungal pathogens associated with loquat. The samples were collected from these districts and their microscopic characterizations were accomplished for reliable identification. Alternaria alternata, Curvularia lunata, Lasiodiplodia theobromae, Aspergilus flavis, Botrytis cinerea, Chaetomium globosum, Pestalotiopsis mangiferae and Phomopsis sp. were the fungal pathogens infesting loquat in the study area. The isolates of A. alternata and C. lunata were isolated from leaf spots and fruit rot, while the isolates of L. theobromae were associated with twig dieback. The remaining pathogens were allied with fruit rot. The nucleotide evidence of internal transcribed spacer (ITS) regions (ITS1, 5.8S, and ITS2) were computed from all the pathogens and submitted in the database of National Center for Biotechnology Information (NCBI). For multigene analysis, beta-tubulin (BT) gene and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) regions were explored for A. alternata and C. lunata isolates, respectively. The virulence scales of leaf spots, fruit rot, and twig dieback diseases of loquat were developed for the first time through this study. It is the first comprehensive study with morpho-molecular identification, and newly developed virulence scales of the fungal pathogens associated with loquat, which improves the understanding of these destructive diseases.

A Polyphasic Approach to Classification and Identification of Species within the Trichophyton benhamiae Complex

In recent years, considerable advances have been made in clearing up the phylogenetic relationships within the Arthrodermataceae family. However, certain closely related taxa still contain poorly resolved species boundaries. Here, we tried to elucidate the species composition of the Trichophyton benhamiae species complex using a combined approach consisting of multi-gene phylogenetic analysis based on internal transcribed spacer (ITS) and beta-tubulin (BT) gene regions, morphological analysis, and spectral comparison using MALDI-ToF. We confirmed the existence of 11 different monophyletic clades within the complex representing either species or genetically distinct groups within species. MALDI-ToF spectrometry analysis revealed that most of these clades were readily distinguishable from one another; however, some closely related sister clades, such as T. europaeum and T. japonicum, were often misidentified as their counterpart. The distinct “yellow” and “white” phenotypes of T. benhamiae do not have a clear genetic basis and should thus be considered as different morphotypes of the same species. Strains traditionally considered T. benhamiae can be divided into three main clades: (i) T. benhamiae, (ii) T. europaeum/T. japonicum, and (iii) the phylogenetically distant T. africanum. While T. europaeum and T. japonicum are distinguishable based on their genotype, spectral and morphological analysis did not provide clear delimiting characteristics.

Development of event-specific detection method for identification of insect resistant NIBGE-1601 cotton harboring double gene Cry1Ac-Cry2Ab construct

Bt cotton expressing Cry1Ac is being cultivated in Pakistan. It has been observed that pink bollworm may have developed resistance against single Bt gene (Cry1Ac). For durable resistance, insect resistant NIBGE-1601 cotton harboring double gene Cry1Ac-Cry2Ab construct was developed. There was a need to characterize NIBGE-1601 event for intellectual property rights protection. The Presence of NIBGE Cry1Ac and NIBGE Cry2Ab genes was checked in NIBGE-1601 cotton plants through PCR, while there was no amplification using primers specific for Monsanto events (MON531, MON15985, MON1445). Using genome walking technology, NIBGE-601 event has been characterized. Event-specific primers of NIBGE-1601 were designed and evaluated to differentiate it from other cotton events mentioned above. NIBGE-1601 event detection primers are highly specific, therefore, can detect NIBGE 1601 event at different conditions using single or multiplex PCR. In the qualitative PCR, using NIBGE-1601 event specific primers, 0.05 ng was the limit of detection for NIBGE-1601double gene cotton genomic DNA. Thus event characterization and development of event-specific diagnostics will help in breeding new cotton varieties resistant to cotton bollworms.

PHYSIOLOGICAL RESPONSE OF CONVENTIONAL AND TRANSGENIC MAIZE TO WATER STRESS

Genetic modifications of plants can affect their ability to use environmental resources. It is known that the anthropic action has caused global climate changes, such as increases in temperature and drought. In view of this, the objective of this study was to evaluate if the addition of the Bt gene influences the physiological performance of isogenic maize hybrids grown under water stress and optimal conditions. Three Bt and non-Bt maize hybrids (Agromen 30A95, Dow 2B707 and BG 7049Y) were cultivated in soil with moisture content at 60% (water stress) and 100% of the field capacity (FC). Among the hybrids, the 30A95 presented greater variation between Bt and non-Bt hybrids in regard to physiological variables. The addition of the Bt gene practically had no impact on the photosynthetic performance of the 2B707 and BG7049 hybrids. The presence of the Bt gene increased the sensitivity to water stress in the hybrids, with reduction of maximal fluorescence and chlorophyll content in the plants. Regardless of the genetic factor (Bt or non-Bt), water stress reduced transpiration, stomatal conductance, photosynthetic rate, and maximum quantum yield of the PSII in maize plants. It was concluded that the presence of the Bt gene in maize indicates a reduction in the photosynthetic potential of the plant grown under water stress.

Bt cotton seed purity in Burkina Faso: Status and lessons learnt

BackgroundSince the commercial release of Bt cotton the issue of seed purity in producers' fields has been little addressed and in an unbalanced way when it was. It is well documented that the loss of purity in conventional seeds has endangered the continuation of organic cotton production. However, studies are rare on the purity of Bt-cotton seeds despite its implications on the effectiveness and sustainability of their use.This paper compensates for the mentioned lack of literature by analyzing data collected in 2015 in Burkina Faso, namely results of ELISA tests on samples of seeds from 646 fields grown with conventional or Bt varieties. ResultsAccording to the conservative criteria retained to declare the presence of Bt gene (more than 10% and 90% of controlled seeds for conventional and Bt variety, respectively), seed purity was very questionable for both types of varieties. For the conventional variety, the presence of Bt gene was observed on 63.6 and 59.3% of samples for Cry1Ac and Cry2Ab, respectively. Only 29.3% of samples corresponded to pure conventional seeds while 52.2% were double Bt seeds. Conversely, for the Bt variety, the presence of Bt gene was observed on 59.6 and 53.6% of samples for Cry1Ac and Cry2Ab, respectively. Actually BG2 seeds with both Bt genes were found in 40.4% of samples against 27.2% of samples of actually conventional seeds while the remaining of 32.4% of samples corresponded to single Bt gene seeds.Two factors affected the severe lack of seed purity. As regard to conventional seeds, it clearly resulted from a phenomenon of contamination, indicative of a failure in adjusting the seed production scheme to the use of Bt-cotton. With regard to the Bt variety, the lack of purity of the original seeds provided to Burkina Faso accounted and should even be the major factor.The observed lack of seed purity is a threat to the initiative of organic cotton production, albeit a very minor production mode in the country. It also calls upon the effectiveness and furthermore the sustainability of Bt cotton to control target pests. ConclusionOur results show the extent of purity loss when no especial attention is paid to the preservation of seed purity. Pure conventional seeds could totally vanish while Bt seeds become a combination of seeds of various types encompassing or not the expected Bt genes.Any country willing to embark the use of Bt cotton, or to resume this use like Burkina Faso, must previously adjust its seed production scheme and enforce its operation. This is a condition to preserve pure seeds both to enable the launch or the continuation of identity-cotton production and to ensure a sustainable effectiveness of Bt-cotton. The mentioned condition implies that seed purity must be checked and the related information shared.

Agronomic parameters and morpho-agronomic characteristics of genetically modified maize hybrids compared to conventional maize hybrids

The objectives were to study the behavior of fifteen pre-commercial upland maize hybrids, analyze their agronomic performance regarding grain yield, and evaluate productivity components, as well as morpho-agronomic characteristics, in the Midwest Region of Brazil. Two experiments were conducted in the municipalities of Formosa-GO and Planaltina-DF, 2016/17 crop year. Both consisted of five pre-commercial maize hybrid platforms (HPA252, HPB262, HPB621, HPB646, and HPD354). Each platform consisted of three different versions: conventional, transgenic with a Bt gene that expresses the protein Cry1F, and transgenic with two Bt genes that express the proteins Cry1F and Cry1AB. The experiment was randomized blocks with four replications. The experimental plot was four lines five meters long considering the two central lines as useful. The lines were spaced 0.75 meters apart, and the final density was five plants per linear meter. To estimate grain yield, the plots were harvested, and the weight was extrapolated to kg.ha-1. The moisture was standardized at 14%. Data were submitted to analysis of variance, and the means were compared by Tukey test at 5% probability using the Sisvar software. Grain yield between treatments ranged from 8,381 to 12,908 kg.ha-1, and the average yield was 11,234 kg.ha-1. The parameters evaluated were divided into two groups. The first group contained parameters determining grain yield: grain depth, thousand grains weight, number of rows of grains, number of grains per row, and grain yield. The second group contained morpho-agronomic parameters that directly interfere with resistance to lodging and plant breaking: plant height, ear insertion height, and mean stem diameter. There was no direct effect of the transgenes on the evaluated hybrids since the classification of productivity was not divided into conventional and transgenic classes. It is suggested that the HPA252YH, HP621H and HP646H versions be discarded because grain yield performance was unsatisfactory compared to their respective conventional and transgenic counterparts. The parameters GD and W1000 are more effective for grain yield estimation than NR and NG. It was observed for HP621H that, in addition to a lower grain yield, there was a significant reduction in stem diameter, indicating a possible reduction in lodging tolerance and/or plant breaking when exposed to adverse climatic conditions such as windstorms. For the HPD354H version, the release of the transgenic counterpart HPD354YH is preferentially indicated since the H version had a significant reduction in stem diameter and a possible greater tolerance to lodging and/or plant breaking under the same conditions.

Does the Introgression of Bt Gene Affect Physiological Cotton Response to Water Deficit?

ABSTRACT: Water deficit may affect the expression of lepidoptera-controlling proteins in cotton. However, it is unknown if there is a differential response of conventional and Bt cotton cultivars to water deficit, what could potentially affect the plant competition with weeds. The objective of this work was to investigate the response of Bt cotton cultivars to water deficit compared with their conventional near-isolines. The experiment was conducted in a greenhouse, where the cotton cultivars FMT 705, FMT 709 and IMACD 8276, with and without the Bt gene, were grown under two water regimens: 100% and 50% (moderate water deficit) of available soil water. Cotton phenology was severely affected by moderate water deficit, with a reduction in shoot and root dry matter production, root length and diameter, plant height and leaf area. No effect of the Bt gene was observed. Water deficit during cotton flowering decrease stomatal conductance, net assimilation of CO2 and transpiration rates. The leaf water potential is lower in plants exposed to a moderate water deficit compared with non-stressed plants. However, the introgression of the Bt gene does not modify cotton physiological and phenotypic response to water deficit.