Assessing the potential of partial root zone drying and mulching for improving the productivity of cotton under arid climate

Water scarcity constrains global cotton production. However, partial root-zone drying (PRD) and mulching can be used as good techniques to save water and enhance crop production, especially in arid regions. This study aimed to evaluate the effects of mulching for water conservation in an arid environment under PRD and to further assess the osmotic adjustment and enzymatic activities for sustainable cotton production. The study was carried out for 2 years in field conditions using mulches (NM = no mulch, BPM = black plastic mulch at 32 kg ha-1, WSM = wheat straw mulch at 3 tons ha-1, CSM = cotton sticks mulch at 10 tons ha-1) and two irrigation levels (FI = full irrigation and PRD (50% less water than FI). High seed cotton yield (SCY) achieved in FI+WSM (4457 and 4248 kg ha-1 in 2017 and 2018, respectively) and even in PRD+WSM followed by BPM>CSM>NM under FI and PRD for both years. The higher SCY and traits observed in FI+WSM and PRD+WSM compared with the others were attributed to the improved water use efficiency and gaseous exchange traits, increased hormone production (ABA), osmolyte accumulation, and enhanced antioxidants to scavenge the excess reactive oxygen. Furthermore, better cotton quality traits were also observed under WSM either with FI or PRD irrigation regimes. Mulches applications found effective to control the weeds in the order as BPM>WSM>CSM. In general, PRD can be used as an effective stratagem to save moisture along with WSM, which ultimately can improve cotton yield in the water-scarce regions under arid climatic regions. It may prove as a good adaptation strategy under current and future water shortage scenarios of climate change.

First report of Alternaria alternata causing Alternaria leaf spot of Fig in Pakistan

Fig (Ficus carica) is a species of flowering plants within the mulberry family. During June 2020, leaf spots were observed on several fig plants (31°26'15.0"N 73°04'25.6"E) at the University of Agriculture, Faisalabad, Pakistan. Early symptoms were small, oval to circular, light brown, sunken spots that were uniformly distributed on the leaves. Spots gradually enlarged and coalesced into circular to irregular dark brown to black spots that could be up to 3cm diam. with no or small sized fruit. Disease incidence was approximately 25%. To identify the causal agent of the disease, 15 symptomatic leaves were collected. Small pieces from all diseased samples were removed from the margin between healthy and diseased tissues were surface disinfested in 70% ethanol for 2 min, rinsed three times with sterile distilled water, plated on Potato dextrose agar and incubated at 25 ± 2°C with a 12-h photoperiod. Fungal isolation on PDA medium frequency was 95% from diseases leaves. Morphological observations were made on 7- day- old single-spore cultures. The colonies initially appeared light grayish which turned sooty black in color. All fungal isolates were characterized by small, short-beaked, multicellular conidia. The conidia were ellipsoidal or ovoid and measured 9 to 25 μm × 5 to 10 μm (n = 40) with longitudinal and transverse septa. The morphological characters matched those of Alternaria alternata (Simmons et al. 2007). Genomic DNA of a representative isolate (FG01-FG03) was extracted using DNAzol reagent (Thermo Fisher Scientific MA, USA) and PCR amplification of the internal transcribed spacer (ITS) rDNA region, was performed with primers ITS1/ITS4 (White et al. 1990), partial RNA polymerase II largest subunit (RPB2) with RPB2-5F/RPB2-7cR (Liu et al. 1999) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene regions was performed with gpd1/gpd2 (Berbee et al. 1999). The obtained sequences were deposited in GenBank with accession numbers MW692903.1 to MW692905.1 for ITS-rDNA gene, MZ066731.1 to MZ066733.1 for RPB2 and MZ066728.1 to MZ066730.1 for GAPDH. BLASTn analysis showed 100% identity with the submitted sequences of A. alternata for ITS rDNA, RPB2, and GAPDH. To confirm pathogenicity, 2-month-old 15 healthy potted F. carica plants were sprayed at true leaf stage with conidial suspension by using an atomizer in a greenhouse. Each representative A. alternata isolate (FG01-FG03) was inoculated on every three plants with conidial suspensions (106 conidia/ml; obtained from 1-week-old cultures) amended with 0.1% (vol/vol) of Tween 20 until runoff (1.5 to 2 ml per plant) whereas, three control plants were sprayed with sterile distilled water amended with 0.1% Tween 20. All plants were incubated at 25 ± 2°C in a greenhouse, and the experiment was conducted twice. After 10 days of inoculation, each isolate induced leaf spots similar to typical spots observed in the field, whereas the control plants remained symptomless. The fungus was re-isolated from symptomatic tissues and reisolation frequency was 100%. Re-isolated fungal cultures were again morphologically and molecularly identical to A. alternata, thus fulfilling Koch's postulates. Previously, A. alternata has been reported cause fruit disease of fig in Pakistan and California, USA (Alam et al. 2021; Latinović et al. 2014). To our knowledge, this is the first report of A. alternata causing leaf spot on common fig in Pakistan. In Pakistan, fig is widely grown for drying, and this disease may represent a threat to fig cultivation.

Alternaria alternata causing Alternaria Leaf Spot of Cucumis melo (Muskmelon) in Pakistan

In July 2019, leaf spot symptoms were observed on muskmelon (Cucumis melo L.) cv. Jackball-1 plants in an experimental field of 2.02 ha with a disease incidence of 30% (31°26'05.4"N 73°04'30.3"E) at the University of Agriculture, Faisalabad, Pakistan. Early symptoms consisted of small, circular, brown, necrotic spots 1 to 2 mm in size covering 10 to 30% of the leaf blade, which gradually enlarged and developed concentric rings. To identify the causal agent of the disease, a total of 20 symptomatic leaves were collected. Small pieces removed from the margin between healthy and diseased tissues were surface disinfected in 70% ethanol for 2 min, rinsed three times with sterile distilled water, plated on Potato dextrose agar and incubated at 25 ± 2°C with a 12-h photoperiod. Morphological observations were made on 7-day-old single-spore cultures. The colonies initially appeared white and then turned olive-green. All 20 fungal isolates were characterized by small, short-beaked, multicellular conidia. The conidia were ellipsoidal or ovoid and measured 11.5 to 30 μm × 7.5 to 15 μm (n = 50) with longitudinal and transverse septa. Conidia were produced on short conidiophores in chains. The beaks were short (often less than one-third the body length) and conical or cylindrical. These morphological features concur with the description of Alternaria alternata (Fr.) Keissler (Woudenberg et al. 2013). For molecular identification, genomic DNA of four representative isolates (HMSMZA 07, 08, 09, 10) were extracted and PCR amplification of the internal transcribed spacer (ITS)-rDNA, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and translation elongation factor-1 alpha (TEF-1α) gene regions were performed (White et al. 1990, Berbee et al. 1999, Carbone & Kohn, 1999) respectively. The obtained sequences were deposited in GenBank with accession numbers MT253643.1-MT253646.1 (ITS-rDNA), MT318260.1-MT318263.1 (GAPDH), and MT318280.1-MT318283.1 (TEF-1α). BLASTn analysis of HMSMZA 07 sequences showed 100% identity with ITS rDNA (MN615420.1), GAPDH (MK637438.1) and TEF-1α (MN807795.1) sequences of A. alternata. To confirm pathogenicity, 5-6 weeks-old Muskmelon (Cucumis melo L.) cv. Jackball-1 plants (true leaf stage) were sprayed until runoff (1.5 to 2 ml per plant) with A. alternata conidial suspension (106 conidia/ml; obtained from 1 week-old cultures) amended with 0.1% (vol/vol) of Tween 20 using an atomizer in the green house. The experiment included four A. alternata isolates inoculated onto three muskmelon plants per each isolate, whereas control plants (n = 3) were sprayed with sterile distilled water amended with 0.1% Tween 20. The plants were incubated at 25 ± 2°C in a greenhouse and the experiment was conducted twice. After 5 to 7 days post inoculation, necrotic leaf spots were observed on the inoculated plants and A. alternata was reisolated and confirmed by morphological and molecular (ITS) features. No disease was observed on control plants. Previously, A. alternata on muskmelon has been reported in Pakistan (Ahmad et al. 1997), however this study provides a detailed description of disease symptoms, morphological and molecular identity of the causal agent including completion of Koch's postulates. The disease could represent a threat for muskmelon crop in Pakistan due to its increasing cultivation and therefore warrants the need to develop disease management strategies.

Occurrence of Leaf Spot Caused by Alternaria alternata on Eggplant (Solanum melongena) in Pakistan

Eggplant (Solanum melongena L.) is a popular vegetable that is grown in both tropical and subtropical regions all year long. The crop is cultivated on small family farms and is a good source of income for resource-limited farmers in Pakistan. In early May 2019, leaf spots on eggplant (cv. Bemisaal) were observed in an experimental field (31°26'14.0"N 73°04'23.4"E) at the University of Agriculture, Faisalabad, Pakistan. Early symptoms were small, circular, brown, necrotic spots uniformly distributed on leaves. The spots gradually enlarged and coalesced into large, nearly circular or irregularly shaped spots that could be up to 3 cm in length. The center of the spots was light tan, surrounded by a dark brown ring, a chlorotic halo, and tended to split in the later developmental stages. Disease incidence was approximately 35% in the infected field. The causal agent of this disease was isolated consistently by plating surface sterilized (1% NaOCl) sections of symptomatic leaf tissue onto potato dextrose agar (PDA). After 6 days incubation at 25°C with a 12-h photoperiod, fungal colonies had round margins and the cottony mycelia were dark olivaceous with a mean diameter of 7.5 cm. For conidial production, the fungus was grown on potato carrot agar (PCA) and V8 agar media under a 16-h/8-h light/ dark photoperiod at 25°C. Conidiophores were septate, light to olive golden brown with a conidial scar, from which conidia were produced. Conidia were borne singly or in short chains and were obpyriform to obclavate, measured 29 ± 4.8 × 13.25 ± 2.78 μm (n=30) with zero to three longitudinal and two to six transversal septa. The morphological characters matched those of Alternaria alternata (Fr.) Keisel (Simmons et al. 2007). DNA was extracted using the DNAzol reagent (Thermo Fisher Scientific MA, USA). For molecular identification, internal transcribed spacer (ITS) region between ITS1 and ITS2, actin gene (β-Actin), translation elongation factor (TEF-1α) gene, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene of two representative isolates (JLUAF1 and JLUAF2) were amplified with primers ITS1/ITS4 (White et al. 1990), β-Actin 512 F/783 R, EF1-728F/-986R (Carbone et al. 1999), and gpd1/gpd2 (Berbee et al. 1999), respectively. The sequences were deposited in GenBank (accession nos. MT228734.1 and MT228735.1 for ITS; MT260151.1 and MT260152.1 for β-Actin, MT260163.1 and MT260164.1, for TEF-1a, and MT260157.1 and MT260158.1 for GAPDH). BLASTn analysis of these sequences showed 100% identity with the sequences of A. alternata for ITS rDNA, β-Actin, TEF-1α, and GAPDH, respectively. Based on the morphological characters and DNA sequences, the leaf spot isolates of eggplant were identified as A. alternata. To confirm the pathogenicity on eggplant, six-week old healthy potted eggplants of cv. Bemisaal were sprayed at the true leaf stage with conidial suspensions of A. alternata (106 conidia/ml; obtained from 1-week-old cultures) amended with 0.1% (vol/vol) of Tween 20 until runoff (1.5 to 2 ml per plant) using an atomizer in the greenhouse. Three plants were inoculated with each of the two isolates (JLUAF1 and JLUAF2), whereas three control plants were sprayed with sterile distilled water amended with 0.1% Tween 20. The plants were incubated at 25 ± 2°C in a greenhouse, and the experiment was conducted twice. After 10 days of inoculation, each isolate induced leaf spots which were similar to typical spots observed in the field, whereas the control plants remained symptomless. The fungus was re-isolated from symptomatic tissues. Re-isolated fungal cultures were morphologically and molecularly identical to A. alternata, thus fulfilling Koch's postulates. Previously, A. alternata has been reported to cause leaf spots on eggplant in India (Raina et al. 2018). To our knowledge, this is the first report of A. alternata causing leaf spot on eggplant in Pakistan. The disease could represent a threat for eggplant crops due to its increasing cultivation. It is important to develop disease management strategies for Alternaria alternata causing leaf spot of Eggplant in Pakistan.

First Report of Aspergillus niger causing Black rot of Grapes in Pakistan

In June 2015 & 2016, a postharvest survey of table grapes (Vitis vinifera) cv. King's Ruby, was carried out in five different commercial fruit markets of Rawalpindi (33°38'19.2″N, 73°01'45.0″E) district, Punjab Province. Symptoms appeared as brownish lesions with black sporulation on grapes berries. The incidence of these symptoms on bunches ranged from 12 to 17% at all sites. Symptomatic tissue pieces were surface-sterilized with 0.1% sodium hypochlorite (NaOCl) for 30 seconds, rinsed three times with sterile distilled water, dried on filter paper for 45 seconds, and incubated on potato dextrose agar (PDA) at 25°C. After 3 days, dark brown to black mycelium were formed on PDA media. A total of 24 isolates were examined morphologically. The apex of the conidiophore was observed to be radiate. Vesicles were found to be spherical and covered with irregular metulae and phialides. Conidia were globose or subglobose measured (3.14 μm ± 2.24 in averaged diameter: n=50), dark brown to black, with roughened cell walls. The conidiophores were also smooth-walled, hyaline, and became melanized toward the vesicle. These characteristics of the fungus were similar to those described for Aspergillus niger van Tiegh (de Hoog et al. 2000). For molecular identification, the internal transcribed spacer (ITS) region, beta-tubulin (Bt) gene and partial RNA polymerase II largest subunit (RPB2) gene of representative isolate (Asp.n02) was amplified using primers ITS1/ITS4, BT2a/BT2b and RPB2-6F/RPB2-7R respectively (White et al., 1990; Glass & Donaldson, 1995; Liu et al. 1999). Sequences were deposited in GenBank (ITS, MN658871; Bt2, MT117924; and RPB2, MT318289). Based on BLAST analysis, sequences of the ITS region, Bt2 genes, and RPB2 gene showed 99 to 100% similarity of isolate Asp.n02 to Aspergillus niger (Accession Nos. MK307680.1, MN195121.1, MF078661.1 for ITS gene, MN567299.1, MK451029.1, MK451020.1 for Bt2 gene, and MK450788.1, MK450790.1 for RPB2 gene). To complete Koch's postulates, 10-µl aliquots of spore suspensions (106 spores/ml) of isolate: Asp.n 02 was pipetted onto three non-wounded and four wounded (5 mm diam) asymptomatic grape berries cv. King's Ruby (seven berries per isolate), Sterile distilled water was applied to asymptomatic berries similaries to serve as a negative control (Ghuffar et al. 2018; Jayawardena et al. 2018). Berries were incubated at 25 ± 2°C in sterile moisture chambers, and the experiment was conducted twice. Brownish lesions leading to black sporulation similar to the original symptoms were observed on both wounded and non-wounded inoculated berries after 3 days, whereas no symptoms were recorded on the negative control. The morphology of the fungus that was re-isolated from each of the inoculated berries was identical to that of the original cultures. Aspergillus niger was reported previously in Europe and Israel causing mycotoxin (Ochratoxin A) OTA production on Table grapes (Bau et al. 2006). To our knowledge, this is the first report of Aspergillus niger causing black rot of grapes in Pakistan. This finding will help to plan effective disease management strategies against the black rot of grapes in Pakistan.

First Report of Aspergillus niger causing Black rot of Grapes in Pakistan

In June 2015 & 2016, a postharvest survey of table grapes (Vitis vinifera) cv. King's Ruby, was carried out in five different commercial fruit markets of Rawalpindi (33°38'19.2″N, 73°01'45.0″E) district, Punjab Province. Symptoms appeared as brownish lesions with black sporulation on grapes berries. The incidence of these symptoms on bunches ranged from 12 to 17% at all sites. Symptomatic tissue pieces were surface-sterilized with 0.1% sodium hypochlorite (NaOCl) for 30 seconds, rinsed three times with sterile distilled water, dried on filter paper for 45 seconds, and incubated on potato dextrose agar (PDA) at 25°C. After 3 days, dark brown to black mycelium were formed on PDA media. A total of 24 isolates were examined morphologically. The apex of the conidiophore was observed to be radiate. Vesicles were found to be spherical and covered with irregular metulae and phialides. Conidia were globose or subglobose measured (3.14 μm ± 2.24 in averaged diameter: n=50), dark brown to black, with roughened cell walls. The conidiophores were also smooth-walled, hyaline, and became melanized toward the vesicle. These characteristics of the fungus were similar to those described for Aspergillus niger van Tiegh (de Hoog et al. 2000). For molecular identification, the internal transcribed spacer (ITS) region, beta-tubulin (Bt) gene and partial RNA polymerase II largest subunit (RPB2) gene of representative isolate (Asp.n02) was amplified using primers ITS1/ITS4, BT2a/BT2b and RPB2-6F/RPB2-7R respectively (White et al., 1990; Glass & Donaldson, 1995; Liu et al. 1999). Sequences were deposited in GenBank (ITS, MN658871; Bt2, MT117924; and RPB2, MT318289). Based on BLAST analysis, sequences of the ITS region, Bt2 genes, and RPB2 gene showed 99 to 100% similarity of isolate Asp.n02 to Aspergillus niger (Accession Nos. MK307680.1, MN195121.1, MF078661.1 for ITS gene, MN567299.1, MK451029.1, MK451020.1 for Bt2 gene, and MK450788.1, MK450790.1 for RPB2 gene). To complete Koch's postulates, 10-µl aliquots of spore suspensions (106 spores/ml) of isolate: Asp.n 02 was pipetted onto three non-wounded and four wounded (5 mm diam) asymptomatic grape berries cv. King's Ruby (seven berries per isolate), Sterile distilled water was applied to asymptomatic berries similaries to serve as a negative control (Ghuffar et al. 2018; Jayawardena et al. 2018). Berries were incubated at 25 ± 2°C in sterile moisture chambers, and the experiment was conducted twice. Brownish lesions leading to black sporulation similar to the original symptoms were observed on both wounded and non-wounded inoculated berries after 3 days, whereas no symptoms were recorded on the negative control. The morphology of the fungus that was re-isolated from each of the inoculated berries was identical to that of the original cultures. Aspergillus niger was reported previously in Europe and Israel causing mycotoxin (Ochratoxin A) OTA production on Table grapes (Bau et al. 2006). To our knowledge, this is the first report of Aspergillus niger causing black rot of grapes in Pakistan. This finding will help to plan effective disease management strategies against the black rot of grapes in Pakistan.

Functional characteristics of chemosensory proteins in the sawyer beetle Monochamus alternatus Hope

The Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae), is a major pest of pines and it is also the key vector of the exotic pinewood nematode in China. In the present study, we cloned, expressed, and purified a chemosensory protein (CSP) in M. alternatus. We surveyed its expression in various developmental stages of male and female adult tissues and determined its binding affinities for different pine volatiles using a competitive binding fluorescence assay. A CSP known as CSP5 in M. alternatus was obtained from an antennal cDNA library and expressed in Escherichia coli. Quantitative reverse transcription polymerase chain reaction results indicated that the CSP5 gene was mainly expressed in male and female antennae. Competitive binding assays were performed to test the binding affinity of recombinant CSP5 to 13 odour molecules of pine volatiles. The results showed that CSP5 showed very strong binding abilities to myrcene, (+)-β-pinene, and (-)-isolongifolene, whereas the volatiles 2-methoxy-4-vinylphenol, p-cymene, and (+)-limonene oxide have relatively weak binding affinity at pH 5.0. Three volatiles myrcene, (+)-β-pinene, and (-)-isolongifolene may play crucial roles in CSP5 binding with ligands but this needs further study for confirmation. The sensitivity of insect to host plant volatiles can effectively be used to control and monitor the population through mass trapping as part of integrated pest management programs.

Host suitability analysis of the bark beetle Scolytus amygdali (Coleoptera: Curculionidae: Scolytinae)

Scolytus amygdali is a polyphagous insect pest that feeds on fruit trees and forest trees. Our study assessed the host preference and reproductive potential of S. amygdali on four tree species: almond (Prunus dulcis), apricot (Prunus armeniaca), peach (Prunus persica), and plum (Prunus domestica). Females of S. amygdali produced maternal galleries that were longer on peach than the other three trees, and female fecundity was highest on peach. Females with longer maternal galleries produced more eggs, indicating a positive correlation between maternal gallery length and female fertility. The under-bark development time of S. amygdali is significantly shorter on plum (45 days) and almond (56 days) than on apricot (65 days) and peach (64 days). Despite this longer development time on peach, our results still suggest that, of the four types of tree tested, peach is the most preferred host for S. amygdali.

Melioidosis: an emerging infectious disease

Infectious diseases account for a third of all the deaths in the developing world. Achievements in understanding the basic microbiology, pathogenesis, host defenses and expanded epidemiology of infectious diseases have resulted in better management and reduced mortality. However, an emerging infectious disease, melioidosis, is becoming endemic in the tropical regions of the world and is spreading to non-endemic areas. This article highlights the current understanding of melioidosis including advances in diagnosis, treatment and prevention. Better understanding of melioidosis is essential, as it is life-threatening and if untreated, patients can succumb to it. Our sources include a literature review, information from international consensus meetings on melioidosis and ongoing discussions within the medical and scientific community.

A case of presumptive monosomy 21 re-diagnosed as unbalanced t(5p;21q) by FISH and review of literature

By using fluorescence in situ hybridization (FISH), we demonstrate a case of monosomy 21 to result from an unbalanced translocation involving the short arm of chromosome 5 and the long arm of chromosome 21. Our case is compared to 3 similar cases of t(5p;21q) reported recently, which were also originally diagnosed as monosomy 21. The breakpoint on chromosome 5 in these cases occurred in the p13-p15 region, whereas the breakpoint on chromosome 21 was in the q21-q22 region. Comparison of the clinical findings in these patients demonstrated great similarities. Furthermore, a strong correlation between the clinical manifestations of these patients with cridu-chat syndrome patients was also noted. We suggest that cases with unbalanced t(5p;21q) represent a distinct syndrome which can be grouped under a new category of "5p/21q deletion syndrome."