Okra Leaf Research Articles

Estimation of Environmental Pollutants in Vegetables

ABSTRACTThe Karachi area is drained by two major river basins used for dumping solid, industrial, agricultural, and domestic waste. The banks of the rivers are used for agricultural purposes and crops irrigated by contaminated river water. The industrial and domestic wastewater contains pollutants that are toxic to environmental and human health. Microbial loads and toxic heavy metals were determined in vegetables grown in the area. High levels of total coliforms count were found in lucerene (Portulaca oleracea L), amaranthus (Amaranthus spp. L.), and spinach (Spinacia oleracea L.) as well as chilies (Capsicum annum L.). Total fecal coliforms were highest in amaranthus, maize (Zea mays L), and gourd (Lagenaria siceraria L). Total fecal streptococci count were high in spinach, maize, and okra. Low levels of bacteria were found in bitter gourd (Momordica charantia L.), luffa (Luffa cylindrica L.), and gourd. There was no Cr and Cd in samples; Cu concentration was highest in beetle leaf (Piper betle L.) and spinach and lowest in luffa. Lead was highest in lucerne and spinach and lowest in bitter gourd. Nickel concentration was highest in okra (Abelmoschus esculentus L.) and beetle leaf and lowest in luffa. Regardless of vegetable tested, none were considered safe for consumption based on levels of toxins and/or bacteria.

Diverse and recombinant begomoviruses and various satellites are associated with Bhendi yellow vein mosaic disease of okra in India

Bhendi/Okra, a common vegetable in the Indian subcontinent, is highly susceptible to the viral disease Bhendi yellow vein mosaic disease (BYVMD), resulting in considerable yield loss to the crop. As a first step towards formulating novel strategies against BYVMD, the identities of the viruses and associated satellite molecules were investigated in BYVMD-affected okra leaf samples taken from ten widely separated locations in India. The amplified nucleotide sequence representing the viral coat protein from the samples indicated the presence of the begomoviruses Bhendi yellow vein mosaic virus (BYVMV) in seven and Mesta yellow vein mosaic virus (MeYVMV) in three samples. Subsequent analysis of the full-length viral sequences revealed the presence of a recombinant viral DNA, having MeYVMV and Malvastrum yellow vein Yunnan virus (MYVYNV), a virus not previously reported from India, as parents. Betasatellite sequences were very similar to previous reports. Analysis of the symptomatic samples by Rolling circle amplification showed, in addition to BYVMV-like sequences, begomoviral sequences reported earlier from cotton and mint and alphasatellites reported previously from cotton and Cyamopsis tetragonoloba were also present. This study indicated that the diversity of begomoviruses and satellites associated with BYVMD is much higher than previously thought.

Begomovirus disease complex: emerging threat to vegetable production systems of West and Central Africa

Vegetables play a major role in the livelihoods of the rural poor in Africa. Among major constraints to vegetable production worldwide are diseases caused by a group of viruses belonging to the genus Begomovirus, family Geminiviridae. Begomoviruses are plant-infecting viruses, which are transmitted by the whitefly vector Bemisia tabaci and have been known to cause extreme yield reduction in a number of economically important vegetables around the world. Several begomoviruses have been detected infecting vegetable crops in West and Central Africa (WCA). Small single stranded circular molecules, alphasatellites and betasatellites, which are about half the size of their helper begomovirus genome, have also been detected in plants infected by begomoviruses. In WCA, B. tabaci has been associated with suspected begomovirus infections in many vegetable crops and weed species. Sequencing of viral genomes from crops such as okra resulted in the identification of two previously known begomovirus species (Cotton leaf curl Gezira virus and Okra yellow crinkle virus) as well as a new recombinant begomovirus species (Okra leaf curl Cameroon virus), a betasatellite (Cotton leaf curl Gezira betasatellite) and new alphasatellites. Tomato and pepper plants with leaf curling were shown to contain isolates of new begomoviruses, collectively referred to as West African tomato-infecting begomoviruses (WATIBs), new alphasatellites and betasatellites. To study the potential of weeds serving as begomovirus reservoirs, begomoviruses and satellites in the weed Ageratum conyzoides were characterized. Sequence analyses showed that they were infected by isolates of a new begomovirus (Ageratum leaf curl Cameroon virus) that belong to the WATIBs group, a new betasatellite (Ageratum leaf curl Cameroon betasatellite), an alphasatellite and two types of defective recombinants between a begomovirus and an alphasatellite. Putative recombinations were detected in begomovirus genomes for all four plant species studied, indicating that recombination is an important mechanism for their evolution. A close relationship between the begomoviruses infecting pepper and tomato and A. conyzoides and the detection of the same alphasatellite in them support the idea that weeds are important reservoirs for begomoviruses and their satellites. With this high diversity, recombination potential and transmission by B. tabaci, begomoviruses and ssDNA satellites pose a serious threat to crop production in West and Central Africa.

Correlation between leaf hopper and whitefly population with phenol and sugar contents of okra leaf

The total soluble sugar in leaves of okra genotypes ranged from 2.47% (AKOV-107-04) to 3.82% (AKOV106) followed by 3.75% (AKOV-98-04-1), and 3.71% (Parbhani Kranti). The phenol content in leaves of okra genotypes ranged from 1.92 (AKOV-106) to 2.64 mg/g (AKOV-107-04). The total soluble sugars and phenols present in leaves of okra genotypes had non significant correlation with leaf hopper and aphid incidence.

English

Of all the several factors that limit okra production in West Africa, okra mosaic virus disease (OMVD) and okra leaf curl disease (OLCD) are rank among the most severe. Twenty three (23) Abelmoschus esculentus and Abelmoschus callei cultivars retrieved from the local farmers were screened in the open field for the resistance against OMVD and OLCD over two cropping seasons in Nsukka, South Eastern Nigeria. The degree of susceptibility was determined by the calculation of yield decline (YD) due to changes in the fruit yield with exposure to the disease causing agents as well as virtual scoring of the exposed plants. The results show that all the A. esculentus cultivars were susceptible to the two diseases. The findings indicate that contrary to general belief, not all A. callei cultivars are resistant to these viral diseases. Any cultivar with a YD score of less than 10% was identified as a potential candidate for the disease resistant genes. Only Ebi Ogwu, Ojo ogwu, Tongolo, VLO, Oru ufie and Ogolo met this criterion. The potentials of transferring these resistant genes from A. callei cultivars to the vulnerable A. esculentus cultivars are discussed. Keywords: Okra, screening, resistance, viral diseases. African Journal of Biotechnology , Vol 13(48) 4419-4429

Genetic variability of Cotton leaf curl betasatellite in Northern India

Cotton is an important crop and its production is affected by various disease pathogens. Monopartite begomovirus associated betasatellites cause Cotton leaf curl disease (CLCuD) in Northern India. In order to access the occurrence and genetic variability of Cotton leaf curl betasatellites, an extensive field survey was conducted in states of Rajasthan, Punjab and Haryana. We selected the betasatellite sequence for analysis as they are reported as important for disease severity and sequence variability. Based on the field observations, the disease incidence ranged from 30% to 80% during the survey. Full genome and DNA β were amplified from various samples while no amplicon was obtained in some samples. The nucleotide sequence homology ranged from 90.0% to 98.7% with Cotton leaf curl virus (CLCuV), 55.2–55.5% with Bhendi yellow vein mosaic virus, 55.8% with Okra leaf curl virus and 51.70% with Tomato leaf curl virus isolates. The lowest similarity (47.8%) was found in CLCuV-Sudan isolate. Phylogenetic analysis showed that analyzed isolates formed a close cluster with various CLCuV isolates reported earlier. The analysis results show sequence variation in Cotton leaf curl betasatellite which could be the result of recombination. The results obtained by genome amplification and sequence variability indicate that some new variants are circulating and causing leaf curl disease in Rajasthan, Punjab and Haryana.

Introduction of Cotton leaf curl Gezira virus into the United Arab Emirates.

Severe leaf curl and small vein thickening symptoms were observed in okra fields in Al-Ain, United Arab Emirates (UAE) during the winter season, 2013. These symptoms were reminiscent of those often associated with begomovirus infection. Based on the symptoms observed in okra plants growing in adjacent fields (20 × 20 m) on two small holding farms, the disease incidence ranged from 90 to 100%. The fields were infested with the whitefly Bemisia tabaci (Genn.), the insect vector of begomoviruses. Total DNA was extracted from four symptomatic okra leaves collected from two plants per field and used for PCR amplification of the core region of the begomovirus coat protein gene using the degenerate primers AVcore 3'-GCCHATRTAYAGRAAGCCMAGRAT-5' and ACcore 3'-GGRTTDGARGCATGHGTACANGCC-5'. Amplicons of the expected size (~579 bp) were cloned and sequenced. BLASTn analysis of the partial coat protein sequences against the NCBI database revealed that the closet match to the four okra isolates was the Cotton leaf curl Gezira virus (CLCuGeV). CLCuGeV is a widespread Old World monopartite begomovirus described from the Nile Basin, sub-Saharan Africa, and southwestern Arabia (1). Recently, this virus has been reported in Jordan (GU945265) and Pakistan (3). To obtain the full-length viral genomic DNA for cloning and sequencing, total DNA extracts were enriched for circular dsDNA by rolling circle amplification (RCA) using Illustra TempliPhi (GE Healthcare, Life Sciences, Piscataway, NJ). The RCA products from each sample were digested with PstI, resulting in ~2.7 and 1.3 kbp molecules, respectively, and cloned into the pGEM plasmid vector (Promega, Madison, WI), linearized with PstI. Two inserts were selected from each cloning event and subjected to DNA sequencing using primer walking. The four resultant sequences of the 2.7 kbp (identified as virus genome) and the 1.3 kbp (betasatellite) inserts shared 99 to 100% nucleotide (nt) identity with each other, respectively. Therefore, only two representative genome and betasatellite sequences of 2,772 bp (KJ939446) and 1,356 bp (KM279620) were deposited in GenBank. Analysis using the Species Demarcation Tool (SDT) (v.1.0) (2) showed that the CLCuGeV UAE isolate sequence shared its highest nt identity (96 to 97%) with isolates from Egypt (AF155064), Pakistan (FR751142), and Jordan (GU945265). In contrast, it was only 93% identical to an isolate of CLCuGeV (HG530540) from the west coast of Saudi Arabia, nonetheless indicating they are all isolates of the same species. Analysis of the CLCuGeV sequence indicated that it was like other monopartite begomoviral genomes, containing a predicted hairpin, REP-binding iterons (GGTACTCA), and a TATA-box in the intergenic region. The genome contained six open reading frames encoding proteins with high homology to other CLCuGeV isolates. The 1,356-bp betasatellite shared its highest nt identity, at 97%, with the Okra leaf curl Oman betasatellite (KF267444) reported from infected okra plants in a neighboring country, Oman. The recent practice of transporting plants between the Gulf countries represents an important means and route for introducing begomoviruses among neighboring countries, compared to the long-distance aerial dispersal of viruliferous whiteflies, which is less likely because the Arabian desert poses a major barrier to long-distance whitefly flights.

Correlation and Path-coefficient Analyses of Lint Yield and Other Traits in Upland Cotton (Gossypium hirsutum L.)

Cotton breeders should have knowledge of traits that affect lint yield before embarking on a breeding program. Twelve diverse germplasm lines of upland cotton were used to investigate the effects of lint turnout, days to maturity, boll weight, number of bolls/plant, plant height, number of seeds/boll, boll width, boll length, seed index, number of locs/boll, number of fibers/seed, fiber density, on lint yield. The 12 lines were planted at two locations each during 2011 and 2012 at Stoneville, Miss. Simple correlation coefficients were subjected to path-coefficient analysis and direct and indirect effects were determined. Across all cultivar groups, lint turnout (0.52), plant height (0.43), number of bolls/plant (0.29), and boll weight (0.22) had the highest direct effects on lint yield. They were also positively and significantly correlated with lint yield. Boll length, fibers/seed, fiber density, number of locs/boll, and days to maturity were negatively correlated and with minimal impact on lint yield. Different path relationships between the naked seed and fuzzy seed groups and the okra and non-okra leaf groups were observed. For the okra leaf cultivars, lint turnout and plant height had the highest direct effects on lint yield. For the non-okra group on the other hand, boll weight and plant height had the highest direct effects; boll weight and number of bolls/plant had the highest direct effects on lint yield for the naked seed cultivars, whereas plant height, lint turnout, and boll weight had high direct effects on lint yield for the fuzzy cultivars.

Association of Begomovirus with Okra (Abelmoschus esculentus L.) leaf curl virus disease in southern India

A B S T R A C T A severe leaf curl disease of Okra with high disease incidence and loss of production was observed during field survey of various locations of Southern India, and causal organism was identified as Begomovirus and its association was confirmed by polymerase chain reaction (PCR) but also by cloning and sequencing of amplified PCR products and whitefly transmission. The DNA β and Coat protein gene was cloned and sequenced. The sequence data were assembled and analyzed by using the Bio-Edit (version 5.0.9). The nucleotide sequences of DNA β and Coat protein gene showed highest identities with Bhendi yellow vein mosaic virus isolates. But the most important and novel observation was recorded that the infected plants with severe leaf curl disease never develops yellow vein mosaic symptoms during same field conditions. These findings suggest that the association of Begomovirus with severe leaf curl disease could be strain of Bhendi yellow vein mosaic virus occurring in southern India. The above findings require more study to confirm strong association of causal organism with this unique symptom.

Detection of Satellite DNA Beta in Tomato Plants with Tomato Yellow Leaf Curl Disease in Jordan.

In Jordan, as well as many countries in the region, tomato production is threatened by begomoviruses belonging to the tomato yellow leaf curl virus complex (1). In 2013, an experiment was conducted at Homret Al-Sahen, Jordan (GPS coordinates 32°05'06″ N, 35°38'52″ E), to evaluate different tomato breeding lines for resistance against viruses causing tomato yellow leaf curl disease (TYLCD). Disease symptoms, typical of those caused by TYLCV complex, were observed in many susceptible lines. However, some lines exhibited unusual symptoms including severe leaf curling and stunting. To identify the causal agent of these symptoms, total nucleic acids were extracted from 21 symptomatic plants and used as templates in PCR analysis using nine primers, previously described to detect Tomato yellow leaf curl virus, Tomato yellow leaf curl Sardinia virus, and two recombinants between TYLCV and TYLCSV (3). In addition, the universal primer pair β01/β02 (2) was used to investigate the association of satDNA β with the disease. The PCR products characteristic of TYLCV (664 bp) could be amplified from five plants indicating single infection, while double infection with TYLCV and satDNA β (1,320 bp) was detected in seven plants. Mixed infection with TYLCV, TYLCSV (628 bp), and satDNA β was detected in another seven symptomatic plants and only one plant was infected with TYLCV and TYLCSV. A single plant had mixed infection with TYLCV, TYLCSV, and RecA (a recombinant between TYLCV/TYLCSV) (538 bp) (3). Amplicons obtained from two plants using β01/β02 primers were directly sequenced as 1,320-bp PCR products. Both sequences were found identical and, therefore, this sequence was deposited in the GenBank under the accession number KJ396939. Phylogenetic analysis revealed that this satDNA β sequence had the highest nucleotide (95%) identity with Okra leaf curl virus (OkLCV) satDNA 3 (AF397217) and OkLCV satDNA 10 (AF397215). The contribution of the satDNA β in the modulation of the TYLCD symptoms will be further investigated. Few years ago, another satDNA (Tomβ01-Om) was reported in Oman to be associated with TYLCD (4). However, to the best of our knowledge, this is the first report on the detection of satDNA β in tomato plants infected with viruses causing TYLCD in Jordan. The increasing diversity of begomoviruses causing TYLCD in the region is of great concern due to the possible emergence of more virulent viruses and subsequent increased losses to tomato production.

Okra Leaf Growth, Fruit Set, and Harvesting Duration With Cultivar and Sowing Date

ABSTRACTProductivity of okra [Abelmoschus esculentus (L) Moench] can be affected by sowing date and/or cultivar. Field experiments were conducted in the tropical rain forest zone of Nigeria to investigate effects of sowing date on leaf growth, pod yield, and fruiting duration of okra cvs. NHae47-4, LD88, and Jokoso. Early sowing supported development of more leaves/plant than normal or late sowing. Highest leaf area (LA) was from regular and late-sown plants in the first year. In the second year, highest LA was from early sown plants. The dwarf cv. Jokoso had the highest leaf area index (LAI) with early sowing in the second year. The cv. NHae47-4 attained first flowering 6 and 7 days earlier than ‘LD 88’ and ‘Jokoso’. Days to 50% flowering was not affected by cultivar or sowing date. With early sowing, cv. NHae47-4 attained first pod harvests in 59 days; cvs. LD 88 and Jokoso attained first pod harvests in 67 and 70 days, respectively. Harvesting lasted for 43 days with early sowing and 37 and 26 days for regular and late sowing, respectively. Number of pods/plant and pod yield were highest with early sowing. Okra leaf growth and pod yield may be improved with early sowing.

Consumption of leafy vegetables in rural households in Ijebu-Igbo, Ogun State, Nigeria.

Problem of low consumption of vegetables by all in order to alleviate nutrition-related diseases is still unresolved. This study investigated the pattern of consumption of leafy vegetables among the inhabitants of Ijebu-Igbo enclave in Ogun State, Nigeria. The instrument of data collection was interview schedule used to collect information from 175 respondents sampled through simple random sampling technique from five quarters in the locality. The head of the household was interviewed and question items ranged from socio-economic characteristics of respondents to handling of and type of leafy vegetables consumed, and awareness of the importance of consumption of these vegetables. Consumption of leafy vegetables which was the dependent variable was measured on an eight point scale. Both descriptive and inferential statistics were used to analyze the data. The descriptive statistics involved frequency tallies, percentages and averages while the inferential statistics used was chi-square analysis ( X 2). The results showed that most (74.9%) of the respondents were literate, having secondary education and above, mostly (69.1%) females, married (56%) and predominantly Christians (74. 3%). They were mostly (37%) traders and (22%) farmers. The level of vegetable consumption was low, an average of 1.57 times weekly in the study area with ‘Ugwu’ being most preferred over other vegetables which were celosia, waterleaf, amaranthus and okra leaf. Only 35.4% of the respondents consumed vegetables adequately but not properly handled or prepared. This is only 31.4% of the recommended intake of 5 times daily. Only 9.1% of them adopted the most appropriate method of preparation and handling of vegetables for maximum absorption of nutrients but the closest method to the recommended method was adopted by most (42%). The results of the hypotheses testing at 95% confidence level showed a significant relationship between marital status (x2=0.26), religion (x2=0.94), awareness level (x2=0.96) and consumption level. The study, therefore, recommended a more strategic awareness-raising campaign and nutrition education to agricultural extension and rural development agencies in order to influence people’s behaviour in making vegetables consumption a lifestyle in the study area. Key words : consumption, leafy vegetable, rural household

Consumption of leafy vegetables in rural households in Ijebu-Igbo, Ogun State, Nigeria

Problem of low consumption of vegetables by all in order to alleviate nutrition-related diseases is still unresolved. This study investigated the pattern of consumption of leafy vegetables among the inhabitants of Ijebu-Igbo enclave in Ogun State, Nigeria. The instrument of data collection was interview schedule used to collect information from 175 respondents sampled through simple random sampling technique from five quarters in the locality. The head of the household was interviewed and question items ranged from socio-economic characteristics of respondents to handling of and type of leafy vegetables consumed, and awareness of the importance of consumption of these vegetables. Consumption of leafy vegetables which was the dependent variable was measured on an eight point scale. Both descriptive and inferential statistics were used to analyze the data. The descriptive statistics involved frequency tallies, percentages and averages while the inferential statistics used was chi-square analysis ( X 2). The results showed that most (74.9%) of the respondents were literate, having secondary education and above, mostly (69.1%) females, married (56%) and predominantly Christians (74. 3%). They were mostly (37%) traders and (22%) farmers. The level of vegetable consumption was low, an average of 1.57 times weekly in the study area with ‘Ugwu’ being most preferred over other vegetables which were celosia, waterleaf, amaranthus and okra leaf. Only 35.4% of the respondents consumed vegetables adequately but not properly handled or prepared. This is only 31.4% of the recommended intake of 5 times daily. Only 9.1% of them adopted the most appropriate method of preparation and handling of vegetables for maximum absorption of nutrients but the closest method to the recommended method was adopted by most (42%). The results of the hypotheses testing at 95% confidence level showed a significant relationship between marital status (x2=0.26), religion (x2=0.94), awareness level (x2=0.96) and consumption level. The study, therefore, recommended a more strategic awareness-raising campaign and nutrition education to agricultural extension and rural development agencies in order to influence people’s behaviour in making vegetables consumption a lifestyle in the study area.

Comparative Efficacy of Plant Extracts in Managing Whitefly (Bemisia tabaci Gen) and Leaf curl Disease in Okra (Abelmoschus esculentus L)

Okra leaf curl disease (OLCD) is an important disease responsible for yield losses in okra in all okra growing regions in the world. Effective management of the OLCD is very important in order to improve yield. The study was conducted to evaluate the effectiveness of different botanicals in the management of the OLCD. The treatments applied were 10% (w/v) crude extract each of neem leaf, garlic, mahogany bark, chili pepper fruit, pawpaw dried leaf, bougainvillea leaf and the control (water), in a randomised complete block design with four replications. The plant extracts significantly reduced the population of whitefly vector, as well as the incidences and severities of OLCD infections and increased fruit yield compared to the control (P 0.05). Fruit yield was also negatively correlated with the severity of OLCD (r = -0.857; P< 0.05) and whitefly population (r = -0.750; P< 0.05). Farmers can manage OLCD in their okra fields by spraying with neem leaf or garlic extracts in order to improve fruit yields.

Identification of a disease complex involving a novel monopartite begomovirus with beta- and alphasatellites associated with okra leaf curl disease in Oman

Okra leaf curl disease (OLCD) is an important viral disease of okra in tropical and subtropical areas. The disease is caused by begomovirus-satellite complexes. A begomovirus and associated betasatellite and alphasatellite were identified in symptomatic okra plants from Barka, in the Al-Batinah region of Oman. Analysis of the begomovirus sequences showed them to represent a new begomovirus most closely related to cotton leaf curl Gezira virus (CLCuGeV), a begomovirus of African origin. The sequences showed less than 85 % nucleotide sequence identity to CLCuGeV isolates. The name okra leaf curl Oman virus (OLCOMV) is proposed for the new virus. Further analysis revealed that the OLCOMV is a recombinant begomovirus that evolved by the recombination of CLCuGeV isolates with tomato yellow leaf curl virus-Oman (TYLCV-OM). An alpha- and a betasatellite were also identified from the same plant sample, which were also unique when compared to sequences available in the databases. However, although the betasatellite appeared to be of African origin, the alphasatellite was most closely related to alphasatellites originating from South Asia. This is the first report of a begomovirus-satellite complex infecting okra in Oman.

Mapping and genomic targeting of the major leaf shape gene (L) in Upland cotton (Gossypium hirsutum L.)

A major leaf shape locus (L) was mapped with molecular markers and genomically targeted to a small region in the D-genome of cotton. By using expression analysis and candidate gene mapping, two LMI1 -like genes are identified as possible candidates for leaf shape trait in cotton. Leaf shape in cotton is an important trait that influences yield, flowering rates, disease resistance, lint trash, and the efficacy of foliar chemical application. The leaves of okra leaf cotton display a significantly enhanced lobing pattern, as well as ectopic outgrowths along the lobe margins when compared with normal leaf cotton. These phenotypes are the hallmark characteristics of mutations in various known modifiers of leaf shape that culminate in the mis/over-expression of Class I KNOX genes. To better understand the molecular and genetic processes underlying leaf shape in cotton, a normal leaf accession (PI607650) was crossed to an okra leaf breeding line (NC05AZ21). An F2 population of 236 individuals confirmed the incompletely dominant single gene nature of the okra leaf shape trait in Gossypium hirsutum L. Molecular mapping with simple sequence repeat markers localized the leaf shape gene to 5.4 cM interval in the distal region of the short arm of chromosome 15. Orthologous mapping of the closely linked markers with the sequenced diploid D-genome (Gossypium raimondii) tentatively resolved the leaf shape locus to a small genomic region. RT-PCR-based expression analysis and candidate gene mapping indicated that the okra leaf shape gene (L (o) ) in cotton might be an upstream regulator of Class I KNOX genes. The linked molecular markers and delineated genomic region in the sequenced diploid D-genome will assist in the future high-resolution mapping and map-based cloning of the leaf shape gene in cotton.

Identification of host plant resistance to silverleaf whitefly in cotton: Implications for breeding

Silverleaf whitefly (SLW), Bemisia tabaci (Gennadius) B Biotype, is an important pest of cotton in many countries, predominantly due to secretion of sugars causing honeydew contamination on lint. This results in downgrading of quality and subsequent price received by the grower. A two year field and glasshouse study evaluated host plant resistance to SLW on a range of cotton genotypes from both tetraploid (Gossypium hirsutum L., Gossypium barbadense L.) and diploid (Gossypium arboreum L., G. thurberi Tod. and Gossypium trilobum (DC.) Skovst) species. The population development of both adult and nymphal stages were compared, together with adult preference and oviposition preference. Sources of resistance to SLW were found in genotypes with okra and/or glabrous leaf traits as well as G. arboreum genotypes that had hairy normal leaves. This study revealed there were three different types of host plant resistance mechanisms against SLW; (1) okra leaf traits which reduced adult preference, (2) glabrous leaf traits which reduced oviposition preference and (3) possible biochemical traits in G. arboreum which reduced immature development and/or survival. Although any potential negative effects of these traits on yield would need to be carefully evaluated, these traits are clear targets for breeding to develop host plant resistant cultivars.

Registration of NC05AZ21 Okra‐Leaf and NC05‐11 Normal‐Leaf Upland Cotton Germplasms

NC05AZ21 (Reg. No. GP‐966, PI 667659) is an okra‐leaf line and NC05‐11 (Reg. No., GP‐965, PI 667658) is a normal‐leaf line of Upland cotton (Gossypium hirsutum L.). NC05AZ21 was developed from a cross of NC 72 and an unknown okra leaf, red stem line from Louisiana while NC05‐11 was developed from a cross of NC 72 and Fiber Max 989 (FM 989). NC 72 is a normal and smooth leaf line. FM 989 is a commercial, normal‐leaf cultivar. A pedigree breeding method was followed in developing these lines. Both lines were compared with two commercial cultivars across multiple environments for agronomic traits. Line NC05AZ21 was also compared with a commercial okra‐leaf cultivar FM 832 for agronomic performance. NC05AZ21 showed superior lint yield and lint percentage to and comparable fiber length as FM 832. It had a lower lint yield but longer fibers than Deltapine 455BG/RR (DP 455BG/RR) and Stoneville 5327B2RF (ST 5327B2RF) and comparable fiber strength. It has good resistance to Fusarium wilt [caused by Fusarium oxysporum Schlet.f.sp. vasinfectum (Atk.) Snyd. &amp;Hans.] as well. It could be a good source of earliness and Fusarium wilt resistance and perhaps tolerance to boll rot (caused by numerous organisms)—the latter because of its okra‐leaf shape. NC05‐11 had comparable lint yields as DP 451BG/RR and DP 455BG/RR with superior fiber length and strength. It also had good resistance to Fusarium wilt. Both NC05AZ21 and NC05‐11 could prove to be valuable sources of additional genetic variability for cotton breeding programs having an emphasis on improving Fusarium wilt resistance and fiber quality.

Detection of begomovirus associated with okra leaf curl disease

Leaf curl and yellow vein mosaic viral disease is the major constraint on okra (Abelmoschus esculentus L.) production in India. Amplified fragment sequence of DNA-β showed highest similarity of 91.7% with Bhendi yellow vein mosaic virus-Tamil Nadu (AJ308425, NC_003405) and lowest similarity of 48.5% with OKLCV (NC_004093), whereas coat protein specific amplified sequence showed highest homology with isolate of Madurai, Haryana, Ludhiana and lowest homology of 92% with Mesta yellow vein mosaic Bahraich virus (MYVMBV) (EU360303). The results obtained in the present study confirm that both the viral diseases of okra reported in southern India are caused by a begomovirus associated with DNA-β in which the plants show leaf curl symptoms and never develops yellow vein mosaic and those plants which show yellow vein mosaic, never develops leaf curl symptoms even in the same rows and field. The okra leaf curl is an emerging virus disease in India.

Molecular characterization of begomoviruses and DNA satellites associated with okra leaf curl disease in Cameroon

Okra leaf curl disease (OLCD) is the most important viral disease of okra in West Africa. In this study, a complex of begomoviruses and associated DNA satellites were identified in symptomatic okra plants from southwestern Cameroon. Sequence analyses showed that two of the plants (Lik1 and Njo5) were infected with a begomovirus being a recombinant of cotton leaf curl Gezira virus (CLCuGeV) and okra yellow crinkle virus (OYCrV). The recombinant genome shared highest nucleotide identity with isolates of CLCuGeV at 87.8% and is therefore considered to be member of a new begomovirus species, Okra leaf curl Cameroon virus (OLCuCMV). One plant (Mue5) was infected by a begomovirus with 95.8% nucleotide identy to CLCuGeV, while in the plants Lik1, Mue1 and Njo5, a begomovirus was identified showing highest nucleotide identity at 93.7% with OYCrV. The nucleotide comparisons and phylogenetic analyses suggest that these isolates represent new Cameroonian strains of CLCuGeV and OYCrV (CLCuGeV-CM and OYCrV-CM). Mixed infection of OLCuCMV and OYCrV-CM was found in two of the plants. A betasatellite and two divergent alphasatellites were also associated with the begomoviruses. The betasatellite was identified as cotton leaf curl Gezira betasatellite (CLCuGeB) with the highest nucleotide identity at 93.3% to other African isolates of CLCuGeB. The alphasatellites, herein named Alpha-1 and Alpha-2, shared 97.3% and 95.2% identity, respectively, with cotton leaf curl Gezira alphasatellite (CLCuGeA) and okra leaf curl Burkina Faso alphasatellite (OLCuBFA). These collective results emphasize the extent of diversity among okra-infecting begomovirus–satellite complexes in western Africa.