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Betasatellites are single-stranded DNA molecules associated with most monopartite begomoviruses of family Geminiviridae. They are symptoms modulating molecules and depend on their helper viruses for replication, encapsidation and movement. To investigate the genetic diversity of cotton leaf curl Multan betasatellite (CLCuMuB), different Pakistani isolates of betasatellites were retrieved from the NCBI data bank. The sequences were compared to all available sequences of CLCuMuB in the database, identified from cotton in Pakistan, India and China. Phylogenetic and recombination analysis showed the sequences are separated into five major groups. This is primarily based on recombination within the satellite conserved region (SCR) of the betasatellite genome. The first group consists of sequences of the original betasatellite associated with the first epidemic of cotton leaf curl disease (CLCuD) in the 1990s, while the second group consists of recombinant betasatellites associated with the second epidemic of CLCuD, containing a short fragment of tomato leaf curl betasatellite (ToLCB) DNA in the “satellite conserved region (SCR)”. The third group contains a short fragment of papaya leaf curl betasatellite (PaLCuB), while the fourth group contains a short fragment of tobacco curly shoot betasatellite (TbCSB) in the SCR region. The fifth group consists of sequences of betasatellite associated with the recent begomovirus disease complex identified from Vehari. This betasatellite contains a short fragment of sequences in the SCR region of a defective betasatellite (KT228331) from India. This new strain of CLCuMuB is named CLCuMuBVeh. Here, the significance of the evolution of CLCuMuB with respect to the CLCuD complex is discussed.

The gamma rays treated seeds of four mungbean varieties (V1=NM-98, V2= KM1, V3= Inqilab mung and V4= Sona mung) were studied for both biochemical and molecular analysis. Randomized Complete Block Design (RCBD) was used for the experiment with four treatments using three replications (T0= Control, T1= 5 krad, T2= 10 krad, T3= 15 krad and T4= 20 Krad). Maximum biochemical and molecular based variability was recorded among genotypes. Higher amount of total sugar and proline contents were recorded in the plants grown from the seeds treated with T1, T2, T3 and T4 as compared to the control (T0) plants. On the other hand, effect on the protein content was inversely proportional to the increasing range of the radiations i.e. in T4 treated plants the protein content was low in comparison to the T3, T2, T1 and T0, respectively. However lower protein content was recorded in all treated samples with increasing of gamma radiation doses. The Random Amplified Polymorphic DNA (RAPD) primers were used to check molecular based variability in the allelic pattern at different gamma irradiation treatments. The three primers (OPS-03, OPB-1 and B-11) amplified four extra alleles in the treated plants. These extra bands were observed in NM-98 (after T1, T2 and T3 treatments), KM-1 (after T2, T3 and T4 treatments), Inqilabmung (after T1 treatment) and Sonamung (after T2, T3 and T4 treatments). Variations in physiological, biochemical and more interestingly the molecular (amplification of extra alleles/bands) attributes of the treated plants grown could possibly be due to the changes in the genome of these varieties. However, this study serves as a model to check the effect of gamma rays on other economically important crop species.

Rice is cultivated worldwide under wide range of ecological conditions and is a daily staple food crop for more than half of world’s population. The morphological characterization is usually performed to select better genotypes. This type of characterization identifies elite genotypes based on qualitative as well as quantitative traits. In present study 45 diverse rice germplasm were screened for important qualitative traits. The experiment was designed as augmented and important qualitative traits including leaf related traits, lodging, panicle shape, seed coat color and awn related traits were studied. Significant variations were observed for all the examined traits. Majority of genotypes showed resistance to lodging, and only few showed slight lodging. The brown seed coat color was found dominant among genotypes. All the studied traits included in the study were found useful for the identification of improved genotypes and these traits have direct relation with yield or yield related traits. However, to elucidate the particular responsible genes for these traits, further molecular based studies are recommended. Keywords: Genetic variability; Lodging; Morphological traits; Rice; Qualitative traits http://dx.doi.org/10.19045/bspab.2019.80056

Whitefly (Bemicia tabaci) is an insect pest that causes severe losses in economically important crops by sucking the plant sap and transmitting plant viruses. We used the promising new approach of plant-mediated artificial miRNA (amiRNA) expression against three essential genes of whitefly. The Arabidopsis thaliana miR159 precursor was modified and engineered to express artificial miRNAs (amiRNAs) targeting three vital genes of whitefly, sex lethal (Sxl) protein, acetylcholinesterase (AChE) and orcokinin (Orc). The amiRNAWF construct was transformed into the Nicotiana tabacum plants. Whiteflies were infested in separate cages on both control and transgenic plants. After four weeks of infestation, the nymphs were counted and real time quantitative PCR (RT-qPCR) was performed to assess the relative expression of whitefly genes. The transgenic N. tabacum plants showed resistance against whitefly and the number of whiteflies in the next generation were substantially reduced on transgenic plants compared to control plants. Abnormal egg hatching and poor development was observed and only a small number of whitefly nymphs matured to adults. RT-qPCR results indicated that the expression of target genes (Sxl, AChE and Orc) in the nymphs was considerably down-regulated in whiteflies reared on transgenic plants. The amiRNA mediated resistance against whitefly in transgenic plants may pave the way for engineering resistance against whitefly in cotton plants.

Cotton leaf curl disease (CLCuD) has been a problem for cotton production in Pakistan and India since the early 1990s. The disease is caused by begomoviruses associated with a specific satellite, the cotton leaf curl Multan betasatellite (CLCuMB). In 2001, resistance introduced into cotton was broken by a recombinant begomovirus, Cotton leaf curl Kokhran virus strain Burewala (CLCuKoV-Bur). Unusually, in resistant cotton, this virus lacked an intact transcriptional activator protein (TrAP) gene, with the capacity to encode only 35 of the usual ~134 amino acids. Recently, isolates of CLCuKoV-Bur with a longer, but still truncated, TrAP gene have been identified in cotton breeding lines lacking the earlier resistance. This suggests that more pathogenic viruses with a full TrAP could return to cotton if the earlier resistance is not maintained in ongoing breeding efforts to produce CLCuD-resistant cotton varieties. This conclusion is supported by recent studies showing the reappearance of pre-resistance-breaking begomoviruses, with full-length TrAP genes, in cotton.

Eggplant (Solanum melongena L.) plants with severe leaf mosaic and mottling were found in a kitchen garden near cotton fields in Pakistan. Rolling Circle Amplification products from six of the naturally infected eggplant plants, subjected to PCR, successfully amplified expected products of 2.8 and 1.4 kb using begomovirus and betasatellite-specific primers, respectively. Based on 99% nucleotide sequence identity, the virus was identified as a variant of Cotton leaf curl Burewala virus (CLCuBuV) (GenBank Accession No. HG428709). Likewise, the sequenced betasatellite with a maximum of 97% nucleotide sequence identity was recognized as a new variant of Cotton leaf curl Multan betasatellite (CLCuMuB Mul ) (GenBank Accession No. HG428708). The symptomatic induction of Cotton leaf curl disease in CLCuBuV susceptible cotton genotype CIM-496 by back-indexing further confirmed the presence of CLCuBuV in eggplant. This is the first report of CLCuBuV and its associate betasatellite in naturally infected plants of eggplant.

Begomoviruses (family Geminiviridae) are whitefly-transmitted viruses with single-stranded DNA genomes that are frequently associated with DNA satellites. These satellites include non-coding satellites, for which the name deltasatellites has been proposed. Although the first deltasatellite was identified in the late 1990s, little is known about the effects they have on infections of their helper begomoviruses. Recently a group of deltasatellites were identified associated with sweepoviruses, a group of phylogenetically distinct begomoviruses that infect plants of the family Convolvulaceae including sweet potato. In this work, the deltasatellites associated with sweepoviruses are shown to be transreplicated and maintained in plants by the virus with which they were identified, sweet potato leaf curl virus (SPLCV). These deltasatellites were shown generally to reduce symptom severity of the virus infection by reducing virus DNA levels. Additionally they were shown to be maintained in plants, and reduce the symptoms induced by two Old World monopartite begomoviruses, tomato yellow leaf curl virus and tomato yellow leaf curl Sardinia virus. Finally one of the satellites was shown to be transmitted plant-to-plant in the presence of SPLCV by the whitefly vector of the virus, Bemisia tabaci, being the first time a deltasatellite has been shown to be insect transmitted.

Cotton leaf curl is devastating disease of cotton characterized by leaf curling, vein darkening and enations. The disease symptoms are induced by DNA satellite known as Cotton leaf curl Multan betasatellite (CLCuMuB), dominant betasatellite in cotton but another betasatellite known as Chili leaf curl betasatellite (ChLCB) is also found associated with the disease. Grafting experiment was performed to determine if host plant resistance is determinant of dominant population of betasatellite in cotton (several distinct strains of CLCuMuB are associated with the disease). Infected scion of Gossypium hirsutum collected from field (the source) was grafted on G. arboreum, a diploid cotton species, resistant to the disease. A healthy scion of G. hirsutum (sink) was grafted at the top of G. arboreum to determine the movement of virus/betasatellite to upper susceptible scion of G. hirsutum. Symptoms of disease appeared in the upper scion and presence of virus/betasatellite in the upper scion was confirmed via molecular techniques, showing that virus/betasatellite was able to move to upper scion through resistant G. arboreum. However, no symptoms appeared on G. arboreum. Betasatelites were cloned and sequenced from lower scion, upper scion and G. arboreum which show that the lower scion contained both CLCuMuB and ChLCB, however only ChLCB was found in G. arboreum. The upper scion contained CLCuMuB with a deletion of 78 nucleotides (nt) in the non-coding region between A-rich sequence and βC1 gene and insertion of 27 nt in the middle of βC1 ORF. This study may help in investigating molecular basis of resistance in G. arboreum.

The complete genome sequences of isolates of two new bipartite begomoviruses (genus Begomovirus, family Geminiviridae) found infecting common bean in Venezuela are provided. The names proposed for each of these viruses are "bean yellow chlorosis virus" (BYCV) and "bean white chlorosis mosaic virus" (BWCMV). Phylogenetic analysis showed that they segregated in two distinct clades of New World begomoviruses. This is the first report of begomoviruses infecting common bean in Venezuela.