Seed ageing is influenced by two environmental factors, RH and temperature. The deterioration of the stored seed is a natural phenomenon and the seeds tend to lose viability even under ideal storage conditions. Accelerated ageing has been recognized as a good predictor of the storability of seed lots. Aged seeds show decreased vigour and produce weak seedlings that are unable to survive once reintroduced into a habitat. Vigour testing becomes more important in seeds stored under unknown or adverse storage conditions. In seed ageing damage to cellular membranes, decrease in mitochondrial dehydrogenases activities and DNA degradation increases.
Chickpea plants showing phytoplasma symptoms were observed in the research plots at University of Agricultural Sciences, Dharwad, Karnataka, India. The symptoms included phyllody, pale green leaves, bushy appearance and excessive axillary proliferation. The causal agent of the phyllody disease was identified based on symptoms, amplification of 16S rDNA of the phytoplasma by nested PCR with primers P1/P7 and R16F2n/R16R2 and 1,800 bp and 1,200 bp size products were amplified in first round PCR and nested-PCR respectively. The PCR product was sequenced and compared with the reference phytoplasma sequences collected from the database (NCBI). 16S rDNA sequences of Dharwad chickpea phytoplasma shared the highest nucleotide identity of (>98%) with Periwinkle phyllody16SrII-E (EU096500). This study indicated the association of 'Candidatus Phytoplasma aurantifolia' the 16SrII-E group infecting chickpea from Northern Karnataka.
During survey, tomato leaf samples showing leaf curl symptoms were collected from different tomato fields of Dharwad, Haveri and Kolar districts. Total nucleic acid extraction was carried out by cetyl trimethyl ammonium bromide (CTAB) method and quantified to perform polymerase chain reaction using Begomovirus group specific coat protein primers targeting the coat protein region and were sequenced. The nucleotide sequences were analyzed using the BLAST tool for which results indicated the presence of Tomato leaf curl virus (ToLCV), Croton yellow vein mosaic virus (CYVMV) and Chilli leaf curl virus (ChiLCV) that shows the association of these viruses in leaf curl symptoms in tomato obtained from the fields. The cluster analysis for all the ten sequences showed the grouping of the Chilli leaf curl virus and Tomato leaf curl virus into separate groups. Besides, the CYVMV was sub-grouped in ToLCV group. Thus this study shows the occurrence of different Begomoirus in leaf curl symptoms associated tomato growing in different regions of Karnataka.
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