Callus induction and plantlet regeneration in <Emphasis Type="Italic">Withania somnifera</Emphasis> (L.) dunal

Summary Callus induction was observed from hypocotyl, root, and cotyledonary leaf segments, grown on Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (KN). Maximum callusing (100%) was obtained from root and cotyledonary leaf segments grown on MS medium supplemented with a combination of 2 mg l⁻¹ (9.1 μM) 2,4-D and 0.2 mg l⁻¹ (0.9 μM) KN. The calluses, when subcultured in the same medium, showed profuse callusing. However, these calluses remained recalcitrant to regenerate regardless of the quality and combinations of plant growth regulators in the nutrient pool. When hypocotyl segments were used as explants, callus induction was noticed in 91% of cultures which showed shoot regeneration on MS medium supplemented with 2 mg l⁻¹ 2,4-D and 0.2 mg l⁻¹ KN. These shoots were transferred to fresh medium containing various concentrations and combinations of 6-benzyladenine (BA) and N⁶-(2-isopentenyl)adenosine (2-iP). Maximum shoot multiplication was observed after 60 d of the second subculture on MS medium containing 2 mg l⁻¹ (8.9 μM) BA. These shoots were rooted best (87%) on MS medium containing 2 mg l⁻¹ (9.9 μM) indole-3-butyric acid (IBA). The plantlets were transferred to the field after acclimatization and showed 60% survival.     

A new esterase, belonging to hormone-sensitive lipase family, cloned from Rheinheimera sp. isolated from industrial effluent

The gene for esterase (rEst1) was isolated from a new species of genus Rheinheimera by functional screening of E. coli cells transformed with the pSMART/HaeIII genomic library. E. coli cells harboring the esterase gene insert could grow and produce clear halo zones on tributyrin agar. The rEst1 ORF consisted of 1,029 bp, corresponding to 342 amino acid residues with a molecular mass of 37 kDa. The signal P program 3.0 revealed the presence of a signal peptide of 25 amino acids. Esterase activity, however, was associated with a homotrimeric form of molecular mass 95 kDa and not with the monomeric form. The deduced amino acid sequence showed only 54% sequence identity with the closest lipase from Cellvibrio japonicus strain Ueda 107. Conserved domain search and multiple sequence alignment revealed the presence of an esterase/ lipase conserved domain consisting of a GXSXG motif, HGGG motif (oxyanion hole) and HGF motif, typical of the class IV hormone sensitive lipase family. On the basis of the sequence comparison with known esterases/ lipases, REst1 represents a new esterase belonging to class IV family. The purified enzyme worked optimally at 50 degrees C and pH 8, utilized pNP esters of short chain lengths, and showed best catalytic activity with p-nitrophenyl butyrate (C?), indicating that it was an esterase. The enzyme was completely inhibited by PMSF and DEPC and showed moderate organotolerance.     

Tomato SlMPK4 is required for resistance against Botrytis cinerea and tolerance to drought stress

Mitogen-activated protein kinases (MPKs) play important roles in biotic and abiotic stress responses. In the present study, we identified a tomato MPK gene, SlMPK4, a possible homolog of Arabidopsis AtMPK4, and performed functional analysis to examine its possible roles in biotic and abiotic responses. Expression of SlMPK4 was induced by infection with Botrytis cinerea and by exogenous application of jasmonic acid and ethylene precursor 1-amino cyclopropane-1-carboxylic acid. Knockdown of the endogenous SlMPK4 expression through virus-induced gene silencing in tomato plants (TRV-SlMPK4) resulted in increased susceptibility to B. cinerea. Expression of defense-related genes SlPR1a and SlPR1b were up-regulated in the SlMPK4-silenced plants. Furthermore, silencing of the SlMPK4 gene also resulted in reduced tolerance against drought stress, leading to earlier wilting symptom under drought stress condition, as compared with the control plants. These results suggest important roles for SlMPK4 in disease resistance against B. cinerea and tolerance to drought stress.     

Field evaluation of eco-friendly biocontrol package for the management of pod borer,Helicoverpa armigera Hubner,and fusarium wilt in chickpea,Cicer arietinum

Helicoverpa armigera is a serious pest of chickpea and causes great damage to crop. Extensive and indiscriminate use of insecticides has led to the development of resistance in H. armigera. Among the several alternative methods for management of H. armigera, the nuclear polyhedrosis virus (NPV) is promising, whereas Trichoderma sp. have shown promising results against chickpea wilt. The experiments to evaluate biocontrol package against H. armigera and wilt disease under field conditions were conducted. Lowest H. armigera larval population (0.71 larvae/plant) was recorded in chemical control, which was at a par with biocontrol package (0.91 larvae/plant), and both the treatments were significantly better than control. Lowest per cent pod damage (3.85%) was recorded in chemical control followed by biocontrol treatment (5.08%) and unsprayed control (8.61%). The yields from biocontrol package (13.45 q/ha) and chemical control (15.37 q/ha) were significantly higher than unsprayed control (10.7 q/ha). There was no disease incidence in all treatments in both 2008 and 2009.     

An efficient micropropagation protocol for Citrus jambhiri Lush. and assessment of clonal fidelity employing anatomical studies and RAPD markers

Citrus jambhiri (rough lemon) is considered a major rootstock source for a number of Citrus species. A simple method for micropropagation from nodal segments is reported. Nodal segments of C. jambhiri were inoculated on MS medium supplemented with different concentrations and combinations of 6-benzylaminopurine (BAP), kinetin, and N6-(2-isopentenyl) adenosine (2iP). Maximum multiple shoot regeneration response (75?%) was observed with BAP at 3?mg?l^?1. Shoots were multiplied for 30?d on fresh medium with similar composition. A total of 67?% of the cultures showed multiplication with the optimum number of shoots (4.02) and height of shoots (1.81?cm) with BAP (3?mg?l^?1) alone. Maximum rooting response (87?%) was observed with naphthaleneacetic acid at 0.5?mg?l^?1. Transverse sections of shoot stems obtained in vivo (sampled from seedlings) and in vitro (regenerated from nodal segments), showed similar anatomies. Randomly amplified polymorphic DNA analysis confirmed that all the regenerated plants were genetically identical to their donor plant, suggesting absence of detectable genetic variation in the regenerated plantlets.     

Comparative genetic analyses of metric traits using diallel and factorial mating designs in bread wheat

Summary For studying the inheritance of metric traits, diallel cross and factorial mating designs are commonly used. Since factorial mating design is less restrictive in crossing plans, the genetic information drawn from it was compared with that from a diallel cross. The comparison was made using graphical, genetic components and combining ability analyses for grain yield, grain weight and spike length in a field experiment of bread wheat (Triticum aestivum L.). Analyses were made on a nine parent diallel cross and a 4 × 5 factorial mating design which was sampled from the diallel cross. In general, there was a high degree of agreement between the results obtained from factorial mating design and diallel cross analyses showing thereby that the former provides almost equivalent genetic information to the latter.     

A modified triple test-cross analysis to test and allow for inadequate testers.

When the population under investigation consists of highly inbred lines the full triple test-cross of Kearsey and Jinks (1968) supplemented by the selfed progenies of the population allows unambiguous and independent tests for epistasis and the adequacy of the pure-breeding testers, L1 and L2. This can also be achieved by supplementing the simplified triple test-cross of Jinks, Perkins and Breese (1969) with the selfed progenies of the L1i and L2i families. If the L1 and L2 testers prove to be inadequate due to the presence of common loci, modifications of the analyses are proposed which correct the resulting biases in the genetical components of variation.