Extent of heterosis in CMS based hybrids of Pigeonpea [Cajanus cajan (L.) Millsp.]

Endowed with several unique characteristics, pigeonpea [Cajanus cajan (L.) Millsp.] holds a prominent position in farm households of semi-arid and arid regions of the world. With the advent of hybrid pigeonpea technology, pigeonpea, once designated as orphan crop, has grown in importance as a commercial crop. Thus, development of more number of quality hybrid varieties has become imperative to meet the future demand. The present study was taken up to elicit the information on magnitude of the genetic variability, heritability, genetic advance as percent of mean, extent of fertility restoration and heterosis in newly developed CMS based pigeonpea hybrids. Twenty four pigeonpea hybrids along with four checks viz., Asha, Maruti, LRG 41 and BDN 711, were evaluated in kharif 2015 at ICRISAT, Patancheru. Analysis of variance showed significant differences among the hybrids for all the characters studied. High genetic variability coupled with high heritability and genetic advance as percent of mean were recorded for number of primary branches, number of secondary branches and pollen fertility percent. Fertility restoration studies showed that 15 out of 24 hybrids recorded high (>80 %) pollen fertility and exhibited better fertility restoration. High levels of heterosis i.e. over 50% in traits like number of pods per plant, pod weight per plant and grain yield per plant. were also recorded. ICPH 3762 and ICPH 4502, with high per se performance and high standard heterosis for grain yield per plant and for majority of yield attributes, were identified as promising hybrids

Enhancement of pigeonpea productivity through adoption of drought mitigating strategies

Pigeonpea (Cajanus cajan (L.) Millspaugh) is an important drought tolerant legume crop in Indian rainfed agriculture. Though India accounts for nearly 90% of the world’s pigeonpea acreage (3.73 million ha) and production (3.07 million t), the productivity is lower at 707 kg/ha than the world average. The Morocco India Food Legumes Initiative in collaboration with the ICRISAT is aimed at improving the livelihood of small farmers to strengthen food and nutritional security through adoption of improved technologies. This paper is focused on developing and disseminating strategies to improve pigeonpea productivity in dryland regions which are characterized by erratic rainfall, frequent and prolonged dry spells and soil nutrient depletion. During 2013-16, demonstrations were conducted in 1200 farmers’ fields in Mahabubnagar district, Telangana, India, with an objective of enhancing the productivity of pigeonpea using three drought mitigating strategies: (i) adoption of short-duration cultivar PRG 176, a high-yielding and early-maturing pedigree selection of ICPL 88034 x ICPL 88039 with a duration of 130-135 days; (ii) foliar application of soluble fertilizer to maintain vegetative growth and ultimately improve pod filling; (iii) life saving irrigation at the rate of 20 mm with water harvested from farm ponds during mid season drought and prolonged dry spells. Adoption of PRG 176 resulted in an average yield of 1400 kg/ha compared to LRG 41 (1120 kg/ha). The yield improvement of 25% can largely be attributed to the good branching habit (8- 13 primary branches) and high flower to pod conversion ratio of PRG 176 under dryland conditions. Foliar application of multi-K during flowering and pod formation stages enhanced the yield to 1360 kg/ha compared to the yield of 1100 kg/ha obtained in fields without foliar spray. Life saving irrigation in PRG 176 during mid season dry spell which persisted for 17-21 days improved the yields by 20 % compared to the yield of 1200 kg/ha obtained in rainfed crop. In conclusion, the study demonstrated that the productivity of pigeonpea in dryland regions can be enhanced to an average 1560 kg/ha through an integrated drought mitigating approach by exploiting the short-duration and high-yielding potential of PRG 176, providing life saving irrigation during critical growth stages and foliar application of nutrients at flowering and pod formation stages

Maturation of germinal center B cells after influenza virus vaccination in humans

Germinal centers (GC) are microanatomical lymphoid structures where affinity-matured memory B cells and long-lived bone marrow plasma cells are primarily generated. It is unclear how the maturation of B cells within the GC impacts the breadth and durability of B cell responses to influenza vaccination in humans. We used fine needle aspiration of draining lymph nodes to longitudinally track antigen-specific GC B cell responses to seasonal influenza vaccination. Antigen-specific GC B cells persisted for at least 13 wk after vaccination in two out of seven individuals. Monoclonal antibodies (mAbs) derived from persisting GC B cell clones exhibit enhanced binding affinity and breadth to influenza hemagglutinin (HA) antigens compared with related GC clonotypes isolated earlier in the response. Structural studies of early and late GC-derived mAbs from one clonal lineage in complex with H1 and H5 HAs revealed an altered binding footprint. Our study shows that inducing sustained GC reactions after influenza vaccination in humans supports the maturation of responding B cells

Studies on CGMS Based Short Duration Hybrids of Pigeonpea [Cajanus cajan (L.) Millsp.] in Terms of Combining Ability

To estimate combining ability, twenty seven hybrids were made from 12 parents in a line × tester mating design during Kharif 2015-16 and tested in a Randomized block design with three replications during Kharif 2016-17. Among these parents ICPL 161 and ICPL 149 had desirable GCA effect for grain yield per plant and its contributing characters. Ten crosses exhibited significant positive SCA effect for grain yield. Out of them most promising crosses in terms of grain yield were ICPA 2039 × ICPL 161, ICPA 2156 × ICPL 86022 and ICPA 2039 × ICPL 90048. On the basis of per se performance and combining ability, the parents ICPA 2039, ICPL 88039, ICPL 161 and ICPL 149 can be used for future hybridization programmes

A novel mitochondrial orf147 causes cytoplasmic male sterility in pigeonpea by modulating aberrant anther dehiscence

Key message A novel open reading frame (ORF) identified and cloned from the A4 cytoplasm of Cajanus cajanifolius induced partial to complete male sterility when introduced into Arabidopsis and tobacco. Abstract Pigeonpea (Cajanus cajan L. Millsp.) is the only legume known to have commercial hybrid seed technology based on cytoplasmic male sterility (CMS). We identified a novel ORF (orf147) from the A4 cytoplasm of C. cajanifolius that was created via rearrangements in the CMS line and co-transcribes with the known and unknown sequences. The bi/poly-cistronic transcripts cause gain-of-function variants in the mitochondrial genome of CMS pigeonpea lines having distinct processing mechanisms and transcription start sites. In presence of orf147, significant repression of Escherichia coli growth indicated its toxicity to the host cells and induced partial to complete male sterility in transgenic progenies of Arabidopsis thaliana and Nicotiana tabacum where phenotype co-segregated with the transgene. The male sterile plants showed aberrant floral development and reduced lignin content in the anthers. Gene expression studies in male sterile pigeonpea, Arabidopsis and tobacco plants confirmed down-regulation of several anther biogenesis genes and key genes involved in monolignol biosynthesis, indicative of regulation of retrograde signaling. Besides providing evidence for the involvement of orf147 in pigeonpea CMS, this study provides valuable insights into its function. Cytotoxicity and aberrant programmed cell death induced by orf147 could be important for mechanism underlying male sterility that offers opportunities for possible translation for these findings for exploiting hybrid vigor in other recalcitrant crops as well

Performance of Parents and Hybrids of Pigeonpea (Cajanus cajan (L.) Millsp.) in terms of Yield and Yield Contributing Characters

Twelve parents were used in the crossing programme to produce 27 hybrids in L×T fashion during kharif 2015-16. In the field conditions, parents and hybrids were planted in Randomized Block Design of three replications and evaluated for the performance in terms of yield and yield contributing characters during kharif 2016-17. Observations were recorded on ten characters viz., plant height, days to 50% flowering, days to maturity, number of primary branches per plant, number of secondary branches per plant, number of pods per plant, number of seeds per pod, 100 seed weight, grain yield per plant and harvest index. It was observed that increase in number of pods per plant directly contributed to increased yield. Among the twenty seven hybrids, ICPA 2039 × ICPL 161, ICPA 2039 × ICPL 90048 and ICPA 2039 × ICPL149 had high grain yield

Study of CGMS based Short Duration Hybrids of Pigeonpea [Cajanus cajan (L.) Millsp.] In Terms of Heterosis

Twenty seven pigeonpea [Cajanus cajan (L.) Millsp.] hybrids were developed by hand pollination using three CMS lines (A lines) and nine testers (R lines). These hybrids along with their parents and two standard checks (VL Arhar1 and ICPL 161) were evaluated in a randomized block design with three replications during kharif 2016-17 for the heterosis studies. Results indicated that the crosses ICPA 2039 x ICPL161 and ICPA 2039 x ICPL 90048 had manifested significant heterobeltiosis and standard heterosis over two checks viz., VL Arhar1 and ICPL 161 for grain yield per plant and yield contributing characters. The stability of these promising crosses can be studied across the different environments and feasibility for their commercial utilisation could be tested in further generations

Pigeonpea Baseline and Early Adoption Surveys in South Asia, Insights from TL-II (Phase 1) Project in India.

Pigeonpea is an important pulse crop particularly in the semi-arid tropics of India contributing towards the nutritional security and also generates significant income to small and marginal farmers. Its share in India’s pulse production is around 16%. India is the largest pigeonpea producing country in the world accounting for nearly 67% of the total production. Being a major pigeonpea consumer in the world, India imports around 0.6 million tons of pigeonpea per year to meet the domestic needs from Africa, Nepal and Myanmar. Area and production of pigeonpea in India showed a steady growth until recently. However, the productivity in the country has stagnated between 700 and 800 kg ha-1. Recent initiatives like National Food Security Mission (NFSM), Accelerated Pulse Production Programme (A3P) and enhancement of minimum support price created more interest in pigeonpea growers in the country. Pigeonpea is one of the mandate crops of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and this premier international institute has been contributing significantly to the genetic improvement and crop management in India and Africa during the last four decades. The generous support received from the Bill and Melinda Gates Foundation (BMGF) has provided ICRISAT an opportunity to work more intensively with its research and development partners to demonstrate the potential of new technologies to enhance the yields, raise the profitability and revive the interest of the farmers in pigeonpea crop in India and the strategy chosen is farmer participatory varietal selection (FPVS). This report synthesizes the efforts made under the Tropical Legumes-II Project during the short period of three years (2007-10) in the states of Andhra Pradesh and Maharashtra for pigeonpea crop improvement in India. Overall, the FPVS results established that the new improved varieties outyielded the respective check varieties in the two states. The diffusion and adoption of these varieties increased significantly in the targeted districts. From the past lessons learnt, the report re-focuses on further efforts needed during the second phase of the project to achieve greater success and impact

Genome‐wide analysis of epigenetic and transcriptional changes associated with heterosis in pigeonpea

Hybrids are extensively used in agriculture to deliver an increase in yield, yet the molecular basisof heterosis is not well understood. Global DNA methylation analysis, transcriptome analysis andsmall RNA profiling were aimed to understand the epigenetic effect of the changes in geneexpression level in the two hybrids and their parental lines. Increased DNA methylation wasobserved in both the hybrids as compared to their parents. This increased DNA methylation inhybrids showed that majority of the 24-nt siRNA clusters had higher expression in hybrids thanthe parents. Transcriptome analysis revealed that various phytohormones (auxin and salicylicacid) responsive hybrid-MPV DEGs were significantly altered in both the hybrids in comparison toMPV. DEGs associated with plant immunity and growth were overexpressed whereas DEGsassociated with basal defence level were repressed. This antagonistic patterns of gene expressionmight contribute to the greater growth of the hybrids. It was also noticed that some common aswell as unique changes in the regulatory pathways were associated with heterotic growth inboth the hybrids. Approximately 70% and 67% of down-regulated hybrid-MPV DEGs werefound to be differentially methylated in ICPH 2671 and ICPH 2740 hybrid, respectively. Thisreflected the association of epigenetic regulation in altered gene expressions. Our findings alsorevealed that miRNAs might play important roles in hybrid vigour in both the hybrids byregulating their target genes, especially in controlling plant growth and development, defenceand stress response pathways. The above finding provides an insight into the molecularmechanism of pigeonpea heterosis

Floating tablets of hydralazine hydrochloride: optimization and evaluation

Hydralazine hydrochloride has a half-life of 2 to 4 hours with an oral bioavailability of 26-50%. Since hydralazine has a demethylating effect on various suppressor genes, it can be used in various types of cancer to support chemotherapy. The purpose of this study was to optimize and evaluate floating tablets of hydralazine hydrochloride designed to prolong the gastric residence time and to provide controlled release of the drug for 14 h. The floating tablets of hydralazine hydrochloride were prepared by the wet granulation method. Semi-synthetic polymers of hydroxy propyl methyl cellulose (HPMC K100M) and ethyl cellulose were used as the release retarding agents. A 2² factorial design was applied to systematically optimize the drug release profile. The concentrations of HPMC K100M and ethyl cellulose were optimized to provide controlled release of hydralazine for 14h. Non-Fickian diffusion release transport was confirmed as the release mechanism for the optimized formulation and the predicted values agreed well with the experimental values. Drug excipient compatibility studies were investigated by FTIR, DSC and XRD. These data indicate that there were no chemical interactions between the drug and the polymer. In vivo X-ray imaging showed floating tablet performance in rabbits