Drought In Chickpea Research Articles

Effect of biopriming and nanopriming on physio-biochemical characteristics of Cicer arietinum L. under drought stress

Drought, a detrimental abiotic stress, disturbs many vital processes critical to plant growth and development resulting in subpar crop yield. Unconventional measures such as biofertilizers and nanofertilizers have been reported as reliable solutions to this, however, outcomes vary greatly depending upon the type of organism/particle and its mode of delivery. Seed priming involves treating seeds with organic/inorganic chemicals to ameliorate drought stress by boosting pre-germinative metabolism, maintaining water potential, scavenging free radicals, etc. Therefore, this study determined the effect of biopriming and nanopriming on germination percentage (GP), leaf water status (LWS), proline, malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and survial percentage (SP) of BG-4958 (Drought tolerant) and ICC-1882 (Drought sensitive) chickpea varieties exposed to polyethylene glycol (PEG) induced moderate (5 %) and severe drought (10 %) at flowering with no drought acting as a control. Experimental setup had three groups, control (untreated), bioprimed with plant growth promoting endophytic bacteria (PGPEB), and nanoprimed with CuNPs synthesised from PGPEB and their chemical counterparts). Crop analysis after 15 DDS (Days to drought stress) revealed that priming significantly altered the physio-biochemical parameters. Consortium and N2X led highest increment in GP and SP for DT and DS varieties, respectively, whereas N1X showed highest increase in LWS of both. Highest accumulation of proline was observed with consortium and N1 (X & Y) in DS variety while only biological CuNPs accumulated proline for DT variety. MDA and H₂O₂ decreased significantly in treated groups thereby reducing oxidative damage with non-significant variations in DT. Lower concentrations of biological CuNPs were found to be more effective in modulating the physio-biochemical machinery of chickpea under drought than their higher concentration as well as chemical counterparts. This study deepens our understanding of the beneficial role of PGPEB and biosynthesized CuNPs in alleviating the adverse effects of drought in chickpea.

Novel insights into drought-induced regulation of ribosomal genes through DNA methylation in chickpea

Modifications within the epigenome of an organism in response to external environmental conditions allow it to withstand the hostile stress factors. Drought in chickpea is a severely limiting abiotic stress factor which is known to cause huge yield loss. To analyse the methylome of chickpea in response to drought stress conditions and how it affects gene expression, we performed whole-genome bisulfite sequencing (WGBS) and RNA-seq of two chickpea genotypes which contrast for drought tolerance. It was observed that the mCHH was most variable under drought stress and the drought tolerant (DT) genotype exhibited substantial genome-wide hypomethylation as compared to the drought sensitive (DS) genotype. Specifically, there was substantial difference in gene expression and methylation for the ribosomal genes for the tolerant and sensitive genotypes. The differential expression of these genes was in complete agreement with earlier reported transcriptomes in chickpea. Many of these genes were hypomethylated (q < 0.01) and downregulated under drought stress (p < 0.01) in the sensitive genotype. The gene RPS6 (ribosomal protein small subunit) was found to be downregulated and hypomethylated in the drought sensitive genotype which could possibly lead to reduced ribosomal biosynthesis. This study provides novel insights into regulation of drought-responsive genes in chickpea.

The chickpea WIP2 gene underlying a major QTL contributes to lateral root development.

Lateral roots are a major component of root system architecture, and lateral root count (LRC) positively contributes to yield under drought in chickpea. To understand the genetic regulation of LRC, a biparental mapping population derived from two chickpea accessions having contrasting LRCs was genotyped by sequencing, and phenotyped to map four major quantitative trait loci (QTLs) contributing to 13-32% of the LRC trait variation. A single- nucleotide polymorphism tightly linked to the locus contributing to highest trait variation was located on the coding region of a gene (CaWIP2), orthologous to NO TRANSMITTING TRACT/WIP domain protein 2 (NTT/WIP2) gene of Arabidopsis thaliana. A polymorphic simple sequence repeat (SSR) in the CaWIP2 promoter showed differentiation between low versus high LRC parents and mapping individuals, suggesting its utility for marker-assisted selection. CaWIP2 promoter showed strong expression in chickpea apical root meristem and lateral root primordia. Expression of CaWIP2 under its native promoter in the Arabidopsis wip2wip4wip5 mutant rescued its rootless phenotype to produce more lateral roots than the wild-type plants, and led to formation of amyloplasts in the columella. CaWIP2 expression also induced the expression of genes that regulate lateral root emergence. Our study identified a gene-based marker for LRC which will be useful for developing drought-tolerant, high-yielding chickpea varieties.

ACC Deaminase Containing Plant Growth Promoting Agrobacterium larrymoorie Strain MZ 3-ABF Confers Tolerance to Drought Stress in Chickpea (Cicer arietinum L.) Seedlings

Plant growth-promoting rhizobacteria (PGPR) that produce 1-aminocyclopropane-1-carboxylate (ACC) deaminase can alleviate plant growth constraints caused by water scarcity. In the present study, six PGPR strains were evaluated to produce several plant growth promoting, and ACC deaminase enzyme isolated from the rhizosphere soil of Chickpea (Cicer arietinum) in arid regions of Telangana State, India. According to their 16S rDNA sequencing analysis, only one of the six strains, MZ 3-ABF, belongs to Agrobacterium larrymoorie. A drought tolerance experiment revealed two PGPR strains with high phosphate solubilization, nitrogen fixation, indoleacetic-3-acid (IAA), and ACC deaminase enzyme secretion potential were constrained to only MZ 3-ABF and MZ 5-ABF. One strain MZ 3-ABF was chosen for use in a pot experiment to assess their growth-promoting effects on chickpea under drought conditions. This PGPR strain inoculation into chickpea seedlings was expected to alleviate the overall growth inhibition caused by drought stress. The inoculation was thought to have the greatest growth-promoting effects. Inoculation with strain MZ 3-ABF altered plant height, root length, dry biomass, and net photosynthetic rate of leaves, allowing chickpea seedlings to cope with drought better. They had an indirect effect on the biochemical and physiological properties of chickpea seedlings in order to alleviate drought stress. These findings suggest that the MZ 3-ABF PGPR may be useful for effectively weakening the growth inhibition caused by drought in chickpea. The strain could also be used as effective bioinoculant to maintain pea quality.

Root traits confer grain yield advantages under terminal drought in chickpea (Cicer arietinum L.)

Chickpea, the second most important legume crop, suffers major yield losses by terminal drought stress (DS). Stronger root system is known to enhance drought yields but this understanding remains controversial. To understand precisely the root traits contribution towards yield, 12 chickpea genotypes with well-known drought response were field evaluated under drought and optimal irrigation. Root traits, such as root length density (RLD), total root dry weight (RDW), deep root dry weight (deep RDW) and root:shoot ratio (RSR), were measured periodically by soil coring up to 1.2m soil depth across drought treatments. Large variations were observed for RLD, RDW, deep RDW and RSR in both the drought treatments. DS increased RLD below 30cm soil depth, deep RDW, RSR but decreased the root diameter. DS increased the genetic variation in RDW more at the penultimate soil depths. Genetic variation under drought was the widest for RLD ∼50 DAS, for deep RDW ∼50–75 DAS and for RSR at 35 DAS. Genotypes ICC 4958, ICC 8261, Annigeri, ICC 14799, ICC 283 and ICC 867 at vegetative stage and genotypes ICC 14778, ICCV 10, ICC 3325, ICC 14799 and ICC 1882 at the reproductive phase produced greater RLD. Path- and correlation coefficients revealed strong positive contributions of RLD after 45 DAS, deep RDW at vicinity of maturity and RSR at early podfill stages to yield under drought. Breeding for the best combination of profuse RLD at surface soil depths, and RDW at deeper soil layers, was proposed to be the best selection strategy, for an efficient water use and an enhanced terminal drought tolerance in chickpea.

Drought-induced changes in free amino acid and ureide concentrations of nitrogen-fixing chickpea

The metabolic products of nitrogen (N) fixation in a legume can be amides or ureides. Chickpea (Cicer arientinum L.) is a cool-season legume which transports both ureides and amides from N fixation. Ureides are purine derivatives which are synthesized solely in the nodules. Drought-sensitive legumes accumulate ureides, but the regulation of these N fixation products during drought in chickpea is not yet known. The objectives of this study were (1) to measure the metabolic products of N fixation during drought and (2) to quantify the differences in N fixation among chickpea cultivars during drought by acetylene reduction activity under controlled environment conditions. Five chickpea cultivars were exposed to drought by soil dehydration. Plants were harvested at 1, 5, 10 and 15 d after drought and were analyzed for leaf and stem ureide concentrations and total N. In separate growth chamber experiments, N fixation was quantified daily. Leaf ureide and free amino acid concentrations were analyzed at 1, 5, and 15 d after drought. Drought increased ureide accumulation in drought-sensitive cultivars and decreased total N, alanine and asparagine concentrations over time. Drought-tolerant chickpea cultivars maintained ureide and amide concentrations during drought. Of the chickpea cultivars examined, Myles was the most drought tolerant and CDC Chico was the least. Further research on leaf ureides, alanine and asparagine concentrations would be valuable to determine if these metabolic products could serve as measures for screening chickpea germplasm for drought-tolerant N fixation. Key words: Ureides, N fixation, Asparagine, Acetylene reduction

Variability of root length density and its contributions to seed yield in chickpea ( Cicer arietinum L.) under terminal drought stress

The importance of root systems in acquiring water has long been recognized as crucial to cope with drought conditions. This investigation was conducted to: (i) evaluate the variability on root length density (RLD) of chickpea in the vegetative growth stage; (ii) estimate the effect of RLD on seed yield under terminal drought conditions; and (iii) set up a procedure to facilitate the screening of chickpea genotypes with large RLD. Twelve diverse chickpea genotypes were grown in tall PVC cylinders with two different soil water treatments in 2000 and 2001, and in field under water deficit conditions during 2000/2001 and 2001/2002. In field trials, the mean RLD at 35 days after sowing showed a significant positive correlation with seed yield in both years. Similarly, the RLD in the 15–30 cm soil depth had significant positive effects to the seed yield in both years. The importance of the root trait was particularly relevant in 2001/2002, a more severe drought year, when the RLD in deeper soil layer, 30–60 cm depth, showed a significant positive relationship with seed yield. Also, the RLD at deeper soil layer, 30–60 cm depth, was higher in 2001/2002 than in 2000/2001, in particular in tolerant genotypes. The PVC cylinder trials were set up to facilitate the screening of chickpea genotypes with large RLD. RLD of plants grown in cylinders with 70% field capacity was correlated with RLD in the field trials ( r = 0.731; p = 0.01). This work highlights the importance of roots in coping with terminal drought in chickpea. The cylinder system offers a much easier procedure to screen chickpea genotypes with large RLD.