Biology subjects

SINGH, P.

Publications and source records attributed to SINGH, P..

7 recordsLinked to original sources

bioRxiv2024

Bolstering Wheat's Immunity: BABA-Mediated Defense Priming Against Bipolaris sorokiniana Amid Competition

Plants encounter numerous biotic and abiotic challenges, with biotic stresses significantly limiting wheat productivity. Competition for nutrients and space among plants adds another layer of stress. Defense priming is a promising approach to enhancing plant protection against these environmental stresses. This study explores BABA ({beta}-aminobutyric acid) priming in wheat against Bipolaris sorokiniana under varying degrees of competition. We assessed growth parameters, disease phenotype, biochemical changes, and yield-related traits in both primed and non-primed wheat under disease pressure and competition. Our findings revealed that growth parameters declined in both primed and non-primed wheat as competition increased. However, primed wheat showed better morphological growth than non-primed wheat at each competition level. Under disease pressure, primed wheat demonstrated protection comparable to non-challenged plants at all competition levels, while non-primed plants were susceptible. Non-primed wheat under high-density (HD) conditions exhibited the highest disease susceptibility due to intense competition. BABA-primed plants showed better disease protection at each competition level compared to non-primed plants. BABA priming allowed plants to mitigate competition effects and maintain a consistent defense response. The yield performance of primed wheat was superior to that of non-primed wheat across all competition levels. Our research suggests BABA priming as an effective pesticide-free strategy for crop protection against pathogens under competitive conditions.

plant biology↗

bioRxiv2023

Plant metabolites modulate animal social networks and lifespan

Social interactions influence disease spread, information flow, and resource allocation across species, yet heterogeneity in social interaction frequency and its fitness consequences remain poorly understood. Additionally, animals can utilize plant metabolites for purposes beyond nutrition, but whether that shapes social networks is unclear. Here, we investigated how non-nutritive plant metabolites impact social interactions and the lifespan of the turnip sawfly, Athalia rosae. Adult sawflies acquire neo-clerodane diterpenoids (clerodanoids) from non-food plants, showing intraspecific variation in natural populations and laboratory-reared individuals. Clerodanoids can also be transferred between conspecifics, leading to increased agonistic social interactions. Network analysis indicated increased social interactions in sawfly groups where some or all individuals had prior access to clerodanoids. Social interaction frequency varied with clerodanoid status, with fitness costs including reduced lifespan resulting from increased interactions. Our findings highlight the role of intraspecific variation in the acquisition of non-nutritional plant metabolites in shaping social networks, with fitness implications on individual social niches.

animal behavior and cognition↗

bioRxiv2022

State-dependency of behavioural traits is a function of the life-stage in a holometabolous insect

State variables, such as body condition, are important predictors of behavioural traits. Depending on the state of an individual, the costs and benefits associated with different behavioural decisions can vary. An individuals state could affect its average behavioural response and also the behavioural repeatability. Moreover, even for the same state, different behavioural strategies may be adaptive depending on the individuals life-stage. Here, we manipulated the body condition in larvae and adults of a holometabolous insect species, Athalia rosae, using starvation. We assessed the effects of starvation on the behavioural traits of post-contact immobility (PCI) and activity levels and tested their repeatability. Our results show state-dependency of behaviour, although the effect varied with life-stage. Starved larvae exhibited shorter PCI duration and higher activity levels, whereas starved adults were less active than non-starved individuals. Moreover, although most behavioural repeatability estimates were significant in both life-stages, we did not find any significant effect of starvation on the estimates. Next, we calculated standardised effect sizes to compare starvation effects across life stages. We found that starvation had a larger and opposite effect in the larval stage than during the adult stage for all behavioural traits. Finally, we conducted microcosm and no-choice bioassay experiments to examine the benefits and costs, respectively, of the behaviour elicited by starvation in the larval stage. We observed that starved larvae located food faster than non-starved larvae but were also attacked sooner by a predator, possibly due to their higher activity levels. Together, our results demonstrate that behavioural state-dependence is a function of the life-stage of an individual. Moreover, the behavioural strategy exhibited can be adaptive for a specific life-stage with respect to certain functions, like foraging, but also carry costs, like risk of predation.

animal behavior and cognition↗

bioRxiv2022

Genetic mapping of some key plant architecture traits in Brassica juncea using a cross between two distinct lines - vegetable type Tumida and oleiferous Varuna

Brassica juncea (AABB, 2n=36), commonly called mustard is an allopolyploid crop of recent origin but has considerable morphological and underlying genetic variation. An F1-derived doubled haploid (F1DH) population developed from a cross between a Indian oleiferous line, Varuna, and a Chinese stem type vegetable mustard, Tumida showed significant variability for some key plant architectural traits, including four stem strength-related traits, stem diameter, plant height, branch initiation height, number of primary branches (Pbr), and days to flowering (Df). Multi-environment QTL analysis identified twenty environmentally stable QTL for the nine plant architectural traits. Both Tumida and Varuna contain some positive QTL that can be used to breed superior ideotypes in mustard. A QTL cluster on LG A10 contained environmentally stable QTL for seven architectural traits. This region also contained overlapping environmentally stable major QTL (phenotypic variance [≥] 10%) for Df and Pbr, with Tumida contributing the trait enhancing alleles for both the traits. Since early flowering is critical for the cultivation of mustard in the Indian subcontinent, this QTL cannot be used for the improvement of Pbr in the Indian gene pool lines. Conditional QTL analysis for Pbr identified the QTL for improvement of Pbr without negative effects on Df. The environmentally stable QTL were projected on the genome assemblies of Tumida and Varuna for the identification of candidate genes. These findings provide insights into the genetics of plant architectural traits in two diverse gene pools of B. juncea and provide opportunities for improvement of the plant architecture through marker-assisted introgressions. Key MessageGenetic mapping of some key plant architectural traits in a vegetable type and an oleiferous B. juncea cross revealed environmentally stable QTL and candidate genes for breeding more productive ideotypes.

genetics↗

bioRxiv2022

Chemical defense acquired via pharmacophagy can lead to herd protection in a sawfly

Predation is an important selection pressure acting on organisms, with organisms evolving diverse anti-predator strategies to combat it. One such widespread strategy is chemical defense in which organisms either synthesize or extrinsically acquire defensive chemicals. Little is known about the intraspecific transfer of such chemicals and if such chemicals acquired from conspecifics can also serve as defense against predation. Here, we used adults of the turnip sawfly, Athalia rosae, which can acquire neo-clerodane diterpenoids ( clerodanoids) via pharmacophagy after exposure to the plant, Ajuga reptans. We show that clerodanoid access mediates protection against predation by mantids for the sawflies, both in a no-choice feeding assay and a microcosm setup. Moreover, even indirect access to clerodanoids, via nibbling on conspecifics that had access to the plant, resulted in protection against predation albeit to a much lower degree than direct access. Furthermore, sawflies that had no direct access to clerodanoids were less consumed by mantids when they were grouped with conspecifics that had direct access. Most, but not all, of such initially undefended sawflies could acquire clerodanoids from conspecifics that had direct access to the plant, although in low quantities. Together our results demonstrate that clerodanoids serve as chemical defense that can be intraspecifically transferred. Moreover, the presence of chemically defended individuals in a group can confer protection onto conspecifics that had no direct access to clerodanoids, suggesting a herd-protection effect.

ecology↗

bioRxiv2020

Evolution of sex allocation plasticity and its predictors in a flatworm genus

Sex allocation (SA) theory in simultaneous hermaphrodites predicts that optimal SA is influenced by local sperm competition (LSC), which occurs when related sperm compete to fertilize a given set of eggs. Different factors, including the mating strategy and the ability to self-fertilize, are predicted to affect LSC and hence the optimal SA. Moreover, since the LSC experienced by an individual can vary temporally and spatially, this can favour the evolution of SA plasticity. Here, using seven species of the free-living flatworm genus Macrostomum, we document sizable interspecific variation in SA, but neither their mating strategy nor their ability to self-fertilize significantly predicted SA among these species. Since we also found considerable interspecific variation in SA plasticity, we further estimated standardized effect sizes for plasticity in response to i) the presence of mating partners (i.e. in isolation vs. with partners) and ii) the strength of LSC (i.e. in small vs. large groups). We found that self-fertilization predicted SA plasticity with respect to the presence of mating partners, with plasticity being lower for self-fertilizing species. Finally, we showed that interspecific variation in SA is higher than intraspecific variation due to SA plasticity. Our study suggests that both SA and SA plasticity are evolutionarily labile, with self-fertilization predicting the latter in Macrostomum.

evolutionary biology↗

bioRxiv2018

Nitric oxide is important for sensing and survival under hypoxia in Arabidopsis

Nitric oxide (NO) is a free radical molecule that plays an important role in hypoxic stress. We studied the impact of hypoxia-induced NO production on the expression of genes and production of metabolites involved in carbon, oxygen sensing, nitrogen, and antioxidant metabolism using wild type (WT), non-symbiotic haemoglobin-overexpressing (Hb+) and nitrate reductase double mutant (nia1,2) of Arabidopsis. Futher application of NO scavenger cPTIO was used to confirm NO role. We found that imposing hypoxia leads to the increaseof NO and reactive oxygen species (ROS) levels in WT, while the reduced levels of NO and higher levels of ROS were observed in roots of Hb+ and nia1,2 mutant. Expression of the genes encoding oxygen sensing and the enzymes involved in fermentative pathways, their activities and metabolite levels were highly induced in WT suggesting that NO plays a role in the induction of fermentation. Several genes and metabolites involved in the TCA cycle were also induced in WT in comparison to Hb+ and nia mutant line suggesting that NO can accelerate TCA cycle to regenerate reducing equivalents under hypoxia. Interestingly, we found that the genes and metabolites involved in the ascorbate-glutathione cycle were modulated by NO under hypoxia. The alternative oxidasegene (AOX1A) was induced under hypoxia in WTdue to increased levels of NO rather than ROS. Futher, we found that NO improves plant survival. Overall these findings suggest that NO is a major player in plant survival under hypoxia by modulating gene expression and metabolite levels of carbon, nitrogen, oxygen sensing and antioxidant metabolism.\n\nHighlightHypoxia-induced nitric oxide plays a central role in activation of genes and metabolites involved in fermentation, TCA cycle, nitrogen and antioxidant metabolism

plant biology↗