Confirmation and characterization of the first case of acetolactate synthase (ALS)-inhibitor resistance in Japanese brome (Bromus japonicus) in the US.

BACKGROUND: Japanese brome (Bromus japonicus Thumb.) is one of the problematic annual weeds in winter wheat (Triticum aestivum L.) and is generally controlled by acetolactate synthase (ALS) inhibitors. Repeated use of the ALS inhibitor propoxycarbazone-Na resulted in the evolution of resistance to this herbicide in three B. japonicus populations, i.e., R1, R2, and R3 in Kansas (KS). However, the level of resistance and mechanism conferring resistance in these populations is unknown. The objectives of this research were to (i) evaluate the level of resistance to propoxycarbazone-Na in R1, R2, and R3 in comparison with a known susceptible population (S1), (ii) investigate the mechanism of resistance involved in conferring ALS-inhibitor resistance, and (iii) investigate the cross-resistance to other ALS inhibitors. RESULTS: Dose-response (0 to 16x; x = 44 g ai ha-1 of propoxycarbazone-Na) assay indicated 167, 125, and 667-fold resistance in R1, R2 and R3 populations, respectively, compared to S1 population. ALS gene sequencing confirmed the mutations resulting in amino acid substitutions, i.e., Pro-197-Thr (R3, R1)/Ser (R2, R1) bestowing resistance to these ALS inhibitors. Such amino acid substitutions also showed differential cross-resistance to sulfosulfuron, mesosulfuron-methyl, pyroxsulam, and imazamox among resistant populations. Pretreatment with malathion (a cytochrome P450 enzyme-inhibitor) followed by imazamox treatment suggested cross-resistance to this herbicide possibly via metabolism only in R3 population. CONCLUSION: Overall, these results confirm the first case of target-site based resistance to ALS inhibitors in B. japonicus in the US, highlighting the need for exploring herbicides with alternative modes of action to enhance weed control in winter wheat. © 2024 Society of Chemical Industry.

Putting CRISPR-Cas system in action: a golden window for efficient and precise genome editing for crop improvement.

The daunting task of feeding an ever-growing population is an immense challenge for the contemporary scientific community, especially in view of the rapidly changing climate throughout the world. Amidst these threatening crises, we witness rapid development in genome editing (GE) technologies, revolutionizing the field of applied genomics and molecular breeding. Various GE tools have been developed during the last two decades, but the CRISPR/Cas system has most recently made a significant impact on crop improvement. The major breakthroughs of this versatile toolbox are genomic modifications like single base-substitutions, multiplex GE, gene regulation, screening mutagenesis, and enhancing the breeding of wild crop plants. Previously, this toolbox was used to modify genes related to significant traits such as biotic/abiotic resistance/tolerance, post-harvest traits, nutritional regulation, and to address self-incompatibility analysis-related challenges. In the present review, we have demonstrated the functional dynamics of CRISPR-based GE and its applicability in targeting genes to accomplish novel editing of crops. The compiled knowledge will provide a solid foundation for highlighting the primary source for applying CRISPR/Cas as a toolbox for enhancing crops, to achieve food and nutritional security.

Alleviation of drought stress through foliar application of thiamine in two varieties of pea (Pisum sativum L.).

Drought stress poorly impacts many morphological and physio-biochemical processes in plants. Pea (Pisum sativum L.) plants are highly nutritious crops destined for human consumption; however, their productivity is threatened under drought stress. Thiamine (vitamin B1) is well-known essential micronutrient, acting as a cofactor in key metabolic processes. Therefore, this study was designed to examine the protective effect of foliar application of thiamine (0, 250, and 500 ppm) on two varieties of pea plants under drought stress. Here, we conducted the pot experiment at the Government College Women University, Faisalabad, to investigate the physio-biochemical and morphological traits of two pea varieties (sarsabz and metior) grown under drought stress and thiamine treatment. Drought stress was applied to plants after germination period of 1 month. Results showed that root fresh and dry weight, shoot fresh and dry weight, number of pods, leaf area, total soluble sugars, total phenolics, total protein contents, catalase, peroxidase, and mineral ions were reduced against drought stress. However, the application of thiamine (both 250 and 500 ppm) overcome the stress and also enhances these parameters, and significantly increases the antioxidant activities (catalase and peroxidase). Moreover, the performance of sarsabz was better under control and drought stress conditions than metior variety. In conclusion, the exogenous application of thiamine enabled the plants to withstand drought stress conditions by regulating several physiological and biochemical mechanisms. In agriculture, it is a great latent to alleviate the antagonistic impact of drought stress on crops through the foliar application of thiamine.

Mitigation of salt stress in Indian mustard (Brassica juncea L.) by the application of triacontanol and hydrogen sulfide.

Salinity stress is a well-known abiotic stress that has been shown to have a negative impact on crop growth, production, and soil richness. The current study was intended to ameliorate salt stress in Indian mustard (Brassica juncea L.), keeping in mind the detrimental influence of salt stress. A pot experimentation was executed on B. juncea to examine the efficacy of exogenous application of triacontanol (TRIA) and hydrogen sulfide (H2S) (NaHS donor), either alone or in combination, on growth attributes, metabolites, and antioxidant defense system exposed to salt stress at three distinct concentrations (50, 100 and 150 mM NaCl). Increase in the concentration of oxidative markers (malondialdehyde and hydrogen peroxide) was found which results in inhibited growth of B. juncea. The growth characteristics of plant, such as root and shoot length, fresh and dry weight under salt stress, were improved by foliar application of TRIA (150 µM) and H2S (25 µM) alone as well as in combination. Additionally, salt stress reduced the levels of protein, metabolites (flavonoids, phenolic and anthocyanin), antioxidant enzyme activity including that of ascorbate peroxidase, catalase, polyphenol oxidase and guaiacol peroxidase as well as the level of ascorbic acid and glutathione (non-enzymatic antioxidants). However, application of TRIA and H2S alone or in grouping substantially raised the content of protein, metabolites and antioxidant defense system in plants of B. juncea.

Integrating genomics and genome editing for orphan crop improvement: a bridge between orphan crops and modern agriculture system.

Domestication of orphan crops could be explored by editing their genomes. Genome editing has a lot of promise for enhancing agricultural output, and there is a lot of interest in furthering breeding in orphan crops, which are sometimes plagued with unwanted traits that resemble wild cousins. Consequently, applying model crop knowledge to orphan crops allows for the rapid generation of targeted allelic diversity and innovative breeding germplasm. We explain how plant breeders could employ genome editing as a novel platform to accelerate the domestication of semi-domesticated or wild plants, resulting in a more diversified base for future food and fodder supplies. This review emphasizes both the practicality of the strategy and the need to invest in research that advances our understanding of plant genomes, genes, and cellular systems. Planting more of these abandoned orphan crops could help alleviate food scarcities in the challenge of future climate crises.

Current status and prospects of herbicide-resistant grain sorghum (Sorghum bicolor).

Grain sorghum is a versatile crop, which can thrive under limited water and other inputs. However, crop loss from weed infestation continues to be a major constraint in grain sorghum production. Particularly, post-emergence grass weed control is a great challenge in grain sorghum due to the lack of herbicide options. Unlike in other major crops, such as maize or soybean, herbicide-resistant sorghum technology that can facilitate weed control throughout crop growing season is not available to growers yet. The development of herbicide-resistant sorghum can have potential to improve weed management, including post-emergence grass weed control. One of the major concerns in the development of such technology in sorghum is escape of resistance traits into weedy relatives of sorghum (e.g. shattercane and johnsongrass). This review focuses on sources of herbicide resistance in sorghum, the status of the development of herbicide-resistant sorghum technologies, overview of breeding methods, and limitations in the development of such sorghum technology as well as economic benefits for sorghum growers. © 2021 Society of Chemical Industry.

Genotypic variation in sorghum [Sorghum bicolor (L.) Moench] exotic germplasm collections for drought and disease tolerance.

Sorghum [Sorghum bicolor (L.) Moench] grain yield is severely affected by abiotic and biotic stresses during post-flowering stages, which has been aggravated by climate change. New parental lines having genes for various biotic and abiotic stress tolerances have the potential to mitigate this negative effect. Field studies were conducted under irrigated and dryland conditions with 128 exotic germplasm and 12 adapted lines to evaluate and identify potential sources for post-flowering drought tolerance and stalk and charcoal rot tolerances. The various physiological and disease related traits were recorded under irrigated and dryland conditions. Under dryland conditions, chlorophyll content (SPAD), grain yield and HI were decreased by 9, 44 and 16%, respectively, compared to irrigated conditions. Genotype RTx7000 and PI475432 had higher leaf temperature and grain yield, however, genotype PI570895 had lower leaf temperature and higher grain yield under dryland conditions. Increased grain yield and optimum leaf temperature was observed in PI510898, IS1212 and PI533946 compared to BTx642 (B35). However, IS14290, IS12945 and IS1219 had decreased grain yield and optimum leaf temperature under dryland conditions. Under irrigated conditions, stalk and charcoal rot disease severity was higher than under dryland conditions. Genotypes IS30562 and 1790E R had tolerance to both stalk rot and charcoal rot respectively and IS12706 was the most susceptible to both diseases. PI510898 showed combined tolerance to drought and Fusarium stalk rot under dryland conditions. The genotypes identified in this study are potential sources of drought and disease tolerance and will be used to develop better adaptable parental lines followed by high yielding hybrids.