**1. Introduction**

All annual oilseed crops have experienced poor growth rates over the previous ten years (negative for area and production), particularly safflower, sunflower, linseed, and niger crops and especially peanut, which has also experienced negative growth for the area [1]. India is the world's largest importer of vegetable oils (15 percent market share), followed by China and the USA, and it relies heavily on imports to meet its edible oil needs [2]. Palm oil accounts for roughly 60% of all imported edible oils, followed by soybean oil (~25%) and sunflower oil (~12%). It is also projected that edible oil demand will be 40.9 Mt by 2026 and that, by 2050, India will need to generate 17.84 Mt of vegetable oils to satisfy the country's estimated 1685 million population [2].

The necessity to scale up oilseed production demands immediate attention, given the rising domestic need for edible oils, alarming shortage, and the expense on the exchequer resulting from imports. Strategies to increase the productivity (and profitability) of oilseedbased production systems include the development of abiotic-stress-tolerant varieties in the

**Citation:** Chugh, V.; Kaur, D.; Purwar, S.; Kaushik, P.; Sharma, V.; Kumar, H.; Rai, A.; Singh, C.M.; Kamaluddin; Dubey, R.B. Applications of Molecular Markers for Developing Abiotic-Stress-Resilient Oilseed Crops. *Life* **2023**, *13*, 88. https:// doi.org/10.3390/life13010088

Academic Editors: Hakim Manghwar and Wajid Zaman

Received: 27 November 2022 Revised: 23 December 2022 Accepted: 25 December 2022 Published: 28 December 2022

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

context of changing climatic conditions. Increased frequency of extreme events (floods, cold, droughts, heat, etc.), altered precipitation patterns, and an increase in average temperature (average high night temperature) are all indicators of climate change. As Earth transitioned between ice ages over the last 800,000 years, atmospheric concentration of CO2 fluctuated between 180 ppm (glacial times) and 280 ppm (interglacial eras). The CO2 concentration has steadily increased from pre-industrial levels of 280 ppm to 384 ppm in 2009, while the mean temperature has risen by 0.76 ◦C over that time. According to projections, atmospheric [CO2] will reach 700 ppm or more by the end of this century, while the global temperature will rise by 1.8–4.0 ◦C depending on the greenhouse emission scenario [3]. With regard to global climate models, the mean ambient temperature is predicted to further increase by 1.5 ◦C within the next two decades [4]. The abiotic stresses have been reported to cause moderate to severe yield loss in various oilseeds (Table 1). To develop abiotic stress resistance and thus increase oil yield per unit area, traditional breeding efforts must be amalgamated with biotechnology methods.


**Table 1.** Yield loss reported in oilseeds due to abiotic stresses.

Molecular markers such as RFLP (Random Amplified Polymorphic DNA), AFLP (Amplified fragment length polymorphism), SSR (Simple Sequence Repeat), RAPD (Random Amplified Polymorphic DNA), SNP (single nucleotide polymorphisms). etc., are DNAbased oligonucleotide sequences facilitating the detection of variations or polymorphisms in the population for specific regions of DNA. Among the various biotechnological interventions, molecular markers have played a pivotal role in accelerating the crop breeding programs employing marker-assisted selection (MAS). The facts that they are abundant, technically easy to use, and detectable at any stage of plant development have given them an added advantage of not being affected by environmental factors. Rapid advancements have been made in the development of a variety of molecular markers over the past 20 years with refinements on a regular basis depending on the available infrastructure, technical skills required, the importance of the crop, and the trait in question. Figure 1 illustrates how molecular and integrated plant breeding is helpful in developing varieties with abiotic stress tolerance using genomic approaches such as MAS [23]. Success has been achieved in breeding oilseeds, such as canola, mustard, sunflower, soybean, and peanut, through the utilization of molecular marker techniques, mapping traits that control seed quality, and biotic and abiotic stress resistance [24–30]. However, though the techniques and available tools for MAS are well established, there is still a dearth of studies conducted using MAS to achieve abiotic stress tolerance for edible oilseed crops, such as sesame, niger, safflower, and the non-edible oil crops castor and linseed. This article discusses case studies involving the use of molecular markers for developing abiotic-stress-tolerant cultivars/genotypes of various oilseed crops.

**Figure 1.** A stepwise presentation of molecular breeding and genomics approaches for the development of abiotic-stress-tolerant cultivars.
