First Report of Sesame Mutants Tolerant to Severe Drought Stress during Germination and Early Seedling Growth Stages

Abstract

In the context of climate change and water scarcity, there is a need to develop and use drought-tolerant sesame cultivars. This study was conducted to evaluate the response of 13 sesame genotypes, including 11 mutants and their wild-types, to drought during germination and early seedling growth. Moderate and severe drought stress was simulated by applying polyethylene glycol (PEG) at two osmotic potentials, −0.6 MPa and −1.2 MPa, respectively, on seeds of two successive mutant generations, M2 and M3. The parameters measured or calculated were germination percentage (GP), germination rate (GR), mean germination time (MGT), root length (RL), shoot length (SL), root to shoot ratio (RSR), and the seedling vigor index (SVI). Results showed the significant effect of genotype, drought, and drought × genotype interaction on all parameters investigated. Under severe drought, seeds of seven genotypes, including wild types, were not able to germinate. There was a drastic decline of all parameters for the rest, except MGT and RSR, which markedly increased. Interestingly, two mutants, “ML2-5” and “ML2-10”, were identified as the most tolerant to severe drought and the most stable over both generations. The present work is the first report of sesame germplasm with such a high level of tolerance to drought during germination and early seedling growth stages.

Comparison of the Differences in Tolerance to Drought Stress across Five Clematis Species Based on Seed Germination and Seedling Growth

“…The VI and GI are highly sensitive to drought and can be considered as effective indicators of drought tolerance in plants [70,71]. Our research results indicated that PEG stress generally decreased the GI and VI of the five species of Clematis (Table 1), as is consistent with previous studies on Triticum aestivum [72], Cicer arietinum [73], Sesamum indicum [70], and other plant species [65,74].…”

Current Research Trends and Prospects for Yield and Quality Improvement in Sesame, an Important Oilseed Crop

“…Earlier studies revealed the role of PEG (in varying concentrations) in examining DS tolerance in sesame plants (Liang et al, 2021). However, only one report has evaluated sesame genotypes under DS (varying PEG concentration) using mutant plants at the seedling stage, establishing two sesame mutants "ML2-5" and "ML2-10" tolerant of severe DS (Kouighat et al, 2021). Very few molecular studies have been conducted in sesame under DS.…”

Moroccan sesame: Current situation, challenges, and recommended actions for its development

“…However, in arid and semi-arid areas, drought often occurs in conjunction with heat or high temperatures, which significantly impairs sesame productivity (Hassanzadeh et al, 2009). Adverse effects on seed yield and quality have been noticed when water stress occurs especially at germination and flowering stages (Hassanzadeh et al, 2009;Boureima et al, 2011;Komivi et al, 2016;Dossa et al, 2017;Kouighat et al, 2021). In Morocco, drought has always been present as a structural element of the climate, with increasing frequency in recent decades, due to climate change (Zraibi et al, 2011).…”

“…As a result, mechanized harvesting is impossible and commercial production will be limited due to costly labor (Langham and Wiemers, 2002). On the other hand, even though sesame is known as a drought-tolerant crop, it is susceptible during germination and flowering (Hassanzadeh et al, 2009;Boureima et al, 2011;Komivi et al, 2016;Dossa et al, 2017;Kouighat et al, 2021). Sesame cultivars grown in Morocco have wild traits including capsule dehiscence, long plant cycle, and sensitivity to biotic and abiotic stresses (El Harfi et al, 2021).…”