Genetic variability for root and shoot traits in a lentil (Lens culinaris Medik.) recombinant inbred line population and their association with drought tolerance

Abstract

Lentil (Lens culinaris Medik.) is usually grown under rainfed environments and often encounters drought stress from limited rainfall. Little information is available about shoot and root traits in association with drought tolerance. We studied variability for root and shoot traits related to drought tolerance using an F6–8 population of 133 recombinant inbred lines (RILs) from the cross ILL6002 × ILL5888. We found important variation between genotypes and also high variation in heritability values for root and shoot traits at 38 days after sowing the parents and RILs under both well-watered and drought-stressed treatments during two consecutive seasons in the greenhouse. The higher heritability values were obtained under drought stress treatment and suggest that selection in water-limited environments would be more effective in achieving genetic gains. Drought had reduced trait values, except root–shoot ratio that was likely to be enhanced underlying the importance of this trait for drought tolerance. The quantitative and continuous distributions of variation are the evidence for polygenic control of these traits and the possibility of mapping the quantitative trait loci (QTL). Statistically significant associations between root and shoot traits such as dry shoot biomass and chlorophyll content were noted, highlighting the reliability of indirect selection for underground traits (root) based on these aboveground traits in breeding programs. Significant correlations and regressions were demonstrated between dry root biomass, lateral root number, root surface area, dry shoot biomass, root–shoot ratio, chlorophyll content and drought tolerance as estimated by wilting severity from limited water supply. This shows the importance of a well-developed root system and early biomass development for drought tolerance. Identification and mapping of QTL related to studied traits in this population would be a first step for starting marker-assisted selection

Molecular Assortment of Lens Species with Different Adaptations to Drought Conditions Using SSR Markers

“…Similar root and shoot traits variability related to drought tolerance in lentil was also observed by Idrissi et al . where they found that drought stress significantly reduced root and shoot characteristics compared to well-watered conditions in RILs derived from a cross between ILL 6002 and ILL 5888 [ 33 ]. Ashraf and Iram also found that imposition of water deficit conditions on Phaseolus vulgaris and Sesbania aculeata plants had significant inhibitory effect on fresh and dry weights of both root and shoot as well as on shoot length [ 54 ].…”

“…and Idrissi et al . [ 16 , 33 ]: 0 = healthy plants with no visible symptoms of drought stress; 1 = green plants with slight wilting; 2 = leaves turning yellowish green with moderate wilting; 3 = leaves yellow—brown with severe wilting and 4 = completely dried leaves and/or stems. The reduction of root length and shoot length, fresh and dry weights was also recorded after 6 days of air exposure at the seedling stage.…”

Identification of Quantitative Trait Loci Controlling Root and Shoot Traits Associated with Drought Tolerance in a Lentil (Lens culinaris Medik.) Recombinant Inbred Line Population

“…These traits were shown to be significantly correlated (Idrissi et al, 2015a). Similarly, a QTL-“hotspot” related to 12 root traits was reported by Varshney et al (2014) in chickpea ( Cicer arietinum L.).…”

“…Idrissi et al (2015a) confirmed evidence of high genetic variability, high heritability and polygenic control of root and shoot characteristics. However, to our knowledge, no QTLs related to root traits have been reported for lentil to date.…”

“…Developing cultivars with enhanced drought tolerance by conventional breeding often has limited success due to the complexity of this trait and the difficulties with finding reliable and suitable phenotyping methods. For example, well-developed root systems have been shown to be linked to drought tolerance as an avoidance mechanism guaranteeing plant productivity under water-limited conditions (Kashiwagi et al, 2005; Sarker et al, 2005; Verslues et al, 2006; Gaur et al, 2008; Vadez et al, 2008; Aswaf and Blair, 2012; Comas et al, 2013; Idrissi et al, 2015a,b). However, it is difficult to screen large numbers of accessions for these root traits using conventional methods.…”