The genetic basis of water‐use efficiency and yield in lettuce

Abstract

Background Water supply limits agricultural productivity of many crops including lettuce. Identifying cultivars within crop species that can maintain productivity with reduced water supply is a significant challenge, but central to developing resilient crops for future water-limited climates. We investigated traits known to be related to water-use efficiency (WUE) and yield in lettuce, a globally important leafy salad crop, in a recombinant inbred line (RIL) lettuce mapping population, produced from a cross between the cultivated Lactuca sativa L. cv. Salinas and its wild progenitor L. serriola L. Results Wild and cultivated lettuce differed in their WUE and we observed transgressive segregation in yield and water-use traits in the RILs. Quantitative trait loci (QTL) analysis identified genomic regions controlling these traits under well-watered and droughted conditions. QTL were detected for carbon isotope discrimination, transpiration, stomatal conductance, leaf temperature and yield, controlling 4–23 % of the phenotypic variation. A QTL hotspot was identified on chromosome 8 that controlled carbon isotope discrimination, stomatal conductance and yield under drought. Several promising candidate genes in this region were associated with WUE, including aquaporins, late embryogenesis abundant proteins, an abscisic acid-responsive element binding protein and glutathione S-transferases involved in redox homeostasis following drought stress were also identified. Conclusions For the first time, we have characterised the genetic basis of WUE of lettuce, a commercially important and water demanding crop. We have identified promising candidate genomic regions determining WUE and yield under well-watered and water-limiting conditions, providing important pre-breeding data for future lettuce selection and breeding where water productivity will be a key target.

Performance Evaluation of a Cascade Cropping System

“…The improvement in WP could impart tolerance to drought and salinity stress, while still accumulating sufficient biomass to make their production commercially viable. According to Damerum et al [33], it is imperative to develop systems for improving crop WP, particularly in the case of crops such as lettuce, where over 75% of the total production in the US is dominated by the state of California. The combination of DS with fresh nutrient solution may allow this goal to be achieved, and should be further investigated.…”

Dynamic QTL mapping revealed primarily the genetic structure of photosynthetic traits in castor (Ricinus communis L.)

“…The improvement of instruments and measurement methods has promoted the study of photosynthetic traits, especially in model plants, a number of genes controlling photosynthetic traits have been found, for example, the genes mediating water use efficiency (Wue) 7 – 11 , transpiration rate (Tr) 12 – 14 and stomatal density 15 , 16 in Arabidopsis , and the genes regulating photosynthetic capacity and Wue in rice 17 – 20 . In addition, some QTLs underlying photosynthetic traits have been successfully detected in other crops, but with low contribution rate (most of them with contribution rate less than 10%) 21 – 24 . Such a situation might be caused by the epistatic effect partially masking the single-locus effect and the joint control of photosynthetic traits by many minor-effect genes 22 .…”