Breeding cereals for Mediterranean conditions: ecophysiological clues for biotechnology application

Abstract

Water stress is the main environmental factor limiting cereal yield in Mediterranean environments. For particular regions, such as the Mediterranean basin, the agroecological conditions are expected to get worse. In response to this challenge attempts are being made to improve crop yield through farmmanagement practices and plant breeding efforts. Here we examine traits that may be used as selection criteria for breeding C 3 cereal crops with improved yield and stability in Mediterranean conditions. Emphasis is made on the potential implications of defining proper selection traits and target environments when adopting biotechnology approaches in breeding programmes. Abbad H, Qariani L, El Jaafari S, Laamarti A, Araus J L. 2003. Comparative relationship of the flag leaf and the ear photosynthesis with the biomass and grain yield of durum wheat under a range of water conditions. Agronomie (In Press). Acevedo E. 1993. Potential of carbon isotope discrimination as a selection criterion in barley breeding. In Stable Isotopes and Plant Carbon/Water Relations, pp. 399-417. Eds J R Ehleringer, A E Hall and G D Farquhar. New York: Academic Press. Amani I, Fischer R A, Reynolds M P. 1996. Canopy temperature depression association with yield of irrigated spring wheat cultivars in hot climate. A, Nachit M M. 1998. Relationships between ash content, carbon isotope discrimination and yield in durum wheat. Australian Journal of Plant Physiology 25:835-842. Araus J L, Brown H R, Febrero A, Bort J, Serret M D. 1993. Ear photosynthesis, carbon isotope discrimination and the contribution of respiratory CO 2 to differences in grain mass in durum wheat. Plant, Cell and Environment 16:383-392. Araus J L, Febrero A, Català M, Molist M, Voltas J, Romagosa I. 1999. Crop water availability in early agriculture: evidence from carbon isotope discrimination of seeds from a tenth millennium BP site on the Euphrates. Global Change Biology 5:233-244. Araus J L, Casadesús J, Bort J, Nachit M M, Villegas D, Aparicio N, Royo C. 2000. Some remarks on ecophysiological traits for breeding. In Durum Wheat Improvement in the Mediterranean Region: New Challenges. Serie A: Séminaires Méditerranéennes, N 40. Options Méditerranéennes, pp. 57-62. Eds C Royo, M M Nachit, N di Fonzo and J L Araus. Zaragoza: IAMZ. Araus J L, Febrero A, Buxó R, Camalich M D, Martín D, Molina F, Rodríguez-Ariza M O, Romagosa I. 1997. Changes in carbon isotope discrimination in grain cereals from different regions of the western Mediterranean Basin during the past seven millennia. Palaeoenvironmental evidence of a differential change in aridity during the late Holocene, Global Change Biology 3:107-118. Araus J L, Villegas D, Aparicio N, García Del Moral L F, El Hani S, Rharrabti Y, Ferrio J P, Royo C. 2003b. Environmental factors determining carbon isotope discrimination and yield in durum wheat under Mediterranean conditions.

The Association Among Gene Expression Responses to Nine Abiotic Stress Treatments in Arabidopsis thaliana

“…A primary challenge, however, may reside in manipulating the expression of genes underlying multiple-stress tolerance without associated costs affecting plant fitness components, particularly if such genes are involved in central metabolic processes (Vinocur and Altman 2005). This challenge has been foreshadowed by decades of artificial selection experiments, in which diminished growth and productivity have often been found to result as a correlated response to selection for increased stress tolerance Hoffmann and Parsons 1989a;Verhoeven et al 2004;Sinebo 2005; but see Araus et al 2003). Similar growth and productivity costs have more recently been found in strains bioengineered for increased tolerance to adverse conditions (e.g., Kasuga et al 1999;Ito et al 2006) and have been an obstacle toward successful bioengineering of stress tolerance in plants (Vinocur and Altman 2005).…”

Quantitative Trait Loci for Grain Yield and Adaptation of Durum Wheat (Triticum durum Desf.) Across a Wide Range of Water Availability

“…This result indicates that no major gene with large effects for HD segregated in the Kofa 3 Svevo population, an important feature when evaluating different genotypes in Mediterranean environments where variation in HD usually shows, on an adaptive basis, significant and negative association with GY in both bread and durum wheat (Richards 1996;Araus et al 1998Araus et al , 2003aDel Moral et al 2003), thus requiring its adoption as a covariate if the objective is the identification of QTL for GY on a per se (i.e., constitutive) basis, rather than on a more adaptive basis.…”

“…), particularly in the Mediterranean basin where $75% of the world's durum grain is produced. Durum wheat is primarily grown under rainfed conditions where the frequent occurrence of drought combined with heat stress is the major factor limiting grain yield (Araus et al 2002(Araus et al , 2003aCondon et al 2004). In the Mediterranean basin, durum wheat is cultivated across a number of macroenvironments that differ widely in the quantity of rainfall as well as in their thermo-pluviometrical patterns during the crop cycle (Leemans and Cramer 1991;Loss and Siddique 1994;Dunkeloh and Jacobeit 2003).…”

Changes in durum wheat root and aerial biomass caused by the introduction of the Rht-B1b dwarfing allele and their effects on yield formation

“…In reduced-input agricultural systems, root traits affecting the acquisition of mineral elements often determine yield (Ehdaie et al 2010;White et al 2013). In the Mediterranean Basin, one of the largest durum wheat producers in the world, more than 50 % of the total grain of durum wheat is produced in arid and semi-arid conditions, with severe drought most years (Loss and Siddique 1994;Araus et al 2003;García del Moral et al 2005). In dryland agricultural systems, a large root system that promotes access to soil water and nutrients is regarded as beneficial for plant growth (Richards 2008), although under terminal drought a greater investment in fine roots at depth would improve yield due to the better access to water and nitrogen (King et al 2003).…”