Indirect changes associated with a selection program for increased seed-yield in wild species of Lesquerella (Brassicaceae): are we developing a phenotype opposite to the expected ideotype?

GONZALEZ PALEO L, Y RAVETTA, D.A.

Industrial Crops and Products

ELSEVIER SCIENCE BV

Año: 2011 vol. 34 p. 1372 - 1380

0926-6690

Seed-yield stability, frequently associated with drought-tolerance strategies, is one of the main breedingobjectives for the development of crops for semi-arid mediterranean-type environments. Since breedingof new industrial crops targeted for arid lands is not appreciably different from that of traditionalcrops, higher yield is achieved by increased harvest-index, at the cost of losing traits associated withdrought-tolerance and reduced seed-yield stability. Using Lesquerella as a model we compared selectedand unselected accessions of annual (L. gracilis and L. angustifolia) and perennial (L. pinetorum and L. mendocina)genotypes grown in field experiments in Patagonia, Argentina. Our objective was to assess theeffects of breeding for increased seed-yield on traits related to the main characteristics that define themost common ideotype for mediterranean-type environments: early vigor, conservative growth strategypost-anthesis and reserves storage. Our specific question was: Have any of the attributes associated withseed-yield stability been indirectly selected during the domestication process? Our results show thatthese characteristics were reduced or lost, in selected lines compared to their wild relatives. Early vigorwas lower in selected accessions and was associated mainly with reduced relative growth rate and CO2assimilation. During the reproductive period the growth strategy was changed by selection towards anon-conservative and more acquisitive resource use strategy. Traits associated with this strategy werelinked to higher water use efficiency and growth capacity (higher CO2 assimilation rate, specific leaf area,and leaf allocation), but also with loss of structural adaptation to low resource environments (i.e. lowspecific leaf area), an increase in nutrient and water demands, and reduced nutrient use efficiency. Carbohydratesaccumulation pre-anthesis was lower in selected accessions of all four species, and also, just inperennials we found lower reserves storage post-anthesis. These changes in the pattern of carbohydratesaccumulation could be associated to lower seed-yield stability due to the loss of buffer capacity linkedwith the use of pre-anthesis reserves for seed filling. On the other hand, in perennial species lower reservesstorage after seed harvest could reduce plant longevity and survival. We conclude that indirect changesoccurred during the preliminary domestication of both annual and perennial species of Lesquerella usedin our experiment. These changes were against those required if these species were to be developed ascrops for semi-arid, mediterranean environments and should result in low seed-yield stability.© 2010 Elsevier B.V. All rights reserved.