Effect of GA-sensitivity on wheat early vigor and yield components under deep sowing

Abstract

Establishment of seedlings is a key factor in achievement of uniform field stands and, consequently, stable yields. Under Mediterranean conditions, soil moisture in the upper layer is limited and seedlings may be exposed to frequent dehydration events. The presence of the Reduced height (Rht)-B1b and Rht-D1b semi-dominant dwarfing alleles results in insensitivity to gibberellin (GAI) and, hence, poor emergence from deep sowing. Introduction of alternative dwarfing genes and, thereby, preservation of the gibberellin response (GAR) and coleoptile length, contributes to better emergence from deep sowing. Initially 47 wheat cultivars carrying different Rht alleles were screened for their ability to emerge from deep sowing, and then 17 of them were selected for detailed physiological characterization in the field. The modern wheat lines containing GAI alleles showed significantly lower percentages of emergence from deep sowing than the GAR lines, i.e., 52 and 74%, respectively. Differences in early developmental stages were associated with grain yield, as indicated by a reduction of 37.3% in the modern GAI cultivars. Our results demonstrate the potential of alternative dwarfing genes for improving seedling establishment and grain yields in Mediterranean-like environments.

Abiotic Stress Signaling in Wheat – An Inclusive Overview of Hormonal Interactions During Abiotic Stress Responses in Wheat

“…GA signaling involves the targeted degradation of a group of GA-response transcriptional repressors, DELLA proteins, upon GA perception ( Golldack et al, 2014 ). This signaling pathway was shown to be paramount to success of wheat seedlings in the Mediterranean soil where the uppermost section of soil is arid and water deficient ( Amram et al, 2015 ). GA insensitive Rht mutants exhibit a dwarf phenotype which reduces their successful emergence under deep sowing conditions important under these soil conditions ( Amram et al, 2015 ).…”

Brassinosteroid and gibberellin control of seedling traits in maize (Zea mays L.)

“…Establishment of seedlings is a key factor for uniform, high-yielding field stands and, consequently, stable yields [31]. Several traits were used to measure seedling vigor in maize, including seed germination rate, seedling shoot length, root length, seedling dry weight, root dry weight, and these traits have been extensively used for correlation studies with adult plant traits in different maize genotypes [32][33][34][35].…”

Genetic improvement of wheat early vigor promote weed-competitiveness under Mediterranean climate

“…S1). In each generation of crossing, the lines were phenotypically selected based on their response to exogenous application of gibberellic acid as described previously [28]. At the last stage, the developed near isogenic lines (NILs) were genetically characterized to validate their genetic composition.…”

“…Genetic improvement of early vigor might be achieved via several traits such as increased grain or embryo size, wider leaf and longer coleoptiles. One strategy to counter this, is using alternative GA-responsive (GAR) dwarfing genes, which reduce plant height while avoiding the reduction effect on early vigor and coleoptile length, and suggested a means to improve early vigor [28][29][30].…”