Abstract
By selecting for prostrate growth habit of the juvenile phase of the cycle, durum wheat cultivars could be developed with improved competitive ability against weeds, and better soil coverage to reduce the soil water lost by evaporation. A panel of 184 durum wheat (Triticum turgidum subsp. durum) genotypes, previously genotyped with DArT-seq markers, was used to perform association mapping analysis of prostrate/erect growth habit trait and to identify candidate genes. Phenotypic data of plant growth habit were recorded during three consecutive growing seasons (2014–2016), two different growth conditions (field trial and greenhouse) and two sowing periods (autumn and spring). Genome-wide association study revealed significant marker-trait associations, twelve of which were specific for a single environment/year, 4 consistent in two environments, and two MTAs for the LSmeans were identified across all environments, on chromosomes 2B and 5A. The co-localization of some MTAs identified in this study with known vernalization and photoperiod genes demonstrated that the sensitivity to vernalization and photoperiod response are actually not only key components of spring/winter growth habit, but they play also an important role in defining the magnitude of the tiller angle during the tillering stage. Many zinc-finger transcription factors, such as C2H2 or CCCH-domain zinc finger proteins, known to be involved in plant growth habit and in leaf angle regulation were found as among the most likely candidate genes. The highest numbers of candidate genes putatively related to the trait were found on chromosomes 3A, 4B, 5A and 6A. Moreover, a bioinformatic approach has been considered to search for functional ortholog genes in wheat by using the sequence of rice and barley tiller angle-related genes. The information generated could be used to improve the understanding of the mechanisms that regulate the prostrate/erect growth habit in wheat and the adaptive potential of durum wheat under resource-limited environmental conditions.
Highlights
Plant architecture integrates a set of important agronomic traits in wheat, such as plant height, tiller number, juvenile growth habit, flag leaf angle and spike characteristics, that are important for increasing crop yield potential
With the longer-term aim of selecting genotypes with a desirable plant architecture to be used in durum wheat breeding, the aim of this study was to perform association mapping for prostrate/erect growth habit trait in a panel of 170 diverse winter and 14 spring durum wheat genotypes, previously genotyped with DArT-seq markers [42], and to identify candidate genes based on available sequences of markers located at the marker-trait associations (MTAs), in order to provide valuable information for better understanding the genetic mechanism of the tiller angle trait in wheat
The deceleration in the relative rate of increase in yields coupled with ongoing climate change and the increase in global population represents a serious challenge for wheat breeders
Summary
Plant architecture integrates a set of important agronomic traits in wheat, such as plant height, tiller number, juvenile growth habit, flag leaf angle and spike characteristics, that are important for increasing crop yield potential. Plant breeders have extensively modulated such architectural traits: the extraordinary increase in wheat yield that has been registered with the introduction of modern semi-dwarf wheat varieties during green revolution was partially due to the improvement of the plant architecture [1], e.g., in terms of plant height [2] and flag leaf angle [3]. For monocotyledonous crops, the dynamics of tiller angle from vertical, during the juvenile growth stage (i.e., from prostrate to semi-prostrate and erect growth habit) is another important agronomic trait that should be considered, because a dense ground cover affects the interception of light for photosynthetic accumulation, the inhibition of weed growth and the reduction of water evaporation from soil [9]
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