Speed breeding for multiple quantitative traits in durum wheat

Abstract

BackgroundPlant breeding requires numerous generations to be cycled and evaluated before an improved cultivar is released. This lengthy process is required to introduce and test multiple traits of interest. However, a technology for rapid generation advance named ‘speed breeding’ was successfully deployed in bread wheat (Triticum aestivum L.) to achieve six generations per year while imposing phenotypic selection for foliar disease resistance and grain dormancy. Here, for the first time the deployment of this methodology is presented in durum wheat (Triticum durum Desf.) by integrating selection for key traits, including above and below ground traits on the same set of plants. This involved phenotyping for seminal root angle (RA), seminal root number (RN), tolerance to crown rot (CR), resistance to leaf rust (LR) and plant height (PH). In durum wheat, these traits are desirable in environments where yield is limited by in-season rainfall with the occurrence of CR and epidemics of LR. To evaluate this multi-trait screening approach, we applied selection to a large segregating F2 population (n = 1000) derived from a bi-parental cross (Outrob4/Caparoi). A weighted selection index (SI) was developed and applied. The gain for each trait was determined by evaluating F3 progeny derived from 100 ‘selected’ and 100 ‘unselected’ F2 individuals.ResultsTransgressive segregation was observed for all assayed traits in the Outrob4/Caparoi F2 population. Application of the SI successfully shifted the population mean for four traits, as determined by a significant mean difference between ‘selected’ and ‘unselected’ F3 families for CR tolerance, LR resistance, RA and RN. No significant shift for PH was observed.ConclusionsThe novel multi-trait phenotyping method presents a useful tool for rapid selection of early filial generations or for the characterization of fixed lines out-of-season. Further, it offers efficient use of resources by assaying multiple traits on the same set of plants. Results suggest that when performed in parallel with speed breeding in early generations, selection will enrich recombinant inbred lines with desirable alleles and will reduce the length and number of years required to combine these traits in elite breeding populations and therefore cultivars.Electronic supplementary materialThe online version of this article (10.1186/s13007-018-0302-y) contains supplementary material, which is available to authorized users.

Root System Architecture and Its Association with Yield under Different Water Regimes in Durum Wheat

“…Here, an attempt was made to adapt low-cost and scalable methodologies to reliably characterize root behavior in durum wheat. The clear pot method has already been used to study other crops and was most recently adapted to durum wheat (Alahmad et al, 2018). Its scalability and reliability have been discussed in depth elsewhere (Richard et al, 2015).…”

Increasing Salinity Tolerance of Crops

“…This process, however, can take many generations and requires the breeder to have a molecular marker specific to the Na + tolerance gene that has been inserted into the genome; otherwise this gene also would be lost [80]. Recent developments in precision breeding in combination with reducing generation time, through speed breeding [185][186][187], will aid the development of salt tolerant crops by considerably reducing the length of time it takes to introduce a desired trait into a crop. Speed breeding involves growing plants under stressful light and watering regimes to shorten time to flowering [185].…”

Accelerating the development of durum wheat adapted to drought and crown rot conditions

“…The panel of 14 genotypes including NAM parents and bread wheat standards (Table 4.1) were phenotyped for SRA, using the 'clear pot' method which is suitable for screening small grains such as bread wheat (Richard et al, 2015;Robinson et al, 2016;Alahmad et al, 2018a). In this experiment, clear pots were filled with composted fine, black-colored pine bark, consisting of 70% particles 0-5 mm in size, pre-mixed with 30% coco peat to increase the water-holding capacity.…”

“…and thousand kernel weight by 9% in environments with limited moisture, compared to genotypes with shallow root systems (El Hassouni et al, 2018). The availability of large genetic variability in terms of rooting patterns and the high heritability of SRA (Manschadi et al, 2006;Maccaferri et al, 2016;Alahmad et al, 2018a;El Hassouni et al, 2018) are two key factors suggesting that optimization of the roots could potentially deliver high yielding durum cultivars in water-limiting environments.…”

“…Recently, a high-throughput, affordable and scalable phenotyping method for screening seminal root angle under controlled conditions has been developed, known as the 'clear pot' method , and has been successfully applied to durum wheat, barley and bread wheat. The technique has facilitated direct phenotypic selection of SRA (Alahmad et al, 2018a;Richard et al, 2018), phenotyping cultivars and breeding lines to investigate yield trends (El Hassouni et al, 2018;Robinson et al, 2018), and phenotyping of mapping populations required for QTL discovery (Robinson et al, 2016). While evaluation of mature RSA in the field is challenging, moderately efficient techniques have been developed, such as 'shovelomics' (Trachsel et al, 2011), soil coring (Wasson et al, 2014) and the 'pasta strainer' method (El Hassouni et al, 2018).…”