NAM gene allelic composition and its relation to grain-filling duration and nitrogen utilisation efficiency of Australian wheat

Abstract

Optimising nitrogen fertiliser management in combination with using high nitrogen efficient wheat cultivars is the most effective strategy to maximise productivity in a cost-efficient manner. The present study was designed to investigate the associations between nitrogen utilisation efficiency (NUtE) and the allelic composition of the NAM genes in Australian wheat cultivars. As results, the non-functional NAM-B1 allele was more responsive to the nitrogen levels and increased NUtE significantly, leading to a higher grain yield but reduced grain protein content. Nitrogen application at different developmental stages (mid-tillering, booting, and flowering) did not show significant differences in grain yield and protein content. The NAM-A1 allelic variation is significantly associated with the length of the grain-filling period. While the NAM-A1 allele a was associated with a short to moderate grain-filling phase, the alleles c and d were related to moderate to long grain-filling phase. Thus, selection of appropriate combinations of NAM gene alleles can fine-tune the duration of growth phases affecting sink-source relationships which offers an opportunity to develop high NUtE cultivars for target environments.

Transcriptomic Study for Identification of Major Nitrogen Stress Responsive Genes in Australian Bread Wheat Cultivars

“…In Mace, GY and GPC were less affected by N stress compared to those in Spitfire and Volcani in glasshouse conditions, although under high N conditions, the GPC of Spitfire and Volcani was higher than that of Mace. In agreement with the previous study (Alhabbar et al, 2018b), this study further confirms that Mace is more tolerant of N stress. It was reported that the GY in maize was decreased by 38% with the change in N treatment from high to low (Gallais and Hirel, 2004), which can be associated with the interrupted synthesis of chlorophyll and photosynthesis performance (McCullough et al, 1994).…”

“…This study investigated three Australian bread wheat varieties, Mace, Spitfire, and Volcani, which are known to have high, medium, and low NUEs, respectively (Alhabbar et al, 2018b). Since gene expression in plants is controlled in a temporal and tissue-specific manner (Koltunow et al, 1990;Maizel and Weigel, 2004) and the N demand is subject to plant developmental stages, the current study used different tissues at different growth stages to unravel the broad picture of transcriptome profile with the objectives of identifying novel genes that are differentially expressed under long-term N stress compared to high N treatment, and by characterizing the underlying physiological and molecular mechanisms of tolerance to N stress.…”

Delaying or Delivering: Identification of novel NAM-1 alleles which delay senescence to extend grain fill duration of wheat

“…Asterisks and bold coloured lettering indicate known variants, including AA substitutions identified for 1189a in orange (G159E, NAM-Al), 2316b in blue (TlSl, NAM-D1), natural NAM-Al variants in pink (Cormier et al , 2015), EMS-induced NAM-Al missense mutations in yellow (Harrington et al , 2019a), EMS-induced knockout mutations in green (Avni et al , 2014) and red (Pearce et al , 2014). In Triticum aestivum NAM-Bl is largely non-functional due to a +1 bp frameshift mutation, or complete deletion (Uauy et al , 2006a; Hagenblad et al , 2012; Alhabbar et al , 2018a; Alhabbar et al , 2018b). Accession numbers are, NAM-Al, TraesCS6A02G108300.1; NAM-Bl, UniProtKB/Swiss-Prot: A0SPJ4.1 (Triticum turgidum ssp.…”

Genome-wide and SNP network analyses reveal genetic control of spikelet sterility and yield-related traits in wheat

“…while the modern wheat cultivars carry the nonfunctional allele 34 . The expression analysis of NAM alleles showed high expression of NAM-A1, -B1 and -D1 in the stamens and spikelets, while NAM-B1 is also expressed in the flag leaf 35 . This can explain the spikelet/floret sterility in the modern cultivars that are carrying alleles NAM-A1 and NAM-D1, and demonstrates the role of NAM-B1 allele in spikelet development in our collection, because of improving nitrogen use efficiency and grain yield.…”