A Molecular Marker Within the NLP3-B1 Gene Is Associated with Earliness in Spring Wheat (Triticum aestivum L.)

Earliness is a critical agronomic trait that enables plants to avoid adverse weather conditions during the late growing season or at harvest. In wheat, earliness is controlled by at least three distinct mechanisms: vernalization requirement, photoperiod sensitivity, and a mechanism independent of the first two, so called, earliness per se. In this work we report a locus on chromosome 3B within NLP3-B1 (TraesCS3B02G190300) gene, coding a nitrate-sensitive transcription factor protein, which is associated with earliness in F5:6 of PI-518620 x CI-17241 spring wheat cross. The variant ‘A’ of the single nucleotide polymorphism NLP3-B1: c.1824+137G>A, which is proper to evolutionary earlier haplotypes, provides heading and anthesis that is 2 days earlier. The effect of this novel marker on earliness was additive to the effect of PPD-D1 locus in the same population; however, the effect of the former was weaker. Similarly, allele Ppd-D1a and the variant ‘A’ of the NLP3-B1: c.1824+137G>A polymorphism statistically significantly reduced the plant height (for 2.2 and 1.3 cm, correspondingly) and changed some other agronomical traits; however, these light pleiotropic effects are not of practical value. The possible direct impact of NLP3-B1 on the timing of flowering via altered nitrate sensitivity has been discussed, and other candidate genes on chromosome 3B have also been suggested.