J. M. Martin’s research while affiliated with Montana State University and other places

Wheat (Triticum aestivum L.) has inflorescences made up of multiple spikelets arranged along a central rachis, with each spikelet producing between one and four grains. The Grain Number Increase 1 (GNI‐A1) gene wheat directly influences grain number per spikelet and grain size. Three naturally occurring alleles have been described previously: GNI‐A1‐105N, 105Y, and 105K. This project's goal was to characterize the impact of these alleles within hard red spring wheat cultivars in Montana, where each of the alleles is common. The 105N allele and the 105K allele were compared through analysis of an F5 Vida by Spring‐Yellowstone recombinant inbred line (RIL) population, and with near isogenic lines (NILs) derived from the same population. The 105N allele and the 105Y allele were compared with NILs derived from an F4 Lanning by Egan RIL population. We analyzed the impact of each of the three alleles and compared their effects on inflorescence architecture, grain size, grain yield, grain quality, and milling quality under Bozeman, MT, field conditions. Data show that either loss‐of‐function alleles (105Y and 105K) increased grain number per spikelet by 5% when compared to the more functional allele (105N) across all years and environments tested. Overall grain size was not significantly reduced and there was also not a significant increase in overall grain yield.

Hard red spring wheat (Triticum aestivum L.) grown in rainfed environments in the northern Great Plains of North America frequently encounter drought and heat stress during grain‐fill, thus reducing yield. Delayed leaf senescence after heading, known as the stay‐green trait, has been found to help spring wheat tolerate drought and heat stress during grain‐fill. To better understand how the stay‐green trait relates to expression of other agronomic traits, data was analyzed from a recombinant inbred line (RIL) population derived from a ‘Vida’/MTHW0202 cross grown in rainfed and irrigated environments. The genetic architecture controlling traits measured in this study were also examined. Results found the stay‐green trait was significantly correlated to overall yield (P < .001, r = .37) in rain‐fed environments, but was not significantly correlated to yield (P = .26, r = .09) in irrigated environments. Three quantitative trait loci (QTL) located on chromosomes 2D, 4A, and 4D were associated with the stay‐green trait. The 4A stay‐green QTL, previously designated QGfd.mst‐4A, was collocated with QTL for seed number per head, thousand kernel weight, and heading date. The 4D stay‐green QTL overlaps the Rht‐D1 plant height gene, and the allele prolonging the stay‐green period co‐segregates with the wild‐type (tall) Rht‐D1a allele. Results from this study provide a better understanding of the relationship between stay‐green and agronomic traits in rainfed vs. irrigated environments. Additionally, understanding the genetic architecture controlling stay‐green and agronomic traits will aid in selecting future drought‐tolerant spring wheat varieties.

The above-mentioned article was published in 2015 with an error in the reverse primer sequence for the PPOA2d1074 marker, which made amplification difficult. The reverse primer was missing a thymine nucleotide at the thirteenth position (GCGGTGCTTCACTTGGT).

Upregulation of starch biosynthesis in either source or sink tissue has been shown to increase yield under non-limiting resources. Previously we demonstrated that overexpression of AGPase in both leaf and seed tissue results in greater yield increases than overexpression in a single tissue alone. This study examines the link between starch biosynthesis, plant yield, and plant nutrition. Rice overexpressing AGPase in leaves and seeds (LS) was grown under four nutrition treatments and compared to wild type (WT) sister plants. In this study yield differences were most pronounced at low to mid nutrition levels. Greatest differences were observed at 0.075 g N L⁻¹, where biomass and seed weight per plant were increased by 45% in LS plants. Alternatively leaf starch trended higher at mid to high nutrition, but was only significant at 0.1 g N L⁻¹, where starch was 2.59 × higher compared to the WT. This was in contrast with photosynthetic rates. Rates were unchanged between LS and WT plants at 0.05 g N L⁻¹ nutrition, but significantly lower by 25% in LS plants at 0.1 g N L⁻¹ and 0.2 g N L⁻¹ nutrition. This study provides further insight into the complex interactions between starch biosynthesis, plant metabolism, and plant growth.

Maturity traits such as days to heading and days to physiological maturity have a large impact on agronomic characteristics of wheat (Triticum aestivum L.) cultivars grown in specific environments. Extended green leaf and green glume duration after heading in hard red spring wheat have been shown to result in longer grain-fill duration, increased kernel weight, and higher grain yield in dry environments. The genetic relationship between maturity traits, seed quality, and functional bread-making characteristics was investigated for three sets of recombinant inbred lines derived from crosses between hard red spring wheat parents. Early heading date was correlated with increased seed quality as indicated by test weight and kernel weight in all three genetic populations. Days to heading was not consistently correlated with functional quality related to bread-baking. Longer green glume and green leaf duration after heading were typically positively related to seed quality traits including test weight and kernel weight in the three populations. However, increased green leaf and green glume duration after heading were often negatively correlated with functional quality parameters related to bread baking. Our results suggest that selection for long green leaf or green glume duration after heading to stabilize grain yield in a warmer climate may also result in a decrease in bread-making potential. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved.

Hard red spring and winter wheat (Triticum aestivum L.) differ due to the need for vernalization to induce flowering in winter wheat, adaptation to different environments, and the requirement for higher grain protein content for end‐use quality in spring wheat. Genetic studies on spring × winter wheat crosses to identify beneficial alleles are difficult due to segregation of vernalization (Vrn) genes. For this experiment, ‘Yellowstone’, a widely grown winter wheat cultivar, was converted to the spring habit through marker‐assisted backcrossing of Vrn‐A1 and is now referred to as ‘S‐Yellowstone’. S‐Yellowstone was crossed to the spring wheat cultivar ‘Choteau’ to produce a population of 95 spring habit recombinant inbred lines (RILs). The RILs and parents were evaluated in field trials for 2 yr where S‐Yellowstone had higher grain yield and lower grain protein than Choteau. A quantitative trait locus (QTL) on chromosome 4A had pleiotropic effects on several traits. The S‐Yellowstone allele at this locus resulted in more seeds per head, accounting for 59.5% of the variation across all environments. The QTL was designated QSnh.mst‐4A. However, the S‐Yellowstone QSnh.mst‐4A allele also resulted in lower grain protein across all environments. Results suggest that the favorable QSnh.mst‐4A allele for seed number per head identified in the winter wheat parent might be useful for increasing yield in spring wheat, but consequences of the negative pleiotropic effects on grain protein content might be significant.

Variability of production environments challenges wheat (Triticum aestivum L.) breeders to develop genotypes with the potential to perform well under different levels of resource availability. An important trait that may provide plasticity to wheat is productive tiller number (PTN). This paper reports two studies. The first study tested the impact of a quantitative trait locus (QTL) for PTN on yield and other traits in a set of near-isogenic lines (NILs) grown over nine environments in the Pacific Northwest. Results showed that an allele for high tiller number at QTn.mst-6B enhanced early tiller (ETN) formation regardless of environments. Under favorable conditions, the large number of early tillers translated into a capacity for high PTN. Seed weight and seed diameter were negatively affected by the QTn.mst-6B high tiller allele. The second study assessed the impact of QTn. mst-6B under different competition and soil resource levels in three trials in Bozeman, MT. Three treatments were imposed on NIL pairs in replicated experiments: (i) bordered rows that limited soil resources to each NIL, (ii) nonbordered rows with less competition that provided more soil resources to each NIL, and (iii) space-planted plants with limited competition for soil resources. Results complemented those found in the multienvironment trials, as the high tiller allele caused high PTN at low competition levels when soil resources were more abundant. Increased yield as a result of the high tiller allele at QTn.mst-6B was only detectable in the highest resource treatment and environment. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved.

Key message The impact of the D genome and QTL in the A and B genomes on agronomic performance of hexaploid wheat and tetraploid durum was determined using novel recombinant inbred line populations derived from interploid crosses. Abstract Genetic differences between common hexaploid (6X) bread wheat (Triticum aestivum, 2n = 6x = 42, genome, AABBDD) and tetraploid (4X) durum wheat (T. turgidum subsp. durum, 2n = 4x = 28, genome, AABB) may exist due to effects of the D genome and allelic differences at loci in the A and B genomes. Previous work allowed identification of a 6X by 4X cross combination that resulted in a large number of fertile recombinant progeny at both ploidy levels. In this study, interspecific recombinant inbred line populations at both 4X and 6X ploidy with 88 and 117 individuals, respectively, were developed from a cross between Choteau spring wheat (6X) and Mountrail durum wheat (4X). The presence of the D genome in the 6X population resulted in increased yield, tiller number, kernel weight, and kernel size, as well as a decrease in stem solidness, test weight and seed per spike. Similar results were found with a second RIL population containing 152 lines from 18 additional 6X by 4X crosses. Several QTL for agronomic and quality traits were identified in both the 4X and 6X populations. Although negatively impacted by the lack of the D genome, kernel weight in Mountrail (4X) was higher than Choteau (6X) due to positive alleles from Mountrail on chromosomes 3B and 7A. These and other favorable alleles may be useful for introgression between ploidy levels.