Agronomic Performance of Rht Alleles in a Spring Wheat Population across a Range of Moisture Levels

Abstract

The Rht-B1b and Rht-D1b alleles, which occur at homoeologous loci on chromosomes 4B and 4D, respec-Reduced height alleles at the Rht-B1 and Rht-D1 loci have been tively, reduce sensitivity to gibberellic acid (GA), which widely incorporated into wheat (Triticum aestivum L.) cultivars with the intent of improving partitioning of assimilates to grain. Although is necessary for stem elongation (Flintham et al., 1997). generally effective at increasing yield in high yield environments, In favorable environments, the reduced demand for astheir effects under heat and drought stress have been variable. We similates by a shorter stem results in improved assimilate undertook this study to evaluate the effects of the Rht-B1b and Rhtpartitioning to the developing head, leading to higher D1b dwarfing alleles in a recombinant inbred line (RIL) spring wheat spikelet fertility and more but smaller grain per head. population under a range of soil moisture conditions. Rht-B1 and Semidwarf wheats have smaller leaves, but compensate Rht-D1 genotypes of 140 RILs derived from a cross between 'Kauz' with increased photosynthetic rates resulting in a bioand MTRWA116 were determined by polymerase chain reactions mass similar to that of tall lines (LeCain et al., 1989;(PCR). The population was evaluated for yield and agronomic traits Morgan et al., 1990;Flintham et al., 1997). in four Colorado environments under fully irrigated, partially irri-The relative yield advantage of dwarf and semidwarf gated, and rainfed conditions in 2001 and 2002. Lines with both dwarfing alleles were significantly (P Ͻ 0.01) shorter, lower yielding, and cultivars varies with spring or winter habit, genetic backlater heading in all environments compared with lines with one or no ground, and environmental conditions. The benefits of dwarfing allele. Lines with both tall alleles performed equal to or the dwarfing alleles are more pronounced in high yieldbetter (P Ͻ 0.05) than all other classes for grain yield, test weight, ing winter wheat environments (Flintham et al., 1997) and kernel weight in all environments. Among lines with a single and in high yielding spring wheat locations at latitudes dwarfing allele, those with Rht-B1b on average outyielded those with less than 40Њ (Fischer and Quail, 1990). However, under Rht-D1b in the fully irrigated environment (5432 versus 4993 kg heat and drought stress, there may be no benefit of the ha Ϫ1 , P Ͻ 0.05), but elsewhere their yields did not differ (P Ͼ 0.05).dwarfing alleles in spring wheat (Flintham et al., 1997; Desirable values for most traits occurred across a relatively wide range Nizam Uddin and Marshall, 1989; Richards, 1992a,b). of plant heights, with the best performing lines either shorter lines inRichards (1992a) concluded that grain yield does not the tall class or taller lines in the semidwarf classes. edu).Published in Crop Sci. 45:939-947 (2005).

Ppd1, Vrn1, ALMT1 and Rht genes and their effects on grain yield in lower rainfall environments in southern Australia

“…However, the Rht-ba genotype was taller than the Rht-ab in Australia, Germany, China and the UK (Fischer and Quail 1990;Börner et al 1993;Tang et al 2009;Kumar et al 2011), suggesting that these genotypes might not be identical for growth and/or development. Although not statistically significant, the Rht-ba genotype was also taller than Rht-ab in the four environments used by Butler et al (2005) in the USA. In a limited number of irrigated experiments in southern New South Wales, Fischer and Quail (1990) suggested that the Rht-ab genotype might have a yield advantage over the Rht-ba genotype at lower yield levels.…”

“…The Rht genes code for DELLA proteins, which are transcription factors that affect plant growth and stress tolerance (Wilhelm et al 2013). In southern Australia, the difference between the Rht-ba and Rht-ab semi-dwarf genotypes with respect to heading date is negligible (Fischer and Quail 1990;Cane et al 2013), which was also the case in Germany and the USA (Börner et al 1993;Butler et al 2005). However, the Rht-ba genotype was taller than the Rht-ab in Australia, Germany, China and the UK (Fischer and Quail 1990;Börner et al 1993;Tang et al 2009;Kumar et al 2011), suggesting that these genotypes might not be identical for growth and/or development.…”

Inheritance of test weight and kernel weight in eight durum wheat crosses

“…However, reduced kernel size and/or low test weight has been a problem in semidwarf compared with conventional (tall) height genotypes. This has been documented in both durum wheat (Joppa 1973;Gale et al 1981;McClung et al 1986) and common wheat (McNeal et al 1972;Knott 1986;Nizam Uddin and Marshall 1989;Butler et al 2005), although, a cross studied by Busch and Chamberlain (1981) did not follow this pattern. Lebsock and Amaya (1969) also found a positive correlation between kernel size and plant height in lines derived from crosses involving non-dwarf durum genotypes of varying height.…”

“…Lebsock and Amaya (1969) also found a positive correlation between kernel size and plant height in lines derived from crosses involving non-dwarf durum genotypes of varying height. Gale et al (1981) speculated that reduced kernel size may be a primary effect of the Rht genes and, similarly, Butler et al (2005) suggested pleiotropy as the cause.…”

Effects of Gibberellic Acid Responsive Dwarfing Gene <i>Rht9</i> on Plant Height and Agronomic Traits in Common Wheat

“…Rht-B1b and Rht-D1b, located on homoeologous chromosome arms of 4BS and 4DS, had pleiotropic effects on plant growth, causing reductions in coleoptile length and seedling leaf area [7]. The effect of the Rht-B1 and Rht-D1 on height reduction is commonly reported at around 20-25% of the wild-type allele but it varies with different genetic background and environment [8][9][10]. Apart from reducing the plant height of wheat, dwarfing genes Rht-B1b, Rht-D1b also decrease the coleoptiles length, the seedling rate and population density [11,12].…”