Search

The gibberellin-responsive dwarfing gene Rht12 can significantly reduce plant height without changing seedling vigor and substantially increase ear fertility in bread wheat (Triticum aestivum. L). However, Rht12 delays heading date and anthesis date, hindering the use of Rht12 in wheat improvement. To promote early flowering of the Rht12 dwarf plants, the photoperiod-insensitive allele Ppd-D1a was introduced through a cross between Jinmai47 (Ppd-D1a) and Karcagi (Rht12). The results showed that Ppd-D1a can rescue the delaying effect of Rht12 on flowering time and promote earlier flowering by 9.0 days (163.2°Cd) in the Rht12 dwarf plants by shortening the late reproduction phase. Plant height was reduced by Rht12 (43.2%) and Ppd-D1a (10.9%), achieving dwarf plants with higher lodging resistance. Ear fertility, like the grain number per spike, was significantly increased by Rht12 (21.3%), while it was reduced by Ppd-D1a (6.5%). However, thousand kernel weight was significantly reduced by Rht12 (12.9%) but significantly increased by Ppd-D1a (16.9%). Finally, plant yield was increased by 16.4 and 8.2%, and harvest index was increased by 24.9 and 15.4% in the Rht12 dwarf lines and tall lines with Ppd-D1a , respectively. Clearly, there was an additive interaction between Rht12 and Ppd-D1 and the introduction of Ppd-D1a advanced the flowering time and improved the yield traits of Rht12 dwarf plants, suggesting that the combination of Rht12 and Ppd-D1a would be conducive to the successful use of Rht12 in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Preliminary evidence indicates that Rht5 , a gibberellin-responsive (GAR) dwarfing gene, could reduce plant height without affecting coleoptile length and seedling vigour. However, Rht5 delayed ear emergence and anthesis, which would hinder its utilization in wheat improvement. To advance the flowering time of Rht5 dwarf plants, the dominant vernalization gene Vrn-B1 and the photoperiod-insensitive gene Ppd-D1 were introduced through two crosses between Ningchun45 ( Vrn-B1 ) and Jinmai47 ( Ppd-D1 ) with Marfed M ( Rht5 ), respectively. Fifty-nine and 71 F 2:3 and F 3:4 homozygous lines from the first and the second cross were used to evaluate the effects of Vrn-B1 and Ppd-D1 , respectively on the developmental and agronomic traits of Rht5 dwarf plants during two growing seasons in Yangling, Shaanxi, China. The results showed that Rht5 significantly reduced plant height (40.1% and 38.9%) but delayed the flowering time (14.0% and 4.8% in thermal time) in both populations. In general, Rht5 significantly decreased the spike length by 22.6% and 16.7, grain number by 14.5% and 11.5%, 1000-grain weight by 24.1% and 18.4%, and grain yield by 35.1% and 21.5% in the two populations, respectively. Vrn-B1 could not compensate for the negative effect of Rht5 on spike development and the flowering time and had no significant effect on plant height or other agronomic traits. However, Ppd-D1 was able to overcome the delaying effect of Rht5 on spike development by shortening the duration of the reproductive phase (double ridge stage-anthesis) and finally promoting earlier flowering (8.7% in thermal time) in Rht5 dwarf lines. Ppd-D1 also reduced plant height (10.0%), and the combination of Ppd-D1 and Rht5 produced even shorter plants (45.0%), achieving dwarf plants with higher lodging resistance. Additionally, Ppd-D1 increased the grain number (6.3% and 9.6%), 1000-grain weight (13.0% and 21.5%), plant yield (22.6% and 39.5%) and harvest index (31.1% and 49.6%) in both tall and dwarf plants, respectively. Clearly, the combination of Rht5 and Ppd-D1 had no negative effect on plant growth or grain yield, advanced spike development and the flowering time, and improved agronomic traits, which may be conducive to exploiting Rht5 for wheat improvement. [ABSTRACT FROM AUTHOR]

• This is the first study on agronomic and quality traits of Rht15 in durum wheat. • Rht15 significantly reduced plant height by shortening the cell length. • Rht15 improved lodging resistance and some quality traits. • Rht15 had a certain negative effect on yield traits. The dwarfing gene Rht15 in durum wheat is considered a GA-responsive dwarfing gene. To explore the use of Rht15 in durum wheat improvement, the effects of Rht15 on plant height, internode characteristics, lodging resistance, yield components and quality traits were evaluated by the Rht15 dwarf and tall F 3:4 , F 4:5 and F 5:6 lines derived from reciprocal crosses between "Durox" (Rht15) and "Langdon" (rht15). Rht15 significantly reduced plant height by 31.5 % on average by shortening the cell length. Furthermore, the diameter and wall thickness of internodes were significantly increased by Rht15 , which decreased the height center of gravity (35.4 %), increased the mechanical strength of the basal internode (41.8 %), and finally improved the lodging resistance index (153.7 %). Rht15 reduced biomass plant−1 (-13.7 %), 1000-kernel weight (-12.9 %), grain number per spike (-2.3 %) and grain yield plant−1 (-10.3 %). However, Rht15 increased the grain protein content (8.7 %), wet gluten content (9.2 %) and starch content (2.3 %). In conclusion, Rht15 significantly reduced plant height and improved lodging resistance and some quality traits but had negative effects on some yield traits. Nonetheless, Rht15 has opened up an opportunity as an alternative dwarfing gene in wheat breeding and improvement. [ABSTRACT FROM AUTHOR]

• Rht14 reduced plant height by about 26.68 % and 27.68 % in two populations, respectively, achieving the dwarf plants with higher lodging resistance. • Rht14 may confer more chlorophyll content and net photosynthetic rate, which may have the capability to improve photosynthesis traits of wheat. • Rht14 did not affect most of the yield components, while significantly decreased 1000-kernel weight. • Rht14 didn't affect the length of coleoptile and seedling root traits when compared with tall lines. • Rht14 had negative and significant effects on the sedimentation value (SV), stability time (ST) and development time (DT). The GA-insensitive dwarf genes, Rht-B1b (Rht1) and Rht-D1b (Rht2), have been used worldwide for reducing plant height, improving lodging resistance and grain yield since the Green Revolution. To explore new dwarf genes for wheat improvement, in this study, the effects of GA-responsive (GAR) dwarf gene, Rht14 , on plant height related traits, agronomic traits, yield traits and quality traits were evaluated in durum wheat by F 2:3 lines, F 3:4 lines and F 4:5 lines that derived from reciprocal crosses between the Rht14 donor Castelporziano (CP) and Langdon (L). These results indicated that Rht14 could reduce plant height by an average of 26.68 % and 27.68 % in the lines of CP × L and L × CP populations, respectively. Furthermore, both the length of peduncle and each internode were all significantly reduced, with the basal one as the most proportion and the peduncle as the largest difference. The flag leaf length, width and area increased significantly in dwarf lines. Rht14 did not affect most of the yield components, including number of tillers plant−1, number of fertile tillers plant−1, spikelet number spike−1, grain number spike−1, biomass plant−1, grain yield plant−1, while significantly decreased 1000-kernel weight. Rht14 didn't affect the length of coleoptile and seedling root traits when compared with tall lines, indicating it may have the potential for good seedling establishment in the field. A negative effect of Rht14 on some quality traits was observed. The results indicate that GAR dwarf gene Rht14 represents a new alternative locus in breeding programs for improving population yield potential and lodging resistance in wheat. [ABSTRACT FROM AUTHOR]