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A novel high-tillering dwarf mutant in common wheat Wangshuibai was characterized and mapped to facilitate breeding for plant height and tiller and the future cloning of the causal gene. Tiller number and plant height are two major agronomic traits in cereal crops affecting plant architecture and grain yield. NAUH167, a mutant of common wheat landrace Wangshuibai induced by ethylmethyl sulfide (EMS) treatment, exhibits higher tiller number and reduced plant height. Microscope observation showed that the dwarf phenotype was attributed to the decrease in the number of cells and their length. The same as the wild type, the mutant was sensitive to exogenous gibberellins. Genetic analysis showed that the high-tillering number and dwarf phenotype were related and controlled by a partial recessive gene. Using a RIL population derived from the cross NAUH167/Sumai3, a molecular marker-based genetic map was constructed. The map consisted of 283 loci, spanning a total length of 1007.98 cM with an average markers interval of 3.56 cM. By composite interval mapping, a stable major QTL designated QHt.nau-2D controlling both traits, was mapped to the short arm of chromosome 2D flanked by markers Xcfd11 and Xgpw361. To further map the QHt.nau-2D loci, another population consisted of 180 F progeny from a cross 2011I-78/NAUH167 was constructed. Finally, QHt.nau-2D was located within a genetic region of 0.8 cM between markers QHT239 and QHT187 covering a predicted physical distance of 6.77 Mb. This research laid the foundation for map-based cloning of QHt.nau-2D and would facilitate the characterization of plant height and tiller number in wheat.

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Plant phenomics bridges the gap between traits of agricultural importance and genomic information. Limitations of current field-based phenotyping solutions include mobility, affordability, throughput, accuracy, scalability and the ability to analyse big data collected. Here, we present a large-scale phenotyping solution that combines a commercial backpack LiDAR device and our analytic software, CropQuant-3D, which have been applied jointly to phenotype wheat (Triticum aestivum) and associated 3D trait analysis. The use of LiDAR can acquire millions of 3D points to represent spatial features of crops, and CropQuant-3D can extract meaningful traits from large, complex point clouds. In a case study examining the response of wheat varieties to three different levels of nitrogen fertilisation in field experiments, the combined solution differentiated significant genotype and treatment effects on crop growth and structural variation in canopy, with strong correlations with manual measurements. Hence, we demonstrate that this system could consistently perform 3D trait analysis at a larger scale and more quickly than heretofore possible and addresses challenges in mobility, throughput, and scalability. To ensure our work could reach non-expert users, we developed an open-source graphical user interface for CropQuant-3D. We therefore believe that the combined system is easy-to-use and could be used as a reliable research tool in multi-location phenotyping for both crop research and breeding. Furthermore, together with the fast maturity of LiDAR technologies, the system has the potential for further development in accuracy and affordability, contributing to the resolution of the phenotyping bottleneck and exploiting available genomic resources more effectively.

Triticum petropavlovskyi, commonly known as Xinjiang rice wheat, is a unique hexaploidy wheat grown in the Xinjiang area. T. petropavlovskyi is marked by its elongated glume (Eg) trait, which is controlled by gene P1 pet located on chromosome 7A (Wang et al., 2002;Watanabe and Imamura, 2002). The origin of T. petropavlovskyi has been disputed. It is generally accepted that P1 pet was introduced from tetraploid polish wheat (T. polonicum) via a hybridization with hexaploid common wheat (T. aestivum) (Akond et al., 2008;Chen et al., 2016). The P1 pet has pleiotropic effects in the increase of spike length, grain length, and grain weight, and decrease of fertility, grain number, and awn length (Okamoto et al., 2013), indicating the potential impact of P1 pet on grain yield-related traits. The cloning of P1 pet will provide evidence for the prognosis of whether a mutation at P1 in T. petropavlovskyi or T. polonicum gave rise to the Eg trait and facilitate the utilization of this unique species in breeding for yield improvement.