Performance and yield stability of doubled haploid population of wheat (Triticum aestivum L.) under high temperature regime.

India, the second most populated country and the largest wheat producer worldwide, is vulnerable to global warming especially heat stress. In the present investigation, the doubled haploid population derived from PBW343/IC252478 cross was characterized for various phenotypic and morpho-physiological traits and subjected to stability analysis under heat stress conditions. These lines were planted on a single location i.e., Agricultural farm of Rajendra Prasad Central Agricultural University, India for two successive seasons 2017/2018 and, 2018/2019 under three different sowing dates (Controlled or timely, late and, very late sown conditions). Here, the location preferred for this study was because it represents a hotspot for wheat production and the major constraint for the wheat grower is inclining heat stress. The alpha lattice design was used for the current investigation with three replicates. The overall objective of this study was to identify the ideal double haploid lines for heat-stressed conditions. The results revealed that heat stress had a significant adverse impact on all considered traits contributed to overall yield losses of about 50%. Stability measurements, and genotype × environment interaction (GGE), were useful tools to determine the ideal lines for late sowing (heat stressed condition) and very late sowing condition (terminal heat stress). Therefore, in the ranking of genotypes for both mean yield and stability performance across the six environments, DH 71, DH 150, DH 64, DH 138, DH 98, DH 84, DH 62, DH 104, DH 74, DH 3, DH 104, DH 107 & DH 156 were ranked closest to ideal genotype, these were highly adapted, most stable, heat tolerant and high yielding lines indicating them as the most desirable genotypes out of 167 lines studied. Hence, the physiological traits SPAD index (Soil plant analysis development) and Canopy temperature (CT) can be used effectively to screen out the line for heat tolerance. In addition, the stable wheat genotypes identified could be used in the future wheat breeding programs.

Fine mapping of the major QTLs for biochemical variation of sulforaphane in broccoli florets using a DH population

Glucoraphanin is a major secondary metabolite found inBrassicaceaevegetables, especially broccoli, and its degradation product sulforaphane plays an essential role in anticancer. The fine mapping of sulforaphane metabolism quantitative trait loci (QTLs) in broccoli florets is necessary for future marker-assisted selection strategies. In this study, we utilized a doubled haploid population consisting of 176 lines derived from two inbred lines (86,101 and 90,196) with significant differences in sulforaphane content, coupled with extensive genotypic and phenotypic data from two independent environments. A linkage map consisting of 438 simple sequence repeats markers was constructed, covering a length of 1168.26 cM. A total of 18 QTLs for sulforaphane metabolism in broccoli florets were detected, 10 were detected in 2017, and the other 8 were detected in 2018. The LOD values of all QTLs ranged from 3.06 to 14.47, explaining 1.74–7.03% of the biochemical variation between two years. Finally, 6 QTLs (qSF-C3-1,qSF-C3-2,qSF-C3-3,qSF-C3-5,qSF-C3-6andqSF-C7) were stably detected in more than one environment, each accounting for 4.54–7.03% of the phenotypic variation explained (PVE) and a total of 30.88–34.86% of PVE. Our study provides new insights into sulforaphane metabolism in broccoli florets and marker-assisted selection breeding inBrassica oleraceacrops.

A 24,482-bp Deletion Increases Seed Weight Through Multiple Pathways in Rapeseed (Brassica Napus L.)

Exploration of the genes controlling seed weight is critical to improve crop yield and understand the mechanisms underlying seed formation in rapeseed (Brassica napus L.). We previously identified the quantitative trait locus (QTL) qSW.C9, for the thousand-seed weight (TSW) trait, in a double haploid population constructed from F1 hybrids between the parental accessions HZ396 and Y106. Here, we confirmed the phenotypic effects associated with qSW.C9 in BC3F2 populations and fine-mapped the candidate causal locus to a 266-kb interval. Sequence and expression analyses revealed that a 24,482-bp deletion in HZ396 containing six predicted genes most likely underlies qSW.C9. Differential gene expression analysis and cytological observations suggested that qSW.C9 affects both cell proliferation and cell expansion through multiple signaling pathways. After genotyping a rapeseed diversity panel to define their haplotype structure, we suggest that the selection of germplasm carrying two specific markers may be effective in improving seed weight in rapeseed. This study provides a solid foundation for the identification of the causal gene of qSW.C9 and offers an attractive target for breeding higher-yielding rapeseed.

Clubroot Symptoms and Resting Spore Production in a Doubled Haploid Population of Oilseed Rape (Brassica napus) Are Controlled by Four Main QTLs

Clubroot, caused by Plasmodiophora brassicae Woronin, is one of the most important diseases of oilseed rape (Brassica napus L.). The rapid erosion of monogenic resistance in clubroot-resistant (CR) varieties underscores the need to diversify resistance sources controlling disease severity and traits related to pathogen fitness, such as resting spore production. The genetic control of disease index (DI) and resting spores per plant (RSP) was evaluated in a doubled haploid (DH) population consisting of 114 winter oilseed rape lines, obtained from the cross ‘Aviso’ × ‘Montego,’ inoculated with P. brassicae isolate “eH.” Linkage analysis allowed the identification of three quantitative trait loci (QTLs) controlling DI (PbBn_di_A02, PbBn_di_A04, and PbBn_di_C03). A significant decrease in DI was observed when combining effects of the three resistance alleles at these QTLs. Only one QTL, PbBn_rsp_C03, was found to control RSP, reducing resting spore production by 40%. PbBn_rsp_C03 partially overlapped with PbBn_di_C03 in a nucleotide-binding leucine-rich repeat (NLR) gene-containing region. Consideration of both DI and RSP in breeding for clubroot resistance is recommended for the long-term management of this disease.