Abstract
In the context of climate change, heat stress during the reproductive stages of chickpea (Cicer arietinum L.) leads to significant yield losses. In order to identify the genomic regions responsible for heat stress tolerance, a recombinant inbred line population derived from DCP 92-3 (heat sensitive) and ICCV 92944 (heat tolerant) was genotyped using the genotyping-by-sequencing approach and evaluated for two consecutive years (2017 and 2018) under normal and late sown or heat stress environments. A high-density genetic map comprising 788 single-nucleotide polymorphism markers spanning 1,125 cM was constructed. Using composite interval mapping, a total of 77 QTLs (37 major and 40 minor) were identified for 12 of 13 traits. A genomic region on CaLG07 harbors quantitative trait loci (QTLs) explaining >30% phenotypic variation for days to pod initiation, 100 seed weight, and for nitrogen balance index explaining >10% PVE. In addition, we also reported for the first time major QTLs for proxy traits (physiological traits such as chlorophyll content, nitrogen balance index, normalized difference vegetative index, and cell membrane stability). Furthermore, 32 candidate genes in the QTL regions that encode the heat shock protein genes, heat shock transcription factors, are involved in flowering time regulation as well as pollen-specific genes. The major QTLs reported in this study, after validation, may be useful in molecular breeding for developing heat-tolerant superior lines or varieties.
Highlights
Given the global climate changes, heat stress is becoming a major challenge to crop production and food safety
We reported the construction of a high-density genetic map using singlenucleotide polymorphism (SNP) derived from the GBS approach and major QTLs for phenological, physiological, yield, and yieldrelated traits based on phenotyping of recombinant inbred line (RIL) population (DCP 92-3 × ICCV 92944) under two environments for 2 years (2017–2018 and 2018–2019)
Transgressive segregates in both directions were observed for days to flower initiation (DFI), filled pods (FP), and SYPP traits in the RIL population (Figure 1)
Summary
Given the global climate changes, heat stress is becoming a major challenge to crop production and food safety. As per Intergovernmental Panel on Climate Change, the current rate of global warming is 0.2◦C per decade and is predicted to reach 1.5◦C between 2,030 and 2,052 Such an increase in temperatures leads to heat stress and costs the global economy US$2.4 trillion a year (https://news.un.org/en/story/2019/07/1041652). 15% of the global land area becomes exposed to high levels of heat stress with an additional 0.5◦C increase to the 2◦C (Sun et al, 2019). Besides affecting producers directly, reduces labor productivity (Kjellstrom, 2016), further compounding the effects of increasing temperature on crop yields. Shifts toward more sustainable and healthy diets, which are typically characterized by high consumption of vegetables and legumes, have been evidenced (Scheelbeek et al, 2018)
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