Rapid generation advance(RGA) in chickpea to produce up to seven generations per year and enable speed breeding

This study was aimed at developing a protocol for increasing the number of generation cycles per year in chickpea(Cicer arietinum L.).Six accessions,two each from early(JG 11 and JG 14),medium(ICCV 10 and JG 16),and late(CDC-Frontier and C 235)maturity groups,were used.The experiment was conducted for two years under glasshouse conditions.The photoperiod was extended to induce early flowering and immature seeds were germinated to further reduce generation cycle time.Compared to control,artificial light caused a reduction in flowering time by respectively 8–19,7–16,and 11–27 days in early-,medium-,and late-maturing accessions.The earliest stage of immature seed able to germinate was 20–23 days after anthesis in accessions of different maturity groups.The time period between germination and the earliest stage of immature seed suitable for germination was considered one generation cycle and spanned respectively 43–60,44–64,and 52–79 days in early-,medium-,and late-maturing accessions.However,the late-maturing accession CDCFrontier could not be advanced further after three generation cycles owing to the strong influence of photoperiod and temperature.The mean total number of generations produced per year were respectively 7,6.2,and 6 in early-,medium-,and late-maturing accessions.These results have encouraging implications for breeding programs:rapid progression toward homozygosity,development of mapping populations,and reduction in time,space and resources in cultivar development(speed breeding).

Speed vernalization to accelerate generation advance in winter cereal crops

There are many challenges facing the development of high-yielding,nutritious crops for future environments.One limiting factor is generation time,which prolongs research and plant breeding timelines.Recent advances in speed breeding protocols have dramatically reduced generation time for many short-day and long-day species by optimizing lightand temperature conditions during plant growth.However,winter crops with a vernalization requirement stillrequire upto 6-10weeks in low-temperature conditions before thetransition to reproductivedevelopment.Here,we tested a suite of environmental conditions and protocols to investigate whether the vernalization process can be accelerated.We identified a vernalization method consisting of exposing seeds at the soil surface to an extended photoperiod of 22 h day:2 h night at 10°C with transfer to speed breeding conditions that dramatically reduces generation time in both winter wheat(Triticum aestivum)and winter barley(Hordeum vulgare).Implementation of the speedvernalization protocolfollowed byspeedbreedingallowed the completion ofuptofivegenerations per yearforwinter wheat or barley,whereas only two generations can be typically completed under standard vernalization and plant growth conditions.The speed vernalization protocol developed in this study has great potential to accelerate biological research and breeding outcomes for winter crops.

Present and future prospects for wheat improvement through genome editing and advanced technologies

Wheat(Triticum aestivum,2n=6x=42,AABBDD)is one of the most important staple food crops in the world.Despite the fact that wheat production has significantly increased over the past decades,future wheat production will face unprecedented challenges from global climate change,increasing world population,and water shortages in arid and semi-arid lands.Furthermore,excessive applications of diverse fertilizers and pesticides are exacerbating environmental pollution and ecological deterioration.To ensure global food and ecosystem security,it is essential to enhance the resilience of wheat production while minimizing environmental pollution through the use of cutting-edge technologies.However,the hexaploid genome and gene redundancy complicate advances in genetic research and precision gene modifications for wheat improvement,thus impeding the breeding of elite wheat cultivars.In this review,we first introduce state-of-the-art genome-editing technologies in crop plants,especially wheat,for both functional genomics and genetic improvement.We then outline applications of other technologies,such as GWAS,high-throughput genotyping and phenotyping,speed breeding,and synthetic biology,in wheat.Finally,we discuss existing challenges in wheat genome editing and future prospects for precision gene modifications using advanced genome-editing technologies.We conclude that the combination of genome editing and other molecular breeding strategies will greatly facilitate genetic improvement ofwheat for sustainable global production.