Biodiversity Assessment of Sugar Beet Species and Its Wild Relatives:Linking Ecological Data with New Genetic Approaches

The value of crop wild relatives has long been acknowledged and this wild resource has been used to improve crop performance with clear economic benefits. Sugar beet (Beta vulgaris subsp. vulgaris) is the most economically valuable crop species in the order Caryophyllales, B. vulgaris subsp. maritima being the ancestor of the cultivated beets. The wild species of the genus Beta s.l. are commonly found in coastal areas of Europe and Mediterranean Region, where a rich genetic heritage still exists. Broadening the genetic base of sugar beet by introgression with wild relatives is a growing need regarding the maintenance of ecologically important traits. Since wild relatives have adapted to specific habitats, they constitute an important source of novel traits for the beet breeding pool. So, we conducted a broader research project aiming to delimit taxa and identify priority locations to establish genetic reserves of the wild Beta species occurring in Portugal (Western Iberian Peninsula). The aim of this study was: 1) to identify and characterize the main habitats of these wild Beta species;and 2) to present a review of some genetic tools available for future application in sugar beet breeding. In this review, we have focused on EcoTILLING as a molecular tool to assess DNA polymerphisms in wild populations of Beta and identify candidate genes related to drought and salt tolerance, as well as addressed some issues related to next-generation sequencing (NGS) technologies as a new molecular tool to assess adaptive genetic variation on the wild relatives of sugar beet.

Water stress resilient cereal crops:Lessons from wild relatives

Cereal crops are significant contributors to global diets.As climate change disrupts weather patterns and wreaks havoc on crops,the need for generating stress-resilient,high-yielding varieties is more urgent than ever.One extremely promising avenue in this regard is to exploit the tremendous genetic diversity expressed by the wild ancestors of current day crop species.These crop wild relatives thrive in a range of environments and accordingly often harbor an array of traits that allow them to do so.The identification and introgression of these traits into our staple cereal crops can lessen yield losses in stressful environments.In the last decades,a surge in extreme drought and flooding events have severely impacted cereal crop production.Climate models predict a persistence of this trend,thus reinforcing the need for research on water stress resilience.Here we review:(i)how water stress(drought and flooding)impacts crop performance;and(ii)how identification of tolerance traits and mechanisms from wild relatives of the main cereal crops,that is,rice,maize,wheat,and barley,can lead to improved survival and sustained yields in these crops under water stress conditions.

A chromosome-scale genome assembly of Dasypyrum villosum provides insights into its application as a broad-spectrum disease resistance resource for wheat improvement

Dasypyrum villosum is one of the most valuable gene resources in wheat improvement,especially for disease resistance.The mining of favorable genes from D.villosum is frustrated by the lack of a whole genome sequence.In this study,we generated a doubled-haploid line,91C43^(DH),using microspore culture and obtained a 4.05-GB high-quality,chromosome-scale genome assembly for D.villosum.The assembly contains39727 high-confidence genes,and 85.31% of the sequences are repetitive.Two reciprocal translocation events were detected,and 7VS-4VL is a unique translocation in D.villosum.The prolamin seed storage protein-coding genes were found to be duplicated;in particular,the genes encoding low-molecular-weight glutenin at the Glu-V3 locus were significantly expanded.RNA sequencing(RNA-seq)analysis indicated that,after Blumeria graminearum f.sp tritici(Bgt)inoculation,there were more upregulated genes involved in the pattern-triggered immunity and effector-triggered immunity defense pathways in D.villosum than in Triticum urartu.MNase hypersensitive sequencing(MH-seq)identified two Bgt-inducible MH sites(MHSs),one in the promoter and one in the 3'terminal region of the powdery mildew resistance(Pm)gene NLR1-V.Each site had two subpeaks and they were termed MHS1(MHS1.1/1.2)and MHS2(MHS2.1/2.2).Bgt-inducible MHS2.2 was uniquely present in D.villosum,and MHS1.1 was more inducible in D.villosum than in wheat,suggesting that MHSs may be critical for regulation of NLR1-V expression and plant defense.In summary,this study provides a valuable genome resource for functional genomics studies and wheat-D.villosum introgression breeding.The identified regulatory mechanisms may also be exploited to develop new strategies for enhancing Pm resistance by optimizing gene expression in wheat.