Grain dormancy genes responsible for preventing pre-harvest sprouting in barley and wheat

Abstract

Pre-harvest sprouting (PHS) remains a long-standing problem for the production of barley (Hordeum vulgare) and wheat (Triticum aestivum) worldwide. Grain dormancy, a key trait for the prevention of PHS, controls the timing of germination. Discovery of the causal sequence polymorphisms (CSPs) that produce naturally occurring variation in dormancy will help improve PHS tolerance. The identification of CSPs for dormancy remains difficult, especially for barley and wheat, because they are the last major cereals to have their genomes sequenced. However, recent work has identified several important CSPs that play pivotal roles in fine-tuning the dormancy levels in barley and wheat cultivars. This review summarizes these recent advances, which can be directly applied in breeding programs to improve PHS tolerance. These recent findings indicate the possibility that barley and wheat cultivars grown in East Asia, where much rain falls during the harvest season, will be rich sources of alleles that confer strong dormancy, since these cultivars have been selected to cope with the regional climate. The newly discovered dormant alleles will be useful for improving PHS tolerance around the world, just as Reduced-height (Rht) alleles from Japanese wheat varieties contributed to yield increases for the Green Revolution.

Effects of TaPHS1 and TaMKK3-A Genes on Wheat Pre-Harvest Sprouting Resistance

“…However, TaPHS1 was more effective on reducing germination rate for plants grown in the spring greenhouse where temperature for wheat seed development was higher than the fall greenhouse (Figure 1), which was contradictory to the previous result that low temperature during seed development increased TaPHS1 expression level [4]. Other environmental factors such as humidity, photoperiod or light quality might also contribute to such a discrepancy, because the TaPHS1 gene is likely to respond to those environmental factors as FT-like and TFL1-like genes did in other species [3,4,31,32]. TaPHS1 and TaMKK3-A demonstrated various effects on germination rates (Figures 1 and 2) in the two field experiments where they had similar temperatures but different precipitations, indicating that humidity might also play an important role in affecting those gene expressions.…”

“…Pre-harvest sprouting (PHS), the germination of physiologically matured grains before harvesting, has been a major problem that causes significant reduction in grain yield and end-use quality in wheat (Triticum aestivum L.) [1][2][3]. PHS resistance is a complex trait controlled by several major quantitative trait loci (QTLs) and many minor QTLs.…”

Whole‐genome resequencing‐based QTL‐seq identified candidate genes and molecular markers for fresh seed dormancy in groundnut

“…FSD/PHST/ in situ germination leads to a reduction in the grain or kernel yield and often attributes to medium to large yield losses and quality deterioration of the produce in both cereals (Abe et al, ; Benech‐Arnold and Rodríguez, ; Gao and Ayele, ; Nakamura, ; Rodríguez et al ., ) and legumes (Dias et al ., ; Patro and Ray, ; Vishwakarma et al ., ). Due to domestication and extensive human‐made selection during varietal development programs, modern groundnut represents much low genetic diversity compared to its wild ancestral species (which produces dormant seeds).…”

“…In recent years, significant efforts have been made in cereals to understand seed dormancy trait in order to reduce the yield loss and the kernel quality caused due to preharvest sprouting (PHS) or in situ seed germination (Gao and Ayele, 2014;Nakamura, 2018). As a result, several quantitative trait loci (QTLs) and candidate genes for PHS have been identified in wheat (Li et al, 2004;Nakamura, 2018;Ogbonnaya et al, 2008), rice (Lee et al, 2017;Li et al, 2004) and barley (Li et al, 2003(Li et al, , 2004Nakamura, 2018). Earlier, a gene GA20-oxidase was also identified as a candidate gene in the QTL region controlling PHS in rice (Li et al, 2004).…”

Important agronomic characteristics of yielding ability in common buckwheat; ecotype and ecological differentiation, preharvest sprouting resistance, shattering resistance, and lodging resistance

“…In addition to the cultivars with low preharvest sprouting mentioned above, a wild species F. homotropicum, known for its very strong seed dormancy (Wang and Campbell 2000) and compatibility to F. esculentum, should be a promising gene donor, although its extreme shattering habit (brittle pedicel) would need to be removed (Matsui et al 2003). In other crops like wheat, barley, maize, and rice, genetic analysis of preharvest sprouting and dormancy has discovered many QTLs and some causal genes (Nakamura 2018). These advances are contributing to breeding efforts through marker-assisted selection and pyramiding of QTLs and genes for several different traits (Kumar et al 2010, Tyagi et al 2014.…”