Abstract
Flowering time, abiotic stress tolerance and disease resistance are important agronomic traits of forage species like Lolium spp. Understanding the genetic control of these traits is enabled by the combination of genomic tools with conventional breeding techniques. Flowering time in this genus represents a complex trait due to the differences in the primary induction requirements among the species. In total, 36 QTLs (Quantitative Trait Locus) were identified across all seven linkage groups of Italian and perennial ryegrass involved in the flowering pathways, with several putative orthologous/homologous genes that have been characterized in other major crops. From the perspective of climate change, abiotic stress tolerance has become an essential feature; many QTLs that are involved in the control of plant responses have been identified, and transcriptional studies focusing on drought tolerance reported several DEGs (Differentially Expressed Genes) involved in carbon and lipid metabolism and signal transduction. Due to the incidence of microbial diseases, QTLs useful to developing cultivars resistant to bacterial wilt (Xanthomonas translucens pv. graminis), ryegrass crown rust (Puccinia coronata f. sp. Lolii) and gray leaf spot (Magnaporthe grisea/oryzae) have been mapped in both L. perenne and L. multiflorum populations. Due to the great importance of Lolium species, especially as forage crops, additional information about the three aforementioned agronomic traits is needed.
Highlights
The genus Lolium, which includes the two economic species L. perenne andL. multiflorum (Italian ryegrass), fulfills most forage needs in Europe, New Zealand and the temperate regions of Japan, Australia, South Africa and South America
The genome is relatively large (1C = 2567 Mb for Italian ryegrass and 1C = 2623 Mb for Perennial ryegrass) and, L. rigidum, L. temulentum, L. remotum and L. loliacuem are regarded as self-fertile species [2], the two economic species are natural cross-pollinators, with a high degree of Agriculture 2020, 10, 425; doi:10.3390/agriculture10100425
A cross-sectoral work focused on the flowering time, the abiotic stress tolerance and the disease resistance would report the available information related to a possible genomic application in breeding ryegrasses
Summary
The genus Lolium, which includes the two economic species L. perenne (perennial ryegrass) and. The truly annual forms of L. multiflorum (Westerwolds ryegrass) can be distinguished by their complete flowering and consequent seed production in the year of sowing This particular habit is probably the result of selection by grassland farmers in the northern part of the Netherlands (from which the name ‘Westerwolds’ originates), who in the late 19th century operated repeated and short harvesting cycles in Italian ryegrass fields. The outcrossing reproductive system of Lolium spp., coupled with its strong self-incompatibility system, leads to breed cultivars usually characterized by a high level of within-population genetic diversity This confers a great advantage in terms of adaptability to multiple environmental conditions, it may constitute a difficulty in breeding programs, especially with respect to the fixation of desired traits. A cross-sectoral work focused on the flowering time, the abiotic stress tolerance and the disease resistance would report the available information related to a possible genomic application in breeding ryegrasses
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