Quantitative trait loci (QTL) for low temperature tolerance at the young microspore stage in rice (<i>Oryza sativa</i> L.) in Australian breeding material

Abstract

Low temperatures at the young microspore stage (YMS) decreases spikelet fertility and is a major limiting factor to rice production in temperate Australia. Low temperature tolerance is a difficult trait to phenotype, hence there is a strong desire for the identification of quantitative trait loci (QTL) for their use in markerassisted selection (MAS). Association mapping was used in several breeding populations with a known source of low temperature tolerance, Norin PL8, to identify QTL for low temperature tolerance. A novel QTL for spikelet fertility was identified on chromosome 6, qYMCT6.1, in which the Australian variety, Kyeema, was the donor for increased fertility. Additional five genomics regions were identified that co-located with previously reported QTL, two of which have been previously cloned. Additionally, for the first time a QTL for spikelet fertility qYMCT10.1, has been shown to co-locate with the number of dehisced anthers qYMCTF10.1 which increases the shedding of pollen from the anthers. This study revealed one new QTL for low temperature tolerance at YMS in temperate japonica germplasm and identified an additional five previously reported. These QTL will be utilised for MAS in the Australian rice breeding program and may have merit for temperate breeding programs globally.

Genomic Regions and Floral Traits Contributing to Low Temperature Tolerance at Young Microspore Stage in a Rice (Oryza sativa L.) Recombinant Inbred Line Population of Sherpa/IRAT109

“…Several genomic regions associated with LT tolerance at various stages of crop development have been previously identified. In terms of the reproductive stage, a few regions have been identified to be associated with tolerance at either YMS or the booting stage (Ye et al, 2010;Lei et al, 2018;Proud et al, 2022). QTL qYMCT3 was found to be located in the short arm of chromosome 3 roughly translating to between 1.25 and 2.98 Mb physical map position.…”