Mapping QTLs influencing rice floral morphology using recombinant inbred lines derived from a cross between Oryza sativa L. and Oryza rufipogon Griff

Abstract

To understand the genetic basis of floral traits associated with the mating system in rice, we analyzed pistil, stamen and glume traits using a recombinant inbred line population, derived from a cross between an Asian cultivated rice ( Oryza sativa L.), Pei-kuh, and a wild rice ( Oryza rufipogon Griff.), W1944. Quantitative trait loci (QTLs) affecting floral morphology were detected by composite interval mapping using a linkage map constructed using 147 markers, mostly RFLPs. A total of 7, 4, 14 and 6 QTLs were detected for traits related to pistil, stamen, and size and shape of the glume, respectively. Comparison of 31 QTLs affecting these organs revealed ten QTLs affecting the different organs in four adjacent regions on chromosomes 2, 4, 5 and 10, but most QTLs (68%) were located separately on the whole chromosomes. Although four QTLs for stigma breadth, anther length and thickness of lemma and palea explained more than 25% of the total phenotypic variance, most QTLs (87%) had smaller effects. These results suggest that quantitative variation observed for pistil, stamen and glume traits is controlled by several distinct genes with small effects.

Quantitative trait loci mapping of the stigma exertion rate and spikelet number per panicle in rice (Oryza sativa L.)

“…In this study, we made several improvements to previously used methods when measuring the stigma exertion rate. In some previous studies, panicles were collected at flowering to avoid damage to exerted stigmas and to improve the accuracy of the collected data (Uga et al, 2003;Yan at al., 2009), whereas in other studies, panicles were collected at approximately 7-10 days post-flowering (Miyata et al, 2007;Takano-kai et al, 2011). Although some exerted stigmas are vulnerable, we noted that the pistil style in the flower remains discernible until the grain-filling period.…”

Identification of Quantitative Trait Loci Controlling Floral Morphology of Rice Using a Backcross Population between Common Cultivated Rice, <i>Oryza sativa</i> and Asian Wild Rice, <i>O. rufipogon</i>

“…These findings suggest that common genetic factors are responsible for the differences in size of lemma and palea. In a previous study [12], QTL analysis for LML and PLL was performed using recombinant inbred lines derived from a cross between a cultivar of O. sativa Pei-kuh and a perennial accession of wild rice O. rufipogon W1944. Distinct QTLs were detected on chrs.…”

Sexual and apomictic plant reproduction in the genomics era: exploring the mechanisms potentially useful in crop plants

“…Variations in floral traits have also been associated with outcrossing in rice and barley. For example, anther and stigma length, percentage of stigma exertion, pollen grain longevity, time interval from flowering to pollen emission and glume traits (length, width and length/width ratio) are associated with outcrossing in some accessions of the wild rice species, Oryza perennis, O. nivara and O. rufipogon (Oka and Morishima 1967;Virmani and Athwal 1973;Uga et al 2003;Grillo et al 2009), while in barley it is the anther extrusion, as well anther and stigma size, which relates to increased outcrossing (Abdel-Ghani et al 2005). Clearly, more research is needed to explore variation for floral traits associated with outcrossing, e.g., stigma exertion, anther and stigma separation, anther extrusion or pollen grain longevity, among others.…”

“…The outcrossing is manifested by the size of the pistil and stamen, stigma exertion and the angle of glume opening (Virmani 1994). Multiple genes control floral traits in rice: 4-7 QTL for glume length, 4-6 QTL for glume width, 1-3 QTL for length-width ratio of the filled glume and 20 QTL for anther length (Uga et al 2003). The comparison of the locations of the QTL affecting pistil, stamen and glume positioning revealed that most QTL are located on different chromosomal regions, suggesting that phenotypic variation for these traits are primarily controlled by genes unique to each organ, while some regions that are associated with more than one organ partially affect those organs.…”