LSCHL4 from Japonica Cultivar, Which Is Allelic to NAL1 , Increases Yield of Indica Super Rice 93-11

Abstract

SUMMARYThe basic premise of high yield in rice is to improve leaf photosynthetic efficiency, and coordinate the source–sink relationship in rice plants. The quantitative trait loci (QTLs) qLSCHL4, japonica NAL1 allele from Nipponbare has a pleiotropic function, effectively increased leaf chlorophyll content, enlarged flag leaf size, and enhanced the yield of indica rice cultivar.

Natural Variation in the Flag Leaf Morphology of Rice Due to a Mutation of the NARROW LEAF 1 Gene in Oryza sativa L.

“…In addition to the increase in WFL and the number of vascular bundles, Nal1 increased the total number of spikelets per panicle, root dry weight, and the rate of filled grains (Fujita et al 2013). Improvements to the panicle, such as increased panicle length, more spikelets per panicle, and more secondary branches per panicle, were also observed after introducing the H-type allele (Zhang et al 2014). Since NAL1 is expressed in the culm, coleoptile, crown root, lateral root, and panicles (Qi et al 2008;Fujita et al 2013;Jiang et al 2015), its regulation of the cell cycle and cell division in these tissues likely explains the pleiotropic effects of the Nal1 mutation.…”

“…In Koshihikari (type VI9), only 20% of NAL1 transcripts contained no retrotransposon, and a NAL1 protein the same size as that encoded by the R-type allele was synthesized (Takai et al 2013). Furthermore, it was shown that NAL1 expression was significantly higher in Nipponbare (type IV9) than in 93-11 (type I), although the expression level was shown to vary among developmental stages (Zhang et al 2014). Overexpression of the Nipponbare allele in Nipponbare increased FWL and LWL through increasing the distance between vascular bundles (Zhang et al 2014), indicating that the NAL1 transcript level is an important factor in leaf morphology.…”

“…Given that NAL1 was the best candidate for the QTL for WFL among the three ORFs, we examined its promoter region, since a previous report suggested that some NAL1 alleles were expressed at different levels (Zhang et al 2014). A pair of recombinant fixed lines, F 5 line_10-7-52-84-3-1 and -2 ( Figure S2D), which had either the Takanari or Akenohoshi fragment in the upstream promoter region but shared the Akenohoshi coding region, exhibited the same WFL and yield.…”

“…These results can be explained if the R-type allele is regarded as an allele with a weaker effect than the H-type allele on cell division in the anticlinal and periclinal directions. This would also explain the increase in WFL when the Daringan allele (H-type allele) was introduced into IR64 (R-type allele) (Fujita et al 2013) and when the Nipponbare allele (H-type allele) was introduced into 93-11 (R-type allele) (Zhang et al 2014). However, it could not explain the results of Chen et al (2012), where the R-type allele increased WFL in mapping of QTL for WFL using hybrid populations originated from a cross between D50 (R-type allele) and HB277 (H-type allele).…”

“…NAL1 was originally isolated as a gene affecting vascular patterns in a study on a classic dwarf mutant with a narrow leaf (Qi et al 2008) and was later shown to affect WFL, total spikelet number per panicle, photosynthetic rate, and chlorophyll content (Chen et al 2012;Fujita et al 2013;Takai et al 2013;Zhang et al 2014). NAL1 encodes a plant-specific protein, and the nal1 mutant with an in-frame deletion of 10 amino acids in exon 4 showed reduced basipetal polar auxin transport and fewer longitudinal veins, compared with wild type (Qi et al 2008).…”