One-sentence summary: Map-based cloning of a gene underlying grain shape in 22 wheat suggests that modest genetic changes induce dramatic phenotypic variations 23 associated with a new wheat subspecies during evolution. ABSTRACT 29 Six subspecies of hexaploid wheat (Triticum spp.) have been identified, but the origin 30 of Indian dwarf wheat (Triticum sphaerococcum Perc.), the only subspecies with 31 round grains, is currently unknown. Here, we isolated the grain-shape gene Tasg-D1 32 in T. sphaerococcum Perc. via positional cloning. Tasg-D1 encodes a serine/threonine 33 protein kinase glycogen synthase kinase 3 (STKc_GSK3) that negatively regulates 34 brassinosteroid signaling. Expression of TaSG-D1 and the mutant form Tasg-D1 in 35 Arabidopsis thaliana suggested that a single amino acid substitution in the TREE 36 domain of TaSG-D1 enhances protein stability in response to brassinosteroids, likely 37 leading to formation of round grains in wheat. This gain-of-function mutation has 38 pleiotropic effects on plant architecture and exhibits incomplete dominance. 39 Haplotype analysis of 898 wheat accessions indicated that the origin of T. 40 sphaerococcum Perc. in ancient India involved at least two independent mutations of 41 TaSG-D1. Our results demonstrate that modest genetic changes in a single gene can 42 induced dramatic phenotypic changes. 43 44 108 glycogen synthase kinase 3 (STKc_GSK3), the wheat orthologue of BIN2. In T. 109 sphaerococcum, a single amino acid substitution of STKc_GSK3 enhances protein 110 5 stability in response to BR, leading to round grain formation. Evolutionary analysis 111 provided evidence that the origin of T. sphaerococcum wheat involved at least two 112 independent mutations of TaSG-D1.

SummaryThe genome of Tolypothrix sp. PCC 7601 carries two copies of a novel insertion sequence, IS Tosp 1. One of the two copies is located upstream of the gene encoding glutamyl-tRNA synthetase, an enzyme playing a key role in protein and pigment synthesis. The tnpA gene of the IS element and gltX were co-transcribed and their expression was transiently upregulated upon retrieval of the ammonium source irrespective of whether nitrate or no nitrogen source were available. The second copy is also transcribed and shows a similar regulatory pattern. Structural elements of the promoter ( -10 and -35 sequences) directing the expression of the tnpA-gltX operon have been localized within the IS. Regulatory sequences involving the NtcA transcription factor in the control of tnpA-gltX expression were found both within and in sequences upstream of the insertion element. The expression of gltX in a closely related cyanobacterium, Nostoc sp. PCC 7120, which lacks the insertion upstream of gltX , decreased upon ammonium retrieval, a regulatory pattern that markedly differs from that observed in Tolypothrix sp. PCC 7601. IS Tosp 1 constitutes a good example of how cells can make use of a transposable element to evolve an original regulatory mechanism.

Agricultural machinery can improve agricultural productivity and promote agricultural scale operation. However, machinery operations lead to increased dust in farmland and affect the atmospheric environment; thus, they have been increasingly emphasized. In this study, the effects of agricultural machinery operations in wheat cultivation were investigated regarding the emissions of three kinds of particulate matters, namely fine particulate matter (PM2.5), inhalable particulate matter (PM10) and total suspended particulate (TSP), from farmland in Beijing. The results showed that the total dust emission from the traditional tillage mode, including straw crushing, rotary tilling and sowing, was 3.990 g per hectare, which was larger than that of the conservation tillage mode including only no-tillage sowing (0.407 g per hectare). The total dust emission for one hectare of farmland under the two modes was 3.415 g, 0.497 g, 0.407 g and 0.078 g for straw shredding, rotary tillage, no-tillage sowing and conventional sowing, respectively. The values of PM2.5/PM10 and PM2.5/TSP decreased in each tillage section after each agricultural machinery operation, while the values of PM10/TSP were basically unchanged, indicating that particulate matter emissions from farmland due to agricultural machinery operations are mainly PM10 and TSP. The dust concentration generated by agricultural machinery increased with an increase in the speed of the machinery operation, provided that the quality of the operation was guaranteed. This study provides guidance for reducing dust emissions from mechanized operations, improving air quality and decreasing health hazards to operators of agricultural machinery.