Fine mapping of two recessive genes TaFLA1 and TaSPL8 controlling flag leaf angle in bread wheat

Flag leaf angle is one of the key target traits in high yield wheat breeding.A smaller flag leaf angle reduces shading and enables plants to grow at a higher density,which increases yield.Here we identified a mutant,je0407,with an 84.34%-89.35%smaller flag leaf angle compared with the wild type.The mutant also had an abnormal lamina joint and no ligule or auricle.Genetic analysis indicated that the ligule was controlled by two recessive genes,which were mapped to chromosomes 2AS and 2DL.The mutant allele on chromosome 2AS was named Tafla1b,and it was fine mapped to a 1 Mb physical interval.The mutant allele on chr.2DL was identified as Taspl8b,a novel allele of TaSPL8 with a missense mutation in the second exon,which was used to develop a cleaved amplified polymorphic sequence marker.F3 and F4 lines derived from crosses between Jing411 and je0407 were genotyped to investigate interactions between the Tafla1b and Taspl8b alleles.Plants with the Tafla1b/Taspl8a genotype had 58.41%-82.76%smaller flag leaf angles,6.4%-24.9%shorter spikes,and a greater spikelet density(0.382 more spikelets per cm)compared with the wild type.Plants with the Tafla1a/Taspl8b genotype had 52.62%-82.24%smaller flag leaf angles and no differences in plant height or spikelet density compared with the wild type.Tafla1b/Taspl8b plants produced erect leaves with an abnormal lamina joint.The two alleles had dosage effects on ligule formation and flag leaf angle,but no significant effect on thousand-grain weight.The mutant alleles provide novel resources for improvement of wheat plant architecture.

Identification of stable quantitative trait loci underlying waterlogging tolerance post-anthesis in common wheat(Triticum aestivum)

Waterlogging is a growing threat to wheat production in high-rainfall areas.In this study,a doubled haploid(DH) population developed from a cross between Yangmai 16(waterlogging-tolerant) and Zhongmai895(waterlogging-sensitive) was used to map quantitative trait loci(QTL) for waterlogging tolerance using a high-density 660K single-nucleotide polymorphism(SNP) array.Two experimental designs,waterlogging concrete tank(CT) and waterlogging plastic tank(PT),were used to simulate waterlogging during anthesis in five environments across three growing seasons.Waterlogging significantly decreased thousand-kernel weight(TKW) relative to non-waterlogged controls,although the degree varied across lines.Three QTL for waterlogging tolerance were identified on chromosomes 4AL,5AS,and 7DL in at least two environments.All favorable alleles were contributed by the waterlogging-tolerant parent Yangmai16.QWTC.caas-4AL exhibited pleiotropic effects on both enhancing waterlogging tolerance and decreasing plant height.Six high-confidence genes were annotated within the QTL interval.The combined effects of QWTC.caas-4AL and QWTC.caas-5AS greatly improved waterlogging tolerance,while the combined effects of all three identified QTL(QWTC.caas-4AL,QWTC.caas-5AS,and QWTC.caas-7DL) exhibited the most significant effect on waterlogging tolerance.Breeder-friendly kompetitive allele-specific PCR(KASP) markers(K_AX_111523809,K_AX_108971224,and K_AX_110553316) flanking the interval of QWTC.caas-4AL,QWTC.caas-5AS,and QWTC.caas-7DL were produced.These markers were tested in a collection of 240 wheat accessions,and three superior polymorphisms of the markers distributed over 67elite cultivars in the test population,from the Chinese provinces of Jiangsu,Anhui,and Hubei.The three KASP markers could be used for marker-assisted selection(MAS) to improve waterlogging tolerance in wheat.

Genome-wide Analysis of a Plant AT-rich Sequence and Zinc-binding Protein (PLATZ) in Triticum Aestivum

Plant AT-rich sequence and zinc-binding protein(PLATZ)is a plant transcription factor that has been studied in corn.PLATZ can non-specifically bind to sequences rich in A/T bases to induce transcriptional repression.It is involved in the regulation of dehydration tolerance in seeds.In this study,we performed bioinformatics analysis to identify and characterize wheat PLATZ(TaPLATZ)genes.We identified 49 wheat PLATZ genes by searching the wheat genome by using known PLATZ gene sequences from rice,Arabidopsis,and maize.Phylogenetic analysis on PLATZ gene sequences from different species was performed.We found that PLATZs could be divided into three groups.The chromosome(chr)distribution analysis revealed that the 49 identified wheat PLATZ genes are distributed in 15 chrs.Gene structure and motif analyses indicated that most PLATZ genes possess conserved exon/intron arrangements and motif compositions.Our analysis of transcriptional data indicated that several wheat PLATZ genes may play an important role in abiotic stress resistance given that they are expressed under salt stress.The results of qRT-PCR further confirmed that TaPLATZ is involved in plant abiotic stress and is also related to the cell differentiation of plant tissues.Our results lay the foundation for further studies on the function of the wheat PLATZ gene family.

Genomic analysis of isopentenyltransferase genes and functional characterization of TaIPT8 indicates positive effects of cytokinins on drought tolerance in wheat

Cytokinins(CKs)function in plant development and during stress responses,but their role in drought tolerance in wheat is unknown.In the present study,24 isopentenyltransferase(IPT)genes,encoding ratelimiting enzymes in CK biosynthesis were identified in the wheat genome.The chromosomal locations and structures of the genes,protein properties,and phylogenetic relationships were characterized.ATP/ADP TaIPT genes showed tissue-specific expression.TaIPT2,TaIPT7,and TaIPT8 expression was rapidly induced by 0.5–1 h drought treatments,which decreased to low levels after 2 h drought treatment,as did most other TaIPT genes.TaIPT8-5a/5b/5d triple mutants showed decreased levels of tZtype CK under normal and drought conditions and reduced drought tolerance,which,however,did not manifest as phenotype alterations.By contrast,transgenic wheat plants with drought-induced TaIPT8showed increased drought tolerance.Our study provides a foundation for further investigation of TaIPT genes and novel insights into the role of CKs in the drought response of wheat.