Allelic variation and haplotype diversity of Matrilineal (MTL) gene governing in vivo maternal haploid induction in maize.

Diverse haploid inducer lines with > 6% of haploid induction rate are now routinely used to develop doubled haploid lines. Though MTL gene regulates haploid induction, its molecular characterization and haplotype analysis in maize and its related species have not been undertaken so far. In the present study, the entire 1812 bp long MTL gene was sequenced among two mutant and eight wild-type inbreds. A 4 bp insertion differentiated the mutant from the wild-type allele. Sequence analysis further revealed 103 polymorphic sites including 38 InDels and 65 SNPs. A total of 15 conserved regions were detected, of which exon-4 was the most conserved. Ten gene-based markers specific to MTL revealed the presence of 40 haplotypes among diverse 48 inbreds of exotic and indigenous origin. It generated 20 alleles with an average of two alleles per locus. The mean polymorphic information content was 0.3247 with mean gene diversity of 0.4135. A total of 15 paralogous sequences of MTL were detected in maize genome with 3-7 exons. Maize MTL proteins of both wild-type and mutant were non-polar in nature, and they possessed four domains. R1-nj-based haploid inducer (HI) lines viz., Pusa-HI-101 and Pusa-HI-102 had an average haploid induction rate of 8.45 ± 0.96% and 10.46 ± 1.15%, respectively. Lines wild-type MTL gene did not generate any haploid. In comparison with 27 orthologues of 21 grass species, maize MTL gene had the closest ancestry with Saccharum spontaneum and Sorghum. The information generated here assumes great significance in understanding the diversity of MTL gene and presence of paralogues and orthologues. This is the first report on haplotype analysis and molecular characterization of MTL gene in maize and related grass species. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01456-3.

Starch and storage protein dynamics in the developing and matured grains of durum wheat and diploid progenitor species.

Durum wheat, less immunogenically intolerant than bread wheat, originates from diploid progenitors known for nutritional quality and stress tolerance. Present study involves the analysis of major grain parameters, viz. size, weight, sugar, starch, and protein content of Triticum durum (AABB genome) and its diploid progenitors, Triticum monococcum (AA genome) and Aegilops speltoides (BB genome). Samples were collected during 2-5 weeks after anthesis (WAA), and at maturity. The investigation revealed that T. durum displayed the maximum grain size and weight. Expression analysis of Grain Weight 2 (GW2) and Glutamine Synthase (GS2), negative and positive regulators of grain weight and size, respectively, revealed higher GW2 expression in Ae. speltoides and higher GS2 expression in T. durum. Further we explored total starch, sugar and protein content, observing higher levels of starch and sugar in durum wheat while AA genome species exhibited higher protein content dominated by the fractions of albumin/globulin. HPLC profiling revealed unique sub-fractions in all three genome species. Additionally, a comparative transcriptome analysis also corroborated with the starch and protein content in the grains. This study provides valuable insights into the genetic and biochemical distinctions among durum wheat and its diploid progenitors, offering a foundation for their nutritional composition.

Variation in anthocyanin pigmentation by R1-navajo gene, development and validation of breeder-friendly markers specific to C1-Inhibitor locus for in-vivo haploid production in maize.

BACKGROUND: In-vivo maternal haploids serve as the basis of doubled haploid (DH) breeding in maize. R1-navajo (R1-nj) gene governing anthocyanin colouration in the endosperm and embryo is widely used to identify haploid seeds. However, the expression of R1-nj depends on genetic-background of source-germplasm used for deriving DH-lines. Further, presence of C1-Inhibitor (C1-I) gene suppresses the expression of R1-nj, thus makes the selection of haploids difficult. METHODS: In the present study, 178 subtropically-adapted maize inbreds were crossed with two R1-nj donors 'that do not have haploid induction genes'. Of these, 76.4% inbreds developed purple colour in endosperm, while 23.6% did not show any colouration. In case of scutellum, 62.9% inbreds possessed colour and 37.1% were colourless. The anthocyanin intensity varied greatly, with 19.66% and 42.98% inbreds displayed the least intensity, while 16.85% and 0.84% inbreds showed the highest intensity in endosperm and scutellum, respectively. Two C1-I specific breeder-friendly markers (MGU-CI-InDel8 and MGU-C1-SNP1) covering (i) 8 bp InDel and (ii) A to G SNP, respectively, were developed. MGU-CI-InDel8 and MGU-C1-SNP1 markers predicted presence of C1-I allele with 92.9% and 84.7% effectiveness, respectively. However, when both markers were considered together, they provided 100% effectiveness. CONCLUSIONS: These markers of C1-I gene would help in saving valuable resources and time during haploid induction in maize. The information generated here assume great significance in DH breeding of maize.

Identification of putative flowering genes and transcription factors from flower de novo transcriptome dataset of tuberose (Polianthes tuberosa L.).

Polianthes tuberosa is commercially popular because of their economic importance in floriculture for cut and loose flowers and in perfume industry because of the unique fragrance. Despite its commercial importance, no ready-to-use transcript sequence information is available in the public database. We have sequenced the RNA obtained from tuberose flowers using the Illumina HiSeq. 2000 platform and have carried out a de novo analysis of the transcriptome data. The de novo assembly generated 11,100 transcripts. These transcripts represent a total of 7876 unigenes that were considered for downstream analysis. These 7876 unigenes, which was further annotated using blast2go and KEGG pathways, were also assigned. Tuberose transcripts were also assigned to metabolic pathways using the Kyoto Encyclopedia of Genes and Genomes database to determine their biochemical functions. 4591 of the tuberose transcripts matched to genes in KEGG pathways and 66 transcripts were mapped to the Flavonoid biosynthesis pathway. 21 flowering genes have been identified in this tuberose transcriptome. Transcription factor analysis helped in the identification of a large number of transcripts similar to key genes in the flowering regulation network of Arabidopsis thaliana. Among the transcription factors identified "NAC" which is associated with plant stress response represented the most abundant category followed by APETALA2 (AP2)/ethylene-responsive element binding proteins (EREBPs) which plays various role in floral organ identity and respond to different biotic and abiotic stress.