Comparative mitochondrial genome analysis reveals a candidate ORF for cytoplasmic male sterility in tropical onion.

Cytoplasmic male sterility (CMS) has been widely exploited for hybrid seed production in onions (Allium cepa L.). In contrast to long-day onion cultivars, short-day onion has not yet been investigated for mitochondrial genome structure and DNA rearrangements associated with CMS activity. Here, we report the 3,16,321 bp complete circular mitochondrial genome of tropical onion CMS line (97A). Due to the substantial number of repetitive regions, the assembled mitochondrial genome of maintainer line (97B) remained linear with 15 scaffolds. Additionally, 13 and 20 chloroplast-derived fragments with a size ranging from 143 to 13,984 bp and 153-17,725 bp were identified in the 97A and 97B genomes, respectively. Genome annotation revealed 24 core protein-coding genes along with 24 and 28 tRNA genes in the mitochondrial genomes of 97A and 97B, respectively. Furthermore, comparative genome analysis of the 97A and 97B mitochondrial genomes showed that gene content was almost similar except for the chimeric ORF725 gene which is the extended form of the COX1 gene. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03850-2.

Utilizing response surface methodology to optimize the extraction and characterization of anthocyanins from Solanum melongena L. fruit.

This research aimed to optimize the extraction of anthocyanin from Solanum melongena L. fruits by studying the effects of extraction time, temperature, pH, and solid-to-liquid ratio using response surface methodology. The Box-Behnken design was used to analyze the anthocyanin concentration under different combinations of these parameters. The optimal conditions for anthocyanin extraction were found to be 7.9 h extraction time, 33.63 °C extraction temperature, 5.39 pH of extraction solvent, and 0.32 solid-liquid ratio. The recovery of 88.12 mg·100 g-1 anthocyanin concentration was achieved with 0.53% relative error compared to the output generated through the chemometric model. Statistical analysis revealed a significant effect of the selected parameters on anthocyanin extraction. The extracted anthocyanin was characterized and found to contain delphinidin. These findings suggest that the optimized method can be used for the efficient extraction and characterization of anthocyanins from Solanum melongena L. fruits.

Identification of a Major-Effect Quantitative Trait Loci Associated with Begomovirus Resistance in Cucurbita moschata.

Begomoviruses, viz. squash leaf curl China virus and tomato leaf curl New Delhi virus causative diseases are major concerns of quantitative and qualitative losses in pumpkin (Cucurbita moschata) worldwide. Punjab Agricultural University (PAU) in India has identified a resistant source (PVR-1343) against mixed infection (MI-Sq/To) of these begomoviruses. Introgression of resistance in diverse genetic backgrounds requires the identification of quantitative trait loci (QTLs) associated with MI-Sq/To resistance. Phenotyping of 229 F2:3 progenies derived from the PVR-1343 × P-135 cross revealed digenic recessive inheritance against MI-Sq/To resistance in PVR-1343. To identify the genomic region, resistant and susceptible bulks were subjected to whole-genome resequencing along with their parents. The whole-genome resequence analysis of parents and bulks using QTLseq/QTLseqr approaches identified an overlapping 1.52 Mb region on chromosome 7 (qMI-Sq/To7.1), while chromosomal region spanning 0.87 Mb on chromosome17 (qMI-Sq/To17.1) was additionally identified by QTLseqr. However, the highest peak value on chromosome 7 with three algorithms {G', ∆(SNP-index) and -log10 (P value)} highlighted the major contribution of qMI-Sq/To7.1 in MI-Sq/To resistance. Nine polymorphic SNPs identified within the highly significant qMI-Sq/To7.1 region were converted into KASP markers. KASP genotyping of F2 individuals narrowed down the qMI-Sq/To7.1 interval to 103 kb region flanked by two markers, Cmo3914729 and Cmo4018182, which contained 16 annotated genes and accounted for 59.84% of phenotypic variation. The Cmo4018182 KASP marker accurately predicted disease reaction in 91% of diverse Cucurbita genotypes and showed nonsynonym substitutions in the coding region of putative candidate SYNTAXIN-121 gene. These findings pave the way for marker-assisted breeding and elucidating the underlying mechanism of begomovirus resistance in C. moschata.

Interspecific hybridization for transfer of hull-less seed trait from Cucurbita pepo to C. moschata.

Hull-less seed trait is preferred by nut and oil industries worldwide for snacking and oil extraction as it evades the expensive decorticating (dehulling) process. This seed trait is available in C. pepo only, which has small seed cavity, sensitive to various biotic and abiotic stresses, and restricted to temperate regions for cultivation. Contrarily, the related species C. moschata has wider adaptability, disease tolerance and high seed yield. Therefore, attempt was made to transfer this trait into C. moschata through conventional pollination and ovule culture using four parents of hull-less C. pepo and six of hulled C. moschata. Through conventional approach, few viable F1 seeds (12-23) were obtained by using C. pepo as female parent, but in three crosses (HLP36 × HM1343, HLP36 × HM1022 and HLP44 × HM1022) only, whereas, its use as male parent was not successful. This incompatibility issue of reciprocals was resolved through ovule culture of C. moschata genotypes HM1343 and HM6711 after 17 to 19 days of pollination with C. pepo genotypes HLP53 and HLP72, respectively. The hybridity of interspecific crosses was confirmed through SSR markers (alleles inherited from both the parents), morphological characters and micromorphological leaf traits (differed from both the parents). The successful transfer through interspecific hybridization was further established with the presence of hull-less seed in fruits of F2 populations. Outcome of this study would pave the way for enhancing the productivity and multi-season cultivation of snack-seeded pumpkin even in subtropical and tropical regions.

Evaluation of biochemical composition of hulled and hull-less genotypes of pumpkin seeds grown in subtropical India.

Pumpkin seeds are one of the functional foods with most potential having myriad of uses, and functioning as both edible seeds and oilseeds. Nevertheless, their utilization is restricted to the presence of a thick seed coat (hull) which subjects them to the process of decortication, increasing the farmers' expense as well as limiting their utilization as oilseeds. Therefore, in the present study, characterization of the biochemical composition of the hulled (Punjab Chappan Kadoo-1 abbreviated as PCK-1) and hull-less (PAU Magaz Kadoo-1 abbreviated as PMK-1) genotype of pumpkin seeds was undertaken to assess the nutritional differences and their efficient application; PMK-1 is a new cultivar of pumpkin released by Punjab Agricultural University in 2018. Based on the characterization, the hulled genotype of pumpkin seeds was observed to possess higher content of total soluble proteins (79.62 mg/100 g), total free amino acids (3.48 g/100 g), moisture (6.74%), fibre content (21.1 g/100 g), antioxidant potential (26.15%), polyamines (19.2 mg/100 g), sterols (387.1 mg/100 g), and specific enzymatic activity whereas the hull-less genotype was observed to possess a higher amount of minerals (4.57 g/100 g), tocopherols (15.76 mg/100 g), and oil content (36%) respectively; most of the biochemical parameters do not differ from each other at a greater fold difference except for total free amino acids and fibre, which are nearly four times and three times higher in hulled seeds in comparison to the naked seeds respectively. The two genotypes of seeds do not compete, rather do complement each other in biochemical and nutritional composition.

Role of phenylalanine/tyrosine ammonia lyase and anthocyanidin synthase enzymes for anthocyanin biosynthesis in developing Solanum melongena L. genotypes.

Solanum melongena is a widely consumed vegetable crop comprising health-benefiting phenolic compounds. It has a complex network of biosynthetic enzymes involved in synthesizing nutraceuticals, including anthocyanins. The present study was conducted to investigate the activities of key enzymes involved in biosynthesis and accumulation of anthocyanins in developing genotypes, such as phenylalanine ammonia lyase (PAL), tyrosine ammonia lyase (TAL), and anthocyanidin synthase (ANS). As inadequate information is available in this context, fruit and leaf tissues were analyzed for enzyme activities and anthocyanin accumulation. The study included characterization of extracted anthocyanin followed by expression studies for gateway enzyme (ANS) involved in anthocyanin biosynthesis. Delphinidin was a major anthocyanidin present in fruit tissues (1.46-110.49 mg/100 g) of S. melongena. Anthocyanin accumulation is backed up by the correlation between biochemical analysis and expression studies. The study has shown variation for PAL, TAL and ANS enzymes in different tissues at developmental stages. Enzyme activities had a strong positive correlation with anthocyanin biosynthesis.

Identification of single major QTL and candidate gene(s) governing hull-less seed trait in pumpkin.

The hull-less pumpkin (Cucurbita pepo) seed does not require de-hulling before use for human consumption, as a result highly preferred by the oil, nut, and baking industries. In hull-less seeds, a single recessive gene is responsible for the absence of outer thick seed coat layers; however, the genomic region and gene(s) controlling the trait are unclear to date. In this study, four crosses attempted to derive F2 and backcross populations confirmed the single recessive gene inheritance of hull-less seed trait in populations adapted to the sub-tropical climate. The candidate genomic region for hull-less seed trait was identified through the BSA-QTLseq approach using bulks of F2:3 progenies from a cross of HP111 (hulled) and HLP36 (hull-less). A novel genomic region on chromosome 12 ranging from 1.80 to 3.86 Mb was associated with the hull-less seed trait. The re-sequencing data identified a total of 396 SNPs within this region and eight were successfully converted into polymorphic KASP assays. The genotyping of segregating F2 (n = 160) with polymorphic KASP assays resulted in a 40.3 cM partial linkage map and identified Cp_3430407 (10 cM) and Cp_3498687 (16.1 cM) as flanking markers for hull-less locus (Cphl-1). These flanking markers correspond to the 68.28 kb region in the reference genome, and the marker, Cp_3430407 successfully predicted the genotype in 93.33% of the C. pepo hull-less germplasm lines, thus can be used for marker-assisted selection in parents polymorphic for the hull-less seed trait. The Cphl-1-linked genomic region (2.06 Mb) encompasses a total of 182 genes, including secondary cell wall and lignin biosynthesis-related transcriptional factors viz., "NAC" (Cp4.1LG12g04350) and "MYB" (Cp4.1LG12g03120). These genes were differentially expressed in the seeds of hulled and hull-less genotypes, and therefore could be the potential candidate genes governing the hull-less seed trait in pumpkin.