Induced mutagenesis is one of the most effective strategies for trait improvement without altering the well-optimized genetic background of the cultivars. In this review, several currently accessible methods such as physical, chemical and insertional mutagenesis have been discussed concerning their efficient exploration for the tomato crop improvement. Similarly, challenges for the adaptation of genome-editing, a newly developed technique providing an opportunity to induce precise mutation, have been addressed. Several efforts of genome-editing have been demonstrated in tomato and other crops, exploring its effectiveness and convenience for crop improvement. Descriptive data compiled here from such efforts will be helpful for the efficient exploration of technological advances. However, uncertainty about the regulation of genome-edited crops is still a significant concern, particularly when timely trait improvement in tomato cultivars is needed. In this regard, random approaches of induced mutagenesis are still promising if efficiently explored in breeding applications. Precise identification of casual mutation is a prerequisite for the molecular understanding of the trait development as well as its utilization for the breeding program. Recent advances in sequencing techniques provide an opportunity for the precise detection of mutagenesis-induced sequence variations at a large scale in the genome. Here, we reviewed several novel next-generation sequencing based mutation mapping approaches including Mutmap, MutChromeSeq, and whole-genome sequencing-based mapping which has enormous potential to accelerate the mutation breeding in tomato. The proper utilization of the existing well-characterized tomato mutant resources combined with novel mapping approaches would inevitably lead to rapid enhancement of tomato quality and yield. This article provides an overview of the principles and applications of mutagenesis approaches in tomato and discusses the current progress and challenges involved in tomato mutagenesis research.

Over the past decades, numerous efforts were made towards the improvement of cereal crops mostly employing traditional or molecular breeding approaches. The current scenario made it possible to efficiently explore molecular understanding by targeting different genes to achieve desirable plants. To provide guaranteed food security for the rising world population particularly under vulnerable climatic condition, development of high yielding stress tolerant crops is needed. In this regard, technologies upgradation in the field of genome editing looks promising. Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 is a rapidly growing genome editing technique being effectively applied in different organisms, that includes both model and crop plants. In recent times CRISPR/Cas9 is being considered as a technology which revolutionized fundamental as well as applied research in plant breeding. Genome editing using CRISPR/Cas9 system has been successfully demonstrated in many cereal crops including rice, wheat, maize, and barley. Availability of whole genome sequence information for number of crops along with the advancement in genome-editing techniques provides several possibilities to achieve desirable traits. In this review, the options available for crop improvement by implementing CRISPR/Cas9 based genome-editing techniques with special emphasis on cereal crops have been summarized. Recent advances providing opportunities to simultaneously edit many target genes were also discussed. The review also addressed recent advancements enabling precise base editing and gene expression modifications. In addition, the article also highlighted limitations such as transformation efficiency, specific promoters and most importantly the ethical and regulatory issues related to commercial release of novel crop varieties developed through genome editing.

The pathogenesis-related proteins have a broad spectrum of roles, ranging from seed germination, development to resistance. The PR-10 is a multigene family differing from other PR proteins in being intracellular, small and acidic with similar 3D structures. We have isolated JcPR-10a cDNA with an ORF of 483 bp from J. curcas, an important biofuel crop grown in the wastelands of India. JcPR-10a gets clustered with dicots in phylogenetic tree. The genomic organisation analysis of JcPR-10a revealed the presence of an intron at conserved 185 bp position. Transcript expression of JcPR-10a was upregulated in response to different stimuli such as NaCl, salicylic acid, methyl jasmonate and M. phaseolina. In response to SA and Macrophomina the transcript was found increased at 48 h, however, in case of NaCl and MeJa a strong induction was observed at 12 h which decreased at 48 h. We first time report the transcript up regulation of PR-10 gene by Macrophomina, a pathogen causing collar rot in Jatropha. The recombinant E. coli cells showed better growth in LB medium supplemented with NaCl, whereas growth of recombinant cells was inhibited in LB medium supplemented with KCl, mannitol, sorbitol, methyl jasmonate and salicylic acid. The JcPR-10a protein was overexpressed in E. coli cells, and was purified to homogeneity, the purified protein exhibited RNase and DNase activity. Furthermore, the protein also showed antifungal activity against Macrophomina, indicating that JcPR-10a can serve as an important candidate to engineer stress tolerance in Jatropha as well as other plants susceptible to collar rot by Macrophomina.

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