Nepal has released and registered a total of 623 genetically uniform (mono genotyped) varieties. These varieties were developed by both conventional and classical plant breeding, biotech-assisted plant breeding, and participatory plant breeding methods. However, these varieties have been shown to vary in their yield performance over the years and locations. Smallholder farmers dominate agriculture with 53% of the land-owning households with their land holding size of less than 0.5 ha in Nepal. Farmers are increasingly losing their own saved seeds. There have been impacts of weather variability, often modern crop varieties are not available to suit with these changing conditions. Farmers are looking for crop varieties that can better adapt to these changing conditions, and seeds of which can be saved for the next season planting. Evolutionary Plant Breeding (EPB), which creates and maintains a high degree of genetic diversity (i.e. polymorphic population), is a choice for breeders and farmers for accelerating the development of climate resilient and sustainably high-performance crop varieties. In 2015, the National Gene Bank in Nepal started an EPB program for the local rice variety, Jumli Marshi with the objective of enhancing genetic conservation through creating a dynamic gene pool. An evolutionary population can be compared to a living gene bank, not only in line with bringing greater yield stability, but also greater diversity in aroma, nutritional value and quality. Evolutionary populations have the potential to produce higher yields and perform better than their local or improved counterparts in adverse, or stress conditions. Under stress conditions, evolutionary populations have also been shown to be more resistant to weeds, diseases and pests damage than homogenous crop populations. Based on the source of diversity used in EPB, two different types of populations- Composite Cross population, and Composite Mixtures, population are developed. With the exception of Europe, and only for some crops, existing seed policies do not favor such populations. Therefore, there is a need to revise seed regulations in order to allow the cultivation of a higher degree of genetic diversity.

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Photoperiod responsive flowering and growth habit might have played a key role in domestication of lablab bean (Lablab purpureus) and currently shifting its cultivation from intercropping to monoculture. Most of the landraces of lablab bean exhibit photoperiod sensitivity in flowering and indeterminate growth habit. A cross was made between GNIB21 and GP189 which are phenotypic extremes for photoperiod responsive flowering. The F1 hybrid exhibited dominant traits like indeterminate growth habit and photosensitive flowering endowed from male parent. Segregation pattern of 3:1 in F2 generation indicated monogenic recessive nature of photoperiod insensitive flowering. Bulk segregant analysis in F2 population revealed association of PvTFLy1, a locus governing determinate growth habit in lablab bean, with photoperiod responsive flowering where an amplicon of 300 bp was observed in photo sensitive GP189 while it was absent in photo insensitive variety GNIB21. Significant ÷2 test indicated coupling phase of linkage between PvTFLY1 and photoperiod responsive flowering. Linkage analysis placed PvTFLY1 at the distance of 19.23 cM from the locus governing photoperiod responsive flowering. The linkage between growth habit and photoperiod responsive flowering in common bean, soybean and Indian bean suggest that these traits may be governed by mutation or deletion of E3 (or GmPhyA3) and Dt1 homologs in Indian bean. Information available on characterized genes for photoperiod responsive flowering and determinate growth habit from common bean, soybean and other related legumes may be utilized for isolation, characterization, mapping and molecular dissection of genes involved in regulation of photoperiod responsive flowering in Indian bean.

Background Biologically important curcuminoids viz curcumin, demethoxycurcumin, and bisdemethoxycurcumin in turmeric rhizome have several health benefits. Pharmaceutical industries synthesize curcuminoids manipulating gene expressions in vitro or in vivo because of their medicinal importance. In this experiment, we studied the gene expressions involved in the curcuminoid biosynthesis pathway in association with curcuminoid yield in turmeric rhizome to study the impact of individual gene expression on curcuminoid biosynthesis. Results Gene expressions at the different growth stages of turmeric rhizome were association tested with respective curcuminoid contents. Gene expression patterns of diketide-CoA synthase (DCS) and multiple curcumin synthases (CURSs) viz curcumin synthase 1 (CURS1), curcumin synthase 2 (CURS2), and curcumin synthase 3 (CURS3) were differentially associated with different curcuminoid contents. Genotype and growth stages showed a significant effect on the gene expressions resulting in a significant impact on curcuminoid balance in turmeric rhizome. DCS and CURS3 expression patterns were similar but distinct from CURS1 and CURS2 expression patterns in turmeric rhizome. DCS expression had a significant positive and CURS3 expression had a significant negative association with curcumin, demethoxycurcumin, bisdemethoxycurcumin, and total curcuminoid in turmeric rhizome. CURS1 expression had a negative association with curcumin whereas CURS2 expression showed a positive association with demethoxycurcumin. Conclusions The effects of DCS and CURS expressions are not always positive with different curcuminoid contents in turmeric rhizome. DCS expression has a positive and CURS3 expression has a negative association with curcuminoids. CURS1 and CURS2 are also associated with curcumin and demethoxycurcumin synthesis. This mechanism of co-expression of diketide-CoA synthase and multiple curcumin synthases in turmeric rhizome has a significant effect on curcuminoid balance in different turmeric cultivars. Further experiment will explore more insights; however, association-based test results from this experiment can be useful in improving curcuminoid yield in turmeric rhizome or in vitro through the application of genetic engineering and biotechnology. Graphical abstract Associating gene expressions with curcuminoid biosynthesis in turmeric

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