**9. Conclusions**

*Plant Communities and Their Environment*

and improved nutrition [132]. Domestication of wild maize, soybean, and barley has resulted in significant increases in seed size [86]. However, there has also been a negative cost associated with domestication [86]. In maize, soybean, and rice, domestication and intensive cultivation have resulted in the elimination of genetic loci in modern crop cultivars [86, 133–136]. Breeding strategies that do not address adaptation and plasticity decrease trait diversity and may limit the development of new crop varieties with the ability to adapt to insects and extreme environmental fluctuations [133–136]. A reduction in heritability of favorable traits within breeding populations has been one of the main reasons plant breeders have explored the possibility of integrating genetic diversity from wild populations (landraces) back into selective breeding programs [133–137]. Two wild plant models that have been very instrumental in the effort to introduce diversity back into breeding population are: (1) barley (*Hordeum vulgare*); a standard model for monocots, and (2) quinoa (*Chenopodium quinoa* Wild); a model for dicots [137–145]. These two models are very powerful because they highlight a clear transition from wild populations to domesticated cultivars. They also provide tools for understanding plasticity by comparing characteristics that have remained constant, changed, or been lost through a history of domestication [137–145]. Barley was domesticated very early in history from the wild grass relative, *Hordeum spontaneum* [137]. Barley, along with einkorn (*T. monococcum*, genomes AmAm) and emmer (*T. turgidum* ssp. *dicoccoides*, genomes BBAA), marked the beginning of domestication in cereals [137]. Barley is often used as a model to improve crops like wheat (*Triticum aestivum*) [138]. Barley demonstrates a wide range of plasticity including superior growth in nutrient-limited environments, and adapted root architecture [139, 140]. Although there are evolutionary similarities between barley and other monocots like wheat, the orthologous genomic regions between the two species have a completely diverged [141–143]. However, genomic similarities between barley and wheat have enriched the comparative studies of plasticity and provide new information about horizontal gene transfer [141–143]. Quinoa, like barley, was recognized as a valuable food resource, and was domes-

ticated very long ago [144]. Although quinoa has been highly domesticated, it retains vast genetic variability and plasticity with a wide range of resistance to many abiotic and biotic stresses [144, 145]. Quinoa thrives in extreme environmental conditions including in regions with high salinity soils, areas of extremely low precipitation, and environments with extremely cold temperatures [105, 146]. Moreover, quinoa grain is resistant to starch degradation in environments susceptible to extreme temperature and moisture fluctuations [147]. The differences in plasticity discovered between wild and domesticated quinoa species illustrate the importance of continued studies identifying physiological and genetic mechanisms regulating plasticity [147]. These discoveries also highlight the feasibility and importance of selectively breeding for gene targets that improve adaptability and fitness [133–136]. Additionally, because quinoa is a polyploid, it is a rich resource for studying how complex genomes contribute new dimensions of genetic regulation to phenological plasticity [147]. Recent studies investigating modern cultivated varieties of quinoa show that cellular plasticity mechanisms, and more specifically ROS homeostasis, are dependent on both genotype and type of stress [123]. The emerging discoveries in quinoa are important because they provide a model for how plasticity mecha-

nisms present in other polyploid crop species may be regulated [123].

The discovery and utilization of improved traits that enhance the adaptability of crops to increasingly variable environments will help to ensure long-term crop

**48**

**8. Discussion**

One of the benefits of increasing genetic diversity in domesticated populations, from a long-term agricultural perspective, is the increased likelihood of plant population survival in unpredictable environments. In the past, evaluating the contributions of specific traits on phenological plasticity in plants was challenging due to experimental limitations and gaps in knowledge. However, emerging research continues to be extended from model systems directly to wild and cultivated plant populations to uncover the full potential of plasticity. New areas of research will need to investigate plasticity using a systems biology approach. Work should continue to explore the degree of conservation of plasticity existing between monocots and dicot crops, as well as comparing the contributions of ploidy on diversity. Other areas of research should address how DNA methylation and epigenetic mechanisms contribute to plant plasticity and may be fully utilized in plant improvement programs. Additional work should focus on how the simultaneous deployment of multiple plasticity mechanisms during plant developmental shift in changing environments using newly identified plasticity markers like the peroxisomes. Continued plasticity research will be is critical for understanding how to maximize the benefits of both domestication and wild genetic diversity to maximize adaptation and fitness in a new area of climate diversity.

*Plant Communities and Their Environment*
