Exploring natural variation of photosynthetic, primary metabolism and growth parameters in a large panel of Capsicum chinense accessions

Abstract

Collectively, the results presented improve upon the utility of an important genetic resource and attest to a complex genetic basis for differences in both leaf metabolism and fruit morphology between natural populations. Diversity of accessions within the same species provides an alternative method to identify physiological and metabolic traits that have large effects on growth regulation, biomass and fruit production. Here, we investigated physiological and metabolic traits as well as parameters related to plant growth and fruit production of 49 phenotypically diverse pepper accessions of Capsicum chinense grown ex situ under controlled conditions. Although single-trait analysis identified up to seven distinct groups of accessions, working with the whole data set by multivariate analyses allowed the separation of the 49 accessions in three clusters. Using all 23 measured parameters and data from the geographic origin for these accessions, positive correlations between the combined phenotypes and geographic origin were observed, supporting a robust pattern of isolation-by-distance. In addition, we found that fruit set was positively correlated with photosynthesis-related parameters, which, however, do not explain alone the differences in accession susceptibility to fruit abortion. Our results demonstrated that, although the accessions belong to the same species, they exhibit considerable natural intraspecific variation with respect to physiological and metabolic parameters, presenting diverse adaptation mechanisms and being a highly interesting source of information for plant breeders. This study also represents the first study combining photosynthetic, primary metabolism and growth parameters for Capsicum to date.

Pepper Photosynthesis, Stomatal Conductance, Transpiration, and Water Use Efficiency Differ with Variety, Indigenous Habitat, and Species of Origin

“…Capsicum P n values varied more in our experiment (3.6-3.7 to 16.3 mmol CO 2 /m 2 /s fixed) than they did in other experiments reported by others; for example, Ou and Zou (2012) reported that the P n of five Capsicum species varied from 15.8 to 21.8 mmol CO 2 /m 2 /s (fixed). Among pepper varieties within a species, P n also varied more in our experiment than it did in others (Ghasemi et al, 2016;Rosado-Souza et al, 2015). Borisev et al 2012reported that the P n of 10 C. annuum varieties differed from 14.5 to 16.6 mmol CO 2 /m 2 /s (fixed); the C. annuum variety P n (22 varieties) in our work ranged from 3.7 to 16.3 mmol CO 2 /m 2 /s (fixed) ( Table 1).…”

“…P erez-Grajales et al (2004) reported similar P n rates (at a lower irradiance of 500 mmol/m 2 /s) for C. pubescens. Rosado-Souza et al (2015) reported that the C. chinense accession P n varied from 17 to 25 mmol CO 2 /m 2 /s (fixed).…”

“…Interestingly, we observed that g S differed among varieties derived from those species. Rosado-Souza et al (2015) reported that the C. annuum variety g S differed. Furthermore, Kang et al (2001) reported that the C. chinense variety g S differed.…”

Genetic divergence between pepper accessions based on quantitative fruit traits

“…Thus, using this diversity through genetic combinations will allow the emergence of genotypes that are more adapted, productive, and resistant to diseases, among other traits of interest to the market (Souza et al, 2011). Furthermore, it will be possible to differentiate accessions and make them more useful (Padilha et al, 2016a), identifying effective traits in several processes, such as growth regulation, biomass, and fruit production (Souza et al, 2015).…”

“…Although there are a lot of divergence studies with Capsicum chinense Jacq. described in the literature, such as Finger et al (2010), Faria et al (2012Faria et al ( , 2013, Vasconcelos et al (2014), Souza et al (2015), Padilha et al (2016b) and Pessoa et al (2018), which only evaluate or characterize genetic diversity for the choice of superior parents, none of them evaluates genetic diversity aiming at recommendations for specific market niches. Moreover, studies that aim to observe traits with redundant information for the prediction of genetic diversity are of interest, since it can lead to cost reduction in new experiments.…”