Transcriptome analyses throughout chili pepper fruit development reveal novel insights into the domestication process

Chili pepper (Capsicum spp.) is an important crop, as well as a model for fruit development studies and domestication. Here, we performed a time-course experiment to estimate standardized gene expression profiles with respect to fruit development for six domesticated and four wild chili pepper ancestors. We sampled the transcriptomes every 10 days from flowering to fruit maturity, and found that the mean standardized expression profiles for domesticated and wild accessions significantly differed. The mean standardized expression was higher and peaked earlier for domesticated vs. wild genotypes, particularly for genes involved in the cell cycle that ultimately control fruit size. We postulate that these gene expression changes are driven by selection pressures during domestication and show a robust network of cell cycle genes with a time shift in expression, which explains some of the differences between domesticated and wild phenotypes

In vitro plantlet regeneration from nodal segments and shoot tips of Capsicum chinense Jacq. cv. Naga King Chili

An in vitro regeneration protocol was developed for Capsicum chinense Jacq. cv. Naga King Chili, a very pungent chili cultivar and an important horticultural crop of Nagaland (Northeast India). Maximum number of shoot (13 ± 0.70) was induced with bud-forming capacity (BFC) index of 10.8, by culturing nodal segments in Murashige and Skoog (MS) medium supplemented with 18.16 μM Thidiazuron (TDZ) followed by 35.52 μM 6-benzylaminopurine (BAP). Using shoot tips as explants, multiple shoot (10 ± 0.37) (BFC 8.3) was also induced in MS medium fortified with either 18.16 μM TDZ or 35.52 μM BAP. Elongated shoots were best rooted in MS medium containing 5.70 μM indole-3-acetic acid (IAA). Rooted plantlets thus developed were hardened in 2–3 weeks time in plastic cups containing potting mixture of a 1:1 mix of soil and cow dung manure and then subsequently transferred to earthen pots. The regenerated plants did not show any variation in the morphology and growth as compared to the parent plant

Polyamines and WOX genes in the recalcitrance to plant conversion of somatic embryos of Habanero pepper (Capsicum chinense Jacq.)

In order to determine the role of polyamines in the formation and development of the somatic embryos of Capsicum chinense, the effect of different concentrations (0, 0.01, 0.1, and 1.0 mM) of Putrescine, Spermidine and Spermine on the efficiency and morphology of the embryos was evaluated. The results show that none of the three polyamines evaluated had a significant effect on the number of embryos formed, except Spermidine (1 mM), which caused a significant reduction in their numbers, in comparison with the control treatment. However, the most noteworthy result was observed in the treatment containing 0.1 mM of Spermine. The embryos developed in this treatment showed harmonic apex-radicle development, pale-green coloration and the formation of two tiny cotyledonary leaves. Real-time PCR was used to analyze the differential expression of the WUS, WOX1 and WOX3 genes in somatic embryos treated with Spermine and untreated, including the zygotic embryo. The transcript levels of the genes analyzed were found to differ significantly between both types of embryos (somatic and zygotic), with the zygotic embryos presenting a higher level of transcripts; however, compared to the untreated somatic embryos, the somatic embryos treated with Spermine showed an increase in the transcript levels of the three genes analyzed (WUS, WOX1 and WOX3); the WOX1 gene in particular presented an accumulation pattern similar to that of the zygotic embryo of the species. Keywords: Somatic embryos, zygotic embryos, polyamines, transcript patterns and morphology.

Evolución del contenido de capsinoides y capsaicinoides durante la maduración de los frutos de ‘Chiltepín’ C. annuum L. var. glabriusculum

El ‘Chiltepín’ es un chile muy popular en México por su intenso color rojo y su característico sabor y picor. Este último atributo es debido a la presencia de unos compuestos pertenecientes a las familias de los capsaicinoides y los capsinoides; sus presencias, así como la distinta relación de sus contenidos perfilan un tipo de picor diferencial. Ambas familias de compuestos han sido estudiadas en el área de la medicina por sus efectos antitumorales y sus actividades antioxidantes y analgésicas, entre otras. La caracterización de estos compuestos bioactivos en distintos estados de desarrollo del fruto permitirá profundizar en el conocimiento de su biosíntesis y control genético. En este trabajo, se ha evaluado por primera vez, la evolución del contenido de capsinoides a lo largo del desarrollo de los frutos de pimiento y su relación con la de los capsaicinoides. Concretamente este trabajo se ha hecho en el tipo ‘Chiltepín’, en el cual el patrón de evolución del contenido de capsinoides fue similar al de capsaicinoides; su biosíntesis se inició entre los 10-20 días post antesis (dpa) y su contenido aumentó hasta alcanzar su máximo a los 40 dpa. Capsiato y dihidrocapsiato han sido cuantificados por primera vez en ‘Chiltepín’, variando respectivamente entre 43,53-234,26 g g-1 materia seca (ms) y 13,73-97,93 g g-1 ms. Las correlaciones entre los distintos compuestos fueron altamente significativas (P< 0,01), con coeficientes que variaron desde 0,923 para dihidrocapsaicina vs. dihidrocapsiato hasta 0,998 para capsaicina vs. dihidrocapsaicina.Publishe