Parthenocarpic potential in Capsicum annuumL. is enhanced by carpelloid structures and controlled by a single recessive gene

Abstract

BackgroundParthenocarpy is a desirable trait in Capsicum annuum production because it improves fruit quality and results in a more regular fruit set. Previously, we identified several C. annuum genotypes that already show a certain level of parthenocarpy, and the seedless fruits obtained from these genotypes often contain carpel-like structures. In the Arabidopsis bel1 mutant ovule integuments are transformed into carpels, and we therefore carefully studied ovule development in C. annuum and correlated aberrant ovule development and carpelloid transformation with parthenocarpic fruit set.ResultsWe identified several additional C. annuum genotypes with a certain level of parthenocarpy, and confirmed a positive correlation between parthenocarpic potential and the development of carpelloid structures. Investigations into the source of these carpel-like structures showed that while the majority of the ovules in C. annuum gynoecia are unitegmic and anatropous, several abnormal ovules were observed, abundant at the top and base of the placenta, with altered integument growth. Abnormal ovule primordia arose from the placenta and most likely transformed into carpelloid structures in analogy to the Arabidopsis bel1 mutant. When pollination was present fruit weight was positively correlated with seed number, but in the absence of seeds, fruit weight proportionally increased with the carpelloid mass and number. Capsicum genotypes with high parthenocarpic potential always showed stronger carpelloid development. The parthenocarpic potential appeared to be controlled by a single recessive gene, but no variation in coding sequence was observed in a candidate gene CaARF8.ConclusionsOur results suggest that in the absence of fertilization most C. annuum genotypes, have parthenocarpic potential and carpelloid growth, which can substitute developing seeds in promoting fruit development.

SmARF8, a transcription factor involved in parthenocarpy in eggplant

“…The tomato gene S1ARF7, expressed in unpollinated mature ovaries, was shown to be a negative regulator of fruit set prior to pollination and fertilization and to moderate the auxin response during fruit growth (de Jong et al 2009). In Capsicum, parthenocarpy appeared to be controlled by a single recessive gene (CaARF8); however, no variation in the coding sequence was observed in CaARF8 (Tiwari et al 2011). Another study demonstrated that silencing the tomato SlAux/IAA9 gene could induce parthenocarpic fruit initiation (Wang et al 2005).…”

Translating the “Banana Genome” to Delineate Stress Resistance, Dwarfing, Parthenocarpy and Mechanisms of Fruit Ripening

“…Though intrinsic mechanism of natural parthenocarpy in plants is still unresolved, it is observed that natural parthenocarpic fruits such as banana (Khalifah, 1966) and mandarin (Talon et al, 1990, 1992) record increase in auxin and gibberellins level while levels of ABA declines (Talon et al, 1990). Genetically, parthenocarpy may happen due to a single partially dominant gene as in cucurbits (Kim et al, 1992; Menezes et al, 2005) or due to a single recessive gene as in sweet pepper (Tiwari et al, 2011) or due pleiotropy of major and minor genes as in brinjal/eggplant (Miyatake et al, 2012). In case of banana, parthenocarpy is hypothesized (Sardos et al, 2016) to be due to a major dominant gene ( P or P1 ) interacting with minor ones (Simmonds, 1953).…”

Involvement of Cytokinins, 3-Indoleacetic Acid, and Gibberellins in Early Fruit Growth in Pepper (<i>Capsicum annuum</i> L.)

“…In many pepper cultivars (Capsicum annuum L.), a low night temperature induces parthenocarpy (Rylski, 1973;Tarchoun et al, 2003;Tiwari et al, 2011). However, in such cultivars, the unpollinated parthenocarpic fruit set is lower than that of pollinated fruit, especially in the absence of low night temperatures.…”