Late-acting self-incompatibility in Acca sellowiana (Myrtaceae)

Abstract

Acca sellowiana (Berg) Burret is a predominantly allogamous species with hermaphrodite flowers that has barriers to self-fertilisation such as dichogamy by protogyny and self-incompatibility. This study aimed to identify when self-incompatibility occurs in A. sellowiana flowers submitted to self-pollinations. Pollinations were made using nine known self-incompatible accessions in several treatments including manual cross-pollination, manual self-pollination, no pollination and natural pollination. Flowers were pollinated and pistils collected at times ranging from 1 to 30 days after pollination (DAP). In both cross- and self-pollinations the fertilisation occurred from 18 DAP and the zygote was visualised at 24 and 26 DAP, respectively. The abscission of the self-pollinated flowers increased from 26 DAP onwards, when significant differences (P < 0.05) were found for the percentage of abscission among self-pollinated and cross-pollinated flowers. At 30 DAP, 72% of self-pollinated flowers were abscised. The size of ovules and ovaries of self-pollinated flowers showed no significant difference from those of non-pollinated flowers throughout 30 DAP, while those from cross-pollinated flowers were significantly larger (P < 0.05) than the other treatments from 22 and 24 DAP, respectively. After 40 DAP, there was no fruit development in self-pollination and non-pollination treatments. Our study brings greater clarity to the mechanism of self-incompatibility in A. sellowiana, indicating late-acting self-incompatibility occurring through the rejection/abscission of self-pollinated flowers precisely after syngamy and zygote formation.

Reproductive Biology and Flowering of Feijoa (Acca sellowiana (Berg) Burret) in Areas of Marginal Occurrence

“…The effective fruit set originating from manually pollinated flowers was greater than the one obtained by open pollination for both the studied sites (Figure 3), which is consistent with what was observed by Finatto et al (2011), who noticed a significant reduction regarding the effective fruit set for open pollination when compared to manual cross-pollination. However, in Dois Vizinhos, there was a significant reduction in the effective fruit set rate for open pollination (5.8%) when compared with Pato Branco (27.5%).…”

Incipient ecological speciation between successional varieties of a dominant tree involves intrinsic postzygotic isolating barriers

“…Mixed mating systems with predominant outcrossing are known in the close relative, Metrosideros excelsa , of New Zealand (Schmidt‐Adam, Gould, & Murray, ) and are common in eucalypts (also in family Myrtaceae), where low self‐fertility is caused frequently by inbreeding depression (see Burrows, ; Potts & Savva, ). If late‐acting self‐incompatibility (i.e., abscission post fertilization; Seavey & Bawa, ), which is known in Myrtaceae (e.g., Finatto et al., ), plays a role in the low self‐fertility seen in M. polymorpha , it varied significantly among individuals within both varieties. Low self‐fertility due to high genetic load is common in trees, where predominant outcrossing, large populations, and long lifespans facilitate the accumulation of mutations (Petit & Hampe, ).…”

Ovarian self-incompatibility inNarcissus papyraceus(Amaryllidaceae) is the result of a pre-zygotic response

“…The difficulty of observing post‐pollination events within ovules has hindered our understanding of the possible mechanisms operating in cases of late‐acting self‐incompatibility in certain species (Gibbs & Bianchi, ; Lipow & Wyatt, ; Aguilar & Bernardello, ; LaDoux & Friar, ; Gibbs, ). In the few detailed studies that are available, both pre‐ and post‐zygotic reactions have been proposed (Cope, ; Kenrick, Kaul & Williams, ; Gibbs, Oliveira & Bianchi, ; Sage & Sampson, ; Valtueña et al ., ; Finatto et al ., ; Ford & Wilkinson, ). However, other studies have stimulated debate regarding the possibility that selfing failure in some species is the result of early acting inbreeding depression rather than any novel late‐acting self‐incompatibility mechanism (Klekowski, ; Manicacci & Barrett, ; Nic Lughadha, ; Lipow & Wyatt, ; Bittencourt, Gibbs & Semir, ; Koehl et al ., ; Hao et al ., ; Gibbs, ).…”