Mates Matter: Gametophyte Kinship Recognition and Inbreeding in the Giant Kelp, Macrocystis pyrifera (Laminariales, Phaeophyceae).

Inbreeding, the mating between genetically related individuals, often results in reduced survival and fecundity of offspring, relative to outcrossing. Yet, high inbreeding rates are commonly observed in seaweeds, suggesting compensatory reproductive traits may affect the costs and benefits of the mating system. We experimentally manipulated inbreeding levels in controlled crossing experiments, using gametophytes from 19 populations of Macrocystis pyrifera along its Eastern Pacific coastal distribution (EPC). The objective was to investigate the effects of male-female kinship on female fecundity and fertility, to estimate inbreeding depression in the F1 progeny, and to assess the variability of these effects among different regions and habitats of the EPC. Results revealed that the presence and kinship of males had a significant effect on fecundity and fertility of female gametophytes. Females left alone or in the presence of sibling males express the highest gametophyte size, number, and size of oogonia, suggesting they were able to sense the presence and the identity of their mates before gamete contact. The opposite trend was observed for the production of embryos per female gametes, indicating higher costs of selfing and parthenogenesis than outcrossing on fertility. However, the increased fecundity compensated for the reduced fertility, leading to a stable overall reproductive output. Inbreeding also affected morphological traits of juvenile sporophytes, but not their heatwave tolerance. The male-female kinship effect was stronger in high-latitude populations, suggesting that females from low-latitude marginal populations might have evolved to mate with any male gamete to guarantee reproductive success.

Anther Rubbing, a New Mechanism That Actively Promotes Selfing in Plants.

Self-fertilization has recurrently evolved in plants, involving different strategies and traits and often loss of attractive functions, collectively known as the selfing syndrome. However, few traits that actively promote self-fertilization have been described. Here we describe a novel mechanism promoting self-fertilization in the Brassicaceae species Erysimum incanum. This mechanism, which we called "anther rubbing," consists of autonomous, repeated, and coordinated movements of the stamens over the stigma during flower opening. We have documented anther rubbing by time-lapse videos and experimentally show that it causes self-pollen deposition on stigmas and is sufficient to achieve maximal reproductive output in E. incanum. We predict that these movements should occur in species with limited inbreeding depression, and indeed we find that inbreeding depression in seed production is negligible in this species. While many studies have documented complex floral traits that promote outcrossing, the occurrence of anther rubbing demonstrates that plants can evolve elaborate and underappreciated adaptations to promote self-fertilization.

Improvement of the Sterol and Triacylglycerol Compositions of Chemlali Virgin Olive Oils through Controlled Crossing with Mediterranean Cultivars.

The chemical composition of extra virgin olive oils (EVOOs) from six new progenies, obtained through controlled crossings between the main Tunisian variety Chemlali and autochthonous (Chemcheli) and foreign cultivars (Sigoise, Coratina, Koroneiki, and Arbequina) used as pollen acceptor or pollinator, were compared with the EVOO of Chemlali cultivar known to be the main one cultivated in Tunisia as it is the most adapted to the arid climate. Several analytical determinations of major and minor components of EVOO were employed, especially triacylglycerol and sterol fractions. All the studied hybrid EVOOs showed an improvement in their chemical composition and stability by comparison with Chemlali EVOO. The main triacylglycerols were 1,2,3-trioleylglycerol (OOO), 2,3-dioleyl-1-palmitoylglycerol (POO), 2,3-dioleyl-1-linoleylglycerol (LOO) and 2,3-dioleyl-1-stearoylglycerol (SOO). ß-sitosterol, Δ5-avenasterol and campesterol were the principal sterols in all samples. Cholesterol, stigmasterol, clerosterol and Δ7-stigmastenol were also found in all samples. Oil samples examined showed inter-variability between the studied cultivars. Results of discriminant and principal component analyses appear to prove that genetic origin of the raw materials has a great influence on the final composition of the oil; especially triacylglycerol and sterol compositions.