Plastic Responses Mediated by Identity Recognition in Below-Ground Competition in Cycas micronesica K.D. Hill

Abstract

We studied the ability of Cycas micronesica roots to recognize the identity of competitor roots using pot culture. Pairs of seedlings were grown in single pots for 10.5 months, and morphological traits of the focal plant were determined when the non-focal plant was a half-sibling, a close relative from a mother 170 m away, a distant relative from a habitat 40 km away, or a different species (Cycas edentata) from Mindanao, Philippines. Most of the measured response traits exhibited similar trends and confirmed that C. micronesica plant roots were able to recognize the identity of competitors. For example, focal plants grown in pots with C. edentata competitors exhibited 66% increase in fine root dry weight, 54% increase in coralloid root dry weight, and 49% increase in total plant dry weight, compared to focal plants grown in competition with half-siblings. Our methods have shown that plot design in ex situ conservation and botanic garden settings would improve by positioning C. micronesica plants adjacent to non-relatives. Recruitment may improve within in situ conservation plots if managers distribute seeds away from the maternal parent so that emerging seedlings are not forced into immediate competition with half-siblings. These findings may be useful for designing more complex experiments to quantify the influence of these plastic root responses on plant nutrient status and physiology.

Talking with Strangers: Improving Serianthes Transplant Quality with Interspecific Companions

“…The endangered Cycas micronesica K.D. Hill is sympatric with S. nelsonii and also expresses kin recognition by increasing root growth when grown in contact with non-kin neighbors [78]. These two highly threatened Guam trees reveal behaviors that indicate root growth improvements in the presence of stranger roots may be widespread for this island's native flora.…”

Light Reflected from Different Plant Canopies Affected Beta Vulgaris Growth and Development

“…Sugarbeet responded to reduced light quality rather than absolute reductions in light quality. Previous studies have shown that Sorghum vulgare [46], Cycas micronesica [15], Cakile edentula [47], Ambrosia artemisiifolia [48] and Trifolium repens [24] were able to discriminate between kin and non-kin. However, there were root interactions in those studies, suggesting that direct root interaction may be required for kin recognition in some plants.…”

“…Kin recognition, or the ability to "discriminate between related and unrelated individuals" [11], has been relatively less studied in plants compared to animals. Most kin recognition studies in plants focused on root interactions and resource competition or volatile compound signals [12][13][14][15][16]. Also, results from photoreceptor-mediated kin recognition studies are not consistent.…”

Root-mediated sex recognition in a dioecious tree

“…These results have indicated that root-level responses are related to neighbour identity in terms of species, kin versus non-kin or self versus non-self 8 , 25 . However, to our knowledge, few studies have investigated the capacity of woody species to discriminate the identity of root neighbours ( but see in Cycas 26 – 28 ).…”