‘MPM1’: a macadamia hybrid showing breakdown of biological rhythm in morphogenesis

Abstract

Macadamia is an Australian native genus, comprising of four species. Commercial cultivars for the production of macadamia nuts are derived from two species, M. tetraphylla and M. integrifolia. The different species of Macadamia have unique leaf and flowering patterns, due to inherent biological rhythms. Usually, M. tetraphylla has four leaves in a whorl, while the other species have three leaves per whorl. All species produce 1-2 florets at each raceme node. We identified a multi-pistillate macadamia genotype ('MPM1') with irregular leaf pattern and floral architecture. The genotype is a progeny of cultivars 'HAES 705' and 'NG18'. In this article, we described the characteristics of this plant and irregularities of its biological rhythm, including the number of leaves per whorl, ranging from 1 to 9, and variation in the number of pistils per floret. This irregular biological rhythm occurred during both vegetative and reproductive growth phases. Future molecular or epigenetic studies could determine the origin and mechanism of these unusual characteristics.