Early Reproductive Ontogeny in Interspecific Crosses of Arachis hypogaea and Section Arachis Species

Abstract

Wild Arachis species have been recognized as sources of resistance to pests and pathogens that infect A. hypogaea L. and cause substantial yield losses. However, utilization of these genetic resources for crop improvement has been difficult. This study was conducted to ( a) understand the processes of early embryo growth and development in four Arachis species, two A. hypogaea cultivars and their hybrids and ( b) identify parental compatibilities in reciprocal crosses of A. hypogaea. The results indicated that delayed fertilization beyond 24 h, coupled with slow proembryo growth, leads to embryo abortion in many interspecific crosses. For example, in female A. cardenasii crosses, lack of or delayed fertilization leads to failure to obtain hybrids. When A. batizocoi was used as a female parent, delayed fertilization and the inability of quiescent proembryos to resume growth after soil penetration caused abortion. Embryos of A. hypogaea × A. glandulifera crosses developed normally during the first 21 d after fertilization, but then aborted at a later time. In this study, A. hypogaea was always a better female parent than the wild Arachis species. Increasing the number of pollinations per cross, using the cultivated species as the female parent, utilizing different A. hypogaea varieties, and embryo rescue techniques are suggested to improve the probability of obtaining interspecific hybrids in Arachis.