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Title: REPRODUCTIVE CHARACTERISTICS OF APOMICTIC MAIZE-TRIPSACUM HYBRIDS.

Author
item Kindiger, Bryan

Submitted to: United States Japan Natural Resources Forage Seed Panel
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2001
Publication Date: 8/13/2001
Citation: KINDIGER, B.K. 2001. REPRODUCTIVE CHARACTERISTICS OF APOMICTIC MAIZE-TRIPSACUM HYBRIDS. COOP. ACTIVITIES OF THE UNITED STATES JAPAN NATURAL RESOURCES FORAGE SEED PANEL. Volume(2) p. 24-36.

Interpretive Summary: Thetransferofapomixistomaizefromitsdistantrelativeeastern gamagrass (Tripsacum sp.) can offer a myriad of agricultural and economic benefits to the hybrid corn industry. Relatively little information is known about the unique reproductive features associated with apomictic maize-Tripsacum hybrids and how these features could be used in developing an apomictic corn hybrid. The objective of this research was to characterize and identify the frequency of several unique reproductive features found in a array of apomictic maize-Tripsacum hybrids and their apomictic offspring. The research identified the following important points: (1) apomixis is a dominant trait; (2) the trait can be transferred to maize via classical breeding methods; (3) apomixis does not preclude some level of genetic change in the offspring; (4) new variants which are apomictic can be generated from these materials; and (5) normal changes in environment do not obviously alter the frequency of the evaluated apomicti reproductive features. This research is valuable to plant breeders and geneticists in the public and private sector interested in developing apomictic corn or other apomictic cereal grain species.

Technical Abstract: Cytogenetic and molecular evaluations were performed on eight apomictic maize-Tripsacumhybridfamiliescarrying36,18,and9Tripsacum chromosomes.Inaddition,oneapomicticfamilypossessingaMz6L-Tr16L translocation was included. Chromosome counts and random amplified polymorphic DNA (RAPD) analyses were used to assess the chromosome constitution, genetic uniformity, and mode of reproduction in nine apomictic lines representing four differing lines of descent. Individuals, regardless of their chromosome constitution, were compared within and among related and unrelated families. The number of progeny generated by apomixis, sexual developmental behaviors, sexual polyploidization, and polyembryony was obtained. Data indicate that apomictic, sexual, BIII derived hybrids and twin offspring occur at similar frequencies regardless of their maize and Tripsacum chromosome constitution. Comparisons on the type and frequency of progeny obtained from identical or closely related families generated during various growing seasons were inconclusive, but suggest that environmental components do not obviously affect apomictic expression. In addition, chromosome and molecular variations were observed in apomictic progeny obtained from apomictic parents, indicating that an infrequent level of partial meiotic activity is occurring in these apomictic individuals.