Tripsazea, a Novel Trihybrid of , , and .

A trispecific hybrid, MTP (hereafter called tripsazea), was developed from intergeneric crosses involving tetraploid (2 = 4 = 40, genome: MMMM), tetraploid (2 = 4 = 72, TTTT), and tetraploid (2 = 4 = 40, PPPP). On crossing maize- (2 = 4 = 56, MMTT) with , 37 progenies with varying chromosome numbers (36-74) were obtained, and a special one (, tripsazea) possessing 2 = 74 chromosomes was generated. Tripsazea is perennial and expresses phenotypic characteristics affected by its progenitor parent. Flow cytometry analysis of tripsazea and its parents showed that tripsazea underwent DNA sequence elimination during allohexaploidization. Of all the chromosomes in diakinesis I, 18.42% participated in heterogenetic pairing, including 16.43% between the M- and P-genomes, 1.59% between the M- and T-genomes, and 0.39% in T- and P-genome pairing. Tripsazea is male sterile and partly female fertile. In comparison with previously synthesized trihybrids containing maize, and teosinte, tripsazea has a higher chromosome number, higher seed setting rate, and vegetative propagation ability of stand and stem. However, few trihybrids possess these valuable traits at the same time. The potential of tripsazea is discussed with respect to the deployment of the genetic bridge for maize improvement and forage breeding.