Tripsazea, a Novel Trihybrid of Zea mays, Tripsacum dactyloides, and Zea perennis

Abstract

A trispecific hybrid, MTP (hereafter called tripsazea), was developed from intergeneric crosses involving tetraploid Zea mays (2n = 4x = 40, genome: MMMM), tetraploid Tripsacum dactyloides (2n = 4x = 72, TTTT), and tetraploid Z. perennis (2n = 4x = 40, PPPP). On crossing maize-Tripsacum (2n = 4x = 56, MMTT) with Z. perennis, 37 progenies with varying chromosome numbers (36-74) were obtained, and a special one (i.e., tripsazea) possessing 2n = 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, Tripsacum 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.

Multi-species polyploidization, chromosome shuffling, and genome extraction inZea/Tripsacumhybrids

“…This research group had already synthesized an intergeneric tri-species hybrid “MTP” by hybridizing (tetraploid maize x tetraploid T. dactyloides ) x tetraploid Z. perennis (Yan et al 2020). It was formed by fertilization of an unreduced gamete of the F1 hybrid with a reduced gamete of Z. perennis and harbored chromosome complements 2n=74=20M+20P+34T (M, P, and T stand for maize, Z. perennis, and T. dactyloides ).…”

“…Tripsacum and Zea diverged from a common ancestor fewer than 1.2 million years ago (Ross-Ibarra et al 2009; Welker et al 2020) and have shared a common polyploidy event (Estep et al 2014). Tripsacum owns excellent genes for biotic and abiotic stress tolerance and apomixis – lacking in maize, thus have often been hybridized with maize (Harlan and Wet 1977; Kindiger and Dewald 1996; Mangelsdorf and Reeves 1931; Yan et al 2020). Natural gene flow from Z. perennis or Tripsacum into cultivated maize is seldom, if any.…”

“…Natural gene flow from Z. perennis or Tripsacum into cultivated maize is seldom, if any. However, artificial hybridization is possible (Harlan and De Wet 1977; Shaver 1964; Tang et al 2005; Yan et al 2020).…”

Plant Biotechnology—An Indispensable Tool for Crop Improvement

“…Higher organic carbon and nitrogen accumulation in soils and improved soil water retention are other advantages [ 17 ]. Attempts to develop perennial rye using perennial wild rye Secale montanum L. [ 13 ] and perennial maize using tetraploid maize ( Zea mays 2n = 4x = 40), tetraploid Tripsacum dactyloides (2n = 4x = 72), and tetraploid Z. perennis (2n = 4x = 40) [ 18 ] are underway.…”

Exploration of incompatible crosses in plants for novel and useful variations

“…GISH in the rare F 1 hybrid between Narenga porphyrocoma and Erianthus rockii was studied in mitotic metaphase stage, which showed n + n transmission of equal chromosomes from both parents (Chang et al, 2020). Chromosome spread and McGISH (multicolour genomic in situ hybridization) technique is used to study chromosome number and composition of the hybrid and the three translocated chromosomes involving maize genomes with a segment of Zea perennis (Yan et al, 2020).…”