Development of Apomictic 56-Chromosomal Maize-Tripsacum Hybrids: A Potential Breakthrough in Heterosis Fixation.

Maize (Zea mays L.) is one of the most demanded grain crops in the world. Currently, production has exceeded one billion tons and is increasing by 3-5% annually. Such growth is due to the genetic potential of the crop and the use of heterosis F1 hybrids in production. However, the need to produce first-generation seed annually poses significant challenges and is an economically costly technology. A solution to this problem may be the transfer of the asexual (apomictic) mode of reproduction to maize from its wild relative, eastern gamagrass (Tripsacum dactyloides L.). In this work, we report the production of 56-chromosome apomictic hybrids of maize (Zea mays L.) with eastern gamagrass (T. dactyloides L.) with restored anther fertility. The mode of reproduction of the plant was confirmed by counting chromosomes and sequencing the nuclear gene (Pox3) and chloroplast tRNA-Leu (trnL) gene. These apomictic hybrids had karyotypes of 2n = 56 = [(10Zm(573MB) + 36Td) + 10Zm(611CB)] and 2n = 56 = [(10Zm(611CB) + 36Td) + 10Zm(611CB)]. The resulting hybrids can be widely used as a fodder crop.

Analysis of the Structural Organization and Expression of the Vrn-D1 Gene Controlling Growth Habit (Spring vs. Winter) in Aegilops tauschii Coss.

The duration of the vegetative period is an important agronomic characteristic of cereal crops. It is mainly influenced by the Vrn (response to vernalization) and Ppd (response to photoperiod) genes. In this work, we searched for alleles of several known genes of these two systems of response to external conditions in 15 accessions of Aegilops tauschii Coss. (syn. Ae. squarrosa L.), with the aim of studying the impact these alleles have on the vegetative period duration and growth habit. As a result, three allelic variants have been found for the Vrn-D1 gene: (i) one intact (winter type), (ii) one with a 5437 bp deletion in the first intron and (iii) one previously undescribed allele with a 3273 bp deletion in the first intron. It has been shown that the spring growth habit of Ae. tauschii can be developed due to the presence of a new allele of the Vrn-D1 gene. Significant differences in expression levels between the new allelic variant of the Vrn-D1 gene and the intact allele vrn-D1 were confirmed by qPCR. The new allele can be introgressed into common wheat to enhance the biodiversity of the spring growth habit and vegetative period duration of plants.