Respuesta de Zea mays a Burkholderia spp endófita de Zea mays var mexicana (teocintle)

Abstract

Zea mays var mexicana or teocinte is a grass, considered one of the main ancestors of Zea mays. Teocinte, like other grasses, is associated with genera of endophytic plant growth promoters (EPGPB) in the interior of plant tissues. Z. mays is a domestic grass normally cultivated under the intensive production system, with relatively high doses of nitrogen fertilizer (NIFE), a possible alternative solution to minimize this problem, is the inoculation of the seed of Z. mays with genera of EPGPB teocinte, which colonize the roots, stems, leaves and promote a healthy growth at a reduced dose up to 50% NIFE such as urea, which is equivalent to decrease from 280 kg/ha-1 to 140 kg/ha-1, of what is recommended for the region of northern Michoacan and southern Guanajuato, Mexico. The objectives of this work were: i) to determine the density of Burkholderia spp BEPCV of teocinte, ii) to analyze the effect of the inoculation of Burkholderia spp EPGPB on the growth of Z. mays, at reduced dose of NIFE in greenhouse, iii) identify Burkholderia spp BEPCV teocinte. The population density of Burkholderia spp EPGPB was determined in tissues (organs), seeds, stem-leaves and roots of teocinte by sowing them on Pseudomonas cepacia azelaic acid tryptamine (PCAT), after incubation. Burkholderia spp colonies were selected for abundance in: leaves, stem, roots and/or seeds. These isolates of Burkholderia spp, were coded with the keys T41 and T42 and inoculated in Z. mays sown in sterile sand, where as the only variable-response the total dry weight was determined compared to the Z. mays cultivated with the recommended NIFE dose, for that region, it was concluded with the biochemical characterization. The results show that in Burkholderia spp BEPCV of teocinte, a density of 3.4 Log CFU/g of fresh weight (GPF) was registered in the root, of 3.0 Log CFU/GPF in the seed and a similar value in the stem-leaves of teocinte The response of Z. mays to Burkholderia T41 caused an increase of 47% in the dry weight of the root to the tillering, and of 57% to the extension of the stem, compared with the Z. mays without inoculating with the maximum level of NIFE (urea) 280 kg/ha-1. The biochemical identification profile of Burkholderia spp supports a genetic relationship with B. vietnamiensis. It is concluded that teocinte is a source of EPGPB for sustainable production Z. mays at a reduced dose of NIFE.