title: Exogenous nitrate induces root branching and inhibits primary root growth in Capsicum chinense Jacq.
abstract: The effects of nitrate (NO₃⁻) on the root system are complex and depend on several factors, such as the concentration available to the plant, endogenous nitrogen status and the sensitivity of the species. Though these effects have been widely documented on Arabidopsis and cereals, no reports are available in the Capsicum genus. In this paper, we have determined the effect of an exogenous in vitro application of this nutrient on root growth in habanero pepper (Capsicum chinense Jacq.). Exposure to NO₃⁻ inhibited primary root growth in both, dose- and time-dependent manners. The highest inhibition was attained with 0.1 mM NO₃⁻ between the fourth and fifth days of treatment. Inhibition of primary root growth was observed by exposing the root to both homogeneous and heterogeneous conditions of the nutrient; in contrast, ammonium was not able to induce similar changes. NO₃⁻-induced inhibition of primary root growth was reversed by treating the roots with IAA or NPA, a polar auxin transport inhibitor. Heterogeneous NO₃⁻ application stimulated the formation and elongation of lateral roots in the segment where the nutrient was present, and this response was influenced by exogenous phytohormones. These results demonstrate that habanero pepper responds to NO₃⁻ in a similar fashion to other species with certain particular differences. Therefore, studies in this model could help to elucidate the mechanisms by which roots respond to NO₃⁻ in fluctuating soil environments.
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán, Mexico.
authors.forename: Teresita de Jesús
authors.initials: Tde J
authors.lastname: Celis-Arámburo
authors.forename: Mildred
authors.initials: M
authors.lastname: Carrillo-Pech
authors.forename: Lizbeth A
authors.initials: LA
authors.lastname: Castro-Concha
authors.forename: María de Lourdes
authors.initials: Mde L
authors.lastname: Miranda-Ham
authors.forename: Manuel
authors.initials: M
authors.lastname: Martínez-Estévez
authors.forename: Ileana
authors.initials: I
authors.lastname: Echevarría-Machado
mesh_terms: D002212:Capsicum / Q000254:growth & development* / Q000378:metabolism; D004777:Environment; D009566:Nitrates / Q000378:metabolism* / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012987:Soil
chemical_list: D009566:Nitrates; D010937:Plant Growth Regulators; D000644:Quaternary Ammonium Compounds; D012987:Soil