Tamayo-Ordóñez M C, Rodriguez-Zapata L C, Narváez-Zapata J A, Tamayo-Ordóñez Y J, Ayil-Gutiérrez B A, Barredo-Pool F, Sánchez-Teyer L F
Unidad de Biotecnología, Centro de Investigación Científica de Yucatán. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatán, Mexico.
Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Blvd. del Maestro, s/n, Esq. Elías Piña, Reynosa 88710, Mexico.
J Plant Physiol. 2016 May 20;195:80-94. doi: 10.1016/j.jplph.2016.03.009. Epub 2016 Mar 22.
Polyploidy has been widely described in many Agave L. species, but its influence on environmental response to stress is still unknown. With the objective of knowing the morphological adaptations and regulation responses of genes related to biotic (LEA) and abiotic (NBS-LRR) stress in species of Agave with different levels of ploidy, and how these factors contribute to major response of Agave against environmental stresses, we analyzed 16 morphological trials on five accessions of three species (Agave tequilana Weber, Agave angustifolia Haw. and Agave fourcroydes Lem.) with different ploidy levels (2n=2x=60 2n=3x=90, 2n=5x=150, 2n=6x=180) and evaluated the expression of NBS-LRR and LEA genes regulated by biotic and abiotic stress. It was possible to associate some morphological traits (spines, nuclei, and stomata) to ploidy level. The genetic characterization of stress-related genes NBS-LRR induced by pathogenic infection and LEA by heat or saline stresses indicated that amino acid sequence analysis in these genes showed more substitutions in higher ploidy level accessions of A. fourcroydes Lem. 'Sac Ki' (2n=5x=150) and A. angustifolia Haw. 'Chelem Ki' (2n=6x=180), and a higher LEA and NBS-LRR representativeness when compared to their diploid and triploid counterparts. In all studied Agave accessions expression of LEA and NBS-LRR genes was induced by saline or heat stresses or by infection with Erwinia carotovora, respectively. The transcriptional activation was also higher in A. angustifolia Haw. 'Chelem Ki' (2n=6x=180) and A. fourcroydes 'Sac Ki' (2n=5x=150) than in their diploid and triploid counterparts, which suggests higher adaptation to stress. Finally, the diploid accession A. tequilana Weber 'Azul' showed a differentiated genetic profile relative to other Agave accessions. The differences include similar or higher genetic representativeness and transcript accumulation of LEA and NBS-LRR genes than in polyploid (2n=5x=150 and 2n=6x=180) Agave accessions, thus suggesting a differentiated selection pressure for overcoming the lower ploidy level of the diploid A. tequilana Weber 'Azul'.
多倍体现象在许多龙舌兰属植物中已有广泛描述，但其对环境胁迫响应的影响仍不清楚。为了解不同倍性水平的龙舌兰属物种中与生物胁迫（LEA）和非生物胁迫（NBS-LRR）相关基因的形态适应和调控反应，以及这些因素如何促成龙舌兰对环境胁迫的主要反应，我们对三个物种（龙舌兰、狭叶龙舌兰和剑麻）的五个种质进行了16项形态学试验，这些种质具有不同的倍性水平（2n = 2x = 60、2n = 3x = 90、2n = 5x = 150、2n = 6x = 180），并评估了受生物和非生物胁迫调控的NBS-LRR和LEA基因的表达。可以将一些形态特征（刺、细胞核和气孔）与倍性水平联系起来。由致病感染诱导的NBS-LRR应激相关基因和由热或盐胁迫诱导的LEA基因的遗传特征表明，这些基因的氨基酸序列分析显示，在剑麻‘Sac Ki’（2n = 5x = 150）和狭叶龙舌兰‘Chelem Ki’（2n = 6x = 180）的高倍性水平种质中存在更多替代，并且与其二倍体和三倍体对应物相比，LEA和NBS-LRR具有更高的代表性。在所有研究的龙舌兰种质中，LEA和NBS-LRR基因的表达分别由盐胁迫或热胁迫或由胡萝卜软腐欧文氏菌感染诱导。狭叶龙舌兰‘Chelem Ki’（2n = 6x = 180）和剑麻‘Sac Ki’（2n = 5x = 150）中的转录激活也高于其二倍体和三倍体对应物，这表明对胁迫的适应性更强。最后，二倍体种质龙舌兰‘Azul’相对于其他龙舌兰种质表现出不同的遗传特征。差异包括LEA和NBS-LRR基因的遗传代表性和转录积累与多倍体（2n = 5x = 150和2n = 6x = 180）龙舌兰种质相似或更高，因此表明为克服二倍体龙舌兰‘Azul’较低的倍性水平而存在不同的选择压力。
