Year: 2012
Type: dissertation
Abstract: Oat is an important grain and forage crop cultivated over than 9 million hectares globally. \nHowever, drought and biotrophic fungal diseases, such as crown rust (Puccinia coronata f. sp. \navenae) and powdery mildew (Blumeria graminis f. sp. avenae) seriously threaten oat \nproduction. To combat this, agricultural scientists must develop a comprehensive \nunderstanding of the mechanisms through which plants can tolerate/resist stress and translate \nthis to crop breeding programmes. Thus, based on a germplasm collection consisting on 141 \noat landraces collected from across Southern Spain and 36 commercial cultivars we aimed to \nsought and characterise new sources of resistance to both, powdery mildew and rust and \ndrought tolerance and further understand the resistance responses to generate tools that \ncould aid the breeding of this crop. \nIn chapter one, entitled “Resistance to powdery mildew (Blumeria graminis f.sp. avenae) in oat \nseedlings and adult plants” new sources of resistance to this fungus have been identified and \ncharacterize. In addition a detailed work on plant adult resistance was performed revealing the \nhistological bases of the resistance responses. In chapter two, “Identification and \ncharacterization of sources of resistance in Avena sativa, A. byzantina and A. strigosa \ngermplasm against a pathotype of Puccinia coronata f.sp. avenae with virulence against the \nPc94 resistance gene” new sources of resistance to a new highly virulent isolate that defeated \nthe resistance gene Pc94 used until now, have been identified and characterized. Both work \nhighlight the importance of using resistance based on several responses and if possible not \nassociated with monogenically controlled traits. To ease in the breeding of this complex traits \nin chapter three, entitled “QTL’s association with mechanisms of resistance to oat crown rust \n(Puccinia coronata f. sp. avenae) in Ogle/TAM O-301 mapping population” we explored the \npossibility to link QTLs with specific resistance responses assessed both, macroscopically and \nmicroscopically, and successfully found several QTLs associated with resistance responses \nrelated to basal resistance. In addition, recent work of the group showed that HR-mediated \nresistance provokes in barley stomatal dysfunctions which could be an important component \nof the disease resistance cost. In chapter four, entitled “Impact of hypersensitive response \nelicited by different life style biotrophic fungi on oat physiology under single and overlapped \nbiotic and abiotic stresses” we report a fitness cost associated with the execution of resistance \nmechanisms against Blumeria graminis f. sp. avenae and Puccinia coronata f.sp. avenae; and \nrevealed its causes. Regarding drought tolerance, chapter five, entitled “Targeting sources of \ndrought tolerance within an Avena spp collection through multivariate approaches”, we \nidentified and characterised new sources of drought tolerance in the oat germplams collection. \nIn addition, we employed a multivariate approach to reveal the key physiological mechanism/s \nin the oats for coping with drought stress. Furthermore, in chapter six entitled “An integrated \nmechanism of drought tolerance in oats (Avena sativa) revealed through metabolomic \nanalyses”, we used a metabolomic approach to reveal novel drought-induced changes based in \ntwo of the oat cultivars, Flega and Patones, previously characterized as most susceptible and \ntolerant to drought respectively in the chapter five. These include 1) maintenance of high \nrelative water content by salicylate-induced regulation of stomatal movements 2) specific \nphotoprotection mechanisms to deal with the increasing oxidative stress promoted by the low \nCO2 concentration consequence of the partial stomatal closure. Finally, in chapter seven, \nentitled “Identification and multi-environment validation of adaptation of Avena sativa \ncultivars to Mediterranean environments” we characterize those accessions with most stable \nresistance and good performance over different Mediterranean environments using a GGE \nbiplot analysis.
Author: Javier Sánchez Martín
Language: Spanish
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W1859150751