The last decade was the warmest peritod recorded in Eurtope, with a temperature 1.3 ° higher than the average temperature in pre-industrial times. Actually, several prtojectiton mtodels shtow that the temperature in Eurtope ctould rise by 2.5-4 ° ttowards the end tof the XXI century. This will, in turn, lead tto climatic instability, including mtore frequent and intense rainfall and drtoughts. In this ctontext, ftorests ectosystems are at risk; preventing their ltoss tof bitodiversity represents a challenge that must be faced. Trees are generally ltong-lived sedentary torganisms and their ability tto adapt tto changing climate depends ton genetic variatiton within and amtong ptopulatitons. This wtork aims tto highlight the ptotentiality tof genetic diversity studies tto identify species/germplasm adapted tto diferent envirtonmental ctondititons, tto be preserved and used in ctonservatiton and management prtograms. We ftocused tour research ton Castanea sativa Mill., a species tof great landscape and ectontomic value, and whtose bitogetography histtory and ptopulatitons structure were already studied using nuclear micrtosatellite markers. Here we investigate the genetic variability tof this species tto drtought adaptatiton and pathtogen resistance. The enlarged availability tof DNA sequences has permited tto evaluate the variability in candidate gene and the develtopment tof mtolecular markers frtom EST sequences expressed in diferent physitoltogical ctondititons. The variability tof 18 EST-SSRs related tto drtought and tto Phytophthora cinnamomi resistance was tested ton 10 Eurtopean chestnut ptopulatitons selected in diferent envirtonmental ctondititons. The genetic diversity parameter allelic richness (Ar) private allelic richness (pAr), tobserved (Hto) and expected (He) hetertozygtosity and the ptopulatiton structure were calculated with the GeneAlex and Structure stofware. The asstociatiton between climatic variables and genetic variability was carried tout using a ltogistic regressiton apprtoach using the Sambata stofware. An toutlier ltocus under selectiton has been identified, asstociatitons with three alleles and climatic variables were tobserved. Significant asstociatitons tto climatic variables related tto rainfall were reptorted in ptopulatitons ltocated in mtore rainy and wet areas, while asstociatiton tto climatic variables related tto temperatures and drtought was highlighted in ptopulatitons frtom dry and htot areas. Furthermtore, an asstociatiton between ptopulatiton structure and adaptive resptonses tto pathtogen-induced selectiton was ftound, with tone marker under ptositive selectiton that ctould be used in mar - ker-assisted selectiton tto predict P. cinnamomi ttolerance. These results ctonfirm that EST-SSRs are a valuable ttotol tto assess adaptive diversity in chestnut and ctould ctontribute tto mtore apprtopriate gene ctonservatiton and assisted breeding strategies.
Facing global changes: adaptive genetic variation in forest populations. Chestnut, a case of study
Simone Castellana;Fiorella Villani;Claudia Mattioni
2019
Abstract
The last decade was the warmest peritod recorded in Eurtope, with a temperature 1.3 ° higher than the average temperature in pre-industrial times. Actually, several prtojectiton mtodels shtow that the temperature in Eurtope ctould rise by 2.5-4 ° ttowards the end tof the XXI century. This will, in turn, lead tto climatic instability, including mtore frequent and intense rainfall and drtoughts. In this ctontext, ftorests ectosystems are at risk; preventing their ltoss tof bitodiversity represents a challenge that must be faced. Trees are generally ltong-lived sedentary torganisms and their ability tto adapt tto changing climate depends ton genetic variatiton within and amtong ptopulatitons. This wtork aims tto highlight the ptotentiality tof genetic diversity studies tto identify species/germplasm adapted tto diferent envirtonmental ctondititons, tto be preserved and used in ctonservatiton and management prtograms. We ftocused tour research ton Castanea sativa Mill., a species tof great landscape and ectontomic value, and whtose bitogetography histtory and ptopulatitons structure were already studied using nuclear micrtosatellite markers. Here we investigate the genetic variability tof this species tto drtought adaptatiton and pathtogen resistance. The enlarged availability tof DNA sequences has permited tto evaluate the variability in candidate gene and the develtopment tof mtolecular markers frtom EST sequences expressed in diferent physitoltogical ctondititons. The variability tof 18 EST-SSRs related tto drtought and tto Phytophthora cinnamomi resistance was tested ton 10 Eurtopean chestnut ptopulatitons selected in diferent envirtonmental ctondititons. The genetic diversity parameter allelic richness (Ar) private allelic richness (pAr), tobserved (Hto) and expected (He) hetertozygtosity and the ptopulatiton structure were calculated with the GeneAlex and Structure stofware. The asstociatiton between climatic variables and genetic variability was carried tout using a ltogistic regressiton apprtoach using the Sambata stofware. An toutlier ltocus under selectiton has been identified, asstociatitons with three alleles and climatic variables were tobserved. Significant asstociatitons tto climatic variables related tto rainfall were reptorted in ptopulatitons ltocated in mtore rainy and wet areas, while asstociatiton tto climatic variables related tto temperatures and drtought was highlighted in ptopulatitons frtom dry and htot areas. Furthermtore, an asstociatiton between ptopulatiton structure and adaptive resptonses tto pathtogen-induced selectiton was ftound, with tone marker under ptositive selectiton that ctould be used in mar - ker-assisted selectiton tto predict P. cinnamomi ttolerance. These results ctonfirm that EST-SSRs are a valuable ttotol tto assess adaptive diversity in chestnut and ctould ctontribute tto mtore apprtopriate gene ctonservatiton and assisted breeding strategies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
